1. 13 12月, 2019 2 次提交
  2. 05 12月, 2019 3 次提交
  3. 01 12月, 2019 4 次提交
  4. 21 11月, 2019 1 次提交
  5. 13 11月, 2019 12 次提交
  6. 12 10月, 2019 3 次提交
    • S
      KVM: nVMX: Fix consistency check on injected exception error code · 63bb8b76
      Sean Christopherson 提交于
      [ Upstream commit 567926cca99ba1750be8aae9c4178796bf9bb90b ]
      
      Current versions of Intel's SDM incorrectly state that "bits 31:15 of
      the VM-Entry exception error-code field" must be zero.  In reality, bits
      31:16 must be zero, i.e. error codes are 16-bit values.
      
      The bogus error code check manifests as an unexpected VM-Entry failure
      due to an invalid code field (error number 7) in L1, e.g. when injecting
      a #GP with error_code=0x9f00.
      
      Nadav previously reported the bug[*], both to KVM and Intel, and fixed
      the associated kvm-unit-test.
      
      [*] https://patchwork.kernel.org/patch/11124749/Reported-by: NNadav Amit <namit@vmware.com>
      Cc: stable@vger.kernel.org
      Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
      Reviewed-by: NJim Mattson <jmattson@google.com>
      Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      Signed-off-by: NSasha Levin <sashal@kernel.org>
      63bb8b76
    • J
      KVM: nVMX: handle page fault in vmread fix · eff3a54a
      Jack Wang 提交于
      During backport f7eea636c3d5 ("KVM: nVMX: handle page fault in vmread"),
      there was a mistake the exception reference should be passed to function
      kvm_write_guest_virt_system, instead of NULL, other wise, we will get
      NULL pointer deref, eg
      
      kvm-unit-test triggered a NULL pointer deref below:
      [  948.518437] kvm [24114]: vcpu0, guest rIP: 0x407ef9 kvm_set_msr_common: MSR_IA32_DEBUGCTLMSR 0x3, nop
      [  949.106464] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
      [  949.106707] PGD 0 P4D 0
      [  949.106872] Oops: 0002 [#1] SMP
      [  949.107038] CPU: 2 PID: 24126 Comm: qemu-2.7 Not tainted 4.19.77-pserver #4.19.77-1+feature+daily+update+20191005.1625+a4168bb~deb9
      [  949.107283] Hardware name: Dell Inc. Precision Tower 3620/09WH54, BIOS 2.7.3 01/31/2018
      [  949.107549] RIP: 0010:kvm_write_guest_virt_system+0x12/0x40 [kvm]
      [  949.107719] Code: c0 5d 41 5c 41 5d 41 5e 83 f8 03 41 0f 94 c0 41 c1 e0 02 e9 b0 ed ff ff 0f 1f 44 00 00 48 89 f0 c6 87 59 56 00 00 01 48 89 d6 <49> c7 00 00 00 00 00 89 ca 49 c7 40 08 00 00 00 00 49 c7 40 10 00
      [  949.108044] RSP: 0018:ffffb31b0a953cb0 EFLAGS: 00010202
      [  949.108216] RAX: 000000000046b4d8 RBX: ffff9e9f415b0000 RCX: 0000000000000008
      [  949.108389] RDX: ffffb31b0a953cc0 RSI: ffffb31b0a953cc0 RDI: ffff9e9f415b0000
      [  949.108562] RBP: 00000000d2e14928 R08: 0000000000000000 R09: 0000000000000000
      [  949.108733] R10: 0000000000000000 R11: 0000000000000000 R12: ffffffffffffffc8
      [  949.108907] R13: 0000000000000002 R14: ffff9e9f4f26f2e8 R15: 0000000000000000
      [  949.109079] FS:  00007eff8694c700(0000) GS:ffff9e9f51a80000(0000) knlGS:0000000031415928
      [  949.109318] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
      [  949.109495] CR2: 0000000000000000 CR3: 00000003be53b002 CR4: 00000000003626e0
      [  949.109671] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
      [  949.109845] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
      [  949.110017] Call Trace:
      [  949.110186]  handle_vmread+0x22b/0x2f0 [kvm_intel]
      [  949.110356]  ? vmexit_fill_RSB+0xc/0x30 [kvm_intel]
      [  949.110549]  kvm_arch_vcpu_ioctl_run+0xa98/0x1b30 [kvm]
      [  949.110725]  ? kvm_vcpu_ioctl+0x388/0x5d0 [kvm]
      [  949.110901]  kvm_vcpu_ioctl+0x388/0x5d0 [kvm]
      [  949.111072]  do_vfs_ioctl+0xa2/0x620
      Signed-off-by: NJack Wang <jinpu.wang@cloud.ionos.com>
      Acked-by: NPaolo Bonzini <pbonzini@redhat.com>
      eff3a54a
    • W
      KVM: X86: Fix userspace set invalid CR4 · 21874027
      Wanpeng Li 提交于
      commit 3ca94192278ca8de169d78c085396c424be123b3 upstream.
      
