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KVM: SVM: suppress unnecessary NMI singlestep on GIF=0 and nested exit 

enable_nmi_window is supposed to be a no-op if we know that we'll see
a VM exit by the time the NMI window opens. This commit adds two more
cases:

* We intercept stgi so we don't need to singlestep on GIF=0.

* We emulate nested vmexit so we don't need to singlestep when nested
  VM exit is required.

Signed-off-by: Ladi Prosek <lprosek@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Ladi Prosek 2017-06-21 09:07:01 +02:00 committed by Paolo Bonzini
parent a12713c25b
commit 1a5e185294
1 changed files with 6 additions and 0 deletions
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6
arch/x86/kvm/svm.c
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@ -4678,6 +4678,12 @@ static void enable_nmi_window(struct kvm_vcpu *vcpu)
== HF_NMI_MASK)
return; /* IRET will cause a vm exit */
if ((svm->vcpu.arch.hflags & HF_GIF_MASK) == 0)
return; /* STGI will cause a vm exit */
if (svm->nested.exit_required)
return; /* we're not going to run the guest yet */
/*
* Something prevents NMI from been injected. Single step over possible
* problem (IRET or exception injection or interrupt shadow)