Commit Graph

2350 Commits

Author SHA1 Message Date
Linus Torvalds
8e5b0adeea Peter Zijlstra says:
"Cleanup of the perf/kvm interaction."
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Merge tag 'perf_core_for_v5.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull perf updates from Borislav Petkov:
 "Cleanup of the perf/kvm interaction."

* tag 'perf_core_for_v5.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf: Drop guest callback (un)register stubs
  KVM: arm64: Drop perf.c and fold its tiny bits of code into arm.c
  KVM: arm64: Hide kvm_arm_pmu_available behind CONFIG_HW_PERF_EVENTS=y
  KVM: arm64: Convert to the generic perf callbacks
  KVM: x86: Move Intel Processor Trace interrupt handler to vmx.c
  KVM: Move x86's perf guest info callbacks to generic KVM
  KVM: x86: More precisely identify NMI from guest when handling PMI
  KVM: x86: Drop current_vcpu for kvm_running_vcpu + kvm_arch_vcpu variable
  perf/core: Use static_call to optimize perf_guest_info_callbacks
  perf: Force architectures to opt-in to guest callbacks
  perf: Add wrappers for invoking guest callbacks
  perf/core: Rework guest callbacks to prepare for static_call support
  perf: Drop dead and useless guest "support" from arm, csky, nds32 and riscv
  perf: Stop pretending that perf can handle multiple guest callbacks
  KVM: x86: Register Processor Trace interrupt hook iff PT enabled in guest
  KVM: x86: Register perf callbacks after calling vendor's hardware_setup()
  perf: Protect perf_guest_cbs with RCU
2022-01-12 16:26:58 -08:00
David Woodhouse
982ed0de47 KVM: Reinstate gfn_to_pfn_cache with invalidation support
This can be used in two modes. There is an atomic mode where the cached
mapping is accessed while holding the rwlock, and a mode where the
physical address is used by a vCPU in guest mode.

For the latter case, an invalidation will wake the vCPU with the new
KVM_REQ_GPC_INVALIDATE, and the architecture will need to refresh any
caches it still needs to access before entering guest mode again.

Only one vCPU can be targeted by the wake requests; it's simple enough
to make it wake all vCPUs or even a mask but I don't see a use case for
that additional complexity right now.

Invalidation happens from the invalidate_range_start MMU notifier, which
needs to be able to sleep in order to wake the vCPU and wait for it.

This means that revalidation potentially needs to "wait" for the MMU
operation to complete and the invalidate_range_end notifier to be
invoked. Like the vCPU when it takes a page fault in that period, we
just spin — fixing that in a future patch by implementing an actual
*wait* may be another part of shaving this particularly hirsute yak.

As noted in the comments in the function itself, the only case where
the invalidate_range_start notifier is expected to be called *without*
being able to sleep is when the OOM reaper is killing the process. In
that case, we expect the vCPU threads already to have exited, and thus
there will be nothing to wake, and no reason to wait. So we clear the
KVM_REQUEST_WAIT bit and send the request anyway, then complain loudly
if there actually *was* anything to wake up.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20211210163625.2886-3-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-01-07 10:44:44 -05:00
David Woodhouse
2efd61a608 KVM: Warn if mark_page_dirty() is called without an active vCPU
The various kvm_write_guest() and mark_page_dirty() functions must only
ever be called in the context of an active vCPU, because if dirty ring
tracking is enabled it may simply oops when kvm_get_running_vcpu()
returns NULL for the vcpu and then kvm_dirty_ring_get() dereferences it.

This oops was reported by "butt3rflyh4ck" <butterflyhuangxx@gmail.com> in
https://lore.kernel.org/kvm/CAFcO6XOmoS7EacN_n6v4Txk7xL7iqRa2gABg3F7E3Naf5uG94g@mail.gmail.com/

That actual bug will be fixed under separate cover but this warning
should help to prevent new ones from being added.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20211210163625.2886-2-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-01-07 10:44:44 -05:00
David Woodhouse
6f2cdbdba4 KVM: Add Makefile.kvm for common files, use it for x86
Splitting kvm_main.c out into smaller and better-organized files is
slightly non-trivial when it involves editing a bunch of per-arch
KVM makefiles. Provide virt/kvm/Makefile.kvm for them to include.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Acked-by: Marc Zyngier <maz@kernel.org>
Message-Id: <20211121125451.9489-3-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-09 12:56:02 -05:00
David Woodhouse
dc70ec217c KVM: Introduce CONFIG_HAVE_KVM_DIRTY_RING
I'd like to make the build include dirty_ring.c based on whether the
arch wants it or not. That's a whole lot simpler if there's a config
symbol instead of doing it implicitly on KVM_DIRTY_LOG_PAGE_OFFSET
being set to something non-zero.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20211121125451.9489-2-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-09 12:55:52 -05:00
Sean Christopherson
d92a5d1c6c KVM: Add helpers to wake/query blocking vCPU
Add helpers to wake and query a blocking vCPU.  In addition to providing
nice names, the helpers reduce the probability of KVM neglecting to use
kvm_arch_vcpu_get_wait().

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-20-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08 04:24:54 -05:00
Sean Christopherson
109a98260b KVM: Don't redo ktime_get() when calculating halt-polling stop/deadline
Calculate the halt-polling "stop" time using "start" instead of redoing
ktime_get().  In practice, the numbers involved are in the noise (e.g.,
in the happy case where hardware correctly predicts do_halt_poll and
there are no interrupts, "start" is probably only a few cycles old)
and either approach is perfectly ok.  But it's more precise to count
any extra latency toward the halt-polling time.

Reviewed-by: David Matlack <dmatlack@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-17-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08 04:24:52 -05:00
Jing Zhang
c3858335c7 KVM: stats: Add stat to detect if vcpu is currently blocking
Add a "blocking" stat that userspace can use to detect the case where a
vCPU is not being run because of an vCPU/guest action, e.g. HLT or WFS on
x86, WFI on arm64, etc...  Current guest/host/halt stats don't show this
well, e.g. if a guest halts for a long period of time then the vCPU could
could appear pathologically blocked due to a host condition, when in
reality the vCPU has been put into a not-runnable state by the guest.

Originally-by: Cannon Matthews <cannonmatthews@google.com>
Suggested-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: David Matlack <dmatlack@google.com>
Signed-off-by: Jing Zhang <jingzhangos@google.com>
[sean: renamed stat to "blocking", massaged changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-16-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08 04:24:52 -05:00
Sean Christopherson
fac4268894 KVM: Split out a kvm_vcpu_block() helper from kvm_vcpu_halt()
Factor out the "block" part of kvm_vcpu_halt() so that x86 can emulate
non-halt wait/sleep/block conditions that should not be subjected to
halt-polling.

No functional change intended.

Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: David Matlack <dmatlack@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-15-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08 04:24:51 -05:00
Sean Christopherson
91b99ea706 KVM: Rename kvm_vcpu_block() => kvm_vcpu_halt()
Rename kvm_vcpu_block() to kvm_vcpu_halt() in preparation for splitting
the actual "block" sequences into a separate helper (to be named
kvm_vcpu_block()).  x86 will use the standalone block-only path to handle
non-halt cases where the vCPU is not runnable.

Rename block_ns to halt_ns to match the new function name.

No functional change intended.

Reviewed-by: David Matlack <dmatlack@google.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-14-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08 04:24:51 -05:00
Sean Christopherson
005467e06b KVM: Drop obsolete kvm_arch_vcpu_block_finish()
Drop kvm_arch_vcpu_block_finish() now that all arch implementations are
nops.

No functional change intended.

Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: David Matlack <dmatlack@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-10-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08 04:24:50 -05:00
Sean Christopherson
f6c60d081e KVM: Don't block+unblock when halt-polling is successful
Invoke the arch hooks for block+unblock if and only if KVM actually
attempts to block the vCPU.  The only non-nop implementation is on x86,
specifically SVM's AVIC, and there is no need to put the AVIC prior to
halt-polling; KVM x86's kvm_vcpu_has_events() will scour the full vIRR
to find pending IRQs regardless of whether the AVIC is loaded/"running".

The primary motivation is to allow future cleanup to split out "block"
from "halt", but this is also likely a small performance boost on x86 SVM
when halt-polling is successful.

Adjust the post-block path to update "cur" after unblocking, i.e. include
AVIC load time in halt_wait_ns and halt_wait_hist, so that the behavior
is consistent.  Moving just the pre-block arch hook would result in only
the AVIC put latency being included in the halt_wait stats.  There is no
obvious evidence that one way or the other is correct, so just ensure KVM
is consistent.

Note, x86 has two separate paths for handling APICv with respect to vCPU
blocking.  VMX uses hooks in x86's vcpu_block(), while SVM uses the arch
hooks in kvm_vcpu_block().  Prior to this path, the two paths were more
or less functionally identical.  That is very much not the case after
this patch, as the hooks used by VMX _must_ fire before halt-polling.
x86's entire mess will be cleaned up in future patches.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-12-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08 04:24:49 -05:00
Sean Christopherson
30c9434717 KVM: Reconcile discrepancies in halt-polling stats
Move the halt-polling "success" and histogram stats update into the
dedicated helper to fix a discrepancy where the success/fail "time" stats
consider polling successful so long as the wait is avoided, but the main
"success" and histogram stats consider polling successful if and only if
a wake event was detected by the halt-polling loop.

Move halt_attempted_poll to the helper as well so that all the stats are
updated in a single location.  While it's a bit odd to update the stat
well after the fact, practically speaking there's no meaningful advantage
to updating before polling.

Note, there is a functional change in addition to the success vs. fail
change.  The histogram updates previously called ktime_get() instead of
using "cur".  But that change is desirable as it means all the stats are
now updated with the same polling time, and avoids the extra ktime_get(),
which isn't expensive but isn't free either.

Reviewed-by: David Matlack <dmatlack@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-8-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08 04:24:48 -05:00
Sean Christopherson
29e72893ce KVM: Refactor and document halt-polling stats update helper
Add a comment to document that halt-polling is considered successful even
if the polling loop itself didn't detect a wake event, i.e. if a wake
event was detect in the final kvm_vcpu_check_block().  Invert the param
to update helper so that the helper is a dumb function that is "told"
whether or not polling was successful, as opposed to determining success
based on blocking behavior.

Opportunistically tweak the params to the update helper to reduce the
line length for the call site so that it fits on a single line, and so
that the prototype conforms to the more traditional kernel style.

No functional change intended.

Reviewed-by: David Matlack <dmatlack@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-7-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08 04:24:47 -05:00
Sean Christopherson
8df6a61c04 KVM: Update halt-polling stats if and only if halt-polling was attempted
Don't update halt-polling stats if halt-polling wasn't attempted.  This is
a nop as @poll_ns is guaranteed to be '0' (poll_end == start); in a future
patch (to move the histogram stats into the helper), it will avoid to
avoid a discrepancy in what is considered a "successful" halt-poll.

No functional change intended.

Reviewed-by: David Matlack <dmatlack@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08 04:24:47 -05:00
Sean Christopherson
510958e997 KVM: Force PPC to define its own rcuwait object
Do not define/reference kvm_vcpu.wait if __KVM_HAVE_ARCH_WQP is true, and
instead force the architecture (PPC) to define its own rcuwait object.
Allowing common KVM to directly access vcpu->wait without a guard makes
it all too easy to introduce potential bugs, e.g. kvm_vcpu_block(),
kvm_vcpu_on_spin(), and async_pf_execute() all operate on vcpu->wait, not
the result of kvm_arch_vcpu_get_wait(), and so may do the wrong thing for
PPC.

Due to PPC's shenanigans with respect to callbacks and waits (it switches
to the virtual core's wait object at KVM_RUN!?!?), it's not clear whether
or not this fixes any bugs.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-5-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08 04:24:46 -05:00
Sean Christopherson
6f390916c4 KVM: s390: Ensure kvm_arch_no_poll() is read once when blocking vCPU
Wrap s390's halt_poll_max_steal with READ_ONCE and snapshot the result of
kvm_arch_no_poll() in kvm_vcpu_block() to avoid a mostly-theoretical,
largely benign bug on s390 where the result of kvm_arch_no_poll() could
change due to userspace modifying halt_poll_max_steal while the vCPU is
blocking.  The bug is largely benign as it will either cause KVM to skip
updating halt-polling times (no_poll toggles false=>true) or to update
halt-polling times with a slightly flawed block_ns.

Note, READ_ONCE is unnecessary in the current code, add it in case the
arch hook is ever inlined, and to provide a hint that userspace can
change the param at will.

Fixes: 8b905d28ee ("KVM: s390: provide kvm_arch_no_poll function")
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08 04:24:46 -05:00
Paolo Bonzini
aefdc2ed44 KVM: Avoid atomic operations when kicking the running vCPU
If we do have the vcpu mutex, as is the case if kvm_running_vcpu is set
to the target vcpu of the kick, changes to vcpu->mode do not need atomic
operations; cmpxchg is only needed _outside_ the mutex to ensure that
the IN_GUEST_MODE->EXITING_GUEST_MODE change does not race with the vcpu
thread going OUTSIDE_GUEST_MODE.

Use this to optimize the case of a vCPU sending an interrupt to itself.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08 04:24:44 -05:00
Ben Gardon
8283e36abf KVM: x86/mmu: Propagate memslot const qualifier
In preparation for implementing in-place hugepage promotion, various
functions will need to be called from zap_collapsible_spte_range, which
has the const qualifier on its memslot argument. Propagate the const
qualifier to the various functions which will be needed. This just serves
to simplify the following patch.

No functional change intended.

Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20211115234603.2908381-11-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08 04:24:43 -05:00
Sean Christopherson
244893fa28 KVM: Dynamically allocate "new" memslots from the get-go
Allocate the "new" memslot for !DELETE memslot updates straight away
instead of filling an intermediate on-stack object and forcing
kvm_set_memslot() to juggle the allocation and do weird things like reuse
the old memslot object in MOVE.

In the MOVE case, this results in an "extra" memslot allocation due to
allocating both the "new" slot and the "invalid" slot, but that's a
temporary and not-huge allocation, and MOVE is a relatively rare memslot
operation.

Regarding MOVE, drop the open-coded management of the gfn tree with a
call to kvm_replace_memslot(), which already handles the case where
new->base_gfn != old->base_gfn.  This is made possible by virtue of not
having to copy the "new" memslot data after erasing the old memslot from
the gfn tree.  Using kvm_replace_memslot(), and more specifically not
reusing the old memslot, means the MOVE case now does hva tree and hash
list updates, but that's a small price to pay for simplifying the code
and making MOVE align with all the other flavors of updates.  The "extra"
updates are firmly in the noise from a performance perspective, e.g. the
"move (in)active area" selfttests show a (very, very) slight improvement.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <f0d8c72727aa825cf682bd4e3da4b3fa68215dd4.1638817641.git.maciej.szmigiero@oracle.com>
2021-12-08 04:24:37 -05:00
Sean Christopherson
0f9bdef3d9 KVM: Wait 'til the bitter end to initialize the "new" memslot
Initialize the "new" memslot in the !DELETE path only after the various
sanity checks have passed.  This will allow a future commit to allocate
@new dynamically without having to copy a memslot, and without having to
deal with freeing @new in error paths and in the "nothing to change" path
that's hiding in the sanity checks.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <a084d0531ca3a826a7f861eb2b08b5d1c06ef265.1638817641.git.maciej.szmigiero@oracle.com>
2021-12-08 04:24:37 -05:00
Maciej S. Szmigiero
44401a2047 KVM: Optimize overlapping memslots check
Do a quick lookup for possibly overlapping gfns when creating or moving
a memslot instead of performing a linear scan of the whole memslot set.

Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
[sean: tweaked params to avoid churn in future cleanup]
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <a4795e5c2f624754e9c0aab023ebda1966feb3e1.1638817641.git.maciej.szmigiero@oracle.com>
2021-12-08 04:24:36 -05:00
Maciej S. Szmigiero
bcb63dcde8 KVM: Call kvm_arch_flush_shadow_memslot() on the old slot in kvm_invalidate_memslot()
kvm_invalidate_memslot() calls kvm_arch_flush_shadow_memslot() on the
active, but KVM_MEMSLOT_INVALID slot.
Do it on the inactive (but valid) old slot instead since arch code really
should not get passed such invalid slot.

Note that this means that the "arch" field of the slot provided to
kvm_arch_flush_shadow_memslot() may have stale data since this function
is called with slots_arch_lock released.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <813595ecc193d6ae39a87709899d4251523b05f8.1638817641.git.maciej.szmigiero@oracle.com>
2021-12-08 04:24:35 -05:00
Maciej S. Szmigiero
a54d806688 KVM: Keep memslots in tree-based structures instead of array-based ones
The current memslot code uses a (reverse gfn-ordered) memslot array for
keeping track of them.

Because the memslot array that is currently in use cannot be modified
every memslot management operation (create, delete, move, change flags)
has to make a copy of the whole array so it has a scratch copy to work on.

Strictly speaking, however, it is only necessary to make copy of the
memslot that is being modified, copying all the memslots currently present
is just a limitation of the array-based memslot implementation.

Two memslot sets, however, are still needed so the VM continues to run
on the currently active set while the requested operation is being
performed on the second, currently inactive one.

