Re: [PATCH v3 18/62] KVM: SVM: Disable (x2)AVIC IPI virtualization if CPU has erratum #1235

Sean Christopherson
2025-06-23T15:30:08Z

On Mon, Jun 23, 2025, Naveen N Rao wrote:
> On Wed, Jun 11, 2025 at 03:45:21PM -0700, Sean Christopherson wrote:
> > diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
> > index 48c737e1200a..bf8b59556373 100644
> > --- a/arch/x86/kvm/svm/avic.c
> > +++ b/arch/x86/kvm/svm/avic.c
> > @@ -1187,6 +1187,14 @@ bool avic_hardware_setup(void)
> > if (x2avic_enabled)
> > pr_info("x2AVIC enabled\n");
> >
> > + /*
> > + * Disable IPI virtualization for AMD Family 17h CPUs (Zen1 and Zen2)
> > + * due to erratum 1235, which results in missed GA log events and thus
> ^^^^^^^^^^^^^
> Not sure I understand the reference to GA log events here -- those are
> only for device interrupts and not IPIs.

Doh, you're absolutely right. I'll fix to this when applying:

/*
* Disable IPI virtualization for AMD Family 17h CPUs (Zen1 and Zen2)
* due to erratum 1235, which results in missed VM-Exits on the sender
* and thus missed wake events for blocking vCPUs due to the CPU
* failing to see a software update to clear IsRunning.
*/