From: Dapeng Mi Starting with Ice Lake, Intel introduces fixed counter 3, which counts TOPDOWN.SLOTS - the number of available slots for an unhalted logical processor. It serves as the denominator for top-level metrics in the Top-down Microarchitecture Analysis method. Emulating this counter on legacy vPMU would require introducing a new generic perf encoding for the Intel-specific TOPDOWN.SLOTS event in order to call perf_get_hw_event_config(). This is undesirable as it would pollute the generic perf event encoding. Moreover, KVM does not intend to emulate IA32_PERF_METRICS in the legacy vPMU model, and without IA32_PERF_METRICS, emulating this counter has little practical value. Therefore, expose fixed counter 3 to guests only when mediated vPMU is enabled. Signed-off-by: Dapeng Mi Co-developed-by: Zide Chen Signed-off-by: Zide Chen --- arch/x86/include/asm/kvm_host.h | 2 +- arch/x86/kvm/pmu.c | 4 ++++ arch/x86/kvm/x86.c | 4 ++-- 3 files changed, 7 insertions(+), 3 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index ff07c45e3c73..4666b2c7988f 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -555,7 +555,7 @@ struct kvm_pmc { #define KVM_MAX_NR_GP_COUNTERS KVM_MAX(KVM_MAX_NR_INTEL_GP_COUNTERS, \ KVM_MAX_NR_AMD_GP_COUNTERS) -#define KVM_MAX_NR_INTEL_FIXED_COUNTERS 3 +#define KVM_MAX_NR_INTEL_FIXED_COUNTERS 4 #define KVM_MAX_NR_AMD_FIXED_COUNTERS 0 #define KVM_MAX_NR_FIXED_COUNTERS KVM_MAX(KVM_MAX_NR_INTEL_FIXED_COUNTERS, \ KVM_MAX_NR_AMD_FIXED_COUNTERS) diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c index bd6b785cf261..ee49395bfb82 100644 --- a/arch/x86/kvm/pmu.c +++ b/arch/x86/kvm/pmu.c @@ -148,6 +148,10 @@ void kvm_init_pmu_capability(struct kvm_pmu_ops *pmu_ops) } memcpy(&kvm_pmu_cap, &kvm_host_pmu, sizeof(kvm_host_pmu)); + + if (!enable_mediated_pmu && kvm_pmu_cap.num_counters_fixed > 3) + kvm_pmu_cap.num_counters_fixed = 3; + kvm_pmu_cap.version = min(kvm_pmu_cap.version, 2); kvm_pmu_cap.num_counters_gp = min(kvm_pmu_cap.num_counters_gp, pmu_ops->MAX_NR_GP_COUNTERS); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 3fb64905d190..2ab7a4958620 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -355,7 +355,7 @@ static const u32 msrs_to_save_base[] = { static const u32 msrs_to_save_pmu[] = { MSR_ARCH_PERFMON_FIXED_CTR0, MSR_ARCH_PERFMON_FIXED_CTR1, - MSR_ARCH_PERFMON_FIXED_CTR0 + 2, + MSR_ARCH_PERFMON_FIXED_CTR2, MSR_ARCH_PERFMON_FIXED_CTR3, MSR_CORE_PERF_FIXED_CTR_CTRL, MSR_CORE_PERF_GLOBAL_STATUS, MSR_CORE_PERF_GLOBAL_CTRL, MSR_IA32_PEBS_ENABLE, MSR_IA32_DS_AREA, MSR_PEBS_DATA_CFG, @@ -7738,7 +7738,7 @@ static void kvm_init_msr_lists(void) { unsigned i; - BUILD_BUG_ON_MSG(KVM_MAX_NR_FIXED_COUNTERS != 3, + BUILD_BUG_ON_MSG(KVM_MAX_NR_FIXED_COUNTERS != 4, "Please update the fixed PMCs in msrs_to_save_pmu[]"); num_msrs_to_save = 0; -- 2.53.0