commit 3491caf275 ("KVM: halt_polling: provide a way to qualify
wakeups during poll") added more aggressive shrinking of the
polling interval if the wakeup did not match some criteria. This
still allows to keep polling enabled if the polling time was
smaller that the current max poll time (block_ns <= vcpu->halt_poll_ns).
Performance measurement shows that even more aggressive shrinking
(shrink polling on any invalid wakeup) reduces absolute and relative
(to the workload) CPU usage even further.
Cc: David Matlack <dmatlack@google.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Some wakeups should not be considered a sucessful poll. For example on
s390 I/O interrupts are usually floating, which means that _ALL_ CPUs
would be considered runnable - letting all vCPUs poll all the time for
transactional like workload, even if one vCPU would be enough.
This can result in huge CPU usage for large guests.
This patch lets architectures provide a way to qualify wakeups if they
should be considered a good/bad wakeups in regard to polls.
For s390 the implementation will fence of halt polling for anything but
known good, single vCPU events. The s390 implementation for floating
interrupts does a wakeup for one vCPU, but the interrupt will be delivered
by whatever CPU checks first for a pending interrupt. We prefer the
woken up CPU by marking the poll of this CPU as "good" poll.
This code will also mark several other wakeup reasons like IPI or
expired timers as "good". This will of course also mark some events as
not sucessful. As KVM on z runs always as a 2nd level hypervisor,
we prefer to not poll, unless we are really sure, though.
This patch successfully limits the CPU usage for cases like uperf 1byte
transactional ping pong workload or wakeup heavy workload like OLTP
while still providing a proper speedup.
This also introduced a new vcpu stat "halt_poll_no_tuning" that marks
wakeups that are considered not good for polling.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Radim Krčmář <rkrcmar@redhat.com> (for an earlier version)
Cc: David Matlack <dmatlack@google.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
[Rename config symbol. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
If we don't support a mechanism for bypassing IRQs, don't register as
a consumer. This eliminates meaningless dev_info()s when the connect
fails between producer and consumer, such as on AMD systems where
kvm_x86_ops->update_pi_irte is not implemented
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
A NULL token is meaningless and can only lead to unintended problems.
Error on registration with a NULL token, ignore de-registrations with
a NULL token.
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The KVM_MAX_VCPUS define provides the maximum number of vCPUs per guest, and
also the upper limit for vCPU ids. This is okay for all archs except PowerPC
which can have higher ids, depending on the cpu/core/thread topology. In the
worst case (single threaded guest, host with 8 threads per core), it limits
the maximum number of vCPUS to KVM_MAX_VCPUS / 8.
This patch separates the vCPU numbering from the total number of vCPUs, with
the introduction of KVM_MAX_VCPU_ID, as the maximal valid value for vCPU ids
plus one.
The corresponding KVM_CAP_MAX_VCPU_ID allows userspace to validate vCPU ids
before passing them to KVM_CREATE_VCPU.
This patch only implements KVM_MAX_VCPU_ID with a specific value for PowerPC.
Other archs continue to return KVM_MAX_VCPUS instead.
Suggested-by: Radim Krcmar <rkrcmar@redhat.com>
Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Currently, the firmware tables are parsed 2 times: once in the GIC
drivers, the other time when initializing the vGIC. It means code
duplication and make more tedious to add the support for another
firmware table (like ACPI).
Use the recently introduced helper gic_get_kvm_info() to get
information about the virtual GIC.
With this change, the virtual GIC becomes agnostic to the firmware
table and KVM will be able to initialize the vGIC on ACPI.
Signed-off-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
The firmware table is currently parsed by the virtual timer code in
order to retrieve the virtual timer interrupt. However, this is already
done by the arch timer driver.
To avoid code duplication, use the newly function arch_timer_get_kvm_info()
which return all the information required by the virtual timer code.
Signed-off-by: Julien Grall <julien.grall@arm.com>
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
On a host that runs NTP, corrections can have a direct impact on
the background timer that we program on the behalf of a vcpu.
In particular, NTP performing a forward correction will result in
a timer expiring sooner than expected from a guest point of view.
Not a big deal, we kick the vcpu anyway.
