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AJvYcCVvdBMB6K2tDuLZAMEyJ9yxQ681oNq9cnEB1kfflHyxS5UgX8MtLVOArykaz3TrIV+EzKa2dZonF/fNGL4=@vger.kernel.org X-Gm-Message-State: AOJu0YylahIXZcMCSZYQrt0eX4ZkFgTBAKqdU55QJl+XWBhsyP8JEY1Q coM+B7IaDF8/zRA22Hm5PGU4VQg69Mbdjp+2QaVYsZ/4f26NrzxzO8bcXwU3Ihs2LWMJioTc6UQ H8ozYbg== X-Received: from pfri1.prod.google.com ([2002:aa7:8d81:0:b0:82c:e328:c2eb]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:301f:b0:81f:3fa0:8c38 with SMTP id d2e1a72fcca58-82d0da90c83mr14676785b3a.20.1775525407009; Mon, 06 Apr 2026 18:30:07 -0700 (PDT) Date: Mon, 6 Apr 2026 18:30:05 -0700 In-Reply-To: <20260326031150.3774017-4-yosry@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260326031150.3774017-1-yosry@kernel.org> <20260326031150.3774017-4-yosry@kernel.org> Message-ID: Subject: Re: [PATCH v4 3/6] KVM: x86/pmu: Disable counters based on Host-Only/Guest-Only bits in SVM From: Sean Christopherson To: Yosry Ahmed Cc: Paolo Bonzini , Jim Mattson , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="us-ascii" On Thu, Mar 26, 2026, Yosry Ahmed wrote: > diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h > index ff5acb8b199b0..5961c002b28eb 100644 > --- a/arch/x86/include/asm/perf_event.h > +++ b/arch/x86/include/asm/perf_event.h > @@ -60,6 +60,8 @@ > #define AMD64_EVENTSEL_INT_CORE_ENABLE (1ULL << 36) > #define AMD64_EVENTSEL_GUESTONLY (1ULL << 40) > #define AMD64_EVENTSEL_HOSTONLY (1ULL << 41) > +#define AMD64_EVENTSEL_HOST_GUEST_MASK \ > + (AMD64_EVENTSEL_HOSTONLY | AMD64_EVENTSEL_GUESTONLY) > > #define AMD64_EVENTSEL_INT_CORE_SEL_SHIFT 37 > #define AMD64_EVENTSEL_INT_CORE_SEL_MASK \ > diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c > index d6ac3c55fce55..e35d598f809a2 100644 > --- a/arch/x86/kvm/pmu.c > +++ b/arch/x86/kvm/pmu.c > @@ -559,6 +559,7 @@ static int reprogram_counter(struct kvm_pmc *pmc) > > if (kvm_vcpu_has_mediated_pmu(pmu_to_vcpu(pmu))) { > kvm_mediated_pmu_refresh_event_filter(pmc); > + kvm_pmu_call(mediated_reprogram_counter)(pmc); I would rather make a single call from kvm_pmu_handle_event(), and let the vendor deal with mediated vs. legacy. I want to avoid mediated-specific ops as much as possible, and I think kvm_x86_ops.reprogram_counters() would be easier to understand overall. diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c index a7b38c104d06..7da0077ae24c 100644 --- a/arch/x86/kvm/pmu.c +++ b/arch/x86/kvm/pmu.c @@ -670,6 +670,8 @@ void kvm_pmu_handle_event(struct kvm_vcpu *vcpu) set_bit(pmc->idx, pmu->reprogram_pmi); } + kvm_pmu_call(reprogram_counters)(vcpu, bitmap); + /* * Release unused perf_events if the corresponding guest MSRs weren't * accessed during the last vCPU time slice (need_cleanup is set when > diff --git a/arch/x86/kvm/svm/pmu.c b/arch/x86/kvm/svm/pmu.c > index 7aa298eeb0721..60931dfd624b2 100644 > --- a/arch/x86/kvm/svm/pmu.c > +++ b/arch/x86/kvm/svm/pmu.c > @@ -260,6 +260,34 @@ static void amd_mediated_pmu_put(struct kvm_vcpu *vcpu) > wrmsrq(MSR_AMD64_PERF_CNTR_GLOBAL_STATUS_CLR, pmu->global_status); > } > > +static void amd_mediated_pmu_handle_host_guest_bits(struct kvm_pmc *pmc) > +{ > + struct kvm_vcpu *vcpu = pmc->vcpu; > + u64 host_guest_bits; > + > + if (!(pmc->eventsel & ARCH_PERFMON_EVENTSEL_ENABLE)) > + return; > + > + /* Count all events if both bits are cleared or both bits are set */ > + host_guest_bits = pmc->eventsel & AMD64_EVENTSEL_HOST_GUEST_MASK; > + if (hweight64(host_guest_bits) != 1) > + return; > + > + /* Host-Only and Guest-Only are ignored if EFER.SVME == 0 */ > + if (!(vcpu->arch.efer & EFER_SVME)) > + return; > + > + if (!!(host_guest_bits & AMD64_EVENTSEL_GUESTONLY) == is_guest_mode(vcpu)) > + return; > + > + pmc->eventsel_hw &= ~ARCH_PERFMON_EVENTSEL_ENABLE; > +} > + > +static void amd_mediated_pmu_reprogram_counter(struct kvm_pmc *pmc) > +{ > + amd_mediated_pmu_handle_host_guest_bits(pmc); And then this doesn't need to be such a wonky wrapper, and the "reprogram on nested transition" logic can also clear the entire bitmap instead of doing things piecemeal, e.g. it can be something like so in the end: if (!kvm_vcpu_has_mediated_pmu(vcpu)) return; bitmap_zero(pmu->pmc_reprogram_on_nested_transition, X86_PMC_IDX_MAX); kvm_for_each_pmc(pmu, pmc, bit, bitmap) amd_mediated_pmu_handle_host_guest_bits(pmc);