[PATCH v8 7/8] KVM: x86/pmu: Emulate RDPMC on performance metrics

[Zide Chen]

If the host has the PERF_METRICS capability but it's not present on
the guest, RDPMC interception must be enabled and KVM should inject
an #GP when the guest attempts a PERF_METRICS RDPMC.

If the guest has PERF_METRICS but RDPMC interception is enabled for
other reasons, KVM needs to emulate RDPMC with type 0x2000.

For simplicity, Metrics Clear Mode is not supported.

Signed-off-by: Zide Chen <zide.chen@xxxxxxxxx>
Reviewed-by: Dapeng Mi <dapeng1.mi@xxxxxxxxxxxxxxx>
---
v8:
- Move kvm_need_perf_metrics_intercept() to patch 5/9.
v6:
- Merge kvm_pmu_rdpmc_metrics() into intel_emulate_rdpmc().
- Reject non-zero index.
v5:
- new patch.
---
 arch/x86/kvm/pmu.c           |  1 +
 arch/x86/kvm/vmx/pmu_intel.c | 14 ++++++++++++++
 2 files changed, 15 insertions(+)

diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index 789624658e8f..dab0bcabaa8f 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -825,6 +825,7 @@ bool kvm_need_rdpmc_intercept(struct kvm_vcpu *vcpu)
 		return true;
 
 	return kvm_need_any_pmc_intercept(vcpu) ||
+	       kvm_need_perf_metrics_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);
 }
diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index bbf4afcffafc..3ca61e4b0ba6 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -31,6 +31,7 @@
  */
 #define INTEL_RDPMC_GP		0
 #define INTEL_RDPMC_FIXED	INTEL_PMC_FIXED_RDPMC_BASE
+#define INTEL_RDPMC_METRICS	INTEL_PMC_FIXED_RDPMC_METRICS
 
 #define INTEL_RDPMC_TYPE_MASK	GENMASK(31, 16)
 #define INTEL_RDPMC_INDEX_MASK	GENMASK(15, 0)
@@ -125,6 +126,19 @@ static int intel_emulate_rdpmc(struct kvm_vcpu *vcpu, unsigned int idx,
 		counters = pmu->gp_counters;
 		num_counters = pmu->nr_arch_gp_counters;
 		break;
+	case INTEL_RDPMC_METRICS:
+		if (!kvm_vcpu_has_perf_metrics(vcpu))
+			return 1;
+
+		/*
+		 * The index in ECX[15:0] is implementation specific, but no
+		 * platform currently supports a non-zero index.
+		 */
+		if (idx)
+			return 1;
+
+		*data = pmu->perf_metrics;
+		return 0;
 	default:
 		return 1;
 	}
-- 
2.55.0