But on wake-up, the vcpu thread is going to perform a check to
find out whether or not it should block. And at that point, the
timer check is going to say "timer has not expired yet, go back
to sleep". This results in the timer event being lost forever.
There are multiple ways to handle this. One would be record that
the timer has expired and let kvm_cpu_has_pending_timer return
true in that case, but that would be fairly invasive. Another is
to check for the "short sleep" condition in the hrtimer callback,
and restart the timer for the remaining time when the condition
is detected.
This patch implements the latter, with a bit of refactoring in
order to avoid too much code duplication.
Cc: <stable@vger.kernel.org>
Reported-by: Alexander Graf <agraf@suse.de>
Reviewed-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
The kernel is written in C, not python, so we need braces around
multi-line if statements. GCC 6 actually warns about this, thanks to the
fantastic new "-Wmisleading-indentation" flag:
| virt/kvm/arm/pmu.c: In function ‘kvm_pmu_overflow_status’:
| virt/kvm/arm/pmu.c:198:3: warning: statement is indented as if it were guarded by... [-Wmisleading-indentation]
| reg &= vcpu_sys_reg(vcpu, PMCNTENSET_EL0);
| ^~~
| arch/arm64/kvm/../../../virt/kvm/arm/pmu.c:196:2: note: ...this ‘if’ clause, but it is not
| if ((vcpu_sys_reg(vcpu, PMCR_EL0) & ARMV8_PMU_PMCR_E))
| ^~
As it turns out, this particular case is harmless (we just do some &=
operations with 0), but worth fixing nonetheless.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
smp_load_acquire() is enough here and it's cheaper than smp_mb().
Adding a comment about reusing memory barrier of kvm_make_all_cpus_request()
here to keep order between modifications to the page tables and reading mode.
Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Moving the initialization earlier is needed in 4.6 because
kvm_arch_init_vm is now using mmu_lock, causing lockdep to
complain:
[ 284.440294] INFO: trying to register non-static key.
[ 284.445259] the code is fine but needs lockdep annotation.
[ 284.450736] turning off the locking correctness validator.
...
[ 284.528318] [<ffffffff810aecc3>] lock_acquire+0xd3/0x240
[ 284.533733] [<ffffffffa0305aa0>] ? kvm_page_track_register_notifier+0x20/0x60 [kvm]
[ 284.541467] [<ffffffff81715581>] _raw_spin_lock+0x41/0x80
[ 284.546960] [<ffffffffa0305aa0>] ? kvm_page_track_register_notifier+0x20/0x60 [kvm]
[ 284.554707] [<ffffffffa0305aa0>] kvm_page_track_register_notifier+0x20/0x60 [kvm]
[ 284.562281] [<ffffffffa02ece70>] kvm_mmu_init_vm+0x20/0x30 [kvm]
[ 284.568381] [<ffffffffa02dbf7a>] kvm_arch_init_vm+0x1ea/0x200 [kvm]
[ 284.574740] [<ffffffffa02bff3f>] kvm_dev_ioctl+0xbf/0x4d0 [kvm]
However, it also helps fixing a preexisting problem, which is why this
patch is also good for stable kernels: kvm_create_vm was incrementing
current->mm->mm_count but not decrementing it at the out_err label (in
case kvm_init_mmu_notifier failed). The new initialization order makes
it possible to add the required mmdrop without adding a new error label.
Cc: stable@vger.kernel.org
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Pull x86 protection key support from Ingo Molnar:
"This tree adds support for a new memory protection hardware feature
that is available in upcoming Intel CPUs: 'protection keys' (pkeys).
There's a background article at LWN.net:
https://lwn.net/Articles/643797/
The gist is that protection keys allow the encoding of
user-controllable permission masks in the pte. So instead of having a
fixed protection mask in the pte (which needs a system call to change
and works on a per page basis), the user can map a (handful of)
protection mask variants and can change the masks runtime relatively
cheaply, without having to change every single page in the affected
virtual memory range.
This allows the dynamic switching of the protection bits of large
amounts of virtual memory, via user-space instructions. It also
allows more precise control of MMU permission bits: for example the
executable bit is separate from the read bit (see more about that
below).
