KVM: x86/svm/pmu: Add AMD PerfMonV2 support

If AMD Performance Monitoring Version 2 (PerfMonV2) is detected by
the guest, it can use a new scheme to manage the Core PMCs using the
new global control and status registers.

In addition to benefiting from the PerfMonV2 functionality in the same
way as the host (higher precision), the guest also can reduce the number
of vm-exits by lowering the total number of MSRs accesses.

In terms of implementation details, amd_is_valid_msr() is resurrected
since three newly added MSRs could not be mapped to one vPMC.
The possibility of emulating PerfMonV2 on the mainframe has also
been eliminated for reasons of precision.

Co-developed-by: Sandipan Das <sandipan.das@amd.com>
Signed-off-by: Sandipan Das <sandipan.das@amd.com>
Signed-off-by: Like Xu <likexu@tencent.com>
[sean: drop "Based on the observed HW." comments]
Link: https://lore.kernel.org/r/20230603011058.1038821-12-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

1 files changed, 45 insertions, 10 deletions

diff --git a/arch/x86/kvm/svm/pmu.c b/arch/x86/kvm/svm/pmu.c
index c03958063a76..cef5a3d0abd0 100644
--- a/arch/x86/kvm/svm/pmu.c
+++ b/arch/x86/kvm/svm/pmu.c
@@ -94,12 +94,6 @@ static struct kvm_pmc *amd_rdpmc_ecx_to_pmc(struct kvm_vcpu *vcpu,
 	return amd_pmc_idx_to_pmc(vcpu_to_pmu(vcpu), idx & ~(3u << 30));
 }
 
-static bool amd_is_valid_msr(struct kvm_vcpu *vcpu, u32 msr)
-{
-	/* All MSRs refer to exactly one PMC, so msr_idx_to_pmc is enough.  */
-	return false;
-}
-
 static struct kvm_pmc *amd_msr_idx_to_pmc(struct kvm_vcpu *vcpu, u32 msr)
 {
 	struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
@@ -111,6 +105,29 @@ static struct kvm_pmc *amd_msr_idx_to_pmc(struct kvm_vcpu *vcpu, u32 msr)
 	return pmc;
 }
 
+static bool amd_is_valid_msr(struct kvm_vcpu *vcpu, u32 msr)
+{
+	struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
+
+	switch (msr) {
+	case MSR_K7_EVNTSEL0 ... MSR_K7_PERFCTR3:
+		return pmu->version > 0;
+	case MSR_F15H_PERF_CTL0 ... MSR_F15H_PERF_CTR5:
+		return guest_cpuid_has(vcpu, X86_FEATURE_PERFCTR_CORE);
+	case MSR_AMD64_PERF_CNTR_GLOBAL_STATUS:
+	case MSR_AMD64_PERF_CNTR_GLOBAL_CTL:
+	case MSR_AMD64_PERF_CNTR_GLOBAL_STATUS_CLR:
+		return pmu->version > 1;
+	default:
+		if (msr > MSR_F15H_PERF_CTR5 &&
+		    msr < MSR_F15H_PERF_CTL0 + 2 * pmu->nr_arch_gp_counters)
+			return pmu->version > 1;
+		break;
+	}
+
+	return amd_msr_idx_to_pmc(vcpu, msr);
+}
+
 static int amd_pmu_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 {
 	struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
@@ -164,23 +181,39 @@ static int amd_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 static void amd_pmu_refresh(struct kvm_vcpu *vcpu)
 {
 	struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
+	union cpuid_0x80000022_ebx ebx;
 
-	if (guest_cpuid_has(vcpu, X86_FEATURE_PERFCTR_CORE))
+	pmu->version = 1;
+	if (guest_cpuid_has(vcpu, X86_FEATURE_PERFMON_V2)) {
+		pmu->version = 2;
+		/*
+		 * Note, PERFMON_V2 is also in 0x80000022.0x0, i.e. the guest
+		 * CPUID entry is guaranteed to be non-NULL.
+		 */
+		BUILD_BUG_ON(x86_feature_cpuid(X86_FEATURE_PERFMON_V2).function != 0x80000022 ||
+			     x86_feature_cpuid(X86_FEATURE_PERFMON_V2).index);
+		ebx.full = kvm_find_cpuid_entry_index(vcpu, 0x80000022, 0)->ebx;
+		pmu->nr_arch_gp_counters = ebx.split.num_core_pmc;
+	} else if (guest_cpuid_has(vcpu, X86_FEATURE_PERFCTR_CORE)) {
 		pmu->nr_arch_gp_counters = AMD64_NUM_COUNTERS_CORE;
-	else
+	} else {
 		pmu->nr_arch_gp_counters = AMD64_NUM_COUNTERS;
+	}
 
 	pmu->nr_arch_gp_counters = min_t(unsigned int, pmu->nr_arch_gp_counters,
 					 kvm_pmu_cap.num_counters_gp);
 
+	if (pmu->version > 1) {
+		pmu->global_ctrl_mask = ~((1ull << pmu->nr_arch_gp_counters) - 1);
+		pmu->global_status_mask = pmu->global_ctrl_mask;
+	}
+
 	pmu->counter_bitmask[KVM_PMC_GP] = ((u64)1 << 48) - 1;
 	pmu->reserved_bits = 0xfffffff000280000ull;
 	pmu->raw_event_mask = AMD64_RAW_EVENT_MASK;
-	pmu->version = 1;
 	/* not applicable to AMD; but clean them to prevent any fall out */
 	pmu->counter_bitmask[KVM_PMC_FIXED] = 0;
 	pmu->nr_arch_fixed_counters = 0;
-	pmu->global_status = 0;
 	bitmap_set(pmu->all_valid_pmc_idx, 0, pmu->nr_arch_gp_counters);
 }
 
@@ -211,6 +244,8 @@ static void amd_pmu_reset(struct kvm_vcpu *vcpu)
 		pmc_stop_counter(pmc);
 		pmc->counter = pmc->prev_counter = pmc->eventsel = 0;
 	}
+
+	pmu->global_ctrl = pmu->global_status = 0;
 }
 
 struct kvm_pmu_ops amd_pmu_ops __initdata = {