Commit Graph

238 Commits

Author SHA1 Message Date
Paolo Bonzini
9b8ebbdb74 KVM: x86: extend usage of RET_MMIO_PF_* constants
The x86 MMU if full of code that returns 0 and 1 for retry/emulate.  Use
the existing RET_MMIO_PF_RETRY/RET_MMIO_PF_EMULATE enum, renaming it to
drop the MMIO part.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-10-12 14:01:56 +02:00
Ladi Prosek
829ee279ae KVM: MMU: always terminate page walks at level 1
is_last_gpte() is not equivalent to the pseudo-code given in commit
6bb69c9b69 ("KVM: MMU: simplify last_pte_bitmap") because an incorrect
value of last_nonleaf_level may override the result even if level == 1.

It is critical for is_last_gpte() to return true on level == 1 to
terminate page walks. Otherwise memory corruption may occur as level
is used as an index to various data structures throughout the page
walking code.  Even though the actual bug would be wherever the MMU is
initialized (as in the previous patch), be defensive and ensure here
that is_last_gpte() returns the correct value.

This patch is also enough to fix CVE-2017-12188.

Fixes: 6bb69c9b69
Cc: stable@vger.kernel.org
Cc: Andy Honig <ahonig@google.com>
Signed-off-by: Ladi Prosek <lprosek@redhat.com>
[Panic if walk_addr_generic gets an incorrect level; this is a serious
 bug and it's not worth a WARN_ON where the recovery path might hide
 further exploitable issues; suggested by Andrew Honig. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-10-10 15:31:28 +02:00
Paolo Bonzini
9034e6e895 KVM: x86: fix use of L1 MMIO areas in nested guests
There is currently some confusion between nested and L1 GPAs.  The
assignment to "direct" in kvm_mmu_page_fault tries to fix that, but
it is not enough.  What this patch does is fence off the MMIO cache
completely when using shadow nested page tables, since we have neither
a GVA nor an L1 GPA to put in the cache.  This also allows some
simplifications in kvm_mmu_page_fault and FNAME(page_fault).

The EPT misconfig likewise does not have an L1 GPA to pass to
kvm_io_bus_write, so that must be skipped for guest mode.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
[Changed comment to say "GPAs" instead of "L1's physical addresses", as
 per David's review. - Radim]
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-08-18 14:37:49 +02:00
Wanpeng Li
26eeb53cf0 KVM: MMU: Bail out immediately if there is no available mmu page
Bailing out immediately if there is no available mmu page to alloc.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-08-11 18:59:29 +02:00
Paolo Bonzini
0780516a18 KVM: nVMX: fix EPT permissions as reported in exit qualification
This fixes the new ept_access_test_read_only and ept_access_test_read_write
testcases from vmx.flat.

The problem is that gpte_access moves bits around to switch from EPT
bit order (XWR) to ACC_*_MASK bit order (RWX).  This results in an
incorrect exit qualification.  To fix this, make pt_access and
pte_access operate on raw PTE values (only with NX flipped to mean
"can execute") and call gpte_access at the end of the walk.  This
lets us use pte_access to compute the exit qualification with XWR
bit order.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Xiao Guangrong <xiaoguangrong@tencent.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-05-15 18:22:40 +02:00
Bandan Das
bab4165e2f kvm: x86: Add a hook for arch specific dirty logging emulation
When KVM updates accessed/dirty bits, this hook can be used
to invoke an arch specific function that implements/emulates
dirty logging such as PML.

Signed-off-by: Bandan Das <bsd@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-05-09 11:54:16 +02:00
Paolo Bonzini
ae1e2d1082 kvm: nVMX: support EPT accessed/dirty bits
Now use bit 6 of EPTP to optionally enable A/D bits for EPTP.  Another
thing to change is that, when EPT accessed and dirty bits are not in use,
VMX treats accesses to guest paging structures as data reads.  When they
are in use (bit 6 of EPTP is set), they are treated as writes and the
corresponding EPT dirty bit is set.  The MMU didn't know this detail,
so this patch adds it.

We also have to fix up the exit qualification.  It may be wrong because
KVM sets bit 6 but the guest might not.