This tree adds the MM infrastructure and low level x86 glue needed for
that, plus it adds a high level API to make use of protection keys -
if a user-space application calls:
mmap(..., PROT_EXEC);
or
mprotect(ptr, sz, PROT_EXEC);
(note PROT_EXEC-only, without PROT_READ/WRITE), the kernel will notice
this special case, and will set a special protection key on this
memory range. It also sets the appropriate bits in the Protection
Keys User Rights (PKRU) register so that the memory becomes unreadable
and unwritable.
So using protection keys the kernel is able to implement 'true'
PROT_EXEC on x86 CPUs: without protection keys PROT_EXEC implies
PROT_READ as well. Unreadable executable mappings have security
advantages: they cannot be read via information leaks to figure out
ASLR details, nor can they be scanned for ROP gadgets - and they
cannot be used by exploits for data purposes either.
We know about no user-space code that relies on pure PROT_EXEC
mappings today, but binary loaders could start making use of this new
feature to map binaries and libraries in a more secure fashion.
There is other pending pkeys work that offers more high level system
call APIs to manage protection keys - but those are not part of this
pull request.
Right now there's a Kconfig that controls this feature
(CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS) that is default enabled
(like most x86 CPU feature enablement code that has no runtime
overhead), but it's not user-configurable at the moment. If there's
any serious problem with this then we can make it configurable and/or
flip the default"
* 'mm-pkeys-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (38 commits)
x86/mm/pkeys: Fix mismerge of protection keys CPUID bits
mm/pkeys: Fix siginfo ABI breakage caused by new u64 field
x86/mm/pkeys: Fix access_error() denial of writes to write-only VMA
mm/core, x86/mm/pkeys: Add execute-only protection keys support
x86/mm/pkeys: Create an x86 arch_calc_vm_prot_bits() for VMA flags
x86/mm/pkeys: Allow kernel to modify user pkey rights register
x86/fpu: Allow setting of XSAVE state
x86/mm: Factor out LDT init from context init
mm/core, x86/mm/pkeys: Add arch_validate_pkey()
mm/core, arch, powerpc: Pass a protection key in to calc_vm_flag_bits()
x86/mm/pkeys: Actually enable Memory Protection Keys in the CPU
x86/mm/pkeys: Add Kconfig prompt to existing config option
x86/mm/pkeys: Dump pkey from VMA in /proc/pid/smaps
x86/mm/pkeys: Dump PKRU with other kernel registers
mm/core, x86/mm/pkeys: Differentiate instruction fetches
x86/mm/pkeys: Optimize fault handling in access_error()
mm/core: Do not enforce PKEY permissions on remote mm access
um, pkeys: Add UML arch_*_access_permitted() methods
mm/gup, x86/mm/pkeys: Check VMAs and PTEs for protection keys
x86/mm/gup: Simplify get_user_pages() PTE bit handling
...
but lots of architecture-specific changes.
* ARM:
- VHE support so that we can run the kernel at EL2 on ARMv8.1 systems
- PMU support for guests
- 32bit world switch rewritten in C
- various optimizations to the vgic save/restore code.
* PPC:
- enabled KVM-VFIO integration ("VFIO device")
- optimizations to speed up IPIs between vcpus
- in-kernel handling of IOMMU hypercalls
- support for dynamic DMA windows (DDW).
* s390:
- provide the floating point registers via sync regs;
- separated instruction vs. data accesses
- dirty log improvements for huge guests
- bugfixes and documentation improvements.
* x86:
- Hyper-V VMBus hypercall userspace exit
- alternative implementation of lowest-priority interrupts using vector
hashing (for better VT-d posted interrupt support)
- fixed guest debugging with nested virtualizations
- improved interrupt tracking in the in-kernel IOAPIC
- generic infrastructure for tracking writes to guest memory---currently
its only use is to speedup the legacy shadow paging (pre-EPT) case, but
in the future it will be used for virtual GPUs as well
- much cleanup (LAPIC, kvmclock, MMU, PIT), including ubsan fixes.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull KVM updates from Paolo Bonzini:
"One of the largest releases for KVM... Hardly any generic
changes, but lots of architecture-specific updates.
