Re: [PATCH v5 2/8] KVM: nSVM: Synthesize DecodeAssists EXITINFO for emulated intercepts

[Tina Zhang]

On 9/5/2026 7:07 AM, Jim Mattson wrote:
> On Mon, Aug 24, 2026 at 5:40 AM Tina Zhang <zhang_wei@xxxxxxxxxxxxxx> wrote:
> > +
> > +       vmcb->control.exit_info_1 = exit_info_1;
> > +       vmcb->control.exit_info_2 = 0;
> > +}
>
> Can this entire function be integrated into the existing switch
> statement in svm_check_intercept()?

Yes, that makes sense.

> And, if !guest_cpu_cap_has(vcpu, X86_FEATURE_DECODEASSISTS), should
> exit_info_1 be cleared for these intercepts?

My reading is that exit_info_1 is undefined for these intercepts when 
DecodeAssists is not exposed, and KVM previously left it untouched. I 
would therefore prefer to preserve the existing behavior and update 
exit_info_1 only when DecodeAssists is exposed. That said, do you see 
any reason why KVM should explicitly clear exit_info_1 when 
guest_cpu_cap_has(vcpu, X86_FEATURE_DECODEASSISTS) returns false?


Thanks,
Tina