      Reported by syzkaller:
      
      	WARNING: CPU: 0 PID: 6544 at /home/kernel/data/kvm/arch/x86/kvm//vmx/vmx.c:4689 handle_desc+0x37/0x40 [kvm_intel]
      	CPU: 0 PID: 6544 Comm: a.out Tainted: G           OE     5.3.0-rc4+ #4
      	RIP: 0010:handle_desc+0x37/0x40 [kvm_intel]
      	Call Trace:
      	 vmx_handle_exit+0xbe/0x6b0 [kvm_intel]
      	 vcpu_enter_guest+0x4dc/0x18d0 [kvm]
      	 kvm_arch_vcpu_ioctl_run+0x407/0x660 [kvm]
      	 kvm_vcpu_ioctl+0x3ad/0x690 [kvm]
      	 do_vfs_ioctl+0xa2/0x690
      	 ksys_ioctl+0x6d/0x80
      	 __x64_sys_ioctl+0x1a/0x20
      	 do_syscall_64+0x74/0x720
      	 entry_SYSCALL_64_after_hwframe+0x49/0xbe
      
      When CR4.UMIP is set, guest should have UMIP cpuid flag. Current
      kvm set_sregs function doesn't have such check when userspace inputs
      sregs values. SECONDARY_EXEC_DESC is enabled on writes to CR4.UMIP
      in vmx_set_cr4 though guest doesn't have UMIP cpuid flag. The testcast
      triggers handle_desc warning when executing ltr instruction since
      guest architectural CR4 doesn't set UMIP. This patch fixes it by
      adding valid CR4 and CPUID combination checking in __set_sregs.
      
      syzkaller source: https://syzkaller.appspot.com/x/repro.c?x=138efb99600000
      
      Reported-by: syzbot+0f1819555fbdce992df9@syzkaller.appspotmail.com
      Cc: stable@vger.kernel.org
      Signed-off-by: NWanpeng Li <wanpengli@tencent.com>
      Reviewed-by: NSean Christopherson <sean.j.christopherson@intel.com>
      Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      21874027
  7. 05 10月, 2019 3 次提交
    • S
      KVM: x86: Manually calculate reserved bits when loading PDPTRS · 496cf984
      Sean Christopherson 提交于
      commit 16cfacc8085782dab8e365979356ce1ca87fd6cc upstream.
      
      Manually generate the PDPTR reserved bit mask when explicitly loading
      PDPTRs.  The reserved bits that are being tracked by the MMU reflect the
      current paging mode, which is unlikely to be PAE paging in the vast
      majority of flows that use load_pdptrs(), e.g. CR0 and CR4 emulation,
      __set_sregs(), etc...  This can cause KVM to incorrectly signal a bad
      PDPTR, or more likely, miss a reserved bit check and subsequently fail
      a VM-Enter due to a bad VMCS.GUEST_PDPTR.
      
      Add a one off helper to generate the reserved bits instead of sharing
      code across the MMU's calculations and the PDPTR emulation.  The PDPTR
      reserved bits are basically set in stone, and pushing a helper into
      the MMU's calculation adds unnecessary complexity without improving
      readability.
      