L1 emulates EPT A/D bits using write permissions, so in principle it may
be possible for EPT A/D bits to be used by L1 even though not available
in hardware.  The problem is that guest page-table walks will be treated
as reads rather than writes, so they would not cause an EPT violation.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[Fixed typo in walk_addr_generic() comment and changed bit clear +
 conditional-set pattern in handle_ept_violation() to conditional-clear]
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-04-07 16:49:00 +02:00
Paolo Bonzini
86407bcb5c kvm: x86: MMU support for EPT accessed/dirty bits
This prepares the MMU paging code for EPT accessed and dirty bits,
which can be enabled optionally at runtime.  Code that updates the
accessed and dirty bits will need a pointer to the struct kvm_mmu.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-04-07 16:49:00 +02:00
Bandan Das
d95c55687e kvm: mmu: track read permission explicitly for shadow EPT page tables
To support execute only mappings on behalf of L1 hypervisors,
reuse ACC_USER_MASK to signify if the L1 hypervisor has the R bit
set.

For the nested EPT case, we assumed that the U bit was always set
since there was no equivalent in EPT page tables.  Strictly
speaking, this was not necessary because handle_ept_violation
never set PFERR_USER_MASK in the error code (uf=0 in the
parlance of update_permission_bitmask).  We now have to set
both U and UF correctly, respectively in FNAME(gpte_access)
and in handle_ept_violation.

Also in handle_ept_violation bit 3 of the exit qualification is
not enough to detect a present PTE; all three bits 3-5 have to
be checked.

Signed-off-by: Bandan Das <bsd@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-07-14 09:03:50 +02:00
Bandan Das
812f30b234 kvm: mmu: remove is_present_gpte()
We have two versions of the above function.
To prevent confusion and bugs in the future, remove
the non-FNAME version entirely and replace all calls
with the actual check.

Signed-off-by: Bandan Das <bsd@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-07-14 09:02:47 +02:00
Xiao Guangrong
7a98205dee KVM: MMU: fix permission_fault()
kvm-unit-tests complained about the PFEC is not set properly, e.g,:
test pte.rw pte.d pte.nx pde.p pde.rw pde.pse user fetch: FAIL: error code 15
expected 5
Dump mapping: address: 0x123400000000
------L4: 3e95007
------L3: 3e96007
------L2: 2000083

It's caused by the reason that PFEC returned to guest is copied from the
PFEC triggered by shadow page table

This patch fixes it and makes the logic of updating errcode more clean

Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
[Do not assume pfec.p=1. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-04-10 21:53:49 +02:00
Lan Tianyu
7bfdf21778 KVM/x86: Call smp_wmb() before increasing tlbs_dirty
Update spte before increasing tlbs_dirty to make sure no tlb flush
in lost after spte is zapped. This pairs with the barrier in the
kvm_flush_remote_tlbs().

Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-03-22 16:38:32 +01:00
Huaitong Han
be94f6b710 KVM, pkeys: add pkeys support for permission_fault
Protection keys define a new 4-bit protection key field (PKEY) in bits
62:59 of leaf entries of the page tables, the PKEY is an index to PKRU
register(16 domains), every domain has 2 bits(write disable bit, access
disable bit).

Static logic has been produced in update_pkru_bitmask, dynamic logic need
read pkey from page table entries, get pkru value, and deduce the correct
result.

[ Huaitong: Xiao helps to modify many sections. ]

Signed-off-by: Huaitong Han <huaitong.han@intel.com>
Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-03-22 16:23:37 +01:00
Paolo Bonzini
f13577e8aa KVM: MMU: return page fault error code from permission_fault
This will help in the implementation of PKRU, where the PK bit of the page
fault error code cannot be computed in advance (unlike I/D, R/W and U/S).

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-03-22 16:20:54 +01:00
Paolo Bonzini
ab92f30875 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
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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
2016-03-09 11:50:42 +01:00
Paolo Bonzini
bb9eadf0c3 KVM: MMU: micro-optimize gpte_access
Avoid AND-NOT, most x86 processor lack an instruction for it.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-03-08 12:33:39 +01:00
Paolo Bonzini
1f50f1b3a4 KVM: MMU: invert return value of mmu.sync_page and *kvm_sync_page*
Return true if the page was synced (and the TLB must be flushed)
and false if the page was zapped.

