[PATCH v2 2/5] KVM: x86/pmu: Expose PDCM feature when PEBS output to PT

[Luwei Kang]

PDCM(Perfmon and Debug Capability) indicates the processor supports
the performance and debug feature indication IA32_PERF_CAPABILITIES.

Expose PDCM feature when PEBS virtualization via Intel PT is supported
in KVM guest.

Signed-off-by: Luwei Kang <luwei.kang@xxxxxxxxx>
---
 arch/x86/include/asm/msr-index.h |  1 +
 arch/x86/kvm/pmu.h               |  1 +
 arch/x86/kvm/vmx/capabilities.h  |  9 +++++++--
 arch/x86/kvm/vmx/pmu_intel.c     | 13 +++++++++++++
 4 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index d3d6e48..750a2d5 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -155,6 +155,7 @@
 #define PERF_CAP_ARCH_REG		BIT_ULL(7)
 #define PERF_CAP_PEBS_FORMAT		0xf00
 #define PERF_CAP_PEBS_BASELINE		BIT_ULL(14)
+#define PERF_CAP_PEBS_OUTPUT_PT		BIT_ULL(16)
 #define MSR_PEBS_LD_LAT_THRESHOLD	0x000003f6
 
 #define MSR_IA32_RTIT_CTL		0x00000570
diff --git a/arch/x86/kvm/pmu.h b/arch/x86/kvm/pmu.h
index d640628..ba8c68d 100644
--- a/arch/x86/kvm/pmu.h
+++ b/arch/x86/kvm/pmu.h
@@ -33,6 +33,7 @@ struct kvm_pmu_ops {
 	int (*is_valid_rdpmc_ecx)(struct kvm_vcpu *vcpu, unsigned int idx);
 	bool (*is_valid_msr)(struct kvm_vcpu *vcpu, u32 msr);
 	bool (*is_pebs_via_ds_supported)(void);
+	bool (*is_pebs_via_pt_supported)(void);
 	bool (*is_pebs_baseline_supported)(void);
 	int (*get_msr)(struct kvm_vcpu *vcpu, u32 msr, u64 *data);
 	int (*set_msr)(struct kvm_vcpu *vcpu, struct msr_data *msr_info);
diff --git a/arch/x86/kvm/vmx/capabilities.h b/arch/x86/kvm/vmx/capabilities.h
index 9e352b5..dc480c9 100644
--- a/arch/x86/kvm/vmx/capabilities.h
+++ b/arch/x86/kvm/vmx/capabilities.h
@@ -154,10 +154,15 @@ static inline bool vmx_pku_supported(void)
 
 static inline bool vmx_pdcm_supported(void)
 {
+	bool ret = 0;
+
 	if (kvm_x86_ops->pmu_ops->is_pebs_via_ds_supported)
-		return kvm_x86_ops->pmu_ops->is_pebs_via_ds_supported();
+		ret |= kvm_x86_ops->pmu_ops->is_pebs_via_ds_supported();
 
-	return false;
+	if (kvm_x86_ops->pmu_ops->is_pebs_via_pt_supported)
+		ret |= kvm_x86_ops->pmu_ops->is_pebs_via_pt_supported();
+
+	return ret;
 }
 
 static inline bool vmx_dtes64_supported(void)
diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index 2db9b9e..f04e5eb 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -221,6 +221,18 @@ static bool intel_is_pebs_via_ds_supported(void)
 	return true;
 }
 
+static bool intel_is_pebs_via_pt_supported(void)
+{
+	u64 misc, perf_cap;
+
+	rdmsrl(MSR_IA32_MISC_ENABLE, misc);
+	rdmsrl(MSR_IA32_PERF_CAPABILITIES, perf_cap);
+
+	return (!(misc & MSR_IA32_MISC_ENABLE_PEBS_UNAVAIL) &&
+		(perf_cap & PERF_CAP_PEBS_OUTPUT_PT) &&
+		(pt_mode == PT_MODE_HOST_GUEST));
+}
+
 static bool intel_is_pebs_baseline_supported(void)
 {
 	u64 perf_cap;
@@ -529,6 +541,7 @@ struct kvm_pmu_ops intel_pmu_ops = {
 	.is_valid_rdpmc_ecx = intel_is_valid_rdpmc_ecx,
 	.is_valid_msr = intel_is_valid_msr,
 	.is_pebs_via_ds_supported = intel_is_pebs_via_ds_supported,
+	.is_pebs_via_pt_supported = intel_is_pebs_via_pt_supported,
 	.is_pebs_baseline_supported = intel_is_pebs_baseline_supported,
 	.get_msr = intel_pmu_get_msr,
 	.set_msr = intel_pmu_set_msr,
-- 
1.8.3.1