ARM:
- VHE support so that we can run the kernel at EL2 on ARMv8.1 systems
- PMU support for guests
- 32bit world switch rewritten in C
- various optimizations to the vgic save/restore code.
PPC:
- enabled KVM-VFIO integration ("VFIO device")
- optimizations to speed up IPIs between vcpus
- in-kernel handling of IOMMU hypercalls
- support for dynamic DMA windows (DDW).
s390:
- provide the floating point registers via sync regs;
- separated instruction vs. data accesses
- dirty log improvements for huge guests
- bugfixes and documentation improvements.
x86:
- Hyper-V VMBus hypercall userspace exit
- alternative implementation of lowest-priority interrupts using
vector hashing (for better VT-d posted interrupt support)
- fixed guest debugging with nested virtualizations
- improved interrupt tracking in the in-kernel IOAPIC
- generic infrastructure for tracking writes to guest
memory - currently its only use is to speedup the legacy shadow
paging (pre-EPT) case, but in the future it will be used for
virtual GPUs as well
- much cleanup (LAPIC, kvmclock, MMU, PIT), including ubsan fixes"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (217 commits)
KVM: x86: remove eager_fpu field of struct kvm_vcpu_arch
KVM: x86: disable MPX if host did not enable MPX XSAVE features
arm64: KVM: vgic-v3: Only wipe LRs on vcpu exit
arm64: KVM: vgic-v3: Reset LRs at boot time
arm64: KVM: vgic-v3: Do not save an LR known to be empty
arm64: KVM: vgic-v3: Save maintenance interrupt state only if required
arm64: KVM: vgic-v3: Avoid accessing ICH registers
KVM: arm/arm64: vgic-v2: Make GICD_SGIR quicker to hit
KVM: arm/arm64: vgic-v2: Only wipe LRs on vcpu exit
KVM: arm/arm64: vgic-v2: Reset LRs at boot time
KVM: arm/arm64: vgic-v2: Do not save an LR known to be empty
KVM: arm/arm64: vgic-v2: Move GICH_ELRSR saving to its own function
KVM: arm/arm64: vgic-v2: Save maintenance interrupt state only if required
KVM: arm/arm64: vgic-v2: Avoid accessing GICH registers
KVM: s390: allocate only one DMA page per VM
KVM: s390: enable STFLE interpretation only if enabled for the guest
KVM: s390: wake up when the VCPU cpu timer expires
KVM: s390: step the VCPU timer while in enabled wait
KVM: s390: protect VCPU cpu timer with a seqcount
KVM: s390: step VCPU cpu timer during kvm_run ioctl
...
Pull scheduler updates from Ingo Molnar:
"The main changes in this cycle are:
- Make schedstats a runtime tunable (disabled by default) and
optimize it via static keys.
As most distributions enable CONFIG_SCHEDSTATS=y due to its
instrumentation value, this is a nice performance enhancement.
(Mel Gorman)
- Implement 'simple waitqueues' (swait): these are just pure
waitqueues without any of the more complex features of full-blown
waitqueues (callbacks, wake flags, wake keys, etc.). Simple
waitqueues have less memory overhead and are faster.
Use simple waitqueues in the RCU code (in 4 different places) and
for handling KVM vCPU wakeups.
