[PATCH 12/15] KVM: x86/pmu: Populate CPUID.0AH:ECX fixed-counter bitmap

[Zide Chen]

PerfMon v5 adds a fixed-counter support bitmap in CPUID.0AH:ECX.
This is the superset of EDX[4:0] which indicates the contiguous
counters starting from 0. For backward compatibility, it's recommended
to use the following to determine if a fixed counter is supported:

FxCtr[i]_is_supported := ECX[i] || (EDX[4:0] > i);

Originally-by: Yang Weijiang <weijiang.yang@xxxxxxxxx>
Signed-off-by: Zide Chen <zide.chen@xxxxxxxxx>
---
 arch/x86/kvm/cpuid.c         | 5 ++++-
 arch/x86/kvm/vmx/pmu_intel.c | 3 +++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 151a4794f834..ae6176fb0a93 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -1533,7 +1533,10 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
 
 		entry->eax = eax.full;
 		entry->ebx = kvm_pmu_cap.events_mask;
-		entry->ecx = 0;
+		if (kvm_pmu_cap.version > 4)
+			entry->ecx &= (u32)kvm_pmu_cap.fixed_cntr_mask64;
+		else
+			entry->ecx = 0;
 		entry->edx = edx.full;
 		break;
 	}
diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index 556c119d5e91..3f41e4916986 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -613,7 +613,10 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu)
 				      kvm_pmu_cap.events_mask_len);
 	pmu->available_event_types = ~entry->ebx & (BIT_ULL(eax.split.mask_length) - 1);
 
+	/* FxCtr[i]_is_supported := ECX[i] || (EDX[4:0] > i) */
 	fixed_cntr_mask = BIT_ULL(edx.split.num_counters_fixed) - 1;
+	if (pmu->version > 4)
+		fixed_cntr_mask |= entry->ecx;
 	fixed_cntr_mask &= kvm_pmu_cap.fixed_cntr_mask64;
 
 	/*
-- 
2.54.0