Re: [PATCH v6 3/3] KVM: selftests: Add self IPI HLT test

[Manali Shukla <manali.shukla@amd.com>]

Hi Sean,

Thank you for reviewing my patches.

On 2/26/2025 6:08 AM, Sean Christopherson wrote:
> On Tue, Jan 28, 2025, Manali Shukla wrote:
>> +	if (kvm_cpu_has(X86_FEATURE_IDLE_HLT))
> 
> Well, shoot.  I gave you bad input, and we're stuck.
> 
> this_cpu_has() isn't correct, because the part of my previous feedback about
> needing to check *KVM* support was 100% correct.  But kvm_cpu_has() isn't right
> either, because that checks what KVM supports exposing to the guest, not what
> KVM itself supports/uses.  E.g. even if we add full nested support, the test would
> fail if nested=0 due to KVM not "supporting" Idle HLT despite using it under the
> hood.
> 
> The lack of a way for KVM to communicate support to the user has come up in the
> past, e.g. in discussion around /proc/cpuinfo.  Sadly, AFAIK there are no (good)
> ideas on what that should look like.
> 
> For now, I'll just skip this patch, even though doing so makes me quite sad.

I understand your point.

-Manali