In order to have two memslot sets, but only one copy of actual memslots
it is necessary to split out the memslot data from the memslot sets.

The memslots themselves should be also kept independent of each other
so they can be individually added or deleted.

These two memslot sets should normally point to the same set of
memslots. They can, however, be desynchronized when performing a
memslot management operation by replacing the memslot to be modified
by its copy.  After the operation is complete, both memslot sets once
again point to the same, common set of memslot data.

This commit implements the aforementioned idea.

For tracking of gfns an ordinary rbtree is used since memslots cannot
overlap in the guest address space and so this data structure is
sufficient for ensuring that lookups are done quickly.

The "last used slot" mini-caches (both per-slot set one and per-vCPU one),
that keep track of the last found-by-gfn memslot, are still present in the
new code.

Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <17c0cf3663b760a0d3753d4ac08c0753e941b811.1638817641.git.maciej.szmigiero@oracle.com>
2021-12-08 04:24:34 -05:00
Maciej S. Szmigiero
ed922739c9 KVM: Use interval tree to do fast hva lookup in memslots
The current memslots implementation only allows quick binary search by gfn,
quick lookup by hva is not possible - the implementation has to do a linear
scan of the whole memslots array, even though the operation being performed
might apply just to a single memslot.

This significantly hurts performance of per-hva operations with higher
memslot counts.

Since hva ranges can overlap between memslots an interval tree is needed
for tracking them.

[sean: handle interval tree updates in kvm_replace_memslot()]
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <d66b9974becaa9839be9c4e1a5de97b177b4ac20.1638817640.git.maciej.szmigiero@oracle.com>
2021-12-08 04:24:32 -05:00
Maciej S. Szmigiero
26b8345abc KVM: Resolve memslot ID via a hash table instead of via a static array
Memslot ID to the corresponding memslot mappings are currently kept as
indices in static id_to_index array.
The size of this array depends on the maximum allowed memslot count
(regardless of the number of memslots actually in use).

This has become especially problematic recently, when memslot count cap was
removed, so the maximum count is now full 32k memslots - the maximum
allowed by the current KVM API.

Keeping these IDs in a hash table (instead of an array) avoids this
problem.

Resolving a memslot ID to the actual memslot (instead of its index) will
also enable transitioning away from an array-based implementation of the
whole memslots structure in a later commit.

Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <117fb2c04320e6cd6cf34f205a72eadb0aa8d5f9.1638817640.git.maciej.szmigiero@oracle.com>
2021-12-08 04:24:32 -05:00
Maciej S. Szmigiero
1e8617d37f KVM: Move WARN on invalid memslot index to update_memslots()
Since kvm_memslot_move_forward() can theoretically return a negative
memslot index even when kvm_memslot_move_backward() returned a positive one
(and so did not WARN) let's just move the warning to the common code.

Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <eeed890ccb951e7b0dce15bc170eb2661d5b02da.1638817640.git.maciej.szmigiero@oracle.com>
2021-12-08 04:24:31 -05:00
Maciej S. Szmigiero
c928bfc263 KVM: Integrate gfn_to_memslot_approx() into search_memslots()
s390 arch has gfn_to_memslot_approx() which is almost identical to
search_memslots(), differing only in that in case the gfn falls in a hole
one of the memslots bordering the hole is returned.

Add this lookup mode as an option to search_memslots() so we don't have two
almost identical functions for looking up a memslot by its gfn.

Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
[sean: tweaked helper names to keep gfn_to_memslot_approx() in s390]
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <171cd89b52c718dbe180ecd909b4437a64a7e2ec.1638817640.git.maciej.szmigiero@oracle.com>
2021-12-08 04:24:30 -05:00
Sean Christopherson
7cd08553ab KVM: Don't make a full copy of the old memslot in __kvm_set_memory_region()
Stop making a full copy of the old memslot in __kvm_set_memory_region()
now that metadata updates are handled by kvm_set_memslot(), i.e. now that
the old memslot's dirty bitmap doesn't need to be referenced after the
memslot and its pointer is modified/invalidated by kvm_set_memslot().

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <5dce0946b41bba8c83f6e3424c6955c56bcc9f86.1638817640.git.maciej.szmigiero@oracle.com>
2021-12-08 04:24:28 -05:00
Sean Christopherson
07921665a6 KVM: Use prepare/commit hooks to handle generic memslot metadata updates
Handle the generic memslot metadata, a.k.a. dirty bitmap, updates at the
same time that arch handles it's own metadata updates, i.e. at memslot
prepare and commit.  This will simplify converting @new to a dynamically
allocated object, and more closely aligns common KVM with architecture
code.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <2ddd5446e3706fe3c1e52e3df279f04c458be830.1638817640.git.maciej.szmigiero@oracle.com>
2021-12-08 04:24:26 -05:00
Sean Christopherson
6a99c6e3f5 KVM: Stop passing kvm_userspace_memory_region to arch memslot hooks
Drop the @mem param from kvm_arch_{prepare,commit}_memory_region() now
that its use has been removed in all architectures.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <aa5ed3e62c27e881d0d8bc0acbc1572bc336dc19.1638817640.git.maciej.szmigiero@oracle.com>
2021-12-08 04:24:25 -05:00
Sean Christopherson
537a17b314 KVM: Let/force architectures to deal with arch specific memslot data
Pass the "old" slot to kvm_arch_prepare_memory_region() and force arch
code to handle propagating arch specific data from "new" to "old" when
necessary.  This is a baby step towards dynamically allocating "new" from
the get go, and is a (very) minor performance boost on x86 due to not
unnecessarily copying arch data.

For PPC HV, copy the rmap in the !CREATE and !DELETE paths, i.e. for MOVE
and FLAGS_ONLY.  This is functionally a nop as the previous behavior
would overwrite the pointer for CREATE, and eventually discard/ignore it
for DELETE.

For x86, copy the arch data only for FLAGS_ONLY changes.  Unlike PPC HV,
x86 needs to reallocate arch data in the MOVE case as the size of x86's
allocations depend on the alignment of the memslot's gfn.

Opportunistically tweak kvm_arch_prepare_memory_region()'s param order to
match the "commit" prototype.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
[mss: add missing RISCV kvm_arch_prepare_memory_region() change]
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <67dea5f11bbcfd71e3da5986f11e87f5dd4013f9.1638817639.git.maciej.szmigiero@oracle.com>
2021-12-08 04:24:20 -05:00
Sean Christopherson
ce5f021562 KVM: Use "new" memslot's address space ID instead of dedicated param
Now that the address space ID is stored in every slot, including fake
slots used for deletion, use the slot's as_id instead of passing in the
redundant information as a param to kvm_set_memslot().  This will greatly
simplify future memslot work by avoiding passing a large number of
variables around purely to honor @as_id.

Drop a comment in the DELETE path about new->as_id being provided purely
for debug, as that's now a lie.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <03189577be214ab8530a4b3a3ee3ed1c2f9e5815.1638817639.git.maciej.szmigiero@oracle.com>
2021-12-08 04:24:19 -05:00
Maciej S. Szmigiero
4e4d30cb9b KVM: Resync only arch fields when slots_arch_lock gets reacquired
There is no need to copy the whole memslot data after releasing
slots_arch_lock for a moment to install temporary memslots copy in
kvm_set_memslot() since this lock only protects the arch field of each
memslot.

Just resync this particular field after reacquiring slots_arch_lock.

Note, this also eliminates the need to manually clear the INVALID flag
when restoring memslots; the "setting" of the INVALID flag was an
unwanted side effect of copying the entire memslots.

Since kvm_copy_memslots() has just one caller remaining now
open-code it instead.

Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
[sean: tweak shortlog, note INVALID flag in changelog, revert comment]
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <b63035d114707792e9042f074478337f770dff6a.1638817638.git.maciej.szmigiero@oracle.com>
2021-12-08 04:24:18 -05:00
Sean Christopherson
47ea7d900b KVM: Open code kvm_delete_memslot() into its only caller
Fold kvm_delete_memslot() into __kvm_set_memory_region() to free up the
"kvm_delete_memslot()" name for use in a future helper.  The delete logic
isn't so complex/long that it truly needs a helper, and it will be
simplified a wee bit further in upcoming commits.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <2887631c31a82947faa488ab72f55f8c68b7c194.1638817638.git.maciej.szmigiero@oracle.com>
2021-12-08 04:24:17 -05:00
Sean Christopherson
afa319a54a KVM: Require total number of memslot pages to fit in an unsigned long
Explicitly disallow creating more memslot pages than can fit in an
unsigned long, KVM doesn't correctly handle a total number of memslot
pages that doesn't fit in an unsigned long and remedying that would be a
waste of time.

For a 64-bit kernel, this is a nop as memslots are not allowed to overlap
in the gfn address space.

With a 32-bit kernel, userspace can at most address 3gb of virtual memory,
whereas wrapping the total number of pages would require 4tb+ of guest
physical memory.  Even with x86's second address space for SMM, userspace
would need to alias all of guest memory more than one _thousand_ times.
And on older x86 hardware with MAXPHYADDR < 43, the guest couldn't
actually access any of those aliases even if userspace lied about
guest.MAXPHYADDR.

On 390 and arm64, this is a nop as they don't support 32-bit hosts.

On x86, practically speaking this is simply acknowledging reality as the
existing kvm_mmu_calculate_default_mmu_pages() assumes the total number
of pages fits in an "unsigned long".

On PPC, this is likely a nop as every flavor of PPC KVM assumes gfns (and
gpas!) fit in unsigned long.  arch/powerpc/kvm/book3s_32_mmu_host.c goes
a step further and fails the build if CONFIG_PTE_64BIT=y, which
presumably means that it does't support 64-bit physical addresses.

On MIPS, this is also likely a nop as the core MMU helpers assume gpas
fit in unsigned long, e.g. see kvm_mips_##name##_pte.

And finally, RISC-V is a "don't care" as it doesn't exist in any release,
i.e. there is no established ABI to break.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <1c2c91baf8e78acccd4dad38da591002e61c013c.1638817638.git.maciej.szmigiero@oracle.com>
2021-12-08 04:24:16 -05:00
Marc Zyngier
46808a4cb8 KVM: Use 'unsigned long' as kvm_for_each_vcpu()'s index
Everywhere we use kvm_for_each_vpcu(), we use an int as the vcpu
index. Unfortunately, we're about to move rework the iterator,
which requires this to be upgrade to an unsigned long.

Let's bite the bullet and repaint all of it in one go.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Message-Id: <20211116160403.4074052-7-maz@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08 04:24:15 -05:00
Marc Zyngier
c5b0775491 KVM: Convert the kvm->vcpus array to a xarray
At least on arm64 and x86, the vcpus array is pretty huge (up to
1024 entries on x86) and is mostly empty in the majority of the cases
(running 1k vcpu VMs is not that common).

This mean that we end-up with a 4kB block of unused memory in the
middle of the kvm structure.

Instead of wasting away this memory, let's use an xarray instead,
which gives us almost the same flexibility as a normal array, but
with a reduced memory usage with smaller VMs.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Message-Id: <20211116160403.4074052-6-maz@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08 04:24:14 -05:00
Marc Zyngier
27592ae8db KVM: Move wiping of the kvm->vcpus array to common code
All architectures have similar loops iterating over the vcpus,
freeing one vcpu at a time, and eventually wiping the reference
off the vcpus array. They are also inconsistently taking
the kvm->lock mutex when wiping the references from the array.

Make this code common, which will simplify further changes.
The locking is dropped altogether, as this should only be called
when there is no further references on the kvm structure.

Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Message-Id: <20211116160403.4074052-2-maz@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08 04:24:13 -05:00
Paolo Bonzini
5f25e71e31 KVM: downgrade two BUG_ONs to WARN_ON_ONCE
This is not an unrecoverable situation.  Users of kvm_read_guest_offset_cached
and kvm_write_guest_offset_cached must expect the read/write to fail, and
therefore it is possible to just return early with an error value.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-11-26 06:43:28 -05:00
Sean Christopherson
6b285a5587 KVM: Disallow user memslot with size that exceeds "unsigned long"
Reject userspace memslots whose size exceeds the storage capacity of an
"unsigned long".  KVM's uAPI takes the size as u64 to support large slots
on 64-bit hosts, but does not account for the size being truncated on
32-bit hosts in various flows.  The access_ok() check on the userspace
virtual address in particular casts the size to "unsigned long" and will
check the wrong number of bytes.

KVM doesn't actually support slots whose size doesn't fit in an "unsigned
long", e.g. KVM's internal kvm_memory_slot.npages is an "unsigned long",
not a "u64", and misc arch specific code follows that behavior.

Fixes: fa3d315a4c ("KVM: Validate userspace_addr of memslot when registered")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <20211104002531.1176691-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-11-18 02:15:19 -05:00
Sean Christopherson
bda44d8447 KVM: Ensure local memslot copies operate on up-to-date arch-specific data
When modifying memslots, snapshot the "old" memslot and copy it to the
"new" memslot's arch data after (re)acquiring slots_arch_lock.  x86 can
change a memslot's arch data while memslot updates are in-progress so
long as it holds slots_arch_lock, thus snapshotting a memslot without
holding the lock can result in the consumption of stale data.

Fixes: b10a038e84 ("KVM: mmu: Add slots_arch_lock for memslot arch fields")
Cc: stable@vger.kernel.org
Cc: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211104002531.1176691-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-11-18 02:15:19 -05:00
Paolo Bonzini
817506df9d Merge branch 'kvm-5.16-fixes' into kvm-master
* Fixes for Xen emulation

* Kill kvm_map_gfn() / kvm_unmap_gfn() and broken gfn_to_pfn_cache

* Fixes for migration of 32-bit nested guests on 64-bit hypervisor

* Compilation fixes

* More SEV cleanups
2021-11-18 02:11:57 -05:00
David Woodhouse
357a18ad23 KVM: Kill kvm_map_gfn() / kvm_unmap_gfn() and gfn_to_pfn_cache
In commit 7e2175ebd6 ("KVM: x86: Fix recording of guest steal time /
preempted status") I removed the only user of these functions because
it was basically impossible to use them safely.

There are two stages to the GFN->PFN mapping; first through the KVM
memslots to a userspace HVA and then through the page tables to
translate that HVA to an underlying PFN. Invalidations of the former
were being handled correctly, but no attempt was made to use the MMU
notifiers to invalidate the cache when the HVA->GFN mapping changed.

As a prelude to reinventing the gfn_to_pfn_cache with more usable
semantics, rip it out entirely and untangle the implementation of
the unsafe kvm_vcpu_map()/kvm_vcpu_unmap() functions from it.

All current users of kvm_vcpu_map() also look broken right now, and
will be dealt with separately. They broadly fall into two classes:

* Those which map, access the data and immediately unmap. This is
  mostly gratuitous and could just as well use the existing user
  HVA, and could probably benefit from a gfn_to_hva_cache as they
  do so.

* Those which keep the mapping around for a longer time, perhaps
  even using the PFN directly from the guest. These will need to
  be converted to the new gfn_to_pfn_cache and then kvm_vcpu_map()
  can be removed too.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20211115165030.7422-8-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-11-18 02:03:45 -05:00
Sean Christopherson
e1bfc24577 KVM: Move x86's perf guest info callbacks to generic KVM
Move x86's perf guest callbacks into common KVM, as they are semantically
identical to arm64's callbacks (the only other such KVM callbacks).
arm64 will convert to the common versions in a future patch.

Implement the necessary arm64 arch hooks now to avoid having to provide
stubs or a temporary #define (from x86) to avoid arm64 compilation errors
when CONFIG_GUEST_PERF_EVENTS=y.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211111020738.2512932-13-seanjc@google.com
2021-11-17 14:49:10 +01:00
Paolo Bonzini
f4d3165370 KVM: generalize "bugged" VM to "dead" VM
Generalize KVM_REQ_VM_BUGGED so that it can be called even in cases
where it is by design that the VM cannot be operated upon.  In this
case any KVM_BUG_ON should still warn, so introduce a new flag
kvm->vm_dead that is separate from kvm->vm_bugged.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-11-11 10:35:26 -05:00
Longpeng(Mike)
515a0c79e7 kvm: irqfd: avoid update unmodified entries of the routing
All of the irqfds would to be updated when update the irq
routing, it's too expensive if there're too many irqfds.

However we can reduce the cost by avoid some unnecessary
updates. For irqs of MSI type on X86, the update can be
saved if the msi values are not change.

The vfio migration could receives benefit from this optimi-
zaiton. The test VM has 128 vcpus and 8 VF (with 65 vectors
enabled), so the VM has more than 520 irqfds. We mesure the
cost of the vfio_msix_enable (in QEMU, it would set routing
for each irqfd) for each VF, and we can see the total cost
can be significantly reduced.

                Origin         Apply this Patch
1st             8              4
2nd             15             5
3rd             22             6
4th             24             6
5th             36             7
6th             44             7
7th             51             8
8th             58             8
Total           258ms          51ms

We're also tring to optimize the QEMU part [1], but it's still
worth to optimize the KVM to gain more benefits.

