From 6ff692048f885fe0f86fc3e8ae3f404f19dad0a0 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Thu, 9 Nov 2023 18:28:48 -0800 Subject: [PATCH] KVM: x86/pmu: Zero out PMU metadata on AMD if PMU is disabled BugLink: https://bugs.launchpad.net/bugs/2070337 [ Upstream commit f933b88e20150f15787390e2a1754a7e412754ed ] Move the purging of common PMU metadata from intel_pmu_refresh() to kvm_pmu_refresh(), and invoke the vendor refresh() hook if and only if the VM is supposed to have a vPMU. KVM already denies access to the PMU based on kvm->arch.enable_pmu, as get_gp_pmc_amd() returns NULL for all PMCs in that case, i.e. KVM already violates AMD's architecture by not virtualizing a PMU (kernels have long since learned to not panic when the PMU is unavailable). But configuring the PMU as if it were enabled causes unwanted side effects, e.g. calls to kvm_pmu_trigger_event() waste an absurd number of cycles due to the all_valid_pmc_idx bitmap being non-zero. Fixes: b1d66dad65dc ("KVM: x86/svm: Add module param to control PMU virtualization") Reported-by: Konstantin Khorenko Closes: https://lore.kernel.org/all/20231109180646.2963718-2-khorenko@virtuozzo.com Link: https://lore.kernel.org/r/20231110022857.1273836-2-seanjc@google.com Signed-off-by: Sean Christopherson Stable-dep-of: de120e1d692d ("KVM: x86/pmu: Set enable bits for GP counters in PERF_GLOBAL_CTRL at "RESET"") Signed-off-by: Sasha Levin Signed-off-by: Manuel Diewald Signed-off-by: Stefan Bader --- arch/x86/kvm/pmu.c | 20 ++++++++++++++++++-- arch/x86/kvm/vmx/pmu_intel.c | 16 ++-------------- 2 files changed, 20 insertions(+), 16 deletions(-) diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c index 87cc6c8809ad..38512954ec26 100644 --- a/arch/x86/kvm/pmu.c +++ b/arch/x86/kvm/pmu.c @@ -741,6 +741,8 @@ static void kvm_pmu_reset(struct kvm_vcpu *vcpu) */ void kvm_pmu_refresh(struct kvm_vcpu *vcpu) { + struct kvm_pmu *pmu = vcpu_to_pmu(vcpu); + if (KVM_BUG_ON(kvm_vcpu_has_run(vcpu), vcpu->kvm)) return; @@ -750,8 +752,22 @@ void kvm_pmu_refresh(struct kvm_vcpu *vcpu) */ kvm_pmu_reset(vcpu); - bitmap_zero(vcpu_to_pmu(vcpu)->all_valid_pmc_idx, X86_PMC_IDX_MAX); - static_call(kvm_x86_pmu_refresh)(vcpu); + pmu->version = 0; + pmu->nr_arch_gp_counters = 0; + pmu->nr_arch_fixed_counters = 0; + pmu->counter_bitmask[KVM_PMC_GP] = 0; + pmu->counter_bitmask[KVM_PMC_FIXED] = 0; + pmu->reserved_bits = 0xffffffff00200000ull; + pmu->raw_event_mask = X86_RAW_EVENT_MASK; + pmu->global_ctrl_mask = ~0ull; + pmu->global_status_mask = ~0ull; + pmu->fixed_ctr_ctrl_mask = ~0ull; + pmu->pebs_enable_mask = ~0ull; + pmu->pebs_data_cfg_mask = ~0ull; + bitmap_zero(pmu->all_valid_pmc_idx, X86_PMC_IDX_MAX); + + if (vcpu->kvm->arch.enable_pmu) + static_call(kvm_x86_pmu_refresh)(vcpu); } void kvm_pmu_init(struct kvm_vcpu *vcpu) diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c index 315c7c2ba89b..600a021ae958 100644 --- a/arch/x86/kvm/vmx/pmu_intel.c +++ b/arch/x86/kvm/vmx/pmu_intel.c @@ -491,19 +491,6 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu) u64 counter_mask; int i; - pmu->nr_arch_gp_counters = 0; - pmu->nr_arch_fixed_counters = 0; - pmu->counter_bitmask[KVM_PMC_GP] = 0; - pmu->counter_bitmask[KVM_PMC_FIXED] = 0; - pmu->version = 0; - pmu->reserved_bits = 0xffffffff00200000ull; - pmu->raw_event_mask = X86_RAW_EVENT_MASK; - pmu->global_ctrl_mask = ~0ull; - pmu->global_status_mask = ~0ull; - pmu->fixed_ctr_ctrl_mask = ~0ull; - pmu->pebs_enable_mask = ~0ull; - pmu->pebs_data_cfg_mask = ~0ull; - memset(&lbr_desc->records, 0, sizeof(lbr_desc->records)); /* @@ -515,8 +502,9 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu) return; entry = kvm_find_cpuid_entry(vcpu, 0xa); - if (!entry || !vcpu->kvm->arch.enable_pmu) + if (!entry) return; + eax.full = entry->eax; edx.full = entry->edx;