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Peter Anvin" , Andy Lutomirski , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Paolo Bonzini , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvm@vger.kernel.org, loongarch@lists.linux.dev, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Kan Liang , Yongwei Ma , Mingwei Zhang , Xiong Zhang , Sandipan Das References: <20250806195706.1650976-1-seanjc@google.com> <20250806195706.1650976-33-seanjc@google.com> <0276af52-c697-46c3-9db8-9284adb6beee@linux.intel.com> Content-Language: en-US From: "Mi, Dapeng" In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 10/16/2025 2:48 AM, Sean Christopherson wrote: > On Thu, Oct 09, 2025, Dapeng Mi wrote: >> On 10/2/2025 2:14 AM, Sean Christopherson wrote: >>> On Fri, Sep 26, 2025, Sandipan Das wrote: >>>> On 8/7/2025 1:26 AM, Sean Christopherson wrote: >>>>> + return kvm_need_perf_global_ctrl_intercept(vcpu) || >>>>> pmu->counter_bitmask[KVM_PMC_GP] != (BIT_ULL(kvm_host_pmu.bit_width_gp) - 1) || >>>>> pmu->counter_bitmask[KVM_PMC_FIXED] != (BIT_ULL(kvm_host_pmu.bit_width_fixed) - 1); >>>>> } >>>> There is a case for AMD processors where the global MSRs are absent in the guest >>>> but the guest still uses the same number of counters as what is advertised by the >>>> host capabilities. So RDPMC interception is not necessary for all cases where >>>> global control is unavailable.o >>> Hmm, I think Intel would be the same? Ah, no, because the host will have fixed >>> counters, but the guest will not. However, that's not directly related to >>> kvm_pmu_has_perf_global_ctrl(), so I think this would be correct? >>> >>> diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c >>> index 4414d070c4f9..4c5b2712ee4c 100644 >>> --- a/arch/x86/kvm/pmu.c >>> +++ b/arch/x86/kvm/pmu.c >>> @@ -744,16 +744,13 @@ int kvm_pmu_rdpmc(struct kvm_vcpu *vcpu, unsigned idx, u64 *data) >>> return 0; >>> } >>> >>> -bool kvm_need_perf_global_ctrl_intercept(struct kvm_vcpu *vcpu) >>> +static bool kvm_need_pmc_intercept(struct kvm_vcpu *vcpu) >> The function name kvm_need_pmc_intercept() seems a little bit misleading >> and make users think this function is used to check if a certain PMC is >> intercepted. Maybe we can rename the function to kvm_need_global_intercept(). > Yeah, I don't love kvm_need_pmc_intercept() either. But kvm_need_global_intercept() > feels too close to kvm_need_perf_global_ctrl_intercept(). > > Maybe something like kvm_need_any_pmc_intercept()? It sounds good to me. Thanks.