Re: [PATCH v2 02/11] KVM: SVM: Don't BUG if userspace injects a soft interrupt with GIF=0

From: Maxim Levitsky
Date: Thu Apr 28 2022 - 10:34:56 EST

On Thu, 2022-04-28 at 15:27 +0200, Maciej S. Szmigiero wrote:
> On 28.04.2022 09:35, Maxim Levitsky wrote:
> > On Sat, 2022-04-23 at 02:14 +0000, Sean Christopherson wrote:
> > > From: Maciej S. Szmigiero <maciej.szmigiero@xxxxxxxxxx>
> > >
> > > Don't BUG/WARN on interrupt injection due to GIF being cleared if the
> > > injected event is a soft interrupt, which are not actually IRQs and thus
> >
> > Are any injected events subject to GIF set? I think that EVENTINJ just injects
> > unconditionaly whatever hypervisor puts in it.
> That's right, EVENTINJ will pretty much always inject, even when the CPU
> is in a 'wrong' state (like for example, injecting a hardware interrupt
> or a NMI with GIF masked).
> But KVM as a L0 is not supposed to inject a hardware interrupt into guest
> with GIF unset since the guest is obviously not expecting it then.
> Hence this WARN_ON().

If you mean L0->L1 injection, that sure, but if L1 injects interrupt to L2,
then it should always be allowed to do so.

I am not sure that I am right here, just noticed something odd. I'll take
a better look at this next week.

Best regards,
Maxim levitsky

> > Best regards,
> > Maxim Levitsky
> Thanks,
> Maciej