Re: [PATCH v6 15/44] KVM: x86/pmu: Snapshot host (i.e. perf's) reported PMU capabilities

Mi, Dapeng
2025-12-25T06:27:06Z

On 12/6/2025 8:16 AM, Sean Christopherson wrote:
> Take a snapshot of the unadulterated PMU capabilities provided by perf so
> that KVM can compare guest vPMU capabilities against hardware capabilities
> when determining whether or not to intercept PMU MSRs (and RDPMC).
>
> Reviewed-by: Sandipan Das <sandipan.das@amd.com>
> Tested-by: Xudong Hao <xudong.hao@intel.com>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> arch/x86/kvm/pmu.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
> index 487ad19a236e..7c219305b61d 100644
> --- a/arch/x86/kvm/pmu.c
> +++ b/arch/x86/kvm/pmu.c
> @@ -108,6 +108,8 @@ void kvm_init_pmu_capability(const struct kvm_pmu_ops *pmu_ops)
> bool is_intel = boot_cpu_data.x86_vendor == X86_VENDOR_INTEL;
> int min_nr_gp_ctrs = pmu_ops->MIN_NR_GP_COUNTERS;
>
> + perf_get_x86_pmu_capability(&kvm_host_pmu);
> +
> /*
> * Hybrid PMUs don't play nice with virtualization without careful
> * configuration by userspace, and KVM's APIs for reporting supported

Hi Sean,

It looks a merging error here. We don't need this patch.

The original patch "51f34b1 ("KVM: x86/pmu: Snapshot host (i.e. perf's)
reported PMU capabilities")" had been merged into upstream and subsequently
we submitted a new patch "034417c1439a ("KVM: x86/pmu: Don't try to get
perf capabilities for hybrid CPUs")" to fix the warning introduced from
previous patch  "51f34b1 ("KVM: x86/pmu: Snapshot host (i.e. perf's)
reported PMU capabilities")". Thanks.

-Dapeng Mi