Reviewed-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-03-08 12:33:26 +01:00
Xiao Guangrong
e5691a81e8 KVM: MMU: clear write-flooding on the fast path of tracked page
If the page fault is caused by write access on write tracked page, the
real shadow page walking is skipped, we lost the chance to clear write
flooding for the page structure current vcpu is using

Fix it by locklessly waking shadow page table to clear write flooding
on the shadow page structure out of mmu-lock. So that we change the
count to atomic_t

Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-03-03 14:36:22 +01:00
Xiao Guangrong
3d0c27ad6e KVM: MMU: let page fault handler be aware tracked page
The page fault caused by write access on the write tracked page can not
be fixed, it always need to be emulated. page_fault_handle_page_track()
is the fast path we introduce here to skip holding mmu-lock and shadow
page table walking

However, if the page table is not present, it is worth making the page
table entry present and readonly to make the read access happy

mmu_need_write_protect() need to be cooked to avoid page becoming writable
when making page table present or sync/prefetch shadow page table entries

Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-03-03 14:36:21 +01:00
Mike Krinkin
17e4bce0ae KVM: x86: MMU: fix ubsan index-out-of-range warning
Ubsan reports the following warning due to a typo in
update_accessed_dirty_bits template, the patch fixes
the typo:

[  168.791851] ================================================================================
[  168.791862] UBSAN: Undefined behaviour in arch/x86/kvm/paging_tmpl.h:252:15
[  168.791866] index 4 is out of range for type 'u64 [4]'
[  168.791871] CPU: 0 PID: 2950 Comm: qemu-system-x86 Tainted: G           O L  4.5.0-rc5-next-20160222 #7
[  168.791873] Hardware name: LENOVO 23205NG/23205NG, BIOS G2ET95WW (2.55 ) 07/09/2013
[  168.791876]  0000000000000000 ffff8801cfcaf208 ffffffff81c9f780 0000000041b58ab3
[  168.791882]  ffffffff82eb2cc1 ffffffff81c9f6b4 ffff8801cfcaf230 ffff8801cfcaf1e0
[  168.791886]  0000000000000004 0000000000000001 0000000000000000 ffffffffa1981600
[  168.791891] Call Trace:
[  168.791899]  [<ffffffff81c9f780>] dump_stack+0xcc/0x12c
[  168.791904]  [<ffffffff81c9f6b4>] ? _atomic_dec_and_lock+0xc4/0xc4
[  168.791910]  [<ffffffff81da9e81>] ubsan_epilogue+0xd/0x8a
[  168.791914]  [<ffffffff81daafa2>] __ubsan_handle_out_of_bounds+0x15c/0x1a3
[  168.791918]  [<ffffffff81daae46>] ? __ubsan_handle_shift_out_of_bounds+0x2bd/0x2bd
[  168.791922]  [<ffffffff811287ef>] ? get_user_pages_fast+0x2bf/0x360
[  168.791954]  [<ffffffffa1794050>] ? kvm_largepages_enabled+0x30/0x30 [kvm]
[  168.791958]  [<ffffffff81128530>] ? __get_user_pages_fast+0x360/0x360
[  168.791987]  [<ffffffffa181b818>] paging64_walk_addr_generic+0x1b28/0x2600 [kvm]
[  168.792014]  [<ffffffffa1819cf0>] ? init_kvm_mmu+0x1100/0x1100 [kvm]
[  168.792019]  [<ffffffff8129e350>] ? debug_check_no_locks_freed+0x350/0x350
[  168.792044]  [<ffffffffa1819cf0>] ? init_kvm_mmu+0x1100/0x1100 [kvm]
[  168.792076]  [<ffffffffa181c36d>] paging64_gva_to_gpa+0x7d/0x110 [kvm]
[  168.792121]  [<ffffffffa181c2f0>] ? paging64_walk_addr_generic+0x2600/0x2600 [kvm]
