Re: [PATCH v3 2/8] KVM: nSVM: Sync interrupt shadow to cached vmcb12 after VMRUN of L2

[Sean Christopherson]

On Fri, Feb 27, 2026, Yosry Ahmed wrote:
> > diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
> > index de90b104a0dd5..9909ff237e5ca 100644
> > --- a/arch/x86/kvm/svm/nested.c
> > +++ b/arch/x86/kvm/svm/nested.c
> > @@ -521,6 +521,7 @@ void nested_sync_control_from_vmcb02(struct vcpu_svm *svm)
> >         u32 mask;
> >         svm->nested.ctl.event_inj      = svm->vmcb->control.event_inj;
> >         svm->nested.ctl.event_inj_err  = svm->vmcb->control.event_inj_err;
> > +       svm->nested.ctl.int_state       = svm->vmcb->control.int_state;
> 
> FWIW, this is an incomplete fix. KVM might update the interrupt shadow
> after this point through __svm_skip_emulated_instruction(), and that
> won't be captured in svm->nested.ctl.int_state.
> 
> I think it's not worth fixing that case too, and any further effort
> should go toward teaching KVM_GET_NESTED_STATE to pull state from the
> correct place as discussed earlier.

+1.  FWIW, AMD doesn't have a MOV/POP SS shadow, so practically speaking the only
impact is that an STI shadow could get extended for one extra instruction.  Unless
the guest is doing e.g. "sti; hlt; cli", that's a non-issue.