[PATCH V3 3/4] KVM: x86/pmu: Support PERF_METRICS MSR in mediated vPMU

[Zide Chen <zide.chen@intel.com>]

From: Dapeng Mi <dapeng1.mi@linux.intel.com>

Bit 15 in IA32_PERF_CAPABILITIES indicates that the CPU provides
built-in support for Topdown Microarchitecture Analysis (TMA) L1
metrics via the IA32_PERF_METRICS MSR.

Expose this capability only when mediated vPMU is enabled, as emulating
IA32_PERF_METRICS in the legacy vPMU model is impractical.

Pass IA32_PERF_METRICS through to the guest only when mediated vPMU is
enabled and bit 15 is set in guest IA32_PERF_CAPABILITIES.  Allow
kvm_pmu_{get,set}_msr() to handle this MSR for host accesses.

Save and restore this MSR on host/guest PMU context switches so that
host PMU activity does not clobber the guest value, and guest state
is not leaked into the host.

Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Signed-off-by: Zide Chen <zide.chen@intel.com>
---
v3:
- Replace WARN_ON() with WARN_ON_ONCE(). (Dapeng)
- Add comments to explain why don't validate writes on PERF_METRICS.
---
 arch/x86/include/asm/kvm_host.h   |  1 +
 arch/x86/include/asm/msr-index.h  |  1 +
 arch/x86/include/asm/perf_event.h |  1 +
 arch/x86/kvm/vmx/pmu_intel.c      | 36 +++++++++++++++++++++++++++++++
 arch/x86/kvm/vmx/pmu_intel.h      |  5 +++++
 arch/x86/kvm/vmx/vmx.c            |  6 ++++++
 arch/x86/kvm/x86.c                |  6 +++++-
 7 files changed, 55 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 754103e7ab4d..9b03475843f3 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -597,6 +597,7 @@ struct kvm_pmu {
 	u64 global_status_rsvd;
 	u64 reserved_bits;
 	u64 raw_event_mask;
+	u64 perf_metrics;
 	struct kvm_pmc gp_counters[KVM_MAX_NR_GP_COUNTERS];
 	struct kvm_pmc fixed_counters[KVM_MAX_NR_FIXED_COUNTERS];
 
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 18c4be75e927..fdcaeb6c8352 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -331,6 +331,7 @@
 #define PERF_CAP_PEBS_FORMAT		0xf00
 #define PERF_CAP_FW_WRITES		BIT_ULL(13)
 #define PERF_CAP_PEBS_BASELINE		BIT_ULL(14)
+#define PERF_CAP_PERF_METRICS		BIT_ULL(15)
 #define PERF_CAP_PEBS_TIMING_INFO	BIT_ULL(17)
 #define PERF_CAP_PEBS_MASK		(PERF_CAP_PEBS_TRAP | PERF_CAP_ARCH_REG | \
 					 PERF_CAP_PEBS_FORMAT | PERF_CAP_PEBS_BASELINE | \
diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
index 1eb13673e889..bc2e1cbcd9b9 100644
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -447,6 +447,7 @@ static inline bool is_topdown_idx(int idx)
 #define GLOBAL_STATUS_ARCH_PEBS_THRESHOLD_BIT	54
 #define GLOBAL_STATUS_ARCH_PEBS_THRESHOLD	BIT_ULL(GLOBAL_STATUS_ARCH_PEBS_THRESHOLD_BIT)
 #define GLOBAL_STATUS_PERF_METRICS_OVF_BIT	48
+#define GLOBAL_STATUS_PERF_METRICS_OVF		BIT_ULL(GLOBAL_STATUS_PERF_METRICS_OVF_BIT)
 
 #define GLOBAL_CTRL_EN_PERF_METRICS		BIT_ULL(48)
 /*
diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index 59b7a90c79e1..19daee29b731 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -188,6 +188,8 @@ static bool intel_is_valid_msr(struct kvm_vcpu *vcpu, u32 msr)
 	switch (msr) {
 	case MSR_CORE_PERF_FIXED_CTR_CTRL:
 		return kvm_pmu_has_perf_global_ctrl(pmu);
+	case MSR_PERF_METRICS:
+		return vcpu_has_perf_metrics(vcpu);
 	case MSR_IA32_PEBS_ENABLE:
 		ret = vcpu_get_perf_capabilities(vcpu) & PERF_CAP_PEBS_FORMAT;
 		break;
@@ -345,6 +347,10 @@ static int intel_pmu_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 	case MSR_CORE_PERF_FIXED_CTR_CTRL:
 		msr_info->data = pmu->fixed_ctr_ctrl;
 		break;
+	case MSR_PERF_METRICS:
+		WARN_ON_ONCE(!msr_info->host_initiated);
+		msr_info->data = pmu->perf_metrics;
+		break;
 	case MSR_IA32_PEBS_ENABLE:
 		msr_info->data = pmu->pebs_enable;
 		break;
@@ -394,6 +400,15 @@ static int intel_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 		if (pmu->fixed_ctr_ctrl != data)
 			reprogram_fixed_counters(pmu, data);
 		break;
+	case MSR_PERF_METRICS:
+		WARN_ON_ONCE(!msr_info->host_initiated);
+
+		/*
+		 * If TMA level 2 is not supported, bits [63:32] are reserved
+		 * and ignored on write, so no validation is needed here.
+		 */
+		pmu->perf_metrics = data;
+		break;
 	case MSR_IA32_PEBS_ENABLE:
 		if (data & pmu->pebs_enable_rsvd)
 			return 1;
@@ -589,6 +604,11 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu)
 		pmu->global_status_rsvd &=
 				~MSR_CORE_PERF_GLOBAL_OVF_CTRL_TRACE_TOPA_PMI;
 