[1] https://lists.gnu.org/archive/html/qemu-devel/2021-08/msg04215.html

Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com>
Message-Id: <20210827080003.2689-1-longpeng2@huawei.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-09-30 04:27:10 -04:00
Juergen Gross
a1c42ddedf kvm: rename KVM_MAX_VCPU_ID to KVM_MAX_VCPU_IDS
KVM_MAX_VCPU_ID is not specifying the highest allowed vcpu-id, but the
number of allowed vcpu-ids. This has already led to confusion, so
rename KVM_MAX_VCPU_ID to KVM_MAX_VCPU_IDS to make its semantics more
clear

Suggested-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210913135745.13944-3-jgross@suse.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-09-30 04:27:05 -04:00
Vitaly Kuznetsov
620b2438ab KVM: Make kvm_make_vcpus_request_mask() use pre-allocated cpu_kick_mask
kvm_make_vcpus_request_mask() already disables preemption so just like
kvm_make_all_cpus_request_except() it can be switched to using
pre-allocated per-cpu cpumasks. This allows for improvements for both
users of the function: in Hyper-V emulation code 'tlb_flush' can now be
dropped from 'struct kvm_vcpu_hv' and kvm_make_scan_ioapic_request_mask()
gets rid of dynamic allocation.

cpumask_available() checks in kvm_make_vcpu_request() and
kvm_kick_many_cpus() can now be dropped as they checks for an impossible
condition: kvm_init() makes sure per-cpu masks are allocated.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210903075141.403071-9-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-09-30 04:27:04 -04:00
Vitaly Kuznetsov
baff59ccdc KVM: Pre-allocate cpumasks for kvm_make_all_cpus_request_except()
Allocating cpumask dynamically in zalloc_cpumask_var() is not ideal.
Allocation is somewhat slow and can (in theory and when CPUMASK_OFFSTACK)
fail. kvm_make_all_cpus_request_except() already disables preemption so
we can use pre-allocated per-cpu cpumasks instead.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210903075141.403071-8-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-09-30 04:27:04 -04:00
Vitaly Kuznetsov
381cecc5d7 KVM: Drop 'except' parameter from kvm_make_vcpus_request_mask()
Both remaining callers of kvm_make_vcpus_request_mask() pass 'NULL' for
'except' parameter so it can just be dropped.

No functional change intended ©.

Suggested-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210903075141.403071-6-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-09-30 04:27:04 -04:00
Vitaly Kuznetsov
ae0946cd36 KVM: Optimize kvm_make_vcpus_request_mask() a bit
Iterating over set bits in 'vcpu_bitmap' should be faster than going
through all vCPUs, especially when just a few bits are set.

Drop kvm_make_vcpus_request_mask() call from kvm_make_all_cpus_request_except()
to avoid handling the special case when 'vcpu_bitmap' is NULL, move the
code to kvm_make_all_cpus_request_except() itself.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210903075141.403071-5-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-09-30 04:27:03 -04:00
Yang Li
11476d277e KVM: use vma_pages() helper
Use vma_pages function on vma object instead of explicit computation.

Fix the following coccicheck warning:
./virt/kvm/kvm_main.c:3526:29-35: WARNING: Consider using vma_pages
helper on vma

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Message-Id: <1632900526-119643-1-git-send-email-yang.lee@linux.alibaba.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-09-30 04:27:03 -04:00
Lai Jiangshan
6bc6db0002 KVM: Remove tlbs_dirty
There is no user of tlbs_dirty.

Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210918005636.3675-4-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-09-23 11:01:12 -04:00
Sean Christopherson
0bbc2ca851 KVM: KVM: Use cpumask_available() to check for NULL cpumask when kicking vCPUs
Check for a NULL cpumask_var_t when kicking multiple vCPUs via
cpumask_available(), which performs a !NULL check if and only if cpumasks
are configured to be allocated off-stack.  This is a meaningless
optimization, e.g. avoids a TEST+Jcc and TEST+CMOV on x86, but more
importantly helps document that the NULL check is necessary even though
all callers pass in a local variable.

No functional change intended.

Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210827092516.1027264-3-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-09-22 10:33:15 -04:00
Sean Christopherson
85b640450d KVM: Clean up benign vcpu->cpu data races when kicking vCPUs
Fix a benign data race reported by syzbot+KCSAN[*] by ensuring vcpu->cpu
is read exactly once, and by ensuring the vCPU is booted from guest mode
if kvm_arch_vcpu_should_kick() returns true.  Fix a similar race in
kvm_make_vcpus_request_mask() by ensuring the vCPU is interrupted if
kvm_request_needs_ipi() returns true.

Reading vcpu->cpu before vcpu->mode (via kvm_arch_vcpu_should_kick() or
kvm_request_needs_ipi()) means the target vCPU could get migrated (change
vcpu->cpu) and enter !OUTSIDE_GUEST_MODE between reading vcpu->cpud and
reading vcpu->mode.  If that happens, the kick/IPI will be sent to the
old pCPU, not the new pCPU that is now running the vCPU or reading SPTEs.

Although failing to kick the vCPU is not exactly ideal, practically
speaking it cannot cause a functional issue unless there is also a bug in
the caller, and any such bug would exist regardless of kvm_vcpu_kick()'s
behavior.

The purpose of sending an IPI is purely to get a vCPU into the host (or
out of reading SPTEs) so that the vCPU can recognize a change in state,
e.g. a KVM_REQ_* request.  If vCPU's handling of the state change is
required for correctness, KVM must ensure either the vCPU sees the change
before entering the guest, or that the sender sees the vCPU as running in
guest mode.  All architectures handle this by (a) sending the request
before calling kvm_vcpu_kick() and (b) checking for requests _after_
setting vcpu->mode.

x86's READING_SHADOW_PAGE_TABLES has similar requirements; KVM needs to
ensure it kicks and waits for vCPUs that started reading SPTEs _before_
MMU changes were finalized, but any vCPU that starts reading after MMU
changes were finalized will see the new state and can continue on
uninterrupted.

For uses of kvm_vcpu_kick() that are not paired with a KVM_REQ_*, e.g.
x86's kvm_arch_sync_dirty_log(), the order of the kick must not be relied
upon for functional correctness, e.g. in the dirty log case, userspace
cannot assume it has a 100% complete log if vCPUs are still running.

All that said, eliminate the benign race since the cost of doing so is an
"extra" atomic cmpxchg() in the case where the target vCPU is loaded by
the current pCPU or is not loaded at all.  I.e. the kick will be skipped
due to kvm_vcpu_exiting_guest_mode() seeing a compatible vcpu->mode as
opposed to the kick being skipped because of the cpu checks.

Keep the "cpu != me" checks even though they appear useless/impossible at
first glance.  x86 processes guest IPI writes in a fast path that runs in
IN_GUEST_MODE, i.e. can call kvm_vcpu_kick() from IN_GUEST_MODE.  And
calling kvm_vm_bugged()->kvm_make_vcpus_request_mask() from IN_GUEST or
READING_SHADOW_PAGE_TABLES is perfectly reasonable.

Note, a race with the cpu_online() check in kvm_vcpu_kick() likely
persists, e.g. the vCPU could exit guest mode and get offlined between
the cpu_online() check and the sending of smp_send_reschedule().  But,
the online check appears to exist only to avoid a WARN in x86's
native_smp_send_reschedule() that fires if the target CPU is not online.
The reschedule WARN exists because CPU offlining takes the CPU out of the
scheduling pool, i.e. the WARN is intended to detect the case where the
kernel attempts to schedule a task on an offline CPU.  The actual sending
of the IPI is a non-issue as at worst it will simpy be dropped on the
floor.  In other words, KVM's usurping of the reschedule IPI could
theoretically trigger a WARN if the stars align, but there will be no
loss of functionality.

[*] https://syzkaller.appspot.com/bug?extid=cd4154e502f43f10808a

Cc: Venkatesh Srinivas <venkateshs@google.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Fixes: 97222cc831 ("KVM: Emulate local APIC in kernel")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210827092516.1027264-2-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-09-22 10:33:15 -04:00
Sergey Senozhatsky
ae232ea460 KVM: do not shrink halt_poll_ns below grow_start
grow_halt_poll_ns() ignores values between 0 and
halt_poll_ns_grow_start (10000 by default). However,
when we shrink halt_poll_ns we may fall way below
halt_poll_ns_grow_start and endup with halt_poll_ns
values that don't make a lot of sense: like 1 or 9,
or 19.

VCPU1 trace (halt_poll_ns_shrink equals 2):

VCPU1 grow 10000
VCPU1 shrink 5000
VCPU1 shrink 2500
VCPU1 shrink 1250
VCPU1 shrink 625
VCPU1 shrink 312
VCPU1 shrink 156
VCPU1 shrink 78
VCPU1 shrink 39
VCPU1 shrink 19
VCPU1 shrink 9
VCPU1 shrink 4

Mirror what grow_halt_poll_ns() does and set halt_poll_ns
to 0 as soon as new shrink-ed halt_poll_ns value falls
below halt_poll_ns_grow_start.

Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210902031100.252080-1-senozhatsky@chromium.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-09-22 10:33:10 -04:00
Peter Xu
109bbba506 KVM: Drop unused kvm_dirty_gfn_invalid()
Drop the unused function as reported by test bot.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20210901230904.15164-1-peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-09-06 08:23:46 -04:00
Paolo Bonzini
e99314a340 KVM/arm64 updates for 5.15
- Page ownership tracking between host EL1 and EL2
 
 - Rely on userspace page tables to create large stage-2 mappings
 
 - Fix incompatibility between pKVM and kmemleak
 
 - Fix the PMU reset state, and improve the performance of the virtual PMU
 
 - Move over to the generic KVM entry code
 
 - Address PSCI reset issues w.r.t. save/restore
 
 - Preliminary rework for the upcoming pKVM fixed feature
 
 - A bunch of MM cleanups
 
 - a vGIC fix for timer spurious interrupts
 
 - Various cleanups
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Merge tag 'kvmarm-5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

KVM/arm64 updates for 5.15

- Page ownership tracking between host EL1 and EL2

- Rely on userspace page tables to create large stage-2 mappings

- Fix incompatibility between pKVM and kmemleak

- Fix the PMU reset state, and improve the performance of the virtual PMU

- Move over to the generic KVM entry code

- Address PSCI reset issues w.r.t. save/restore

- Preliminary rework for the upcoming pKVM fixed feature

- A bunch of MM cleanups

- a vGIC fix for timer spurious interrupts

- Various cleanups
2021-09-06 06:34:48 -04:00
Jing Zhang
3cc4e148b9 KVM: stats: Add VM stat for remote tlb flush requests
Add a new stat that counts the number of times a remote TLB flush is
requested, regardless of whether it kicks vCPUs out of guest mode. This
allows us to look at how often flushes are initiated.

Unlike remote_tlb_flush, this one applies to ARM's instruction-set-based
TLB flush implementation, so apply it there too.

Original-by: David Matlack <dmatlack@google.com>
Signed-off-by: Jing Zhang <jingzhangos@google.com>
Message-Id: <20210817002639.3856694-1-jingzhangos@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-09-06 06:30:45 -04:00
Sean Christopherson
fdde13c13f KVM: Remove unnecessary export of kvm_{inc,dec}_notifier_count()
Don't export KVM's MMU notifier count helpers, under no circumstance
should any downstream module, including x86's vendor code, have a
legitimate reason to piggyback KVM's MMU notifier logic.  E.g in the x86
case, only KVM's MMU should be elevating the notifier count, and that
code is always built into the core kvm.ko module.

Fixes: edb298c663 ("KVM: x86/mmu: bump mmu notifier count in kvm_zap_gfn_range")
Cc: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210902175951.1387989-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-09-06 06:21:29 -04:00
Jing Zhang
8ccba534a1 KVM: stats: Add halt polling related histogram stats
Add three log histogram stats to record the distribution of time spent
on successful polling, failed polling and VCPU wait.
halt_poll_success_hist: Distribution of spent time for a successful poll.
halt_poll_fail_hist: Distribution of spent time for a failed poll.
halt_wait_hist: Distribution of time a VCPU has spent on waiting.

Signed-off-by: Jing Zhang <jingzhangos@google.com>
Message-Id: <20210802165633.1866976-6-jingzhangos@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-08-20 16:06:33 -04:00
Jing Zhang
87bcc5fa09 KVM: stats: Add halt_wait_ns stats for all architectures
Add simple stats halt_wait_ns to record the time a VCPU has spent on
waiting for all architectures (not just powerpc).

Signed-off-by: Jing Zhang <jingzhangos@google.com>
Message-Id: <20210802165633.1866976-5-jingzhangos@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-08-20 16:06:33 -04:00
Maxim Levitsky
edb298c663 KVM: x86/mmu: bump mmu notifier count in kvm_zap_gfn_range
This together with previous patch, ensures that
kvm_zap_gfn_range doesn't race with page fault
running on another vcpu, and will make this page fault code
retry instead.

This is based on a patch suggested by Sean Christopherson:
https://lkml.org/lkml/2021/7/22/1025

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210810205251.424103-5-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-08-20 16:06:19 -04:00
Peter Xu
3165af738e KVM: Allow to have arch-specific per-vm debugfs files
Allow archs to create arch-specific nodes under kvm->debugfs_dentry directory
besides the stats fields.  The new interface kvm_arch_create_vm_debugfs() is
defined but not yet used.  It's called after kvm->debugfs_dentry is created, so
it can be referenced directly in kvm_arch_create_vm_debugfs().  Arch should
define their own versions when they want to create extra debugfs nodes.

Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20210730220455.26054-2-peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-08-13 03:35:17 -04:00
Paolo Bonzini
ee3b6e41bc KVM: stats: remove dead stores
These stores are copied and pasted from the "if" statements above.
They are dead and while they are not really a bug, they can be
confusing to anyone reading the code as well.  Remove them.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-08-13 03:35:15 -04:00
Paolo Bonzini
c3e9434c98 Merge branch 'kvm-vmx-secctl' into HEAD
Merge common topic branch for 5.14-rc6 and 5.15 merge window.
2021-08-10 13:45:26 -04:00
David Matlack
fe22ed827c KVM: Cache the last used slot index per vCPU
The memslot for a given gfn is looked up multiple times during page
fault handling. Avoid binary searching for it multiple times by caching
the most recently used slot. There is an existing VM-wide last_used_slot
but that does not work well for cases where vCPUs are accessing memory
in different slots (see performance data below).

Another benefit of caching the most recently use slot (versus looking
up the slot once and passing around a pointer) is speeding up memslot
lookups *across* faults and during spte prefetching.

To measure the performance of this change I ran dirty_log_perf_test with
64 vCPUs and 64 memslots and measured "Populate memory time" and
"Iteration 2 dirty memory time".  Tests were ran with eptad=N to force
dirty logging to use fast_page_fault so its performance could be
measured.

Config     | Metric                        | Before | After
---------- | ----------------------------- | ------ | ------
tdp_mmu=Y  | Populate memory time          | 6.76s  | 5.47s
tdp_mmu=Y  | Iteration 2 dirty memory time | 2.83s  | 0.31s
tdp_mmu=N  | Populate memory time          | 20.4s  | 18.7s
tdp_mmu=N  | Iteration 2 dirty memory time | 2.65s  | 0.30s

The "Iteration 2 dirty memory time" results are especially compelling
because they are equivalent to running the same test with a single
memslot. In other words, fast_page_fault performance no longer scales
with the number of memslots.

Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20210804222844.1419481-4-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-08-06 07:52:29 -04:00
David Matlack
87689270b1 KVM: Rename lru_slot to last_used_slot
lru_slot is used to keep track of the index of the most-recently used
memslot. The correct acronym would be "mru" but that is not a common
acronym. So call it last_used_slot which is a bit more obvious.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20210804222844.1419481-2-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-08-06 07:52:28 -04:00
Paolo Bonzini
85cd39af14 KVM: Do not leak memory for duplicate debugfs directories
KVM creates a debugfs directory for each VM in order to store statistics
about the virtual machine.  The directory name is built from the process
pid and a VM fd.  While generally unique, it is possible to keep a
file descriptor alive in a way that causes duplicate directories, which
manifests as these messages:

  [  471.846235] debugfs: Directory '20245-4' with parent 'kvm' already present!

Even though this should not happen in practice, it is more or less
expected in the case of KVM for testcases that call KVM_CREATE_VM and
close the resulting file descriptor repeatedly and in parallel.

When this happens, debugfs_create_dir() returns an error but
kvm_create_vm_debugfs() goes on to allocate stat data structs which are
later leaked.  The slow memory leak was spotted by syzkaller, where it
caused OOM reports.

Since the issue only affects debugfs, do a lookup before calling
debugfs_create_dir, so that the message is downgraded and rate-limited.
While at it, ensure kvm->debugfs_dentry is NULL rather than an error
if it is not created.  This fixes kvm_destroy_vm_debugfs, which was not
checking IS_ERR_OR_NULL correctly.

Cc: stable@vger.kernel.org
Fixes: 536a6f88c4 ("KVM: Create debugfs dir and stat files for each VM")
Reported-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-08-04 06:02:03 -04:00
Paolo Bonzini
071064f14d KVM: Don't take mmu_lock for range invalidation unless necessary
Avoid taking mmu_lock for .invalidate_range_{start,end}() notifications
that are unrelated to KVM.  This is possible now that memslot updates are
blocked from range_start() to range_end(); that ensures that lock elision
happens in both or none, and therefore that mmu_notifier_count updates
(which must occur while holding mmu_lock for write) are always paired
across start->end.