      Oppurtunistically fix/update the comment for load_pdptrs().
      
      Note, the buggy commit also introduced a deliberate functional change,
      "Also remove bit 5-6 from rsvd_bits_mask per latest SDM.", which was
      effectively (and correctly) reverted by commit cd9ae5fe ("KVM: x86:
      Fix page-tables reserved bits").  A bit of SDM archaeology shows that
      the SDM from late 2008 had a bug (likely a copy+paste error) where it
      listed bits 6:5 as AVL and A for PDPTEs used for 4k entries but reserved
      for 2mb entries.  I.e. the SDM contradicted itself, and bits 6:5 are and
      always have been reserved.
      
      Fixes: 20c466b5 ("KVM: Use rsvd_bits_mask in load_pdptrs()")
      Cc: stable@vger.kernel.org
      Cc: Nadav Amit <nadav.amit@gmail.com>
      Reported-by: NDoug Reiland <doug.reiland@intel.com>
      Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
      Reviewed-by: NPeter Xu <peterx@redhat.com>
      Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      496cf984
    • J
      KVM: x86: set ctxt->have_exception in x86_decode_insn() · 933e3e2b
      Jan Dakinevich 提交于
      commit c8848cee74ff05638e913582a476bde879c968ad upstream.
      
      x86_emulate_instruction() takes into account ctxt->have_exception flag
      during instruction decoding, but in practice this flag is never set in
      x86_decode_insn().
      
      Fixes: 6ea6e843 ("KVM: x86: inject exceptions produced by x86_decode_insn")
      Cc: stable@vger.kernel.org
      Cc: Denis Lunev <den@virtuozzo.com>
      Cc: Roman Kagan <rkagan@virtuozzo.com>
      Cc: Denis Plotnikov <dplotnikov@virtuozzo.com>
      Signed-off-by: NJan Dakinevich <jan.dakinevich@virtuozzo.com>
      Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      933e3e2b
    • J
      KVM: x86: always stop emulation on page fault · 9723e445
      Jan Dakinevich 提交于
      commit 8530a79c5a9f4e29e6ffb35ec1a79d81f4968ec8 upstream.
      
      inject_emulated_exception() returns true if and only if nested page
      fault happens. However, page fault can come from guest page tables
      walk, either nested or not nested. In both cases we should stop an
      attempt to read under RIP and give guest to step over its own page
      fault handler.
      
      This is also visible when an emulated instruction causes a #GP fault
      and the VMware backdoor is enabled.  To handle the VMware backdoor,
      KVM intercepts #GP faults; with only the next patch applied,
      x86_emulate_instruction() injects a #GP but returns EMULATE_FAIL
      instead of EMULATE_DONE.   EMULATE_FAIL causes handle_exception_nmi()
      (or gp_interception() for SVM) to re-inject the original #GP because it
      thinks emulation failed due to a non-VMware opcode.  This patch prevents
      the issue as x86_emulate_instruction() will return EMULATE_DONE after
      injecting the #GP.
      
      Fixes: 6ea6e843 ("KVM: x86: inject exceptions produced by x86_decode_insn")
      Cc: stable@vger.kernel.org
      Cc: Denis Lunev <den@virtuozzo.com>
      Cc: Roman Kagan <rkagan@virtuozzo.com>
      Cc: Denis Plotnikov <dplotnikov@virtuozzo.com>
      Signed-off-by: NJan Dakinevich <jan.dakinevich@virtuozzo.com>
      Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      9723e445
  8. 19 9月, 2019 2 次提交
  9. 16 9月, 2019 10 次提交
    • W
      KVM: VMX: check CPUID before allowing read/write of IA32_XSS · beeeead9
      Wanpeng Li 提交于
      [ Upstream commit 4d763b168e9c5c366b05812c7bba7662e5ea3669 ]
      
      Raise #GP when guest read/write IA32_XSS, but the CPUID bits
      say that it shouldn't exist.
      