+	if (perf_capabilities & PERF_CAP_PERF_METRICS) {
+		pmu->global_ctrl_rsvd &= ~GLOBAL_CTRL_EN_PERF_METRICS;
+		pmu->global_status_rsvd &= ~GLOBAL_STATUS_PERF_METRICS_OVF;
+	}
+
 	if (perf_capabilities & PERF_CAP_PEBS_FORMAT) {
 		if (perf_capabilities & PERF_CAP_PEBS_BASELINE) {
 			pmu->pebs_enable_rsvd = counter_rsvd;
@@ -632,6 +652,9 @@ static void intel_pmu_init(struct kvm_vcpu *vcpu)
 
 static void intel_pmu_reset(struct kvm_vcpu *vcpu)
 {
+	struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
+
+	pmu->perf_metrics = 0;
 	intel_pmu_release_guest_lbr_event(vcpu);
 }
 
@@ -803,6 +826,13 @@ static void intel_mediated_pmu_load(struct kvm_vcpu *vcpu)
 	struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
 	u64 global_status, toggle;
 
+	/*
+	 * PERF_METRICS MSR must be restored closely after fixed counter 3
+	 * (kvm_pmu_load_guest_pmcs()).
+	 */
+	if (vcpu_has_perf_metrics(vcpu))
+		wrmsrq(MSR_PERF_METRICS, pmu->perf_metrics);
+
 	rdmsrq(MSR_CORE_PERF_GLOBAL_STATUS, global_status);
 	toggle = pmu->global_status ^ global_status;
 	if (global_status & toggle)
@@ -831,6 +861,12 @@ static void intel_mediated_pmu_put(struct kvm_vcpu *vcpu)
 	 */
 	if (pmu->fixed_ctr_ctrl_hw)
 		wrmsrq(MSR_CORE_PERF_FIXED_CTR_CTRL, 0);
+
+	if (vcpu_has_perf_metrics(vcpu)) {
+		pmu->perf_metrics = rdpmc(INTEL_PMC_FIXED_RDPMC_METRICS);
+		if (pmu->perf_metrics)
+			wrmsrq(MSR_PERF_METRICS, 0);
+	}
 }
 
 struct kvm_pmu_ops intel_pmu_ops __initdata = {
diff --git a/arch/x86/kvm/vmx/pmu_intel.h b/arch/x86/kvm/vmx/pmu_intel.h
index 5d9357640aa1..2ec547223b09 100644
--- a/arch/x86/kvm/vmx/pmu_intel.h
+++ b/arch/x86/kvm/vmx/pmu_intel.h
@@ -40,4 +40,9 @@ struct lbr_desc {
 
 extern struct x86_pmu_lbr vmx_lbr_caps;
 
+static inline bool vcpu_has_perf_metrics(struct kvm_vcpu *vcpu)
+{
+	return !!(vcpu_get_perf_capabilities(vcpu) & PERF_CAP_PERF_METRICS);
+}
+
 #endif /* __KVM_X86_VMX_PMU_INTEL_H */
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index c548f22375ad..7cffe1619a1f 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -4264,6 +4264,9 @@ static void vmx_recalc_pmu_msr_intercepts(struct kvm_vcpu *vcpu)
 				  MSR_TYPE_RW, intercept);
 	vmx_set_intercept_for_msr(vcpu, MSR_CORE_PERF_GLOBAL_OVF_CTRL,
 				  MSR_TYPE_RW, intercept);
+
+	vmx_set_intercept_for_msr(vcpu, MSR_PERF_METRICS, MSR_TYPE_RW,
+				  !vcpu_has_perf_metrics(vcpu));
 }
 
 static void vmx_recalc_msr_intercepts(struct kvm_vcpu *vcpu)
@@ -8088,6 +8091,9 @@ static __init u64 vmx_get_perf_capabilities(void)
 		perf_cap &= ~PERF_CAP_PEBS_BASELINE;
 	}
 
+	if (enable_mediated_pmu)
+		perf_cap |= host_perf_cap & PERF_CAP_PERF_METRICS;
+
 	return perf_cap;
 }
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b9cca855bc10..2ac297ba3598 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -352,7 +352,7 @@ static const u32 msrs_to_save_pmu[] = {
 	MSR_ARCH_PERFMON_FIXED_CTR0, MSR_ARCH_PERFMON_FIXED_CTR1,
 	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_CORE_PERF_GLOBAL_CTRL, MSR_PERF_METRICS,
 	MSR_IA32_PEBS_ENABLE, MSR_IA32_DS_AREA, MSR_PEBS_DATA_CFG,
 
 	/* This part of MSRs should match KVM_MAX_NR_INTEL_GP_COUNTERS. */
@@ -7679,6 +7679,10 @@ static void kvm_probe_msr_to_save(u32 msr_index)
 		     intel_pt_validate_hw_cap(PT_CAP_num_address_ranges) * 2))
 			return;
 		break;
+	case MSR_PERF_METRICS:
+		if (!(kvm_caps.supported_perf_cap & PERF_CAP_PERF_METRICS))
+			return;
+		break;
 	case MSR_ARCH_PERFMON_PERFCTR0 ...
 	     MSR_ARCH_PERFMON_PERFCTR0 + KVM_MAX_NR_GP_COUNTERS - 1:
 		if (msr_index - MSR_ARCH_PERFMON_PERFCTR0 >=
-- 
2.54.0