Re: [PATCH v9 05/12] KVM: x86/pmu: Support PERF_METRICS MSR in mediated vPMU

[Yosry Ahmed]

On Thu, Oct 29, 2026 at 4:17 PM Chen, Zide <zide.chen@xxxxxxxxx> wrote:
>
>
>
> On 10/29/2026 5:06 PM, Yosry Ahmed wrote:
> >> diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
> >> index 448044a2b121..f4d3801b97bc 100644
> >> --- a/arch/x86/kvm/pmu.c
> >> +++ b/arch/x86/kvm/pmu.c
> >> @@ -806,9 +806,16 @@ static bool kvm_need_any_pmc_intercept(struct kvm_vcpu *vcpu)
> >>                pmu->nr_arch_fixed_counters != kvm_host_pmu.num_counters_fixed;
> >>  }
> >>
> >> +static bool kvm_need_perf_metrics_intercept(struct kvm_vcpu *vcpu)
> >
> > The name is confusing, this doesn't control the intercept of
> > PERF_METRICS (and it wouldn't be correct to use it for that AFAICT).
>
> Right, these two APIs do not directly determine whether the mentioned
> resources need interception:
>
> kvm_need_any_pmc_intercept()
> kvm_need_perf_metrics_intercept()

Jim suggested folding kvm_need_perf_metrics_intercept() into
kvm_need_any_pmc_intercept(). The name of kvm_need_any_pmc_intercept()
might be confusing as well, but at least it's one less interface to
worry about?

>
> This is different from kvm_need_perf_global_ctrl_intercept() and
> kvm_need_rdpmc_intercept().
>
> How about change them to something like these?
>
> kvm_pmu_has_unexposed_pmcs()
> kvm_pmu_has_unexposed_perf_metrics()
>
> Or merge them into one single API? kvm_pmu_has_unexposed_resources()

I don't like this name any better, but I don't have better
suggestions. Since we already have kvm_need_any_pmc_intercept(), let's
just use it for now?