      Fixes: 20300099 (kvm: vmx: add MSR logic for XSAVES)
      Reported-by: NXiaoyao Li <xiaoyao.li@linux.intel.com>
      Reported-by: NTao Xu <tao3.xu@intel.com>
      Cc: Paolo Bonzini <pbonzini@redhat.com>
      Cc: Radim Krčmář <rkrcmar@redhat.com>
      Cc: stable@vger.kernel.org
      Signed-off-by: NWanpeng Li <wanpengli@tencent.com>
      Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      Signed-off-by: NSasha Levin <sashal@kernel.org>
      beeeead9
    • S
      KVM: VMX: Fix handling of #MC that occurs during VM-Entry · 891011ca
      Sean Christopherson 提交于
      [ Upstream commit beb8d93b3e423043e079ef3dda19dad7b28467a8 ]
      
      A previous fix to prevent KVM from consuming stale VMCS state after a
      failed VM-Entry inadvertantly blocked KVM's handling of machine checks
      that occur during VM-Entry.
      
      Per Intel's SDM, a #MC during VM-Entry is handled in one of three ways,
      depending on when the #MC is recognoized.  As it pertains to this bug
      fix, the third case explicitly states EXIT_REASON_MCE_DURING_VMENTRY
      is handled like any other VM-Exit during VM-Entry, i.e. sets bit 31 to
      indicate the VM-Entry failed.
      
      If a machine-check event occurs during a VM entry, one of the following occurs:
       - The machine-check event is handled as if it occurred before the VM entry:
              ...
       - The machine-check event is handled after VM entry completes:
              ...
       - A VM-entry failure occurs as described in Section 26.7. The basic
         exit reason is 41, for "VM-entry failure due to machine-check event".
      
      Explicitly handle EXIT_REASON_MCE_DURING_VMENTRY as a one-off case in
      vmx_vcpu_run() instead of binning it into vmx_complete_atomic_exit().
      Doing so allows vmx_vcpu_run() to handle VMX_EXIT_REASONS_FAILED_VMENTRY
      in a sane fashion and also simplifies vmx_complete_atomic_exit() since
      VMCS.VM_EXIT_INTR_INFO is guaranteed to be fresh.
      
      Fixes: b060ca3b ("kvm: vmx: Handle VMLAUNCH/VMRESUME failure properly")
      Cc: stable@vger.kernel.org
      Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
      Reviewed-by: NJim Mattson <jmattson@google.com>
      Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      Signed-off-by: NSasha Levin <sashal@kernel.org>
      891011ca
    • S
      KVM: VMX: Always signal #GP on WRMSR to MSR_IA32_CR_PAT with bad value · 74ce1333
      Sean Christopherson 提交于
      [ Upstream commit d28f4290b53a157191ed9991ad05dffe9e8c0c89 ]
      
      The behavior of WRMSR is in no way dependent on whether or not KVM
      consumes the value.
      
      Fixes: 4566654b ("KVM: vmx: Inject #GP on invalid PAT CR")
      Cc: stable@vger.kernel.org
      Cc: Nadav Amit <nadav.amit@gmail.com>
      Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
      Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      Signed-off-by: NSasha Levin <sashal@kernel.org>
      74ce1333
    • P
      KVM: x86: optimize check for valid PAT value · 74fd8aae
      Paolo Bonzini 提交于
      [ Upstream commit 674ea351cdeb01d2740edce31db7f2d79ce6095d ]
      
      This check will soon be done on every nested vmentry and vmexit,
      "parallelize" it using bitwise operations.
      Reviewed-by: NSean Christopherson <sean.j.christopherson@intel.com>
      Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      Signed-off-by: NSasha Levin <sashal@kernel.org>
      74fd8aae
    • P
      kvm: Check irqchip mode before assign irqfd · d5f65393
      Peter Xu 提交于
      [ Upstream commit 654f1f13ea56b92bacade8ce2725aea0457f91c0 ]
      
      When assigning kvm irqfd we didn't check the irqchip mode but we allow
      KVM_IRQFD to succeed with all the irqchip modes.  However it does not
      make much sense to create irqfd even without the kernel chips.  Let's
      provide a arch-dependent helper to check whether a specific irqfd is
      allowed by the arch.  At least for x86, it should make sense to check:
      
      - when irqchip mode is NONE, all irqfds should be disallowed, and,
      
      - when irqchip mode is SPLIT, irqfds that are with resamplefd should
        be disallowed.
      