Based on patches originally written by Ben Gardon.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-08-03 03:54:08 -04:00
Paolo Bonzini
52ac8b358b KVM: Block memslot updates across range_start() and range_end()
We would like to avoid taking mmu_lock for .invalidate_range_{start,end}()
notifications that are unrelated to KVM.  Because mmu_notifier_count
must be modified while holding mmu_lock for write, and must always
be paired across start->end to stay balanced, lock elision must
happen in both or none.  Therefore, in preparation for this change,
this patch prevents memslot updates across range_start() and range_end().

Note, technically flag-only memslot updates could be allowed in parallel,
but stalling a memslot update for a relatively short amount of time is
not a scalability issue, and this is all more than complex enough.

A long note on the locking: a previous version of the patch used an rwsem
to block the memslot update while the MMU notifier run, but this resulted
in the following deadlock involving the pseudo-lock tagged as
"mmu_notifier_invalidate_range_start".

   ======================================================
   WARNING: possible circular locking dependency detected
   5.12.0-rc3+ #6 Tainted: G           OE
   ------------------------------------------------------
   qemu-system-x86/3069 is trying to acquire lock:
   ffffffff9c775ca0 (mmu_notifier_invalidate_range_start){+.+.}-{0:0}, at: __mmu_notifier_invalidate_range_end+0x5/0x190

   but task is already holding lock:
   ffffaff7410a9160 (&kvm->mmu_notifier_slots_lock){.+.+}-{3:3}, at: kvm_mmu_notifier_invalidate_range_start+0x36d/0x4f0 [kvm]

   which lock already depends on the new lock.

This corresponds to the following MMU notifier logic:

    invalidate_range_start
      take pseudo lock
      down_read()           (*)
      release pseudo lock
    invalidate_range_end
      take pseudo lock      (**)
      up_read()
      release pseudo lock

At point (*) we take the mmu_notifiers_slots_lock inside the pseudo lock;
at point (**) we take the pseudo lock inside the mmu_notifiers_slots_lock.

This could cause a deadlock (ignoring for a second that the pseudo lock
is not a lock):

- invalidate_range_start waits on down_read(), because the rwsem is
held by install_new_memslots

- install_new_memslots waits on down_write(), because the rwsem is
held till (another) invalidate_range_end finishes

- invalidate_range_end sits waits on the pseudo lock, held by
invalidate_range_start.

Removing the fairness of the rwsem breaks the cycle (in lockdep terms,
it would change the *shared* rwsem readers into *shared recursive*
readers), so open-code the wait using a readers count and a
spinlock.  This also allows handling blockable and non-blockable
critical section in the same way.

Losing the rwsem fairness does theoretically allow MMU notifiers to
block install_new_memslots forever.  Note that mm/mmu_notifier.c's own
retry scheme in mmu_interval_read_begin also uses wait/wake_up
and is likewise not fair.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-08-03 03:44:03 -04:00
Peter Xu
605c713023 KVM: Introduce kvm_get_kvm_safe()
Introduce this safe version of kvm_get_kvm() so that it can be called even
during vm destruction.  Use it in kvm_debugfs_open() and remove the verbose
comment.  Prepare to be used elsewhere.

Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20210625153214.43106-3-peterx@redhat.com>
[Preserve the comment in kvm_debugfs_open. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-08-02 11:01:46 -04:00
Sean Christopherson
0b8f11737c KVM: Add infrastructure and macro to mark VM as bugged
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <3a0998645c328bf0895f1290e61821b70f048549.1625186503.git.isaku.yamahata@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-08-02 09:36:35 -04:00
Marc Zyngier
36c3ce6c0d KVM: Get rid of kvm_get_pfn()
Nobody is using kvm_get_pfn() anymore. Get rid of it.

Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210726153552.1535838-7-maz@kernel.org
2021-08-02 14:05:58 +01:00
Marc Zyngier
205d76ff06 KVM: Remove kvm_is_transparent_hugepage() and PageTransCompoundMap()
Now that arm64 has stopped using kvm_is_transparent_hugepage(),
we can remove it, as well as PageTransCompoundMap() which was
only used by the former.

Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210726153552.1535838-5-maz@kernel.org
2021-08-02 14:05:58 +01:00
Paolo Bonzini
8750f9bbda KVM: add missing compat KVM_CLEAR_DIRTY_LOG
The arguments to the KVM_CLEAR_DIRTY_LOG ioctl include a pointer,
therefore it needs a compat ioctl implementation.  Otherwise,
32-bit userspace fails to invoke it on 64-bit kernels; for x86
it might work fine by chance if the padding is zero, but not
on big-endian architectures.

Reported-by: Thomas Sattler
Cc: stable@vger.kernel.org
Fixes: 2a31b9db15 ("kvm: introduce manual dirty log reprotect")
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-07-27 16:59:01 -04:00
Li RongQing
7477565433 KVM: use cpu_relax when halt polling
SMT siblings share caches and other hardware, and busy halt polling
will degrade its sibling performance if its sibling is working

Sean Christopherson suggested as below:

"Rather than disallowing halt-polling entirely, on x86 it should be
sufficient to simply have the hardware thread yield to its sibling(s)
via PAUSE.  It probably won't get back all performance, but I would
expect it to be close.
This compiles on all KVM architectures, and AFAICT the intended usage
of cpu_relax() is identical for all architectures."

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Message-Id: <20210727111247.55510-1-lirongqing@baidu.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-07-27 16:59:01 -04:00
Linus Torvalds
405386b021 * Allow again loading KVM on 32-bit non-PAE builds
* Fixes for host SMIs on AMD
 
 * Fixes for guest SMIs on AMD
 
 * Fixes for selftests on s390 and ARM
 
 * Fix memory leak
 
 * Enforce no-instrumentation area on vmentry when hardware
   breakpoints are in use.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull kvm fixes from Paolo Bonzini:

 - Allow again loading KVM on 32-bit non-PAE builds

 - Fixes for host SMIs on AMD

 - Fixes for guest SMIs on AMD

 - Fixes for selftests on s390 and ARM

 - Fix memory leak

 - Enforce no-instrumentation area on vmentry when hardware breakpoints
   are in use.

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (25 commits)
  KVM: selftests: smm_test: Test SMM enter from L2
  KVM: nSVM: Restore nested control upon leaving SMM
  KVM: nSVM: Fix L1 state corruption upon return from SMM
  KVM: nSVM: Introduce svm_copy_vmrun_state()
  KVM: nSVM: Check that VM_HSAVE_PA MSR was set before VMRUN
  KVM: nSVM: Check the value written to MSR_VM_HSAVE_PA
  KVM: SVM: Fix sev_pin_memory() error checks in SEV migration utilities
  KVM: SVM: Return -EFAULT if copy_to_user() for SEV mig packet header fails
  KVM: SVM: add module param to control the #SMI interception
  KVM: SVM: remove INIT intercept handler
  KVM: SVM: #SMI interception must not skip the instruction
  KVM: VMX: Remove vmx_msr_index from vmx.h
  KVM: X86: Disable hardware breakpoints unconditionally before kvm_x86->run()
  KVM: selftests: Address extra memslot parameters in vm_vaddr_alloc
  kvm: debugfs: fix memory leak in kvm_create_vm_debugfs
  KVM: x86/pmu: Clear anythread deprecated bit when 0xa leaf is unsupported on the SVM
  KVM: mmio: Fix use-after-free Read in kvm_vm_ioctl_unregister_coalesced_mmio
  KVM: SVM: Revert clearing of C-bit on GPA in #NPF handler
  KVM: x86/mmu: Do not apply HPA (memory encryption) mask to GPAs
  KVM: x86: Use kernel's x86_phys_bits to handle reduced MAXPHYADDR
  ...
2021-07-15 11:56:07 -07:00
Pavel Skripkin
004d62eb4e kvm: debugfs: fix memory leak in kvm_create_vm_debugfs
In commit bc9e9e672d ("KVM: debugfs: Reuse binary stats descriptors")
loop for filling debugfs_stat_data was copy-pasted 2 times, but
in the second loop pointers are saved over pointers allocated
in the first loop.  All this causes is a memory leak, fix it.

Fixes: bc9e9e672d ("KVM: debugfs: Reuse binary stats descriptors")
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Reviewed-by: Jing Zhang <jingzhangos@google.com>
Message-Id: <20210701195500.27097-1-paskripkin@gmail.com>
Reviewed-by: Jing Zhang <jingzhangos@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-07-15 10:19:40 -04:00
Kefeng Wang
23fa2e46a5 KVM: mmio: Fix use-after-free Read in kvm_vm_ioctl_unregister_coalesced_mmio
BUG: KASAN: use-after-free in kvm_vm_ioctl_unregister_coalesced_mmio+0x7c/0x1ec arch/arm64/kvm/../../../virt/kvm/coalesced_mmio.c:183
Read of size 8 at addr ffff0000c03a2500 by task syz-executor083/4269

CPU: 5 PID: 4269 Comm: syz-executor083 Not tainted 5.10.0 #7
Hardware name: linux,dummy-virt (DT)
Call trace:
 dump_backtrace+0x0/0x2d0 arch/arm64/kernel/stacktrace.c:132
 show_stack+0x28/0x34 arch/arm64/kernel/stacktrace.c:196
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x110/0x164 lib/dump_stack.c:118
 print_address_description+0x78/0x5c8 mm/kasan/report.c:385
 __kasan_report mm/kasan/report.c:545 [inline]
 kasan_report+0x148/0x1e4 mm/kasan/report.c:562
 check_memory_region_inline mm/kasan/generic.c:183 [inline]
 __asan_load8+0xb4/0xbc mm/kasan/generic.c:252
 kvm_vm_ioctl_unregister_coalesced_mmio+0x7c/0x1ec arch/arm64/kvm/../../../virt/kvm/coalesced_mmio.c:183
 kvm_vm_ioctl+0xe30/0x14c4 arch/arm64/kvm/../../../virt/kvm/kvm_main.c:3755
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl fs/ioctl.c:739 [inline]
 __arm64_sys_ioctl+0xf88/0x131c fs/ioctl.c:739
 __invoke_syscall arch/arm64/kernel/syscall.c:36 [inline]
 invoke_syscall arch/arm64/kernel/syscall.c:48 [inline]
 el0_svc_common arch/arm64/kernel/syscall.c:158 [inline]
 do_el0_svc+0x120/0x290 arch/arm64/kernel/syscall.c:220
 el0_svc+0x1c/0x28 arch/arm64/kernel/entry-common.c:367
 el0_sync_handler+0x98/0x170 arch/arm64/kernel/entry-common.c:383
 el0_sync+0x140/0x180 arch/arm64/kernel/entry.S:670

Allocated by task 4269:
 stack_trace_save+0x80/0xb8 kernel/stacktrace.c:121
 kasan_save_stack mm/kasan/common.c:48 [inline]
 kasan_set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc+0xdc/0x120 mm/kasan/common.c:461
 kasan_kmalloc+0xc/0x14 mm/kasan/common.c:475
 kmem_cache_alloc_trace include/linux/slab.h:450 [inline]
 kmalloc include/linux/slab.h:552 [inline]
 kzalloc include/linux/slab.h:664 [inline]
 kvm_vm_ioctl_register_coalesced_mmio+0x78/0x1cc arch/arm64/kvm/../../../virt/kvm/coalesced_mmio.c:146
 kvm_vm_ioctl+0x7e8/0x14c4 arch/arm64/kvm/../../../virt/kvm/kvm_main.c:3746
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl fs/ioctl.c:739 [inline]
 __arm64_sys_ioctl+0xf88/0x131c fs/ioctl.c:739
 __invoke_syscall arch/arm64/kernel/syscall.c:36 [inline]
 invoke_syscall arch/arm64/kernel/syscall.c:48 [inline]
 el0_svc_common arch/arm64/kernel/syscall.c:158 [inline]
 do_el0_svc+0x120/0x290 arch/arm64/kernel/syscall.c:220
 el0_svc+0x1c/0x28 arch/arm64/kernel/entry-common.c:367
 el0_sync_handler+0x98/0x170 arch/arm64/kernel/entry-common.c:383
 el0_sync+0x140/0x180 arch/arm64/kernel/entry.S:670

Freed by task 4269:
 stack_trace_save+0x80/0xb8 kernel/stacktrace.c:121
 kasan_save_stack mm/kasan/common.c:48 [inline]
 kasan_set_track+0x38/0x6c mm/kasan/common.c:56
 kasan_set_free_info+0x20/0x40 mm/kasan/generic.c:355
 __kasan_slab_free+0x124/0x150 mm/kasan/common.c:422
 kasan_slab_free+0x10/0x1c mm/kasan/common.c:431
 slab_free_hook mm/slub.c:1544 [inline]
 slab_free_freelist_hook mm/slub.c:1577 [inline]
 slab_free mm/slub.c:3142 [inline]
 kfree+0x104/0x38c mm/slub.c:4124
 coalesced_mmio_destructor+0x94/0xa4 arch/arm64/kvm/../../../virt/kvm/coalesced_mmio.c:102
 kvm_iodevice_destructor include/kvm/iodev.h:61 [inline]
 kvm_io_bus_unregister_dev+0x248/0x280 arch/arm64/kvm/../../../virt/kvm/kvm_main.c:4374
 kvm_vm_ioctl_unregister_coalesced_mmio+0x158/0x1ec arch/arm64/kvm/../../../virt/kvm/coalesced_mmio.c:186
 kvm_vm_ioctl+0xe30/0x14c4 arch/arm64/kvm/../../../virt/kvm/kvm_main.c:3755
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl fs/ioctl.c:739 [inline]
 __arm64_sys_ioctl+0xf88/0x131c fs/ioctl.c:739
 __invoke_syscall arch/arm64/kernel/syscall.c:36 [inline]
 invoke_syscall arch/arm64/kernel/syscall.c:48 [inline]
 el0_svc_common arch/arm64/kernel/syscall.c:158 [inline]
 do_el0_svc+0x120/0x290 arch/arm64/kernel/syscall.c:220
 el0_svc+0x1c/0x28 arch/arm64/kernel/entry-common.c:367
 el0_sync_handler+0x98/0x170 arch/arm64/kernel/entry-common.c:383
 el0_sync+0x140/0x180 arch/arm64/kernel/entry.S:670

If kvm_io_bus_unregister_dev() return -ENOMEM, we already call kvm_iodevice_destructor()
inside this function to delete 'struct kvm_coalesced_mmio_dev *dev' from list
and free the dev, but kvm_iodevice_destructor() is called again, it will lead
the above issue.

Let's check the the return value of kvm_io_bus_unregister_dev(), only call
kvm_iodevice_destructor() if the return value is 0.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Message-Id: <20210626070304.143456-1-wangkefeng.wang@huawei.com>
Cc: stable@vger.kernel.org
Fixes: 5d3c4c7938 ("KVM: Stop looking for coalesced MMIO zones if the bus is destroyed", 2021-04-20)
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-07-14 12:17:56 -04:00
Paolo Bonzini
f3cf800778 Merge tag 'kvm-s390-master-5.14-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD
KVM: selftests: Fixes

- provide memory model for  IBM z196 and zEC12
- do not require 64GB of memory
2021-07-14 12:14:27 -04:00
Linus Torvalds
65090f30ab Merge branch 'akpm' (patches from Andrew)
Merge misc updates from Andrew Morton:
 "191 patches.

  Subsystems affected by this patch series: kthread, ia64, scripts,
  ntfs, squashfs, ocfs2, kernel/watchdog, and mm (gup, pagealloc, slab,
  slub, kmemleak, dax, debug, pagecache, gup, swap, memcg, pagemap,
  mprotect, bootmem, dma, tracing, vmalloc, kasan, initialization,
  pagealloc, and memory-failure)"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (191 commits)
  mm,hwpoison: make get_hwpoison_page() call get_any_page()
  mm,hwpoison: send SIGBUS with error virutal address
  mm/page_alloc: split pcp->high across all online CPUs for cpuless nodes
  mm/page_alloc: allow high-order pages to be stored on the per-cpu lists
  mm: replace CONFIG_FLAT_NODE_MEM_MAP with CONFIG_FLATMEM
  mm: replace CONFIG_NEED_MULTIPLE_NODES with CONFIG_NUMA
  docs: remove description of DISCONTIGMEM
  arch, mm: remove stale mentions of DISCONIGMEM
  mm: remove CONFIG_DISCONTIGMEM
  m68k: remove support for DISCONTIGMEM
  arc: remove support for DISCONTIGMEM
  arc: update comment about HIGHMEM implementation
  alpha: remove DISCONTIGMEM and NUMA
  mm/page_alloc: move free_the_page
  mm/page_alloc: fix counting of managed_pages
  mm/page_alloc: improve memmap_pages dbg msg
  mm: drop SECTION_SHIFT in code comments
  mm/page_alloc: introduce vm.percpu_pagelist_high_fraction
  mm/page_alloc: limit the number of pages on PCP lists when reclaim is active
  mm/page_alloc: scale the number of pages that are batch freed
  ...
2021-06-29 17:29:11 -07:00
Liam Howlett
fc98c03ba9 virt/kvm: use vma_lookup() instead of find_vma_intersection()
vma_lookup() finds the vma of a specific address with a cleaner interface
and is more readable.