[  168.792130]  [<ffffffff812e848b>] ? debug_lockdep_rcu_enabled+0x7b/0x90
[  168.792178]  [<ffffffffa17d9a4a>] emulator_read_write_onepage+0x27a/0x1150 [kvm]
[  168.792208]  [<ffffffffa1794d44>] ? __kvm_read_guest_page+0x54/0x70 [kvm]
[  168.792234]  [<ffffffffa17d97d0>] ? kvm_task_switch+0x160/0x160 [kvm]
[  168.792238]  [<ffffffff812e848b>] ? debug_lockdep_rcu_enabled+0x7b/0x90
[  168.792263]  [<ffffffffa17daa07>] emulator_read_write+0xe7/0x6d0 [kvm]
[  168.792290]  [<ffffffffa183b620>] ? em_cr_write+0x230/0x230 [kvm]
[  168.792314]  [<ffffffffa17db005>] emulator_write_emulated+0x15/0x20 [kvm]
[  168.792340]  [<ffffffffa18465f8>] segmented_write+0xf8/0x130 [kvm]
[  168.792367]  [<ffffffffa1846500>] ? em_lgdt+0x20/0x20 [kvm]
[  168.792374]  [<ffffffffa14db512>] ? vmx_read_guest_seg_ar+0x42/0x1e0 [kvm_intel]
[  168.792400]  [<ffffffffa1846d82>] writeback+0x3f2/0x700 [kvm]
[  168.792424]  [<ffffffffa1846990>] ? em_sidt+0xa0/0xa0 [kvm]
[  168.792449]  [<ffffffffa185554d>] ? x86_decode_insn+0x1b3d/0x4f70 [kvm]
[  168.792474]  [<ffffffffa1859032>] x86_emulate_insn+0x572/0x3010 [kvm]
[  168.792499]  [<ffffffffa17e71dd>] x86_emulate_instruction+0x3bd/0x2110 [kvm]
[  168.792524]  [<ffffffffa17e6e20>] ? reexecute_instruction.part.110+0x2e0/0x2e0 [kvm]
[  168.792532]  [<ffffffffa14e9a81>] handle_ept_misconfig+0x61/0x460 [kvm_intel]
[  168.792539]  [<ffffffffa14e9a20>] ? handle_pause+0x450/0x450 [kvm_intel]
[  168.792546]  [<ffffffffa15130ea>] vmx_handle_exit+0xd6a/0x1ad0 [kvm_intel]
[  168.792572]  [<ffffffffa17f6a6c>] ? kvm_arch_vcpu_ioctl_run+0xbdc/0x6090 [kvm]
[  168.792597]  [<ffffffffa17f6bcd>] kvm_arch_vcpu_ioctl_run+0xd3d/0x6090 [kvm]
[  168.792621]  [<ffffffffa17f6a6c>] ? kvm_arch_vcpu_ioctl_run+0xbdc/0x6090 [kvm]
[  168.792627]  [<ffffffff8293b530>] ? __ww_mutex_lock_interruptible+0x1630/0x1630
[  168.792651]  [<ffffffffa17f5e90>] ? kvm_arch_vcpu_runnable+0x4f0/0x4f0 [kvm]
[  168.792656]  [<ffffffff811eeb30>] ? preempt_notifier_unregister+0x190/0x190
[  168.792681]  [<ffffffffa17e0447>] ? kvm_arch_vcpu_load+0x127/0x650 [kvm]
[  168.792704]  [<ffffffffa178e9a3>] kvm_vcpu_ioctl+0x553/0xda0 [kvm]
[  168.792727]  [<ffffffffa178e450>] ? vcpu_put+0x40/0x40 [kvm]
[  168.792732]  [<ffffffff8129e350>] ? debug_check_no_locks_freed+0x350/0x350
[  168.792735]  [<ffffffff82946087>] ? _raw_spin_unlock+0x27/0x40
[  168.792740]  [<ffffffff8163a943>] ? handle_mm_fault+0x1673/0x2e40
[  168.792744]  [<ffffffff8129daa8>] ? trace_hardirqs_on_caller+0x478/0x6c0
[  168.792747]  [<ffffffff8129dcfd>] ? trace_hardirqs_on+0xd/0x10
[  168.792751]  [<ffffffff812e848b>] ? debug_lockdep_rcu_enabled+0x7b/0x90
[  168.792756]  [<ffffffff81725a80>] do_vfs_ioctl+0x1b0/0x12b0
[  168.792759]  [<ffffffff817258d0>] ? ioctl_preallocate+0x210/0x210
[  168.792763]  [<ffffffff8174aef3>] ? __fget+0x273/0x4a0
[  168.792766]  [<ffffffff8174acd0>] ? __fget+0x50/0x4a0
[  168.792770]  [<ffffffff8174b1f6>] ? __fget_light+0x96/0x2b0
[  168.792773]  [<ffffffff81726bf9>] SyS_ioctl+0x79/0x90
[  168.792777]  [<ffffffff82946880>] entry_SYSCALL_64_fastpath+0x23/0xc1
[  168.792780] ================================================================================