(Peter Zijlstra, Daniel Wagner, Thomas Gleixner, Paul Gortmaker,
Marcelo Tosatti)
- sched/numa enhancements (Rik van Riel)
- NOHZ performance enhancements (Rik van Riel)
- Various sched/deadline enhancements (Steven Rostedt)
- Various fixes (Peter Zijlstra)
- ... and a number of other fixes, cleanups and smaller enhancements"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (29 commits)
sched/cputime: Fix steal_account_process_tick() to always return jiffies
sched/deadline: Remove dl_new from struct sched_dl_entity
Revert "kbuild: Add option to turn incompatible pointer check into error"
sched/deadline: Remove superfluous call to switched_to_dl()
sched/debug: Fix preempt_disable_ip recording for preempt_disable()
sched, time: Switch VIRT_CPU_ACCOUNTING_GEN to jiffy granularity
time, acct: Drop irq save & restore from __acct_update_integrals()
acct, time: Change indentation in __acct_update_integrals()
sched, time: Remove non-power-of-two divides from __acct_update_integrals()
sched/rt: Kick RT bandwidth timer immediately on start up
sched/debug: Add deadline scheduler bandwidth ratio to /proc/sched_debug
sched/debug: Move sched_domain_sysctl to debug.c
sched/debug: Move the /sys/kernel/debug/sched_features file setup into debug.c
sched/rt: Fix PI handling vs. sched_setscheduler()
sched/core: Remove duplicated sched_group_set_shares() prototype
sched/fair: Consolidate nohz CPU load update code
sched/fair: Avoid using decay_load_missed() with a negative value
sched/deadline: Always calculate end of period on sched_yield()
sched/cgroup: Fix cgroup entity load tracking tear-down
rcu: Use simple wait queues where possible in rcutree
...
When growing halt-polling, there is no check that the poll time exceeds
the limit. It's possible for vcpu->halt_poll_ns grow once past
halt_poll_ns, and stay there until a halt which takes longer than
vcpu->halt_poll_ns. For example, booting a Linux guest with
halt_poll_ns=11000:
... kvm:kvm_halt_poll_ns: vcpu 0: halt_poll_ns 0 (shrink 10000)
... kvm:kvm_halt_poll_ns: vcpu 0: halt_poll_ns 10000 (grow 0)
... kvm:kvm_halt_poll_ns: vcpu 0: halt_poll_ns 20000 (grow 10000)
Signed-off-by: David Matlack <dmatlack@google.com>
Fixes: aca6ff29c4
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
- VHE support so that we can run the kernel at EL2 on ARMv8.1 systems
- PMU support for guests
- 32bit world switch rewritten in C
- Various optimizations to the vgic save/restore code
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Merge tag 'kvm-arm-for-4.6' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD
KVM/ARM updates for 4.6
- VHE support so that we can run the kernel at EL2 on ARMv8.1 systems
- PMU support for guests
- 32bit world switch rewritten in C
- Various optimizations to the vgic save/restore code
Conflicts:
include/uapi/linux/kvm.h
In order to let the GICv3 code be more lazy in the way it
accesses the LRs, it is necessary to start with a clean slate.
Let's reset the LRs on each CPU when the vgic is probed (which
includes a round trip to EL2...).
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Just like on GICv2, we're a bit hammer-happy with GICv3, and access
them more often than we should.
Adopt a policy similar to what we do for GICv2, only save/restoring
the minimal set of registers. As we don't access the registers
linearly anymore (we may skip some), the convoluted accessors become
slightly simpler, and we can drop the ugly indexing macro that
tended to confuse the reviewers.
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
The GICD_SGIR register lives a long way from the beginning of
the handler array, which is searched linearly. As this is hit
pretty often, let's move it up. This saves us some precious
cycles when the guest is generating IPIs.
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
So far, we're always writing all possible LRs, setting the empty
ones with a zero value. This is obvious doing a lot of work for
nothing, and we're better off clearing those we've actually
dirtied on the exit path (it is very rare to inject more than one
interrupt at a time anyway).
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
In order to let make the GICv2 code more lazy in the way it
accesses the LRs, it is necessary to start with a clean slate.
Let's reset the LRs on each CPU when the vgic is probed.
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
On exit, any empty LR will be signaled in GICH_ELRSR*. Which
means that we do not have to save it, and we can just clear
its state in the in-memory copy.
Take this opportunity to move the LR saving code into its
own function.
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
In order to make the saving path slightly more readable and
prepare for some more optimizations, let's move the GICH_ELRSR
saving to its own function.
No functional change.
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Next on our list of useless accesses is the maintenance interrupt
status registers (GICH_MISR, GICH_EISR{0,1}).
It is pointless to save them if we haven't asked for a maintenance
interrupt the first place, which can only happen for two reasons:
- Underflow: GICH_HCR_UIE will be set,
- EOI: GICH_LR_EOI will be set.
These conditions can be checked on the in-memory copies of the regs.
Should any of these two condition be valid, we must read GICH_MISR.
