From: Dapeng Mi <dapeng1.mi@linux.intel.com>
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 <dapeng1.mi@linux.intel.com>
Co-developed-by: Zide Chen <zide.chen@intel.com>
Signed-off-by: Zide Chen <zide.chen@intel.com>
---
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