Re: [PATCH v3 2/3] KVM: SVM: Disable x2AVIC RDMSR interception for MSRs KVM actually supports

[Sean Christopherson <seanjc@google.com>]

On Fri, May 15, 2026, Naveen N Rao wrote:
> On Thu, May 14, 2026 at 02:31:14PM -0700, Sean Christopherson wrote:
> > When toggling x2AVIC on/off, use KVM's curated mask of x2APIC MSRs that
> > can/should be passed through to the guest (or not) when 2AVIC is enabled.
> > Using the effective list provided by the local APIC emulation fixes
> > multiple (classes of) bugs, as the existing hand-coded list of MSRs is
> > wrong on multiple fronts:
> > 
> >  - ARBPRI isn't supported by x2APIC, but its unaccelerated AVIC intercept
> >    is fault-like; disabling interception is nonsensical and suboptimal as
> >    the access generates a #VMEXIT that requires decoding the instruction.
> 
> Nit: unless you decided against incorporating the changes we discussed 
> in v2, please update this part while applying.

Gah, I just spaced it.  I'll reword to:

 - ARBPRI isn't supported by KVM, isn't accelerated by AVIC (for read or
   write), and its #VMEXIT is fault-like, i.e. requires decoding the
   instruction.  Disabling interception is nonsensical and suboptimal.