We can then check for GICH_MISR_EOI, and only when set read
GICH_EISR*.
This means that in most case, we don't have to save them at all.
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
GICv2 registers are *slow*. As in "terrifyingly slow". Which is bad.
But we're equaly bad, as we make a point in accessing them even if
we don't have any interrupt in flight.
A good solution is to first find out if we have anything useful to
write into the GIC, and if we don't, to simply not do it. This
involves tracking which LRs actually have something valid there.
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
For the kvm_is_error_hva, ubsan complains if the uninitialized writable
is passed to __direct_map, even though the value itself is not used
(__direct_map goes to mmu_set_spte->set_spte->set_mmio_spte but never
looks at that argument).
Ensuring that __gfn_to_pfn_memslot initializes *writable is cheap and
avoids this kind of issue.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Programming the active state in the (re)distributor can be an
expensive operation so it makes some sense to try and reduce
the number of accesses as much as possible. So far, we
program the active state on each VM entry, but there is some
opportunity to do less.
An obvious solution is to cache the active state in memory,
and only program it in the HW when conditions change. But
because the HW can also change things under our feet (the active
state can transition from 1 to 0 when the guest does an EOI),
some precautions have to be taken, which amount to only caching
an "inactive" state, and always programing it otherwise.
With this in place, we observe a reduction of around 700 cycles
on a 2GHz GICv2 platform for a NULL hypercall.
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
To configure the virtual PMUv3 overflow interrupt number, we use the
vcpu kvm_device ioctl, encapsulating the KVM_ARM_VCPU_PMU_V3_IRQ
attribute within the KVM_ARM_VCPU_PMU_V3_CTRL group.
After configuring the PMUv3, call the vcpu ioctl with attribute
KVM_ARM_VCPU_PMU_V3_INIT to initialize the PMUv3.
Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Acked-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
To support guest PMUv3, use one bit of the VCPU INIT feature array.
Initialize the PMU when initialzing the vcpu with that bit and PMU
overflow interrupt set.
Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Acked-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
When KVM frees VCPU, it needs to free the perf_event of PMU.
Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
When resetting vcpu, it needs to reset the PMU state to initial status.
Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
When calling perf_event_create_kernel_counter to create perf_event,
assign a overflow handler. Then when the perf event overflows, set the
corresponding bit of guest PMOVSSET register. If this counter is enabled
and its interrupt is enabled as well, kick the vcpu to sync the
interrupt.
On VM entry, if there is counter overflowed and interrupt level is
changed, inject the interrupt with corresponding level. On VM exit, sync
the interrupt level as well if it has been changed.
Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
According to ARMv8 spec, when writing 1 to PMCR.E, all counters are
enabled by PMCNTENSET, while writing 0 to PMCR.E, all counters are
disabled. When writing 1 to PMCR.P, reset all event counters, not
including PMCCNTR, to zero. When writing 1 to PMCR.C, reset PMCCNTR to
zero.
Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Add access handler which emulates writing and reading PMSWINC
register and add support for creating software increment event.
Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Since the reset value of PMOVSSET and PMOVSCLR is UNKNOWN, use
reset_unknown for its reset handler. Add a handler to emulate writing
PMOVSSET or PMOVSCLR register.
When writing non-zero value to PMOVSSET, the counter and its interrupt
is enabled, kick this vcpu to sync PMU interrupt.
Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
When we use tools like perf on host, perf passes the event type and the
id of this event type category to kernel, then kernel will map them to
hardware event number and write this number to PMU PMEVTYPER<n>_EL0
register. When getting the event number in KVM, directly use raw event
type to create a perf_event for it.
Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Since the reset value of PMCNTENSET and PMCNTENCLR is UNKNOWN, use
reset_unknown for its reset handler. Add a handler to emulate writing
PMCNTENSET or PMCNTENCLR register.
When writing to PMCNTENSET, call perf_event_enable to enable the perf
event. When writing to PMCNTENCLR, call perf_event_disable to disable
the perf event.
Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
These kind of registers include PMEVCNTRn, PMCCNTR and PMXEVCNTR which
is mapped to PMEVCNTRn.
