Re: [PATCH 1/2] KVM: x86: Add emulation support for #GP triggered by VM instructions

Sean Christopherson
2021-01-12T18:00:12Z

On Tue, Jan 12, 2021, Sean Christopherson wrote:
> On Tue, Jan 12, 2021, Wei Huang wrote:
> > From: Bandan Das <bsd@redhat.com>
> >
> > While running VM related instructions (VMRUN/VMSAVE/VMLOAD), some AMD
> > CPUs check EAX against reserved memory regions (e.g. SMM memory on host)
> > before checking VMCB's instruction intercept.
>
> It would be very helpful to list exactly which CPUs are/aren't affected, even if
> that just means stating something like "all CPUs before XYZ". Given patch 2/2,
> I assume it's all CPUs without the new CPUID flag?

Ah, despite calling this an 'errata', the bad behavior is explicitly documented
in the APM, i.e. it's an architecture bug, not a silicon bug.

Can you reword the changelog to make it clear that the premature #GP is the
correct architectural behavior for CPUs without the new CPUID flag?