Signed-off-by: Mike Krinkin <krinkin.m.u@gmail.com>
Reviewed-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-02-25 09:50:35 +01:00
Takuya Yoshikawa
e9ee956e31 KVM: x86: MMU: Move handle_mmio_page_fault() call to kvm_mmu_page_fault()
Rather than placing a handle_mmio_page_fault() call in each
vcpu->arch.mmu.page_fault() handler, moving it up to
kvm_mmu_page_fault() makes the code better:

 - avoids code duplication
 - for kvm_arch_async_page_ready(), which is the other caller of
   vcpu->arch.mmu.page_fault(), removes an extra error_code check
 - avoids returning both RET_MMIO_PF_* values and raw integer values
   from vcpu->arch.mmu.page_fault()

Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-02-23 14:20:27 +01:00
Dan Williams
ba049e93ae kvm: rename pfn_t to kvm_pfn_t
To date, we have implemented two I/O usage models for persistent memory,
PMEM (a persistent "ram disk") and DAX (mmap persistent memory into
userspace).  This series adds a third, DAX-GUP, that allows DAX mappings
to be the target of direct-i/o.  It allows userspace to coordinate
DMA/RDMA from/to persistent memory.

The implementation leverages the ZONE_DEVICE mm-zone that went into
4.3-rc1 (also discussed at kernel summit) to flag pages that are owned
and dynamically mapped by a device driver.  The pmem driver, after
mapping a persistent memory range into the system memmap via
devm_memremap_pages(), arranges for DAX to distinguish pfn-only versus
page-backed pmem-pfns via flags in the new pfn_t type.

The DAX code, upon seeing a PFN_DEV+PFN_MAP flagged pfn, flags the
resulting pte(s) inserted into the process page tables with a new
_PAGE_DEVMAP flag.  Later, when get_user_pages() is walking ptes it keys
off _PAGE_DEVMAP to pin the device hosting the page range active.
Finally, get_page() and put_page() are modified to take references
against the device driver established page mapping.

Finally, this need for "struct page" for persistent memory requires
memory capacity to store the memmap array.  Given the memmap array for a
large pool of persistent may exhaust available DRAM introduce a
mechanism to allocate the memmap from persistent memory.  The new
"struct vmem_altmap *" parameter to devm_memremap_pages() enables
arch_add_memory() to use reserved pmem capacity rather than the page
allocator.

This patch (of 18):

The core has developed a need for a "pfn_t" type [1].  Move the existing
pfn_t in KVM to kvm_pfn_t [2].

[1]: https://lists.01.org/pipermail/linux-nvdimm/2015-September/002199.html
[2]: https://lists.01.org/pipermail/linux-nvdimm/2015-September/002218.html

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-15 17:56:32 -08:00
Takuya Yoshikawa
bb11c6c965 KVM: x86: MMU: Remove unused parameter parent_pte from kvm_mmu_get_page()
Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-11-26 15:31:36 +01:00
Takuya Yoshikawa
98bba23842 KVM: x86: MMU: Move parent_pte handling from kvm_mmu_get_page() to link_shadow_page()
Every time kvm_mmu_get_page() is called with a non-NULL parent_pte
argument, link_shadow_page() follows that to set the parent entry so
that the new mapping will point to the returned page table.