Link: https://lkml.kernel.org/r/20210521174745.2219620-11-Liam.Howlett@Oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: Laurent Dufour <ldufour@linux.ibm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-29 10:53:51 -07:00
Linus Torvalds
36824f198c ARM:
- Add MTE support in guests, complete with tag save/restore interface
 
 - Reduce the impact of CMOs by moving them in the page-table code
 
 - Allow device block mappings at stage-2
 
 - Reduce the footprint of the vmemmap in protected mode
 
 - Support the vGIC on dumb systems such as the Apple M1
 
 - Add selftest infrastructure to support multiple configuration
   and apply that to PMU/non-PMU setups
 
 - Add selftests for the debug architecture
 
 - The usual crop of PMU fixes
 
 PPC:
 
 - Support for the H_RPT_INVALIDATE hypercall
 
 - Conversion of Book3S entry/exit to C
 
 - Bug fixes
 
 S390:
 
 - new HW facilities for guests
 
 - make inline assembly more robust with KASAN and co
 
 x86:
 
 - Allow userspace to handle emulation errors (unknown instructions)
 
 - Lazy allocation of the rmap (host physical -> guest physical address)
 
 - Support for virtualizing TSC scaling on VMX machines
 
 - Optimizations to avoid shattering huge pages at the beginning of live migration
 
 - Support for initializing the PDPTRs without loading them from memory
 
 - Many TLB flushing cleanups
 
 - Refuse to load if two-stage paging is available but NX is not (this has
   been a requirement in practice for over a year)
 
 - A large series that separates the MMU mode (WP/SMAP/SMEP etc.) from
   CR0/CR4/EFER, using the MMU mode everywhere once it is computed
   from the CPU registers
 
 - Use PM notifier to notify the guest about host suspend or hibernate
 
 - Support for passing arguments to Hyper-V hypercalls using XMM registers
 
 - Support for Hyper-V TLB flush hypercalls and enlightened MSR bitmap on
   AMD processors
 
 - Hide Hyper-V hypercalls that are not included in the guest CPUID
 
 - Fixes for live migration of virtual machines that use the Hyper-V
   "enlightened VMCS" optimization of nested virtualization
 
 - Bugfixes (not many)
 
 Generic:
 
 - Support for retrieving statistics without debugfs
 
 - Cleanups for the KVM selftests API
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull kvm updates from Paolo Bonzini:
 "This covers all architectures (except MIPS) so I don't expect any
  other feature pull requests this merge window.

  ARM:

   - Add MTE support in guests, complete with tag save/restore interface

   - Reduce the impact of CMOs by moving them in the page-table code

   - Allow device block mappings at stage-2

   - Reduce the footprint of the vmemmap in protected mode

   - Support the vGIC on dumb systems such as the Apple M1

   - Add selftest infrastructure to support multiple configuration and
     apply that to PMU/non-PMU setups

   - Add selftests for the debug architecture

   - The usual crop of PMU fixes

  PPC:

   - Support for the H_RPT_INVALIDATE hypercall

   - Conversion of Book3S entry/exit to C

   - Bug fixes

  S390:

   - new HW facilities for guests

   - make inline assembly more robust with KASAN and co

  x86:

   - Allow userspace to handle emulation errors (unknown instructions)

   - Lazy allocation of the rmap (host physical -> guest physical
     address)

   - Support for virtualizing TSC scaling on VMX machines

   - Optimizations to avoid shattering huge pages at the beginning of
     live migration

   - Support for initializing the PDPTRs without loading them from
     memory

   - Many TLB flushing cleanups

   - Refuse to load if two-stage paging is available but NX is not (this
     has been a requirement in practice for over a year)

   - A large series that separates the MMU mode (WP/SMAP/SMEP etc.) from
     CR0/CR4/EFER, using the MMU mode everywhere once it is computed
     from the CPU registers

   - Use PM notifier to notify the guest about host suspend or hibernate

   - Support for passing arguments to Hyper-V hypercalls using XMM
     registers

   - Support for Hyper-V TLB flush hypercalls and enlightened MSR bitmap
     on AMD processors

   - Hide Hyper-V hypercalls that are not included in the guest CPUID

   - Fixes for live migration of virtual machines that use the Hyper-V
     "enlightened VMCS" optimization of nested virtualization

   - Bugfixes (not many)

  Generic:

   - Support for retrieving statistics without debugfs

   - Cleanups for the KVM selftests API"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (314 commits)
  KVM: x86: rename apic_access_page_done to apic_access_memslot_enabled
  kvm: x86: disable the narrow guest module parameter on unload
  selftests: kvm: Allows userspace to handle emulation errors.
  kvm: x86: Allow userspace to handle emulation errors
  KVM: x86/mmu: Let guest use GBPAGES if supported in hardware and TDP is on
  KVM: x86/mmu: Get CR4.SMEP from MMU, not vCPU, in shadow page fault
  KVM: x86/mmu: Get CR0.WP from MMU, not vCPU, in shadow page fault
  KVM: x86/mmu: Drop redundant rsvd bits reset for nested NPT
  KVM: x86/mmu: Optimize and clean up so called "last nonleaf level" logic
  KVM: x86: Enhance comments for MMU roles and nested transition trickiness
  KVM: x86/mmu: WARN on any reserved SPTE value when making a valid SPTE
  KVM: x86/mmu: Add helpers to do full reserved SPTE checks w/ generic MMU
  KVM: x86/mmu: Use MMU's role to determine PTTYPE
  KVM: x86/mmu: Collapse 32-bit PAE and 64-bit statements for helpers
  KVM: x86/mmu: Add a helper to calculate root from role_regs
  KVM: x86/mmu: Add helper to update paging metadata
  KVM: x86/mmu: Don't update nested guest's paging bitmasks if CR0.PG=0
  KVM: x86/mmu: Consolidate reset_rsvds_bits_mask() calls
  KVM: x86/mmu: Use MMU role_regs to get LA57, and drop vCPU LA57 helper
  KVM: x86/mmu: Get nested MMU's root level from the MMU's role
  ...
2021-06-28 15:40:51 -07:00
Linus Torvalds
54a728dc5e Scheduler udpates for this cycle:
- Changes to core scheduling facilities:
 
     - Add "Core Scheduling" via CONFIG_SCHED_CORE=y, which enables
       coordinated scheduling across SMT siblings. This is a much
       requested feature for cloud computing platforms, to allow
       the flexible utilization of SMT siblings, without exposing
       untrusted domains to information leaks & side channels, plus
       to ensure more deterministic computing performance on SMT
       systems used by heterogenous workloads.
 
       There's new prctls to set core scheduling groups, which
       allows more flexible management of workloads that can share
       siblings.
 
     - Fix task->state access anti-patterns that may result in missed
       wakeups and rename it to ->__state in the process to catch new
       abuses.
 
  - Load-balancing changes:
 
      - Tweak newidle_balance for fair-sched, to improve
        'memcache'-like workloads.
 
      - "Age" (decay) average idle time, to better track & improve workloads
        such as 'tbench'.
 
      - Fix & improve energy-aware (EAS) balancing logic & metrics.
 
      - Fix & improve the uclamp metrics.
 
      - Fix task migration (taskset) corner case on !CONFIG_CPUSET.
 
      - Fix RT and deadline utilization tracking across policy changes
 
      - Introduce a "burstable" CFS controller via cgroups, which allows
        bursty CPU-bound workloads to borrow a bit against their future
        quota to improve overall latencies & batching. Can be tweaked
        via /sys/fs/cgroup/cpu/<X>/cpu.cfs_burst_us.
 
      - Rework assymetric topology/capacity detection & handling.
 
  - Scheduler statistics & tooling:
 
      - Disable delayacct by default, but add a sysctl to enable
        it at runtime if tooling needs it. Use static keys and
        other optimizations to make it more palatable.
 
      - Use sched_clock() in delayacct, instead of ktime_get_ns().
 
  - Misc cleanups and fixes.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2021-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler udpates from Ingo Molnar:

 - Changes to core scheduling facilities:

    - Add "Core Scheduling" via CONFIG_SCHED_CORE=y, which enables
      coordinated scheduling across SMT siblings. This is a much
      requested feature for cloud computing platforms, to allow the
      flexible utilization of SMT siblings, without exposing untrusted
      domains to information leaks & side channels, plus to ensure more
      deterministic computing performance on SMT systems used by
      heterogenous workloads.

      There are new prctls to set core scheduling groups, which allows
      more flexible management of workloads that can share siblings.

    - Fix task->state access anti-patterns that may result in missed
      wakeups and rename it to ->__state in the process to catch new
      abuses.

 - Load-balancing changes:

    - Tweak newidle_balance for fair-sched, to improve 'memcache'-like
      workloads.

    - "Age" (decay) average idle time, to better track & improve
      workloads such as 'tbench'.

    - Fix & improve energy-aware (EAS) balancing logic & metrics.

    - Fix & improve the uclamp metrics.

    - Fix task migration (taskset) corner case on !CONFIG_CPUSET.

    - Fix RT and deadline utilization tracking across policy changes

    - Introduce a "burstable" CFS controller via cgroups, which allows
      bursty CPU-bound workloads to borrow a bit against their future
      quota to improve overall latencies & batching. Can be tweaked via
      /sys/fs/cgroup/cpu/<X>/cpu.cfs_burst_us.

    - Rework assymetric topology/capacity detection & handling.

 - Scheduler statistics & tooling:

    - Disable delayacct by default, but add a sysctl to enable it at
      runtime if tooling needs it. Use static keys and other
      optimizations to make it more palatable.

    - Use sched_clock() in delayacct, instead of ktime_get_ns().

 - Misc cleanups and fixes.

* tag 'sched-core-2021-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (72 commits)
  sched/doc: Update the CPU capacity asymmetry bits
  sched/topology: Rework CPU capacity asymmetry detection
  sched/core: Introduce SD_ASYM_CPUCAPACITY_FULL sched_domain flag
  psi: Fix race between psi_trigger_create/destroy
  sched/fair: Introduce the burstable CFS controller
  sched/uclamp: Fix uclamp_tg_restrict()
  sched/rt: Fix Deadline utilization tracking during policy change
  sched/rt: Fix RT utilization tracking during policy change
  sched: Change task_struct::state
  sched,arch: Remove unused TASK_STATE offsets
  sched,timer: Use __set_current_state()
  sched: Add get_current_state()
  sched,perf,kvm: Fix preemption condition
  sched: Introduce task_is_running()
  sched: Unbreak wakeups
  sched/fair: Age the average idle time
  sched/cpufreq: Consider reduced CPU capacity in energy calculation
  sched/fair: Take thermal pressure into account while estimating energy
  thermal/cpufreq_cooling: Update offline CPUs per-cpu thermal_pressure
  sched/fair: Return early from update_tg_cfs_load() if delta == 0
  ...
2021-06-28 12:14:19 -07:00
Jing Zhang
bc9e9e672d KVM: debugfs: Reuse binary stats descriptors
To remove code duplication, use the binary stats descriptors in the
implementation of the debugfs interface for statistics. This unifies
the definition of statistics for the binary and debugfs interfaces.

Signed-off-by: Jing Zhang <jingzhangos@google.com>
Message-Id: <20210618222709.1858088-8-jingzhangos@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-24 18:00:29 -04:00
Jing Zhang
ce55c04945 KVM: stats: Support binary stats retrieval for a VCPU
Add a VCPU ioctl to get a statistics file descriptor by which a read
functionality is provided for userspace to read out VCPU stats header,
descriptors and data.
Define VCPU statistics descriptors and header for all architectures.

Reviewed-by: David Matlack <dmatlack@google.com>
Reviewed-by: Ricardo Koller <ricarkol@google.com>
Reviewed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com> #arm64
Signed-off-by: Jing Zhang <jingzhangos@google.com>
Message-Id: <20210618222709.1858088-5-jingzhangos@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-24 18:00:19 -04:00
Jing Zhang
fcfe1baedd KVM: stats: Support binary stats retrieval for a VM
Add a VM ioctl to get a statistics file descriptor by which a read
functionality is provided for userspace to read out VM stats header,
descriptors and data.
Define VM statistics descriptors and header for all architectures.

Reviewed-by: David Matlack <dmatlack@google.com>
Reviewed-by: Ricardo Koller <ricarkol@google.com>
Reviewed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com> #arm64
Signed-off-by: Jing Zhang <jingzhangos@google.com>
Message-Id: <20210618222709.1858088-4-jingzhangos@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-24 18:00:10 -04:00
Nicholas Piggin
f8be156be1 KVM: do not allow mapping valid but non-reference-counted pages
It's possible to create a region which maps valid but non-refcounted
pages (e.g., tail pages of non-compound higher order allocations). These
host pages can then be returned by gfn_to_page, gfn_to_pfn, etc., family
of APIs, which take a reference to the page, which takes it from 0 to 1.
When the reference is dropped, this will free the page incorrectly.

Fix this by only taking a reference on valid pages if it was non-zero,
which indicates it is participating in normal refcounting (and can be
released with put_page).

This addresses CVE-2021-22543.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Tested-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-24 11:55:11 -04:00
Jing Zhang
cb082bfab5 KVM: stats: Add fd-based API to read binary stats data
This commit defines the API for userspace and prepare the common
functionalities to support per VM/VCPU binary stats data readings.

The KVM stats now is only accessible by debugfs, which has some
shortcomings this change series are supposed to fix:
1. The current debugfs stats solution in KVM could be disabled
   when kernel Lockdown mode is enabled, which is a potential
   rick for production.
2. The current debugfs stats solution in KVM is organized as "one
   stats per file", it is good for debugging, but not efficient
   for production.
3. The stats read/clear in current debugfs solution in KVM are
   protected by the global kvm_lock.

Besides that, there are some other benefits with this change:
1. All KVM VM/VCPU stats can be read out in a bulk by one copy
   to userspace.
2. A schema is used to describe KVM statistics. From userspace's
   perspective, the KVM statistics are self-describing.
3. With the fd-based solution, a separate telemetry would be able
   to read KVM stats in a less privileged environment.
4. After the initial setup by reading in stats descriptors, a
   telemetry only needs to read the stats data itself, no more
   parsing or setup is needed.

Reviewed-by: David Matlack <dmatlack@google.com>
Reviewed-by: Ricardo Koller <ricarkol@google.com>
Reviewed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com> #arm64
Signed-off-by: Jing Zhang <jingzhangos@google.com>
Message-Id: <20210618222709.1858088-3-jingzhangos@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-24 11:47:57 -04:00
Jing Zhang
0193cc908b KVM: stats: Separate generic stats from architecture specific ones
Generic KVM stats are those collected in architecture independent code
or those supported by all architectures; put all generic statistics in
a separate structure.  This ensures that they are defined the same way
in the statistics API which is being added, removing duplication among
different architectures in the declaration of the descriptors.

No functional change intended.

Reviewed-by: David Matlack <dmatlack@google.com>
Reviewed-by: Ricardo Koller <ricarkol@google.com>
Reviewed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Signed-off-by: Jing Zhang <jingzhangos@google.com>
Message-Id: <20210618222709.1858088-2-jingzhangos@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-24 11:47:56 -04:00
Peter Zijlstra
3ba9f93b12 sched,perf,kvm: Fix preemption condition
When ran from the sched-out path (preempt_notifier or perf_event),
p->state is irrelevant to determine preemption. You can get preempted
with !task_is_running() just fine.

The right indicator for preemption is if the task is still on the
runqueue in the sched-out path.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20210611082838.285099381@infradead.org
2021-06-18 11:43:07 +02:00
Paolo Bonzini
e3cb6fa0e2 KVM: switch per-VM stats to u64
Make them the same type as vCPU stats.  There is no reason
to limit the counters to unsigned long.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-17 14:25:27 -04:00
Sergey Senozhatsky
2fdef3a2ae kvm: add PM-notifier
Add KVM PM-notifier so that architectures can have arch-specific
VM suspend/resume routines. Such architectures need to select
CONFIG_HAVE_KVM_PM_NOTIFIER and implement kvm_arch_pm_notifier().

Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Acked-by: Marc Zyngier <maz@kernel.org>
Message-Id: <20210606021045.14159-1-senozhatsky@chromium.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-17 13:09:32 -04:00
Ben Gardon
b10a038e84 KVM: mmu: Add slots_arch_lock for memslot arch fields
Add a new lock to protect the arch-specific fields of memslots if they
need to be modified in a kvm->srcu read critical section. A future
commit will use this lock to lazily allocate memslot rmaps for x86.

Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20210518173414.450044-5-bgardon@google.com>
[Add Documentation/ hunk. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-17 13:09:26 -04:00
Ben Gardon
ddc12f2a12 KVM: mmu: Refactor memslot copy
Factor out copying kvm_memslots from allocating the memory for new ones
in preparation for adding a new lock to protect the arch-specific fields
of the memslots.

No functional change intended.

Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20210518173414.450044-4-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-17 13:09:26 -04:00
Marcelo Tosatti
a2486020a8 KVM: VMX: update vcpu posted-interrupt descriptor when assigning device
For VMX, when a vcpu enters HLT emulation, pi_post_block will:

1) Add vcpu to per-cpu list of blocked vcpus.

2) Program the posted-interrupt descriptor "notification vector"
to POSTED_INTR_WAKEUP_VECTOR

With interrupt remapping, an interrupt will set the PIR bit for the
vector programmed for the device on the CPU, test-and-set the
ON bit on the posted interrupt descriptor, and if the ON bit is clear
generate an interrupt for the notification vector.