The access handler translates all aarch32 register offsets to aarch64
ones and uses vcpu_sys_reg() to access their values to avoid taking care
of big endian.
When reading these registers, return the sum of register value and the
value perf event counts.
Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
We already have virt/kvm/arm/ containing timer and vgic stuff.
Add yet another subdirectory to contain the hyp-specific files
(timer and vgic again).
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
The problem:
On -rt, an emulated LAPIC timer instances has the following path:
1) hard interrupt
2) ksoftirqd is scheduled
3) ksoftirqd wakes up vcpu thread
4) vcpu thread is scheduled
This extra context switch introduces unnecessary latency in the
LAPIC path for a KVM guest.
The solution:
Allow waking up vcpu thread from hardirq context,
thus avoiding the need for ksoftirqd to be scheduled.
Normal waitqueues make use of spinlocks, which on -RT
are sleepable locks. Therefore, waking up a waitqueue
waiter involves locking a sleeping lock, which
is not allowed from hard interrupt context.
cyclictest command line:
This patch reduces the average latency in my tests from 14us to 11us.
Daniel writes:
Paolo asked for numbers from kvm-unit-tests/tscdeadline_latency
benchmark on mainline. The test was run 1000 times on
tip/sched/core 4.4.0-rc8-01134-g0905f04:
./x86-run x86/tscdeadline_latency.flat -cpu host
with idle=poll.
The test seems not to deliver really stable numbers though most of
them are smaller. Paolo write:
"Anything above ~10000 cycles means that the host went to C1 or
lower---the number means more or less nothing in that case.
The mean shows an improvement indeed."
Before:
min max mean std
count 1000.000000 1000.000000 1000.000000 1000.000000
mean 5162.596000 2019270.084000 5824.491541 20681.645558
std 75.431231 622607.723969 89.575700 6492.272062
min 4466.000000 23928.000000 5537.926500 585.864966
25% 5163.000000 1613252.750000 5790.132275 16683.745433
50% 5175.000000 2281919.000000 5834.654000 23151.990026
75% 5190.000000 2382865.750000 5861.412950 24148.206168
max 5228.000000 4175158.000000 6254.827300 46481.048691
After
min max mean std
count 1000.000000 1000.00000 1000.000000 1000.000000
mean 5143.511000 2076886.10300 5813.312474 21207.357565
std 77.668322 610413.09583 86.541500 6331.915127
min 4427.000000 25103.00000 5529.756600 559.187707
25% 5148.000000 1691272.75000 5784.889825 17473.518244
50% 5160.000000 2308328.50000 5832.025000 23464.837068
75% 5172.000000 2393037.75000 5853.177675 24223.969976
max 5222.000000 3922458.00000 6186.720500 42520.379830
[Patch was originaly based on the swait implementation found in the -rt
tree. Daniel ported it to mainline's version and gathered the
benchmark numbers for tscdeadline_latency test.]
Signed-off-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: linux-rt-users@vger.kernel.org
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1455871601-27484-4-git-send-email-wagi@monom.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
- Fix per-vcpu vgic bitmap allocation
- Do not give copy random memory on MMIO read
- Fix GICv3 APR register restore order
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Merge tag 'kvm-arm-for-4.5-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into kvm-master
KVM/ARM fixes for 4.5-rc6
- Fix per-vcpu vgic bitmap allocation
- Do not give copy random memory on MMIO read
- Fix GICv3 APR register restore order
When we allocate bitmaps in vgic_vcpu_init_maps, we divide the number of
bits we need by 8 to figure out how many bytes to allocate. However,
bitmap elements are always accessed as unsigned longs, and if we didn't
happen to allocate a size such that size % sizeof(unsigned long) == 0,
bitmap accesses may go past the end of the allocation.
