On Tue, 2022-06-07 at 16:10 +0300, Maxim Levitsky wrote:
> On Thu, 2022-06-02 at 19:56 +0530, Santosh Shukla wrote:
> > In the VNMI case, Report NMI is not allowed when the processor set the
> > V_NMI_MASK to 1 which means the Guest is busy handling VNMI.
> >
> > Signed-off-by: Santosh Shukla <santosh.shukla@xxxxxxx>
> > ---
> > arch/x86/kvm/svm/svm.c | 6 ++++++
> > 1 file changed, 6 insertions(+)
> >
> > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> > index d67a54517d95..a405e414cae4 100644
> > --- a/arch/x86/kvm/svm/svm.c
> > +++ b/arch/x86/kvm/svm/svm.c
> > @@ -3483,6 +3483,9 @@ bool svm_nmi_blocked(struct kvm_vcpu *vcpu)
> > struct vmcb *vmcb = svm->vmcb;
> > bool ret;
> >
> > + if (is_vnmi_enabled(vmcb) && is_vnmi_mask_set(vmcb))
> > + return true;
>
> How does this interact with GIF? if the guest does clgi, will the
> CPU update the V_NMI_MASK on its own If vGIF is enabled?
>
> What happens if vGIF is disabled and vNMI is enabled? KVM then intercepts
> the stgi/clgi, and it should then update the V_NMI_MASK?
>
>
>
>
> > +
> > if (!gif_set(svm))
> > return true;
> >
> > @@ -3618,6 +3621,9 @@ static void svm_enable_nmi_window(struct kvm_vcpu *vcpu)
> > {
> > struct vcpu_svm *svm = to_svm(vcpu);
> >
> > + if (is_vnmi_enabled(svm->vmcb) && is_vnmi_mask_set(svm->vmcb))
> > + return;
>
> This might have hidden assumption that we will only enable NMI window when vNMI is masked.
Also what if vNMI is already pending?
Best regards,
Maxim Levitsky
>
>
>
> > +
> > if ((vcpu->arch.hflags & (HF_NMI_MASK | HF_IRET_MASK)) == HF_NMI_MASK)
> > return; /* IRET will cause a vm exit */
> >
>
>
> Best regards,
> Maxim Levitsky