This way, the target CPU wakes upon a device interrupt and wakes up
the target vcpu.

Problem is that pi_post_block only programs the notification vector
if kvm_arch_has_assigned_device() is true. Its possible for the
following to happen:

1) vcpu V HLTs on pcpu P, kvm_arch_has_assigned_device is false,
notification vector is not programmed
2) device is assigned to VM
3) device interrupts vcpu V, sets ON bit
(notification vector not programmed, so pcpu P remains in idle)
4) vcpu 0 IPIs vcpu V (in guest), but since pi descriptor ON bit is set,
kvm_vcpu_kick is skipped
5) vcpu 0 busy spins on vcpu V's response for several seconds, until
RCU watchdog NMIs all vCPUs.

To fix this, use the start_assignment kvm_x86_ops callback to kick
vcpus out of the halt loop, so the notification vector is
properly reprogrammed to the wakeup vector.

Reported-by: Pei Zhang <pezhang@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Message-Id: <20210526172014.GA29007@fuller.cnet>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-05-27 07:58:23 -04:00
Marcelo Tosatti
084071d5e9 KVM: rename KVM_REQ_PENDING_TIMER to KVM_REQ_UNBLOCK
KVM_REQ_UNBLOCK will be used to exit a vcpu from
its inner vcpu halt emulation loop.

Rename KVM_REQ_PENDING_TIMER to KVM_REQ_UNBLOCK, switch
PowerPC to arch specific request bit.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

Message-Id: <20210525134321.303768132@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-05-27 07:57:38 -04:00
Wanpeng Li
6bd5b74368 KVM: PPC: exit halt polling on need_resched()
This is inspired by commit 262de4102c (kvm: exit halt polling on
need_resched() as well). Due to PPC implements an arch specific halt
polling logic, we have to the need_resched() check there as well. This
patch adds a helper function that can be shared between book3s and generic
halt-polling loops.

Reviewed-by: David Matlack <dmatlack@google.com>
Reviewed-by: Venkatesh Srinivas <venkateshs@chromium.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Venkatesh Srinivas <venkateshs@chromium.org>
Cc: Jim Mattson <jmattson@google.com>
Cc: David Matlack <dmatlack@google.com>
Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1621339235-11131-1-git-send-email-wanpengli@tencent.com>
[Make the function inline. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-05-27 07:45:50 -04:00
Paolo Bonzini
a4345a7cec KVM/arm64 fixes for 5.13, take #1
- Fix regression with irqbypass not restarting the guest on failed connect
 - Fix regression with debug register decoding resulting in overlapping access
 - Commit exception state on exit to usrspace
 - Fix the MMU notifier return values
 - Add missing 'static' qualifiers in the new host stage-2 code
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Merge tag 'kvmarm-fixes-5.13-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

KVM/arm64 fixes for 5.13, take #1

- Fix regression with irqbypass not restarting the guest on failed connect
- Fix regression with debug register decoding resulting in overlapping access
- Commit exception state on exit to usrspace
- Fix the MMU notifier return values
- Add missing 'static' qualifiers in the new host stage-2 code
2021-05-17 09:55:12 +02:00
Zhu Lingshan
e44b49f623 Revert "irqbypass: do not start cons/prod when failed connect"
This reverts commit a979a6aa00.

The reverted commit may cause VM freeze on arm64 with GICv4,
where stopping a consumer is implemented by suspending the VM.
Should the connect fail, the VM will not be resumed, which
is a bit of a problem.

It also erroneously calls the producer destructor unconditionally,
which is unexpected.

Reported-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
Suggested-by: Marc Zyngier <maz@kernel.org>
Acked-by: Jason Wang <jasowang@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Tested-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
[maz: tags and cc-stable, commit message update]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Fixes: a979a6aa00 ("irqbypass: do not start cons/prod when failed connect")
Link: https://lore.kernel.org/r/3a2c66d6-6ca0-8478-d24b-61e8e3241b20@hisilicon.com
Link: https://lore.kernel.org/r/20210508071152.722425-1-lingshan.zhu@intel.com
Cc: stable@vger.kernel.org
2021-05-15 10:26:55 +01:00
David Matlack
258785ef08 kvm: Cap halt polling at kvm->max_halt_poll_ns
When growing halt-polling, there is no check that the poll time exceeds
the per-VM limit. It's possible for vcpu->halt_poll_ns to grow past
kvm->max_halt_poll_ns and stay there until a halt which takes longer
than kvm->halt_poll_ns.

Signed-off-by: David Matlack <dmatlack@google.com>
Signed-off-by: Venkatesh Srinivas <venkateshs@chromium.org>
Message-Id: <20210506152442.4010298-1-venkateshs@chromium.org>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-05-07 06:06:22 -04:00
Benjamin Segall
262de4102c kvm: exit halt polling on need_resched() as well
single_task_running() is usually more general than need_resched()
but CFS_BANDWIDTH throttling will use resched_task() when there
is just one task to get the task to block. This was causing
long-need_resched warnings and was likely allowing VMs to
overrun their quota when halt polling.

Signed-off-by: Ben Segall <bsegall@google.com>
Signed-off-by: Venkatesh Srinivas <venkateshs@chromium.org>
Message-Id: <20210429162233.116849-1-venkateshs@chromium.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: stable@vger.kernel.org
Reviewed-by: Jim Mattson <jmattson@google.com>
2021-05-03 11:25:36 -04:00
Wanpeng Li
52acd22faa KVM: Boost vCPU candidate in user mode which is delivering interrupt
Both lock holder vCPU and IPI receiver that has halted are condidate for
boost. However, the PLE handler was originally designed to deal with the
lock holder preemption problem. The Intel PLE occurs when the spinlock
waiter is in kernel mode. This assumption doesn't hold for IPI receiver,
they can be in either kernel or user mode. the vCPU candidate in user mode
will not be boosted even if they should respond to IPIs. Some benchmarks
like pbzip2, swaptions etc do the TLB shootdown in kernel mode and most
of the time they are running in user mode. It can lead to a large number
of continuous PLE events because the IPI sender causes PLE events
repeatedly until the receiver is scheduled while the receiver is not
candidate for a boost.

This patch boosts the vCPU candidiate in user mode which is delivery
interrupt. We can observe the speed of pbzip2 improves 10% in 96 vCPUs
VM in over-subscribe scenario (The host machine is 2 socket, 48 cores,
96 HTs Intel CLX box). There is no performance regression for other
benchmarks like Unixbench spawn (most of the time contend read/write
lock in kernel mode), ebizzy (most of the time contend read/write sem
and TLB shoodtdown in kernel mode).

Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1618542490-14756-1-git-send-email-wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-21 12:20:03 -04:00
Nathan Tempelman
54526d1fd5 KVM: x86: Support KVM VMs sharing SEV context
Add a capability for userspace to mirror SEV encryption context from
one vm to another. On our side, this is intended to support a
Migration Helper vCPU, but it can also be used generically to support
other in-guest workloads scheduled by the host. The intention is for
the primary guest and the mirror to have nearly identical memslots.

The primary benefits of this are that:
1) The VMs do not share KVM contexts (think APIC/MSRs/etc), so they
can't accidentally clobber each other.
2) The VMs can have different memory-views, which is necessary for post-copy
migration (the migration vCPUs on the target need to read and write to
pages, when the primary guest would VMEXIT).

This does not change the threat model for AMD SEV. Any memory involved
is still owned by the primary guest and its initial state is still
attested to through the normal SEV_LAUNCH_* flows. If userspace wanted
to circumvent SEV, they could achieve the same effect by simply attaching
a vCPU to the primary VM.
This patch deliberately leaves userspace in charge of the memslots for the
mirror, as it already has the power to mess with them in the primary guest.

This patch does not support SEV-ES (much less SNP), as it does not
handle handing off attested VMSAs to the mirror.

For additional context, we need a Migration Helper because SEV PSP
migration is far too slow for our live migration on its own. Using
an in-guest migrator lets us speed this up significantly.

Signed-off-by: Nathan Tempelman <natet@google.com>
Message-Id: <20210408223214.2582277-1-natet@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-21 12:20:02 -04:00
Sean Christopherson
7c896d3755 KVM: Add proper lockdep assertion in I/O bus unregister
Convert a comment above kvm_io_bus_unregister_dev() into an actual
lockdep assertion, and opportunistically add curly braces to a multi-line
for-loop.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210412222050.876100-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-20 04:18:51 -04:00
Sean Christopherson
5d3c4c7938 KVM: Stop looking for coalesced MMIO zones if the bus is destroyed
Abort the walk of coalesced MMIO zones if kvm_io_bus_unregister_dev()
fails to allocate memory for the new instance of the bus.  If it can't
instantiate a new bus, unregister_dev() destroys all devices _except_ the
target device.   But, it doesn't tell the caller that it obliterated the
bus and invoked the destructor for all devices that were on the bus.  In
the coalesced MMIO case, this can result in a deleted list entry
dereference due to attempting to continue iterating on coalesced_zones
after future entries (in the walk) have been deleted.

Opportunistically add curly braces to the for-loop, which encompasses
many lines but sneaks by without braces due to the guts being a single
if statement.

Fixes: f65886606c ("KVM: fix memory leak in kvm_io_bus_unregister_dev()")
Cc: stable@vger.kernel.org
Reported-by: Hao Sun <sunhao.th@gmail.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210412222050.876100-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-20 04:18:51 -04:00
Sean Christopherson
2ee3757424 KVM: Destroy I/O bus devices on unregister failure _after_ sync'ing SRCU
If allocating a new instance of an I/O bus fails when unregistering a
device, wait to destroy the device until after all readers are guaranteed
to see the new null bus.  Destroying devices before the bus is nullified
could lead to use-after-free since readers expect the devices on their
reference of the bus to remain valid.

Fixes: f65886606c ("KVM: fix memory leak in kvm_io_bus_unregister_dev()")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210412222050.876100-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-20 04:18:50 -04:00
Sean Christopherson
8931a454ae KVM: Take mmu_lock when handling MMU notifier iff the hva hits a memslot
Defer acquiring mmu_lock in the MMU notifier paths until a "hit" has been
detected in the memslots, i.e. don't take the lock for notifications that
don't affect the guest.

For small VMs, spurious locking is a minor annoyance.  And for "volatile"
setups where the majority of notifications _are_ relevant, this barely
qualifies as an optimization.

But, for large VMs (hundreds of threads) with static setups, e.g. no
page migration, no swapping, etc..., the vast majority of MMU notifier
callbacks will be unrelated to the guest, e.g. will often be in response
to the userspace VMM adjusting its own virtual address space.  In such
large VMs, acquiring mmu_lock can be painful as it blocks vCPUs from
handling page faults.  In some scenarios it can even be "fatal" in the
sense that it causes unacceptable brownouts, e.g. when rebuilding huge
pages after live migration, a significant percentage of vCPUs will be
attempting to handle page faults.

x86's TDP MMU implementation is especially susceptible to spurious
locking due it taking mmu_lock for read when handling page faults.
Because rwlock is fair, a single writer will stall future readers, while
the writer is itself stalled waiting for in-progress readers to complete.
This is exacerbated by the MMU notifiers often firing multiple times in
quick succession, e.g. moving a page will (always?) invoke three separate
notifiers: .invalidate_range_start(), invalidate_range_end(), and
.change_pte().  Unnecessarily taking mmu_lock each time means even a
single spurious sequence can be problematic.

Note, this optimizes only the unpaired callbacks.  Optimizing the
.invalidate_range_{start,end}() pairs is more complex and will be done in
a future patch.

Suggested-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210402005658.3024832-9-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-17 08:31:08 -04:00
Sean Christopherson
f922bd9bf3 KVM: Move MMU notifier's mmu_lock acquisition into common helper
Acquire and release mmu_lock in the __kvm_handle_hva_range() helper
instead of requiring the caller to do the same.  This paves the way for
future patches to take mmu_lock if and only if an overlapping memslot is
found, without also having to introduce the on_lock() shenanigans used
to manipulate the notifier count and sequence.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210402005658.3024832-8-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-17 08:31:08 -04:00
Sean Christopherson
b4c5936c47 KVM: Kill off the old hva-based MMU notifier callbacks
Yank out the hva-based MMU notifier APIs now that all architectures that
use the notifiers have moved to the gfn-based APIs.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210402005658.3024832-7-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-17 08:31:08 -04:00
Sean Christopherson
3039bcc744 KVM: Move x86's MMU notifier memslot walkers to generic code
Move the hva->gfn lookup for MMU notifiers into common code.  Every arch
does a similar lookup, and some arch code is all but identical across
multiple architectures.

In addition to consolidating code, this will allow introducing
optimizations that will benefit all architectures without incurring
multiple walks of the memslots, e.g. by taking mmu_lock if and only if a
relevant range exists in the memslots.

The use of __always_inline to avoid indirect call retpolines, as done by
x86, may also benefit other architectures.

Consolidating the lookups also fixes a wart in x86, where the legacy MMU
and TDP MMU each do their own memslot walks.

Lastly, future enhancements to the memslot implementation, e.g. to add an
interval tree to track host address, will need to touch far less arch
specific code.

MIPS, PPC, and arm64 will be converted one at a time in future patches.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210402005658.3024832-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-17 08:31:06 -04:00
Sean Christopherson
c13fda237f KVM: Assert that notifier count is elevated in .change_pte()
In KVM's .change_pte() notification callback, replace the notifier
sequence bump with a WARN_ON assertion that the notifier count is
elevated.  An elevated count provides stricter protections than bumping
the sequence, and the sequence is guarnateed to be bumped before the
count hits zero.

When .change_pte() was added by commit 828502d300 ("ksm: add
mmu_notifier set_pte_at_notify()"), bumping the sequence was necessary
as .change_pte() would be invoked without any surrounding notifications.

However, since commit 6bdb913f0a ("mm: wrap calls to set_pte_at_notify
with invalidate_range_start and invalidate_range_end"), all calls to
.change_pte() are guaranteed to be surrounded by start() and end(), and
so are guaranteed to run with an elevated notifier count.

Note, wrapping .change_pte() with .invalidate_range_{start,end}() is a
bug of sorts, as invalidating the secondary MMU's (KVM's) PTE defeats
the purpose of .change_pte().  Every arch's kvm_set_spte_hva() assumes
.change_pte() is called when the relevant SPTE is present in KVM's MMU,
as the original goal was to accelerate Kernel Samepage Merging (KSM) by
updating KVM's SPTEs without requiring a VM-Exit (due to invalidating
the SPTE).  I.e. it means that .change_pte() is effectively dead code
on _all_ architectures.

x86 and MIPS are clearcut nops if the old SPTE is not-present, and that
is guaranteed due to the prior invalidation.  PPC simply unmaps the SPTE,
which again should be a nop due to the invalidation.  arm64 is a bit
murky, but it's also likely a nop because kvm_pgtable_stage2_map() is
called without a cache pointer, which means it will map an entry if and
only if an existing PTE was found.

For now, take advantage of the bug to simplify future consolidation of
KVMs's MMU notifier code.   Doing so will not greatly complicate fixing
.change_pte(), assuming it's even worth fixing.  .change_pte() has been
broken for 8+ years and no one has complained.  Even if there are
KSM+KVM users that care deeply about its performance, the benefits of
avoiding VM-Exits via .change_pte() need to be reevaluated to justify
the added complexity and testing burden.  Ripping out .change_pte()
entirely would be a lot easier.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-17 08:31:06 -04:00
Sean Christopherson
85f4793083 KVM: Explicitly use GFP_KERNEL_ACCOUNT for 'struct kvm_vcpu' allocations
Use GFP_KERNEL_ACCOUNT when allocating vCPUs to make it more obvious that
that the allocations are accounted, to make it easier to audit KVM's
allocations in the future, and to be consistent with other cache usage in
KVM.

When using SLAB/SLUB, this is a nop as the cache itself is created with
SLAB_ACCOUNT.

When using SLOB, there are caveats within caveats.  SLOB doesn't honor
SLAB_ACCOUNT, so passing GFP_KERNEL_ACCOUNT will result in vCPU
allocations now being accounted.   But, even that depends on internal
SLOB details as SLOB will only go to the page allocator when its cache is
depleted.  That just happens to be extremely likely for vCPUs because the
size of kvm_vcpu is larger than the a page for almost all combinations of
architecture and page size.  Whether or not the SLOB behavior is by
design is unknown; it's just as likely that no SLOB users care about
accounding and so no one has bothered to implemented support in SLOB.
Regardless, accounting vCPU allocations will not break SLOB+KVM+cgroup
users, if any exist.

Reviewed-by: Wanpeng Li <kernellwp@gmail.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210406190740.4055679-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-17 08:31:04 -04:00
Sean Christopherson
501b918525 KVM: Move arm64's MMU notifier trace events to generic code
Move arm64's MMU notifier trace events into common code in preparation
for doing the hva->gfn lookup in common code.  The alternative would be
to trace the gfn instead of hva, but that's not obviously better and
could also be done in common code.  Tracing the notifiers is also quite
handy for debug regardless of architecture.