Moving parent_pte handling there allows to clean up the code because
parent_pte is passed to kvm_mmu_get_page() just for mark_unsync() and
mmu_page_add_parent_pte().

In addition, the patch avoids calling mark_unsync() for other parents in
the sp->parent_ptes chain than the newly added parent_pte, because they
have been there since before the current page fault handling started.

Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Cc: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-11-26 15:31:24 +01:00
Takuya Yoshikawa
029499b477 KVM: x86: MMU: Make mmu_set_spte() return emulate value
mmu_set_spte()'s code is based on the assumption that the emulate
parameter has a valid pointer value if set_spte() returns true and
write_fault is not zero.  In other cases, emulate may be NULL, so a
NULL-check is needed.

Stop passing emulate pointer and make mmu_set_spte() return the emulate
value instead to clean up this complex interface.  Prefetch functions
can just throw away the return value.

Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-11-25 17:26:28 +01:00
Paolo Bonzini
0e3d0648bd KVM: x86: MMU: always set accessed bit in shadow PTEs
Commit 7a1638ce42 ("nEPT: Redefine EPT-specific link_shadow_page()",
2013-08-05) says:

    Since nEPT doesn't support A/D bit, we should not set those bit
    when building the shadow page table.

but this is not necessary.  Even though nEPT doesn't support A/D
bits, and hence the vmcs12 EPT pointer will never enable them,
we always use them for shadow page tables if available (see
construct_eptp in vmx.c).  So we can set the A/D bits freely
in the shadow page table.

This patch hence basically reverts commit 7a1638ce42.

Cc: Yang Zhang <yang.z.zhang@Intel.com>
Cc: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-11-25 17:24:23 +01:00
Paolo Bonzini
450869d6db KVM: x86: merge handle_mmio_page_fault and handle_mmio_page_fault_common
They are exactly the same, except that handle_mmio_page_fault
has an unused argument and a call to WARN_ON.  Remove the unused
argument from the callers, and move the warning to (the former)
handle_mmio_page_fault_common.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-11-10 12:06:03 +01:00
Takuya Yoshikawa
8c85ac1c0a KVM: x86: MMU: Initialize force_pt_level before calling mapping_level()
Commit fd13690218 ("KVM: x86: MMU: Move mapping_level_dirty_bitmap()
call in mapping_level()") forgot to initialize force_pt_level to false
in FNAME(page_fault)() before calling mapping_level() like
nonpaging_map() does.  This can sometimes result in forcing page table
level mapping unnecessarily.

Fix this and move the first *force_pt_level check in mapping_level()
before kvm_vcpu_gfn_to_memslot() call to make it a bit clearer that
the variable must be initialized before mapping_level() gets called.

This change can also avoid calling kvm_vcpu_gfn_to_memslot() when
!check_hugepage_cache_consistency() check in tdp_page_fault() forces
page table level mapping.

Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-10-19 11:36:05 +02:00
Takuya Yoshikawa
fd13690218 KVM: x86: MMU: Move mapping_level_dirty_bitmap() call in mapping_level()
This is necessary to eliminate an extra memory slot search later.

Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-10-16 10:34:00 +02:00
Takuya Yoshikawa
5ed5c5c8fd KVM: x86: MMU: Simplify force_pt_level calculation code in FNAME(page_fault)()
As a bonus, an extra memory slot search can be eliminated when
is_self_change_mapping is true.

Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-10-16 10:34:00 +02:00
Takuya Yoshikawa
cd1872f028 KVM: x86: MMU: Make force_pt_level bool
This will be passed to a function later.

Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-10-16 10:33:59 +02:00
Xiao Guangrong
d2b0f98125 KVM: MMU: move FNAME(is_rsvd_bits_set) to mmu.c
FNAME(is_rsvd_bits_set) does not depend on guest mmu mode, move it
to mmu.c to stop being compiled multiple times

Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-08-05 12:47:22 +02:00
Paolo Bonzini
54bf36aac5 KVM: x86: use vcpu-specific functions to read/write/translate GFNs
We need to hide SMRAM from guests not running in SMM.  Therefore,
all uses of kvm_read_guest* and kvm_write_guest* must be changed to
check whether the VCPU is in system management mode and use a
different set of memslots.  Switch from kvm_* to the newly-introduced
kvm_vcpu_*, which call into kvm_arch_vcpu_memslots_id.

Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-06-05 17:26:36 +02:00
Xiao Guangrong
ceee7df749 KVM: MMU: fix smap permission check
Current permission check assumes that RSVD bit in PFEC is always zero,
however, it is not true since MMIO #PF will use it to quickly identify
MMIO access

Fix it by clearing the bit if walking guest page table is needed

Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-05-08 10:51:47 +02:00
Nadav Amit
1715d0dcb0 KVM: x86: Wrong assertion on paging_tmpl.h
Even after the recent fix, the assertion on paging_tmpl.h is triggered.
Apparently, the assertion wants to check that the PAE is always set on
long-mode, but does it in incorrect way.  Note that the assertion is not
enabled unless the code is debugged by defining MMU_DEBUG.

Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2014-10-24 13:30:37 +02:00
Nadav Amit
d5262739cb KVM: x86: Remove debug assertion of non-PAE reserved bits
Commit 346874c950 ("KVM: x86: Fix CR3 reserved bits") removed non-PAE
reserved bits which were not according to Intel SDM.  However, residue was left
in a debug assertion (CR3_NONPAE_RESERVED_BITS).  Remove it.

Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2014-09-24 14:07:55 +02:00
Paolo Bonzini
54987b7afa KVM: x86: propagate exception from permission checks on the nested page fault
Currently, if a permission error happens during the translation of
the final GPA to HPA, walk_addr_generic returns 0 but does not fill
in walker->fault.  To avoid this, add an x86_exception* argument
to the translate_gpa function, and let it fill in walker->fault.
The nested_page_fault field will be true, since the walk_mmu is the
nested_mmu and translate_gpu instead operates on the "outer" (NPT)
instance.

Reported-by: Valentine Sinitsyn <valentine.sinitsyn@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2014-09-05 12:01:13 +02:00
Paolo Bonzini
5e35251951 KVM: nSVM: propagate the NPF EXITINFO to the guest
This is similar to what the EPT code does with the exit qualification.
This allows the guest to see a valid value for bits 33:32.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2014-09-03 10:18:54 +02:00
Xiao Guangrong
a086f6a1eb Revert "KVM: Simplify kvm->tlbs_dirty handling"
This reverts commit 5befdc385d.

Since we will allow flush tlb out of mmu-lock in the later
patch

Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2014-04-23 17:49:48 -03:00
Feng Wu
97ec8c067d KVM: Add SMAP support when setting CR4
This patch adds SMAP handling logic when setting CR4 for guests

Thanks a lot to Paolo Bonzini for his suggestion to use the branchless
way to detect SMAP violation.

Signed-off-by: Feng Wu <feng.wu@intel.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2014-04-14 17:50:34 -03:00
Takuya Yoshikawa
5befdc385d KVM: Simplify kvm->tlbs_dirty handling
When this was introduced, kvm_flush_remote_tlbs() could be called
without holding mmu_lock.  It is now acknowledged that the function
must be called before releasing mmu_lock, and all callers have already
been changed to do so.

There is no need to use smp_mb() and cmpxchg() any more.

Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2014-02-18 10:07:26 +01:00
Marcelo Tosatti
37f6a4e237 KVM: x86: handle invalid root_hpa everywhere
Rom Freiman <rom@stratoscale.com> notes other code paths vulnerable to
bug fixed by 989c6b34f6.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2014-01-15 12:16:16 +01:00
Paolo Bonzini
ba6a354154 KVM: mmu: allow page tables to be in read-only slots
Page tables in a read-only memory slot will currently cause a triple
fault because the page walker uses gfn_to_hva and it fails on such a slot.

OVMF uses such a page table; however, real hardware seems to be fine with
that as long as the accessed/dirty bits are set.  Save whether the slot
is readonly, and later check it when updating the accessed and dirty bits.

Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Reviewed-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2013-09-17 12:52:31 +03:00
Yang Zhang
25d92081ae nEPT: Add nEPT violation/misconfigration support
Inject nEPT fault to L1 guest. This patch is original from Xinhao.

Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Jun Nakajima <jun.nakajima@intel.com>
Signed-off-by: Xinhao Xu <xinhao.xu@intel.com>
Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2013-08-07 15:57:40 +02:00
Yang Zhang
7a1638ce42 nEPT: Redefine EPT-specific link_shadow_page()
Since nEPT doesn't support A/D bit, so we should not set those bit
when build shadow page table.

Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2013-08-07 15:57:39 +02:00
Nadav Har'El
37406aaaee nEPT: Add EPT tables support to paging_tmpl.h
This is the first patch in a series which adds nested EPT support to KVM's
nested VMX. Nested EPT means emulating EPT for an L1 guest so that L1 can use
EPT when running a nested guest L2. When L1 uses EPT, it allows the L2 guest
to set its own cr3 and take its own page faults without either of L0 or L1
getting involved. This often significanlty improves L2's performance over the
previous two alternatives (shadow page tables over EPT, and shadow page
tables over shadow page tables).

This patch adds EPT support to paging_tmpl.h.

paging_tmpl.h contains the code for reading and writing page tables. The code
for 32-bit and 64-bit tables is very similar, but not identical, so
paging_tmpl.h is #include'd twice in mmu.c, once with PTTTYPE=32 and once
with PTTYPE=64, and this generates the two sets of similar functions.

There are subtle but important differences between the format of EPT tables
and that of ordinary x86 64-bit page tables, so for nested EPT we need a
third set of functions to read the guest EPT table and to write the shadow
EPT table.

So this patch adds third PTTYPE, PTTYPE_EPT, which creates functions (prefixed
with "EPT") which correctly read and write EPT tables.

Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Nadav Har'El <nyh@il.ibm.com>
Signed-off-by: Jun Nakajima <jun.nakajima@intel.com>
Signed-off-by: Xinhao Xu <xinhao.xu@intel.com>
Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2013-08-07 15:57:38 +02:00
Gleb Natapov
61719a8fff nEPT: Support shadow paging for guest paging without A/D bits
Some guest paging modes do not support A/D bits. Add support for such
modes in shadow page code. For such modes PT_GUEST_DIRTY_MASK,
PT_GUEST_ACCESSED_MASK, PT_GUEST_DIRTY_SHIFT and PT_GUEST_ACCESSED_SHIFT
should be set to zero.

Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2013-08-07 15:57:37 +02:00
Gleb Natapov
d8089baca4 nEPT: make guest's A/D bits depends on guest's paging mode
This patch makes guest A/D bits definition to be dependable on paging
mode, so when EPT support will be added it will be able to define them
differently.

Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2013-08-07 15:57:37 +02:00
Nadav Har'El
0ad805a0c3 nEPT: Move common code to paging_tmpl.h
For preparation, we just move gpte_access(), prefetch_invalid_gpte(),
s_rsvd_bits_set(), protect_clean_gpte() and is_dirty_gpte() from mmu.c
to paging_tmpl.h.

Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Nadav Har'El <nyh@il.ibm.com>
Signed-off-by: Jun Nakajima <jun.nakajima@intel.com>
Signed-off-by: Xinhao Xu <xinhao.xu@intel.com>
Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>
Signed-off-by: Jun Nakajima <jun.nakajima@intel.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2013-08-07 15:57:36 +02:00
Xiao Guangrong
027664216d KVM: MMU: fix check the reserved bits on the gpte of L2
Current code always uses arch.mmu to check the reserved bits on guest gpte
which is valid only for L1 guest, we should use arch.nested_mmu instead when
we translate gva to gpa for the L2 guest

Fix it by using @mmu instead since it is adapted to the current mmu mode
automatically

The bug can be triggered when nested npt is used and L1 guest and L2 guest
use different mmu mode

Reported-by: Jan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2013-08-07 15:57:33 +02:00