When using KASAN (which does byte-granular access checks), this results
in a continuous stream of BUGs whenever these bitmaps are accessed:
=============================================================================
BUG kmalloc-128 (Tainted: G B ): kasan: bad access detected
-----------------------------------------------------------------------------
INFO: Allocated in vgic_init.part.25+0x55c/0x990 age=7493 cpu=3 pid=1730
INFO: Slab 0xffffffbde6d5da40 objects=16 used=15 fp=0xffffffc935769700 flags=0x4000000000000080
INFO: Object 0xffffffc935769500 @offset=1280 fp=0x (null)
Bytes b4 ffffffc9357694f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Object ffffffc935769500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Object ffffffc935769510: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Object ffffffc935769520: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Object ffffffc935769530: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Object ffffffc935769540: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Object ffffffc935769550: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Object ffffffc935769560: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Object ffffffc935769570: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Padding ffffffc9357695b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Padding ffffffc9357695c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Padding ffffffc9357695d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Padding ffffffc9357695e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Padding ffffffc9357695f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
CPU: 3 PID: 1740 Comm: kvm-vcpu-0 Tainted: G B 4.4.0+ #17
Hardware name: ARM Juno development board (r1) (DT)
Call trace:
[<ffffffc00008e770>] dump_backtrace+0x0/0x280
[<ffffffc00008ea04>] show_stack+0x14/0x20
[<ffffffc000726360>] dump_stack+0x100/0x188
[<ffffffc00030d324>] print_trailer+0xfc/0x168
[<ffffffc000312294>] object_err+0x3c/0x50
[<ffffffc0003140fc>] kasan_report_error+0x244/0x558
[<ffffffc000314548>] __asan_report_load8_noabort+0x48/0x50
[<ffffffc000745688>] __bitmap_or+0xc0/0xc8
[<ffffffc0000d9e44>] kvm_vgic_flush_hwstate+0x1bc/0x650
[<ffffffc0000c514c>] kvm_arch_vcpu_ioctl_run+0x2ec/0xa60
[<ffffffc0000b9a6c>] kvm_vcpu_ioctl+0x474/0xa68
[<ffffffc00036b7b0>] do_vfs_ioctl+0x5b8/0xcb0
[<ffffffc00036bf34>] SyS_ioctl+0x8c/0xa0
[<ffffffc000086cb0>] el0_svc_naked+0x24/0x28
Memory state around the buggy address:
ffffffc935769400: 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffffffc935769480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffffffc935769500: 04 fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffffffc935769580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffffffc935769600: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
Fix the issue by always allocating a multiple of sizeof(unsigned long),
as we do elsewhere in the vgic code.
Fixes: c1bfb577a ("arm/arm64: KVM: vgic: switch to dynamic allocation")
Cc: stable@vger.kernel.org
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
To make the intention clearer, use list_first_entry instead of
list_entry.
Signed-off-by: Geliang Tang <geliangtang@163.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Use list_for_each_entry_safe() instead of list_for_each_safe() to
simplify the code.
Signed-off-by: Geliang Tang <geliangtang@163.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Right now halt_poll_ns can be change during runtime. The
grow and shrink factors can only be set during module load.
Lets fix several aspects of grow shrink:
- make grow/shrink changeable by root
- make all variables unsigned int
- read the variables once to prevent races
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
We will soon modify the vanilla get_user_pages() so it can no
longer be used on mm/tasks other than 'current/current->mm',
which is by far the most common way it is called. For now,
we allow the old-style calls, but warn when they are used.
(implemented in previous patch)
This patch switches all callers of:
get_user_pages()
get_user_pages_unlocked()
get_user_pages_locked()
to stop passing tsk/mm so they will no longer see the warnings.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: jack@suse.cz
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20160212210156.113E9407@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
For protection keys, we need to understand whether protections
should be enforced in software or not. In general, we enforce
protections when working on our own task, but not when on others.
We call these "current" and "remote" operations.
This patch introduces a new get_user_pages() variant:
get_user_pages_remote()
Which is a replacement for when get_user_pages() is called on
non-current tsk/mm.
We also introduce a new gup flag: FOLL_REMOTE which can be used
for the "__" gup variants to get this new behavior.
The uprobes is_trap_at_addr() location holds mmap_sem and
calls get_user_pages(current->mm) on an instruction address. This
makes it a pretty unique gup caller. Being an instruction access
and also really originating from the kernel (vs. the app), I opted
to consider this a 'remote' access where protection keys will not
be enforced.
Without protection keys, this patch should not change any behavior.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: jack@suse.cz
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20160212210154.3F0E51EA@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