Remove a completely redundant tracepoint from PPC e500.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210326021957.1424875-10-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-17 08:30:56 -04:00
David Stevens
4a42d848db KVM: x86/mmu: Consider the hva in mmu_notifier retry
Track the range being invalidated by mmu_notifier and skip page fault
retries if the fault address is not affected by the in-progress
invalidation. Handle concurrent invalidations by finding the minimal
range which includes all ranges being invalidated. Although the combined
range may include unrelated addresses and cannot be shrunk as individual
invalidation operations complete, it is unlikely the marginal gains of
proper range tracking are worth the additional complexity.

The primary benefit of this change is the reduction in the likelihood of
extreme latency when handing a page fault due to another thread having
been preempted while modifying host virtual addresses.

Signed-off-by: David Stevens <stevensd@chromium.org>
Message-Id: <20210222024522.1751719-3-stevensd@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-02-22 13:16:53 -05:00
Sean Christopherson
a9545779ee KVM: Use kvm_pfn_t for local PFN variable in hva_to_pfn_remapped()
Use kvm_pfn_t, a.k.a. u64, for the local 'pfn' variable when retrieving
a so called "remapped" hva/pfn pair.  In theory, the hva could resolve to
a pfn in high memory on a 32-bit kernel.

This bug was inadvertantly exposed by commit bd2fae8da7 ("KVM: do not
assume PTE is writable after follow_pfn"), which added an error PFN value
to the mix, causing gcc to comlain about overflowing the unsigned long.

  arch/x86/kvm/../../../virt/kvm/kvm_main.c: In function ‘hva_to_pfn_remapped’:
  include/linux/kvm_host.h:89:30: error: conversion from ‘long long unsigned int’
                                  to ‘long unsigned int’ changes value from
                                  ‘9218868437227405314’ to ‘2’ [-Werror=overflow]
   89 | #define KVM_PFN_ERR_RO_FAULT (KVM_PFN_ERR_MASK + 2)
      |                              ^
virt/kvm/kvm_main.c:1935:9: note: in expansion of macro ‘KVM_PFN_ERR_RO_FAULT’

Cc: stable@vger.kernel.org
Fixes: add6a0cd1c ("KVM: MMU: try to fix up page faults before giving up")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210208201940.1258328-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-02-09 07:05:44 -05:00
Paolo Bonzini
9fd6dad126 mm: provide a saner PTE walking API for modules
Currently, the follow_pfn function is exported for modules but
follow_pte is not.  However, follow_pfn is very easy to misuse,
because it does not provide protections (so most of its callers
assume the page is writable!) and because it returns after having
already unlocked the page table lock.

Provide instead a simplified version of follow_pte that does
not have the pmdpp and range arguments.  The older version
survives as follow_invalidate_pte() for use by fs/dax.c.

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-02-09 07:05:44 -05:00
Ben Gardon
531810caa9 KVM: x86/mmu: Use an rwlock for the x86 MMU
Add a read / write lock to be used in place of the MMU spinlock on x86.
The rwlock will enable the TDP MMU to handle page faults, and other
operations in parallel in future commits.

Reviewed-by: Peter Feiner <pfeiner@google.com>
Signed-off-by: Ben Gardon <bgardon@google.com>

Message-Id: <20210202185734.1680553-19-bgardon@google.com>
[Introduce virt/kvm/mmu_lock.h - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-02-04 05:27:43 -05:00
Tian Tao
c910662c7c KVM: X86: use vzalloc() instead of vmalloc/memset
fixed the following warning:
/virt/kvm/dirty_ring.c:70:20-27: WARNING: vzalloc should be used for
ring -> dirty_gfns, instead of vmalloc/memset.

Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
Message-Id: <1611547045-13669-1-git-send-email-tiantao6@hisilicon.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-02-04 05:27:15 -05:00
Paolo Bonzini
bd2fae8da7 KVM: do not assume PTE is writable after follow_pfn
In order to convert an HVA to a PFN, KVM usually tries to use
the get_user_pages family of functinso.  This however is not
possible for VM_IO vmas; in that case, KVM instead uses follow_pfn.

In doing this however KVM loses the information on whether the
PFN is writable.  That is usually not a problem because the main
use of VM_IO vmas with KVM is for BARs in PCI device assignment,
however it is a bug.  To fix it, use follow_pte and check pte_write
while under the protection of the PTE lock.  The information can
be used to fail hva_to_pfn_remapped or passed back to the
caller via *writable.

Usage of follow_pfn was introduced in commit add6a0cd1c ("KVM: MMU: try to fix
up page faults before giving up", 2016-07-05); however, even older version
have the same issue, all the way back to commit 2e2e3738af ("KVM:
Handle vma regions with no backing page", 2008-07-20), as they also did
not check whether the PFN was writable.

Fixes: 2e2e3738af ("KVM: Handle vma regions with no backing page")
Reported-by: David Stevens <stevensd@google.com>
Cc: 3pvd@google.com
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-02-04 05:27:14 -05:00
Paolo Bonzini
615099b01e KVM/arm64 fixes for 5.11, take #2
- Don't allow tagged pointers to point to memslots
 - Filter out ARMv8.1+ PMU events on v8.0 hardware
 - Hide PMU registers from userspace when no PMU is configured
 - More PMU cleanups
 - Don't try to handle broken PSCI firmware
 - More sys_reg() to reg_to_encoding() conversions
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Merge tag 'kvmarm-fixes-5.11-2' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

KVM/arm64 fixes for 5.11, take #2

- Don't allow tagged pointers to point to memslots
- Filter out ARMv8.1+ PMU events on v8.0 hardware
- Hide PMU registers from userspace when no PMU is configured
- More PMU cleanups
- Don't try to handle broken PSCI firmware
- More sys_reg() to reg_to_encoding() conversions
2021-01-25 18:52:01 -05:00
Marc Zyngier
139bc8a614 KVM: Forbid the use of tagged userspace addresses for memslots
The use of a tagged address could be pretty confusing for the
whole memslot infrastructure as well as the MMU notifiers.

Forbid it altogether, as it never quite worked the first place.

Cc: stable@vger.kernel.org
Reported-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
2021-01-21 14:17:36 +00:00
Linus Torvalds
2a190b22aa x86:
* Fixes for the new scalable MMU
 * Fixes for migration of nested hypervisors on AMD
 * Fix for clang integrated assembler
 * Fix for left shift by 64 (UBSAN)
 * Small cleanups
 * Straggler SEV-ES patch
 
 ARM:
 * VM init cleanups
 * PSCI relay cleanups
 * Kill CONFIG_KVM_ARM_PMU
 * Fixup __init annotations
 * Fixup reg_to_encoding()
 * Fix spurious PMCR_EL0 access
 
 * selftests cleanups
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull kvm fixes from Paolo Bonzini:
 "x86:
   - Fixes for the new scalable MMU
   - Fixes for migration of nested hypervisors on AMD
   - Fix for clang integrated assembler
   - Fix for left shift by 64 (UBSAN)
   - Small cleanups
   - Straggler SEV-ES patch

  ARM:
   - VM init cleanups
   - PSCI relay cleanups
   - Kill CONFIG_KVM_ARM_PMU
   - Fixup __init annotations
   - Fixup reg_to_encoding()
   - Fix spurious PMCR_EL0 access

  Misc:
   - selftests cleanups"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (38 commits)
  KVM: x86: __kvm_vcpu_halt can be static
  KVM: SVM: Add support for booting APs in an SEV-ES guest
  KVM: nSVM: cancel KVM_REQ_GET_NESTED_STATE_PAGES on nested vmexit
  KVM: nSVM: mark vmcb as dirty when forcingly leaving the guest mode
  KVM: nSVM: correctly restore nested_run_pending on migration
  KVM: x86/mmu: Clarify TDP MMU page list invariants
  KVM: x86/mmu: Ensure TDP MMU roots are freed after yield
  kvm: check tlbs_dirty directly
  KVM: x86: change in pv_eoi_get_pending() to make code more readable
  MAINTAINERS: Really update email address for Sean Christopherson
  KVM: x86: fix shift out of bounds reported by UBSAN
  KVM: selftests: Implement perf_test_util more conventionally
  KVM: selftests: Use vm_create_with_vcpus in create_vm
  KVM: selftests: Factor out guest mode code
  KVM/SVM: Remove leftover __svm_vcpu_run prototype from svm.c
  KVM: SVM: Add register operand to vmsave call in sev_es_vcpu_load
  KVM: x86/mmu: Optimize not-present/MMIO SPTE check in get_mmio_spte()
  KVM: x86/mmu: Use raw level to index into MMIO walks' sptes array
  KVM: x86/mmu: Get root level from walkers when retrieving MMIO SPTE
  KVM: x86/mmu: Use -1 to flag an undefined spte in get_mmio_spte()
  ...
2021-01-08 15:06:02 -08:00
Lai Jiangshan
88bf56d04b kvm: check tlbs_dirty directly
In kvm_mmu_notifier_invalidate_range_start(), tlbs_dirty is used as:
        need_tlb_flush |= kvm->tlbs_dirty;
with need_tlb_flush's type being int and tlbs_dirty's type being long.

It means that tlbs_dirty is always used as int and the higher 32 bits
is useless.  We need to check tlbs_dirty in a correct way and this
change checks it directly without propagating it to need_tlb_flush.

Note: it's _extremely_ unlikely this neglecting of higher 32 bits can
cause problems in practice.  It would require encountering tlbs_dirty
on a 4 billion count boundary, and KVM would need to be using shadow
paging or be running a nested guest.

Cc: stable@vger.kernel.org
Fixes: a4ee1ca4a3 ("KVM: MMU: delay flush all tlbs on sync_page path")
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Message-Id: <20201217154118.16497-1-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-01-07 18:11:30 -05:00
Linus Torvalds
6a447b0e31 ARM:
* PSCI relay at EL2 when "protected KVM" is enabled
 * New exception injection code
 * Simplification of AArch32 system register handling
 * Fix PMU accesses when no PMU is enabled
 * Expose CSV3 on non-Meltdown hosts
 * Cache hierarchy discovery fixes
 * PV steal-time cleanups
 * Allow function pointers at EL2
 * Various host EL2 entry cleanups
 * Simplification of the EL2 vector allocation
 
 s390:
 * memcg accouting for s390 specific parts of kvm and gmap
 * selftest for diag318
 * new kvm_stat for when async_pf falls back to sync
 
 x86:
 * Tracepoints for the new pagetable code from 5.10
 * Catch VFIO and KVM irqfd events before userspace
 * Reporting dirty pages to userspace with a ring buffer
 * SEV-ES host support
 * Nested VMX support for wait-for-SIPI activity state
 * New feature flag (AVX512 FP16)
 * New system ioctl to report Hyper-V-compatible paravirtualization features
 
 Generic:
 * Selftest improvements
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull KVM updates from Paolo Bonzini:
 "Much x86 work was pushed out to 5.12, but ARM more than made up for it.

  ARM:
   - PSCI relay at EL2 when "protected KVM" is enabled
   - New exception injection code
   - Simplification of AArch32 system register handling
   - Fix PMU accesses when no PMU is enabled
   - Expose CSV3 on non-Meltdown hosts
   - Cache hierarchy discovery fixes
   - PV steal-time cleanups
   - Allow function pointers at EL2
   - Various host EL2 entry cleanups
   - Simplification of the EL2 vector allocation

  s390:
   - memcg accouting for s390 specific parts of kvm and gmap
   - selftest for diag318
   - new kvm_stat for when async_pf falls back to sync

  x86:
   - Tracepoints for the new pagetable code from 5.10
   - Catch VFIO and KVM irqfd events before userspace
   - Reporting dirty pages to userspace with a ring buffer
   - SEV-ES host support
   - Nested VMX support for wait-for-SIPI activity state
   - New feature flag (AVX512 FP16)
   - New system ioctl to report Hyper-V-compatible paravirtualization features

  Generic:
   - Selftest improvements"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (171 commits)
  KVM: SVM: fix 32-bit compilation
  KVM: SVM: Add AP_JUMP_TABLE support in prep for AP booting
  KVM: SVM: Provide support to launch and run an SEV-ES guest
  KVM: SVM: Provide an updated VMRUN invocation for SEV-ES guests
  KVM: SVM: Provide support for SEV-ES vCPU loading
  KVM: SVM: Provide support for SEV-ES vCPU creation/loading
  KVM: SVM: Update ASID allocation to support SEV-ES guests
  KVM: SVM: Set the encryption mask for the SVM host save area
  KVM: SVM: Add NMI support for an SEV-ES guest
  KVM: SVM: Guest FPU state save/restore not needed for SEV-ES guest
  KVM: SVM: Do not report support for SMM for an SEV-ES guest
  KVM: x86: Update __get_sregs() / __set_sregs() to support SEV-ES
  KVM: SVM: Add support for CR8 write traps for an SEV-ES guest
  KVM: SVM: Add support for CR4 write traps for an SEV-ES guest
  KVM: SVM: Add support for CR0 write traps for an SEV-ES guest
  KVM: SVM: Add support for EFER write traps for an SEV-ES guest
  KVM: SVM: Support string IO operations for an SEV-ES guest
  KVM: SVM: Support MMIO for an SEV-ES guest
  KVM: SVM: Create trace events for VMGEXIT MSR protocol processing
  KVM: SVM: Create trace events for VMGEXIT processing
  ...
2020-12-20 10:44:05 -08:00
Shakeel Butt
93bb59ca5e mm, kvm: account kvm_vcpu_mmap to kmemcg
A VCPU of a VM can allocate couple of pages which can be mmap'ed by the
user space application. At the moment this memory is not charged to the
memcg of the VMM. On a large machine running large number of VMs or
small number of VMs having large number of VCPUs, this unaccounted
memory can be very significant. So, charge this memory to the memcg of
the VMM. Please note that lifetime of these allocations corresponds to
the lifetime of the VMM.

Link: https://lkml.kernel.org/r/20201106202923.2087414-1-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-12-19 11:18:37 -08:00
Peter Xu
044c59c409 KVM: Don't allocate dirty bitmap if dirty ring is enabled
Because kvm dirty rings and kvm dirty log is used in an exclusive way,
Let's avoid creating the dirty_bitmap when kvm dirty ring is enabled.
At the meantime, since the dirty_bitmap will be conditionally created
now, we can't use it as a sign of "whether this memory slot enabled
dirty tracking".  Change users like that to check against the kvm
memory slot flags.

Note that there still can be chances where the kvm memory slot got its
dirty_bitmap allocated, _if_ the memory slots are created before
enabling of the dirty rings and at the same time with the dirty
tracking capability enabled, they'll still with the dirty_bitmap.
However it should not hurt much (e.g., the bitmaps will always be
freed if they are there), and the real users normally won't trigger
this because dirty bit tracking flag should in most cases only be
applied to kvm slots only before migration starts, that should be far
latter than kvm initializes (VM starts).

Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20201001012226.5868-1-peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-11-15 09:49:16 -05:00
Peter Xu
b2cc64c4f3 KVM: Make dirty ring exclusive to dirty bitmap log
There's no good reason to use both the dirty bitmap logging and the
new dirty ring buffer to track dirty bits.  We should be able to even
support both of them at the same time, but it could complicate things
which could actually help little.  Let's simply make it the rule
before we enable dirty ring on any arch, that we don't allow these two
interfaces to be used together.

The big world switch would be KVM_CAP_DIRTY_LOG_RING capability
enablement.  That's where we'll switch from the default dirty logging
way to the dirty ring way.  As long as kvm->dirty_ring_size is setup
correctly, we'll once and for all switch to the dirty ring buffer mode
for the current virtual machine.

Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20201001012224.5818-1-peterx@redhat.com>
[Change errno from EINVAL to ENXIO. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-11-15 09:49:16 -05:00
Peter Xu
fb04a1eddb KVM: X86: Implement ring-based dirty memory tracking
This patch is heavily based on previous work from Lei Cao
<lei.cao@stratus.com> and Paolo Bonzini <pbonzini@redhat.com>. [1]

KVM currently uses large bitmaps to track dirty memory.  These bitmaps
are copied to userspace when userspace queries KVM for its dirty page
information.  The use of bitmaps is mostly sufficient for live
migration, as large parts of memory are be dirtied from one log-dirty
pass to another.  However, in a checkpointing system, the number of
dirty pages is small and in fact it is often bounded---the VM is
paused when it has dirtied a pre-defined number of pages. Traversing a
large, sparsely populated bitmap to find set bits is time-consuming,
as is copying the bitmap to user-space.

A similar issue will be there for live migration when the guest memory
is huge while the page dirty procedure is trivial.  In that case for
each dirty sync we need to pull the whole dirty bitmap to userspace
and analyse every bit even if it's mostly zeros.

The preferred data structure for above scenarios is a dense list of
guest frame numbers (GFN).  This patch series stores the dirty list in
kernel memory that can be memory mapped into userspace to allow speedy
harvesting.

This patch enables dirty ring for X86 only.  However it should be
easily extended to other archs as well.

[1] https://patchwork.kernel.org/patch/10471409/

Signed-off-by: Lei Cao <lei.cao@stratus.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20201001012222.5767-1-peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-11-15 09:49:15 -05:00
Peter Xu
28bd726aa4 KVM: Pass in kvm pointer into mark_page_dirty_in_slot()
The context will be needed to implement the kvm dirty ring.

Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20201001012044.5151-5-peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-11-15 09:49:13 -05:00
Paolo Bonzini
2f5414423e KVM: remove kvm_clear_guest_page
kvm_clear_guest_page is not used anymore after "KVM: X86: Don't track dirty
for KVM_SET_[TSS_ADDR|IDENTITY_MAP_ADDR]", except from kvm_clear_guest.
We can just inline it in its sole user.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-11-15 09:49:13 -05:00
David Woodhouse
b59e00dd8c kvm/eventfd: Drain events from eventfd in irqfd_wakeup()
Don't allow the events to accumulate in the eventfd counter, drain them
as they are handled.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20201027135523.646811-4-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-11-15 09:49:11 -05:00
David Woodhouse
e8dbf19508 kvm/eventfd: Use priority waitqueue to catch events before userspace
As far as I can tell, when we use posted interrupts we silently cut off
the events from userspace, if it's listening on the same eventfd that
feeds the irqfd.

I like that behaviour. Let's do it all the time, even without posted
interrupts. It makes it much easier to handle IRQ remapping invalidation
without having to constantly add/remove the fd from the userspace poll
set. We can just leave userspace polling on it, and the bypass will...
well... bypass it.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20201026175325.585623-2-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-11-15 09:49:10 -05:00
Ben Gardon
a6a0b05da9 kvm: x86/mmu: Support dirty logging for the TDP MMU
Dirty logging is a key feature of the KVM MMU and must be supported by
the TDP MMU. Add support for both the write protection and PML dirty
logging modes.

Tested by running kvm-unit-tests and KVM selftests on an Intel Haswell
machine. This series introduced no new failures.

This series can be viewed in Gerrit at:
	https://linux-review.googlesource.com/c/virt/kvm/kvm/+/2538

Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20201014182700.2888246-16-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-10-23 03:42:13 -04:00
Peter Xu
9e9eb226b9 KVM: Cache as_id in kvm_memory_slot
Cache the address space ID just like the slot ID.  It will be used in
order to fill in the dirty ring entries.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Suggested-by: Sean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20201014182700.2888246-7-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-10-21 18:17:01 -04:00
Rustam Kovhaev
871c433bae KVM: use struct_size() and flex_array_size() helpers in kvm_io_bus_unregister_dev()
Make use of the struct_size() helper to avoid any potential type
mistakes and protect against potential integer overflows
Make use of the flex_array_size() helper to calculate the size of a
flexible array member within an enclosing structure

Suggested-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Rustam Kovhaev <rkovhaev@gmail.com>
Message-Id: <20200918120500.954436-1-rkovhaev@gmail.com>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-09-28 07:57:17 -04:00
Yi Li
2fc4f15dac kvm/eventfd: move wildcard calculation outside loop
There is no need to calculate wildcard in each iteration
since wildcard is not changed.

Signed-off-by: Yi Li <yili@winhong.com>
Message-Id: <20200911055652.3041762-1-yili@winhong.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-09-28 07:57:08 -04:00
Rustam Kovhaev
f65886606c KVM: fix memory leak in kvm_io_bus_unregister_dev()
when kmalloc() fails in kvm_io_bus_unregister_dev(), before removing
the bus, we should iterate over all other devices linked to it and call
kvm_iodevice_destructor() for them

Fixes: 90db10434b ("KVM: kvm_io_bus_unregister_dev() should never fail")
Cc: stable@vger.kernel.org
Reported-and-tested-by: syzbot+f196caa45793d6374707@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?extid=f196caa45793d6374707
Signed-off-by: Rustam Kovhaev <rkovhaev@gmail.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200907185535.233114-1-rkovhaev@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-09-11 13:15:11 -04:00
Paolo Bonzini
1b67fd086d KVM/arm64 fixes for Linux 5.9, take #1
- Multiple stolen time fixes, with a new capability to match x86
 - Fix for hugetlbfs mappings when PUD and PMD are the same level
 - Fix for hugetlbfs mappings when PTE mappings are enforced
   (dirty logging, for example)
 - Fix tracing output of 64bit values
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Merge tag 'kvmarm-fixes-5.9-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

KVM/arm64 fixes for Linux 5.9, take #1

- Multiple stolen time fixes, with a new capability to match x86
- Fix for hugetlbfs mappings when PUD and PMD are the same level
- Fix for hugetlbfs mappings when PTE mappings are enforced
  (dirty logging, for example)
- Fix tracing output of 64bit values
2020-09-11 13:12:11 -04:00
Will Deacon
fdfe7cbd58 KVM: Pass MMU notifier range flags to kvm_unmap_hva_range()
The 'flags' field of 'struct mmu_notifier_range' is used to indicate
whether invalidate_range_{start,end}() are permitted to block. In the
case of kvm_mmu_notifier_invalidate_range_start(), this field is not
forwarded on to the architecture-specific implementation of
kvm_unmap_hva_range() and therefore the backend cannot sensibly decide
whether or not to block.

Add an extra 'flags' parameter to kvm_unmap_hva_range() so that
architectures are aware as to whether or not they are permitted to block.

Cc: <stable@vger.kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: James Morse <james.morse@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Message-Id: <20200811102725.7121-2-will@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-08-21 18:03:47 -04:00
Linus Torvalds
9ad57f6dfc Merge branch 'akpm' (patches from Andrew)
Merge more updates from Andrew Morton:

 - most of the rest of MM (memcg, hugetlb, vmscan, proc, compaction,
   mempolicy, oom-kill, hugetlbfs, migration, thp, cma, util,
   memory-hotplug, cleanups, uaccess, migration, gup, pagemap),

 - various other subsystems (alpha, misc, sparse, bitmap, lib, bitops,
   checkpatch, autofs, minix, nilfs, ufs, fat, signals, kmod, coredump,
   exec, kdump, rapidio, panic, kcov, kgdb, ipc).

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (164 commits)
  mm/gup: remove task_struct pointer for all gup code
  mm: clean up the last pieces of page fault accountings
  mm/xtensa: use general page fault accounting
  mm/x86: use general page fault accounting
  mm/sparc64: use general page fault accounting
  mm/sparc32: use general page fault accounting
  mm/sh: use general page fault accounting
  mm/s390: use general page fault accounting
  mm/riscv: use general page fault accounting
  mm/powerpc: use general page fault accounting
  mm/parisc: use general page fault accounting
  mm/openrisc: use general page fault accounting
  mm/nios2: use general page fault accounting
  mm/nds32: use general page fault accounting
  mm/mips: use general page fault accounting
  mm/microblaze: use general page fault accounting
  mm/m68k: use general page fault accounting
  mm/ia64: use general page fault accounting
  mm/hexagon: use general page fault accounting
  mm/csky: use general page fault accounting
  ...
2020-08-12 11:24:12 -07:00
Peter Xu
64019a2e46 mm/gup: remove task_struct pointer for all gup code
After the cleanup of page fault accounting, gup does not need to pass
task_struct around any more.  Remove that parameter in the whole gup
stack.

Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Link: http://lkml.kernel.org/r/20200707225021.200906-26-peterx@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-08-12 10:58:04 -07:00
Linus Torvalds
57b0779392 virtio: fixes, features
IRQ bypass support for vdpa and IFC
 MLX5 vdpa driver
 Endian-ness fixes for virtio drivers
 Misc other fixes
 
 Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost

Pull virtio updates from Michael Tsirkin:

 - IRQ bypass support for vdpa and IFC

 - MLX5 vdpa driver

 - Endianness fixes for virtio drivers

 - Misc other fixes

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost: (71 commits)
  vdpa/mlx5: fix up endian-ness for mtu
  vdpa: Fix pointer math bug in vdpasim_get_config()
  vdpa/mlx5: Fix pointer math in mlx5_vdpa_get_config()
  vdpa/mlx5: fix memory allocation failure checks
  vdpa/mlx5: Fix uninitialised variable in core/mr.c
  vdpa_sim: init iommu lock
  virtio_config: fix up warnings on parisc
  vdpa/mlx5: Add VDPA driver for supported mlx5 devices
  vdpa/mlx5: Add shared memory registration code
  vdpa/mlx5: Add support library for mlx5 VDPA implementation
  vdpa/mlx5: Add hardware descriptive header file
  vdpa: Modify get_vq_state() to return error code
  net/vdpa: Use struct for set/get vq state
  vdpa: remove hard coded virtq num
  vdpasim: support batch updating
  vhost-vdpa: support IOTLB batching hints
  vhost-vdpa: support get/set backend features
  vhost: generialize backend features setting/getting
  vhost-vdpa: refine ioctl pre-processing
  vDPA: dont change vq irq after DRIVER_OK
  ...
2020-08-11 14:34:17 -07:00
Linus Torvalds
97d052ea3f A set of locking fixes and updates:
- Untangle the header spaghetti which causes build failures in various
     situations caused by the lockdep additions to seqcount to validate that
     the write side critical sections are non-preemptible.
 
   - The seqcount associated lock debug addons which were blocked by the
     above fallout.
 
     seqcount writers contrary to seqlock writers must be externally
     serialized, which usually happens via locking - except for strict per
     CPU seqcounts. As the lock is not part of the seqcount, lockdep cannot
     validate that the lock is held.
 
     This new debug mechanism adds the concept of associated locks.
     sequence count has now lock type variants and corresponding
     initializers which take a pointer to the associated lock used for
     writer serialization. If lockdep is enabled the pointer is stored and
     write_seqcount_begin() has a lockdep assertion to validate that the
     lock is held.
 
     Aside of the type and the initializer no other code changes are
     required at the seqcount usage sites. The rest of the seqcount API is
     unchanged and determines the type at compile time with the help of
     _Generic which is possible now that the minimal GCC version has been
     moved up.
 
     Adding this lockdep coverage unearthed a handful of seqcount bugs which
     have been addressed already independent of this.
 
     While generaly useful this comes with a Trojan Horse twist: On RT
     kernels the write side critical section can become preemtible if the
     writers are serialized by an associated lock, which leads to the well
     known reader preempts writer livelock. RT prevents this by storing the
     associated lock pointer independent of lockdep in the seqcount and
     changing the reader side to block on the lock when a reader detects
     that a writer is in the write side critical section.
 
  - Conversion of seqcount usage sites to associated types and initializers.
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Merge tag 'locking-urgent-2020-08-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Thomas Gleixner:
 "A set of locking fixes and updates:

   - Untangle the header spaghetti which causes build failures in
     various situations caused by the lockdep additions to seqcount to
     validate that the write side critical sections are non-preemptible.

   - The seqcount associated lock debug addons which were blocked by the
     above fallout.

     seqcount writers contrary to seqlock writers must be externally
     serialized, which usually happens via locking - except for strict
     per CPU seqcounts. As the lock is not part of the seqcount, lockdep
     cannot validate that the lock is held.

     This new debug mechanism adds the concept of associated locks.
     sequence count has now lock type variants and corresponding
     initializers which take a pointer to the associated lock used for
     writer serialization. If lockdep is enabled the pointer is stored
     and write_seqcount_begin() has a lockdep assertion to validate that
     the lock is held.

     Aside of the type and the initializer no other code changes are
     required at the seqcount usage sites. The rest of the seqcount API
     is unchanged and determines the type at compile time with the help
     of _Generic which is possible now that the minimal GCC version has
     been moved up.

     Adding this lockdep coverage unearthed a handful of seqcount bugs
     which have been addressed already independent of this.

     While generally useful this comes with a Trojan Horse twist: On RT
     kernels the write side critical section can become preemtible if
     the writers are serialized by an associated lock, which leads to
     the well known reader preempts writer livelock. RT prevents this by
     storing the associated lock pointer independent of lockdep in the
     seqcount and changing the reader side to block on the lock when a
     reader detects that a writer is in the write side critical section.

   - Conversion of seqcount usage sites to associated types and
     initializers"

* tag 'locking-urgent-2020-08-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (25 commits)
  locking/seqlock, headers: Untangle the spaghetti monster
  locking, arch/ia64: Reduce <asm/smp.h> header dependencies by moving XTP bits into the new <asm/xtp.h> header
  x86/headers: Remove APIC headers from <asm/smp.h>
  seqcount: More consistent seqprop names
  seqcount: Compress SEQCNT_LOCKNAME_ZERO()
  seqlock: Fold seqcount_LOCKNAME_init() definition
  seqlock: Fold seqcount_LOCKNAME_t definition
  seqlock: s/__SEQ_LOCKDEP/__SEQ_LOCK/g
  hrtimer: Use sequence counter with associated raw spinlock
  kvm/eventfd: Use sequence counter with associated spinlock
  userfaultfd: Use sequence counter with associated spinlock
  NFSv4: Use sequence counter with associated spinlock
  iocost: Use sequence counter with associated spinlock
  raid5: Use sequence counter with associated spinlock
  vfs: Use sequence counter with associated spinlock
  timekeeping: Use sequence counter with associated raw spinlock
  xfrm: policy: Use sequence counters with associated lock
  netfilter: nft_set_rbtree: Use sequence counter with associated rwlock
  netfilter: conntrack: Use sequence counter with associated spinlock
  sched: tasks: Use sequence counter with associated spinlock
  ...
2020-08-10 19:07:44 -07:00
Linus Torvalds
921d2597ab s390: implement diag318
x86:
 * Report last CPU for debugging
 * Emulate smaller MAXPHYADDR in the guest than in the host
 * .noinstr and tracing fixes from Thomas
 * nested SVM page table switching optimization and fixes
 
 Generic:
 * Unify shadow MMU cache data structures across architectures
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull KVM updates from Paolo Bonzini:
 "s390:
   - implement diag318

  x86:
   - Report last CPU for debugging
   - Emulate smaller MAXPHYADDR in the guest than in the host
   - .noinstr and tracing fixes from Thomas
   - nested SVM page table switching optimization and fixes

  Generic:
   - Unify shadow MMU cache data structures across architectures"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (127 commits)
  KVM: SVM: Fix sev_pin_memory() error handling
  KVM: LAPIC: Set the TDCR settable bits
  KVM: x86: Specify max TDP level via kvm_configure_mmu()
  KVM: x86/mmu: Rename max_page_level to max_huge_page_level
  KVM: x86: Dynamically calculate TDP level from max level and MAXPHYADDR
  KVM: VXM: Remove temporary WARN on expected vs. actual EPTP level mismatch
  KVM: x86: Pull the PGD's level from the MMU instead of recalculating it
  KVM: VMX: Make vmx_load_mmu_pgd() static
  KVM: x86/mmu: Add separate helper for shadow NPT root page role calc
  KVM: VMX: Drop a duplicate declaration of construct_eptp()
  KVM: nSVM: Correctly set the shadow NPT root level in its MMU role
  KVM: Using macros instead of magic values
  MIPS: KVM: Fix build error caused by 'kvm_run' cleanup
  KVM: nSVM: remove nonsensical EXITINFO1 adjustment on nested NPF
  KVM: x86: Add a capability for GUEST_MAXPHYADDR < HOST_MAXPHYADDR support
  KVM: VMX: optimize #PF injection when MAXPHYADDR does not match
  KVM: VMX: Add guest physical address check in EPT violation and misconfig
  KVM: VMX: introduce vmx_need_pf_intercept
  KVM: x86: update exception bitmap on CPUID changes
  KVM: x86: rename update_bp_intercept to update_exception_bitmap
  ...
2020-08-06 12:59:31 -07:00
Zhu Lingshan
a979a6aa00 irqbypass: do not start cons/prod when failed connect
If failed to connect, there is no need to start consumer nor
producer.

Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
Suggested-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20200731065533.4144-7-lingshan.zhu@intel.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2020-08-05 11:08:42 -04:00
Ahmed S. Darwish
5c73b9a2b1 kvm/eventfd: Use sequence counter with associated spinlock
A sequence counter write side critical section must be protected by some
form of locking to serialize writers. A plain seqcount_t does not
contain the information of which lock must be held when entering a write
side critical section.

Use the new seqcount_spinlock_t data type, which allows to associate a
spinlock with the sequence counter. This enables lockdep to verify that
the spinlock used for writer serialization is held when the write side
critical section is entered.

If lockdep is disabled this lock association is compiled out and has
neither storage size nor runtime overhead.

Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lkml.kernel.org/r/20200720155530.1173732-24-a.darwish@linutronix.de
2020-07-29 16:14:29 +02:00
Thomas Gleixner
935ace2fb5 entry: Provide infrastructure for work before transitioning to guest mode
Entering a guest is similar to exiting to user space. Pending work like
handling signals, rescheduling, task work etc. needs to be handled before
that.

Provide generic infrastructure to avoid duplication of the same handling
code all over the place.

The transfer to guest mode handling is different from the exit to usermode
handling, e.g. vs. rseq and live patching, so a separate function is used.

The initial list of work items handled is:

    TIF_SIGPENDING, TIF_NEED_RESCHED, TIF_NOTIFY_RESUME

Architecture specific TIF flags can be added via defines in the
architecture specific include files.

The calling convention is also different from the syscall/interrupt entry
functions as KVM invokes this from the outer vcpu_run() loop with
interrupts and preemption enabled. To prevent missing a pending work item
it invokes a check for pending TIF work from interrupt disabled code right
before transitioning to guest mode. The lockdep, RCU and tracing state
handling is also done directly around the switch to and from guest mode.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200722220519.833296398@linutronix.de
2020-07-24 15:03:42 +02:00