      For either of the case, previously we'll silently ignore the irq or
      the irq ack event if the irqchip mode is incorrect.  However that can
      cause misterious guest behaviors and it can be hard to triage.  Let's
      fail KVM_IRQFD even earlier to detect these incorrect configurations.
      
      CC: Paolo Bonzini <pbonzini@redhat.com>
      CC: Radim Krčmář <rkrcmar@redhat.com>
      CC: Alex Williamson <alex.williamson@redhat.com>
      CC: Eduardo Habkost <ehabkost@redhat.com>
      Signed-off-by: NPeter Xu <peterx@redhat.com>
      Cc: stable@vger.kernel.org
      Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      Signed-off-by: NSasha Levin <sashal@kernel.org>
      d5f65393
    • S
      KVM: x86: Always use 32-bit SMRAM save state for 32-bit kernels · df5d4ea2
      Sean Christopherson 提交于
      [ Upstream commit b68f3cc7d978943fcf85148165b00594c38db776 ]
      
      Invoking the 64-bit variation on a 32-bit kenrel will crash the guest,
      trigger a WARN, and/or lead to a buffer overrun in the host, e.g.
      rsm_load_state_64() writes r8-r15 unconditionally, but enum kvm_reg and
      thus x86_emulate_ctxt._regs only define r8-r15 for CONFIG_X86_64.
      
      KVM allows userspace to report long mode support via CPUID, even though
      the guest is all but guaranteed to crash if it actually tries to enable
      long mode.  But, a pure 32-bit guest that is ignorant of long mode will
      happily plod along.
      
      SMM complicates things as 64-bit CPUs use a different SMRAM save state
      area.  KVM handles this correctly for 64-bit kernels, e.g. uses the
      legacy save state map if userspace has hid long mode from the guest,
      but doesn't fare well when userspace reports long mode support on a
      32-bit host kernel (32-bit KVM doesn't support 64-bit guests).
      
      Since the alternative is to crash the guest, e.g. by not loading state
      or explicitly requesting shutdown, unconditionally use the legacy SMRAM
      save state map for 32-bit KVM.  If a guest has managed to get far enough
      to handle SMIs when running under a weird/buggy userspace hypervisor,
      then don't deliberately crash the guest since there are no downsides
      (from KVM's perspective) to allow it to continue running.
      
      Fixes: 660a5d51 ("KVM: x86: save/load state on SMM switch")
      Cc: stable@vger.kernel.org
      Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
      Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      Signed-off-by: NSasha Levin <sashal@kernel.org>
      df5d4ea2
    • W
      x86/kvm: move kvm_load/put_guest_xcr0 into atomic context · 7a74d806
      WANG Chao 提交于
      [ Upstream commit 1811d979c71621aafc7b879477202d286f7e863b ]
      
      guest xcr0 could leak into host when MCE happens in guest mode. Because
      do_machine_check() could schedule out at a few places.
      
      For example:
      
      kvm_load_guest_xcr0
      ...
      kvm_x86_ops->run(vcpu) {
        vmx_vcpu_run
          vmx_complete_atomic_exit
            kvm_machine_check
              do_machine_check
                do_memory_failure
                  memory_failure
                    lock_page
      
      In this case, host_xcr0 is 0x2ff, guest vcpu xcr0 is 0xff. After schedule
      out, host cpu has guest xcr0 loaded (0xff).
      
      In __switch_to {
           switch_fpu_finish
             copy_kernel_to_fpregs
               XRSTORS
      
      If any bit i in XSTATE_BV[i] == 1 and xcr0[i] == 0, XRSTORS will
      generate #GP (In this case, bit 9). Then ex_handler_fprestore kicks in
      and tries to reinitialize fpu by restoring init fpu state. Same story as
      last #GP, except we get DOUBLE FAULT this time.
      
