On Mon, Sep 5, 2022 at 5:45 AM Like Xu <like.xu.linux@xxxxxxxxx> wrote: > > From: Sandipan Das <sandipan.das@xxxxxxx> > > CPUID leaf 0x80000022 i.e. ExtPerfMonAndDbg advertises some > new performance monitoring features for AMD processors. > > Bit 0 of EAX indicates support for Performance Monitoring > Version 2 (PerfMonV2) features. If found to be set during > PMU initialization, the EBX bits of the same CPUID function > can be used to determine the number of available PMCs for > different PMU types. > > Expose the relevant bits via KVM_GET_SUPPORTED_CPUID so > that guests can make use of the PerfMonV2 features. > > Co-developed-by: Like Xu <likexu@xxxxxxxxxxx> > Signed-off-by: Like Xu <likexu@xxxxxxxxxxx> > Signed-off-by: Sandipan Das <sandipan.das@xxxxxxx> > --- > arch/x86/include/asm/perf_event.h | 8 ++++++++ > arch/x86/kvm/cpuid.c | 21 ++++++++++++++++++++- > 2 files changed, 28 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h > index f6fc8dd51ef4..c848f504e467 100644 > --- a/arch/x86/include/asm/perf_event.h > +++ b/arch/x86/include/asm/perf_event.h > @@ -214,6 +214,14 @@ union cpuid_0x80000022_ebx { > unsigned int full; > }; > > +union cpuid_0x80000022_eax { > + struct { > + /* Performance Monitoring Version 2 Supported */ > + unsigned int perfmon_v2:1; > + } split; > + unsigned int full; > +}; > + > struct x86_pmu_capability { > int version; > int num_counters_gp; > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index 75dcf7a72605..08a29ab096d2 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -1094,7 +1094,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) > entry->edx = 0; > break; > case 0x80000000: > - entry->eax = min(entry->eax, 0x80000021); > + entry->eax = min(entry->eax, 0x80000022); > /* > * Serializing LFENCE is reported in a multitude of ways, and > * NullSegClearsBase is not reported in CPUID on Zen2; help > @@ -1203,6 +1203,25 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) > if (!static_cpu_has_bug(X86_BUG_NULL_SEG)) > entry->eax |= BIT(6); > break; > + /* AMD Extended Performance Monitoring and Debug */ > + case 0x80000022: { > + union cpuid_0x80000022_eax eax; > + union cpuid_0x80000022_ebx ebx; > + > + entry->eax = entry->ebx = entry->ecx = entry->edx = 0; > + if (!enable_pmu) > + break; > + > + if (kvm_pmu_cap.version > 1) { > + /* AMD PerfMon is only supported up to V2 in the KVM. */ > + eax.split.perfmon_v2 = 1; > + ebx.split.num_core_pmc = min(kvm_pmu_cap.num_counters_gp, > + KVM_AMD_PMC_MAX_GENERIC); Note that the number of core PMCs has to be at least 6 if guest_cpuid_has(vcpu, X86_FEATURE_PERFCTR_CORE). I suppose this leaf could claim fewer, but the first 6 PMCs must work, per the v1 PMU spec. That is, software that knows about PERFCTR_CORE, but not about PMU v2, can rightfully expect 6 PMCs. > + } > + entry->eax = eax.full; > + entry->ebx = ebx.full; > + break; > + } > /*Add support for Centaur's CPUID instruction*/ > case 0xC0000000: > /*Just support up to 0xC0000004 now*/ > -- > 2.37.3 >