diff options
| author | Vitaly Kuznetsov <vkuznets@redhat.com> | 2018-01-25 16:37:07 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-01-09 16:16:45 +0100 |
| commit | 737dcb98a359e16bc03a2eef83fc5ec88b75e01c (patch) | |
| tree | e2647b99585e6d08104a5f5c4dfc0bf15e6ee0ff /arch/x86/kvm/x86.c | |
| parent | 40738b6a0428a5660f937f3f3f090b1eb9035c63 (diff) | |
x86/kvm/vmx: do not use vm-exit instruction length for fast MMIO when running nested
commit d391f1207067268261add0485f0f34503539c5b0 upstream.
I was investigating an issue with seabios >= 1.10 which stopped working
for nested KVM on Hyper-V. The problem appears to be in
handle_ept_violation() function: when we do fast mmio we need to skip
the instruction so we do kvm_skip_emulated_instruction(). This, however,
depends on VM_EXIT_INSTRUCTION_LEN field being set correctly in VMCS.
However, this is not the case.
Intel's manual doesn't mandate VM_EXIT_INSTRUCTION_LEN to be set when
EPT MISCONFIG occurs. While on real hardware it was observed to be set,
some hypervisors follow the spec and don't set it; we end up advancing
IP with some random value.
I checked with Microsoft and they confirmed they don't fill
VM_EXIT_INSTRUCTION_LEN on EPT MISCONFIG.
Fix the issue by doing instruction skip through emulator when running
nested.
Fixes: 68c3b4d1676d870f0453c31d5a52e7e65c7448ae
Suggested-by: Radim Krčmář <rkrcmar@redhat.com>
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
[mhaboustak: backport to 4.9.y]
Signed-off-by: Mike Haboustak <haboustak@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/x86/kvm/x86.c')
| -rw-r--r-- | arch/x86/kvm/x86.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 27d13b870e07..46e0ad71b4da 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -5707,7 +5707,8 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, * handle watchpoints yet, those would be handled in * the emulate_ops. */ - if (kvm_vcpu_check_breakpoint(vcpu, &r)) + if (!(emulation_type & EMULTYPE_SKIP) && + kvm_vcpu_check_breakpoint(vcpu, &r)) return r; ctxt->interruptibility = 0; |