      Cc: stable@vger.kernel.org
      Signed-off-by: NWANG Chao <chao.wang@ucloud.cn>
      Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      Signed-off-by: NSasha Levin <sashal@kernel.org>
      7a74d806
    • B
      kvm: mmu: Fix overflow on kvm mmu page limit calculation · 163b24b1
      Ben Gardon 提交于
      [ Upstream commit bc8a3d8925a8fa09fa550e0da115d95851ce33c6 ]
      
      KVM bases its memory usage limits on the total number of guest pages
      across all memslots. However, those limits, and the calculations to
      produce them, use 32 bit unsigned integers. This can result in overflow
      if a VM has more guest pages that can be represented by a u32. As a
      result of this overflow, KVM can use a low limit on the number of MMU
      pages it will allocate. This makes KVM unable to map all of guest memory
      at once, prompting spurious faults.
      
      Tested: Ran all kvm-unit-tests on an Intel Haswell machine. This patch
      	introduced no new failures.
      Signed-off-by: NBen Gardon <bgardon@google.com>
      Cc: stable@vger.kernel.org
      Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      Signed-off-by: NSasha Levin <sashal@kernel.org>
      163b24b1
    • S
      KVM: VMX: Compare only a single byte for VMCS' "launched" in vCPU-run · cd490d44
      Sean Christopherson 提交于
      [ Upstream commit 61c08aa9606d4e48a8a50639c956448a720174c3 ]
      
      The vCPU-run asm blob does a manual comparison of a VMCS' launched
      status to execute the correct VM-Enter instruction, i.e. VMLAUNCH vs.
      VMRESUME.  The launched flag is a bool, which is a typedef of _Bool.
      C99 does not define an exact size for _Bool, stating only that is must
      be large enough to hold '0' and '1'.  Most, if not all, compilers use
      a single byte for _Bool, including gcc[1].
      
      Originally, 'launched' was of type 'int' and so the asm blob used 'cmpl'
      to check the launch status.  When 'launched' was moved to be stored on a
      per-VMCS basis, struct vcpu_vmx's "temporary" __launched flag was added
      in order to avoid having to pass the current VMCS into the asm blob.
      The new  '__launched' was defined as a 'bool' and not an 'int', but the
      'cmp' instruction was not updated.
      
      This has not caused any known problems, likely due to compilers aligning
      variables to 4-byte or 8-byte boundaries and KVM zeroing out struct
      vcpu_vmx during allocation.  I.e. vCPU-run accesses "junk" data, it just
      happens to always be zero and so doesn't affect the result.
      
      [1] https://gcc.gnu.org/ml/gcc-patches/2000-10/msg01127.html
      
      Fixes: d462b819 ("KVM: VMX: Keep list of loaded VMCSs, instead of vcpus")
      Cc: <stable@vger.kernel.org>
      Reviewed-by: NJim Mattson <jmattson@google.com>
      Reviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
      Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
      Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      Signed-off-by: NSasha Levin <sashal@kernel.org>
      cd490d44
    • V
      x86/kvm/lapic: preserve gfn_to_hva_cache len on cache reinit · 796469e3
      Vitaly Kuznetsov 提交于
      [ Upstream commit a7c42bb6da6b1b54b2e7bd567636d72d87b10a79 ]
      
      vcpu->arch.pv_eoi is accessible through both HV_X64_MSR_VP_ASSIST_PAGE and
      MSR_KVM_PV_EOI_EN so on migration userspace may try to restore them in any
      order. Values match, however, kvm_lapic_enable_pv_eoi() uses different
      length: for Hyper-V case it's the whole struct hv_vp_assist_page, for KVM
      native case it is 8. In case we restore KVM-native MSR last cache will
      be reinitialized with len=8 so trying to access VP assist page beyond
      8 bytes with kvm_read_guest_cached() will fail.
      
      Check if we re-initializing cache for the same address and preserve length
      in case it was greater.
      Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
      Cc: stable@vger.kernel.org
      Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      Signed-off-by: NSasha Levin <sashal@kernel.org>
      796469e3