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| author | Wanpeng Li <kernellwp@gmail.com> | 2017-07-25 03:40:46 -0700 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2017-07-26 18:57:46 +0200 |
| commit | 2d6144e366fb39609aecf7a658e2e10af37627e9 (patch) | |
| tree | 220cc344d2e3f14de0bae0551a618bd095f26e68 /arch/x86 | |
| parent | 06a5524f091b6b41b0007810c74cc9315923a145 (diff) | |
| download | linux-2d6144e366fb39609aecf7a658e2e10af37627e9.tar.bz2 | |
KVM: nVMX: Fix loss of L2's NMI blocking state
Run kvm-unit-tests/eventinj.flat in L1 w/ ept=0 on both L0 and L1:
Before NMI IRET test
Sending NMI to self
NMI isr running stack 0x461000
Sending nested NMI to self
After nested NMI to self
Nested NMI isr running rip=40038e
After iret
After NMI to self
FAIL: NMI
Commit 4c4a6f790ee862 (KVM: nVMX: track NMI blocking state separately
for each VMCS) tracks NMI blocking state separately for vmcs01 and
vmcs02. However it is not enough:
- The L2 (kvm-unit-tests/eventinj.flat) generates NMI that will fault
on IRET, so the L2 can generate #PF which can be intercepted by L0.
- L0 walks L1's guest page table and sees the mapping is invalid, it
resumes the L1 guest and injects the #PF into L1. At this point the
vmcs02 has nmi_known_unmasked=true.
- L1 sets set bit 3 (blocking by NMI) in the interruptibility-state field
of vmcs12 (and fixes the shadow page table) before resuming L2 guest.
- L1 executes VMRESUME to resume L2, causing a vmexit to L0
- during VMRESUME emulation, prepare_vmcs02 sets bit 3 in the
interruptibility-state field of vmcs02, but nmi_known_unmasked is
still true.
- L2 immediately exits to L0 with another page fault, because L0 still has
not updated the NGVA->HPA page tables. However, nmi_known_unmasked is
true so vmx_recover_nmi_blocking does not do anything.
The fix is to update nmi_known_unmasked when preparing vmcs02 from vmcs12.
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>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kvm/vmx.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 497cf64794fd..39a6222bf968 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -10042,6 +10042,8 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12, vmcs12->vm_entry_instruction_len); vmcs_write32(GUEST_INTERRUPTIBILITY_INFO, vmcs12->guest_interruptibility_info); + vmx->loaded_vmcs->nmi_known_unmasked = + !(vmcs12->guest_interruptibility_info & GUEST_INTR_STATE_NMI); } else { vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, 0); } |