Re: [PATCH v2 42/54] KVM: x86/pmu: Implement emulated counter increment for passthrough PMU

Mingwei Zhang
2024-05-30T04:20:12Z

On Thu, May 09, 2024, Mi, Dapeng wrote:
>
> On 5/9/2024 2:28 AM, Chen, Zide wrote:
> >
> > On 5/5/2024 10:30 PM, Mingwei Zhang wrote:
> >> @@ -896,6 +924,12 @@ void kvm_pmu_trigger_event(struct kvm_vcpu *vcpu, u64 eventsel)
> >> return;
> >>
> >> kvm_for_each_pmc(pmu, pmc, i, bitmap) {
> >> + if (is_passthrough)
> >> + is_pmc_allowed = pmc_speculative_in_use(pmc) &&
> >> + check_pmu_event_filter(pmc);
> >> + else
> >> + is_pmc_allowed = pmc_event_is_allowed(pmc);
> >> +
> > Why don't need to check pmc_is_globally_enabled() in PMU passthrough
> > case? Sorry if I missed something.
>
> Not sure if it's because the historical reason. Since pmu->global_ctrl
> would be updated in each vm-exit right now, we may not need to skip
> pmc_is_globally_enabled() anymore. Need Mingwei to confirm.
>
yeah, this is a historical reason and how it becomes a bug. I will fix
that in next version.