linux-kernel - [PATCH v5 09/13] KVM: selftests: Test Intel PMU architectural events on fixed counters

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Message-ID: <20231024002633.2540714-10-seanjc@google.com>
Date:   Mon, 23 Oct 2023 17:26:29 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jinrong Liang <cloudliang@...cent.com>,
        Like Xu <likexu@...cent.com>
Subject: [PATCH v5 09/13] KVM: selftests: Test Intel PMU architectural events
 on fixed counters

From: Jinrong Liang <cloudliang@...cent.com>

Update test to cover Intel PMU architectural events on fixed counters.
Per Intel SDM, PMU users can also count architecture performance events
on fixed counters (specifically, FIXED_CTR0 for the retired instructions
and FIXED_CTR1 for cpu core cycles event). Therefore, if guest's CPUID
indicates that an architecture event is not available, the corresponding
fixed counter will also not count that event.

Co-developed-by: Like Xu <likexu@...cent.com>
Signed-off-by: Like Xu <likexu@...cent.com>
Signed-off-by: Jinrong Liang <cloudliang@...cent.com>
Co-developed-by: Sean Christopherson <seanjc@...gle.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 .../selftests/kvm/x86_64/pmu_counters_test.c  | 54 ++++++++++++++++---
 1 file changed, 46 insertions(+), 8 deletions(-)

diff --git a/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c b/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c
index 2a6336b994d5..410d09f788ef 100644
--- a/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c
+++ b/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c
@@ -85,23 +85,44 @@ static void guest_measure_pmu_v1(struct kvm_x86_pmu_feature event,
 	GUEST_DONE();
 }
 
+#define X86_PMU_FEATURE_NULL						\
+({									\
+	struct kvm_x86_pmu_feature feature = {};			\
+									\
+	feature;							\
+})
+
+static bool pmu_is_null_feature(struct kvm_x86_pmu_feature event)
+{
+	return !(*(u64 *)&event);
+}
+
 static void guest_measure_loop(uint8_t idx)
 {
 	const struct {
 		struct kvm_x86_pmu_feature gp_event;
+		struct kvm_x86_pmu_feature fixed_event;
 	} intel_event_to_feature[] = {
-		[INTEL_ARCH_CPU_CYCLES]		   = { X86_PMU_FEATURE_CPU_CYCLES },
-		[INTEL_ARCH_INSTRUCTIONS_RETIRED]  = { X86_PMU_FEATURE_INSNS_RETIRED },
-		[INTEL_ARCH_REFERENCE_CYCLES]	   = { X86_PMU_FEATURE_REFERENCE_CYCLES },
-		[INTEL_ARCH_LLC_REFERENCES]	   = { X86_PMU_FEATURE_LLC_REFERENCES },
-		[INTEL_ARCH_LLC_MISSES]		   = { X86_PMU_FEATURE_LLC_MISSES },
-		[INTEL_ARCH_BRANCHES_RETIRED]	   = { X86_PMU_FEATURE_BRANCH_INSNS_RETIRED },
-		[INTEL_ARCH_BRANCHES_MISPREDICTED] = { X86_PMU_FEATURE_BRANCHES_MISPREDICTED },
+		[INTEL_ARCH_CPU_CYCLES]		   = { X86_PMU_FEATURE_CPU_CYCLES, X86_PMU_FEATURE_CPU_CYCLES_FIXED },
+		[INTEL_ARCH_INSTRUCTIONS_RETIRED]  = { X86_PMU_FEATURE_INSNS_RETIRED, X86_PMU_FEATURE_INSNS_RETIRED_FIXED },
+		/*
+		 * Note, the fixed counter for reference cycles is NOT the same
+		 * as the general purpose architectural event (because the GP
+		 * event is garbage).  The fixed counter explicitly counts at
+		 * the same frequency as the TSC, whereas the GP event counts
+		 * at a fixed, but uarch specific, frequency.  Bundle them here
+		 * for simplicity.
+		 */
+		[INTEL_ARCH_REFERENCE_CYCLES]	   = { X86_PMU_FEATURE_REFERENCE_CYCLES, X86_PMU_FEATURE_REFERENCE_CYCLES_FIXED },
+		[INTEL_ARCH_LLC_REFERENCES]	   = { X86_PMU_FEATURE_LLC_REFERENCES, X86_PMU_FEATURE_NULL },
+		[INTEL_ARCH_LLC_MISSES]		   = { X86_PMU_FEATURE_LLC_MISSES, X86_PMU_FEATURE_NULL },
+		[INTEL_ARCH_BRANCHES_RETIRED]	   = { X86_PMU_FEATURE_BRANCH_INSNS_RETIRED, X86_PMU_FEATURE_NULL },
+		[INTEL_ARCH_BRANCHES_MISPREDICTED] = { X86_PMU_FEATURE_BRANCHES_MISPREDICTED, X86_PMU_FEATURE_NULL },
 	};
 
 	uint32_t nr_gp_counters = this_cpu_property(X86_PROPERTY_PMU_NR_GP_COUNTERS);
 	uint32_t pmu_version = this_cpu_property(X86_PROPERTY_PMU_VERSION);
-	struct kvm_x86_pmu_feature gp_event;
+	struct kvm_x86_pmu_feature gp_event, fixed_event;
 	uint32_t counter_msr;
 	unsigned int i;
 
@@ -132,6 +153,23 @@ static void guest_measure_loop(uint8_t idx)
 			GUEST_ASSERT_EQ(this_pmu_has(gp_event), !!_rdpmc(i));
 	}
 
+	fixed_event = intel_event_to_feature[idx].fixed_event;
+	if (pmu_is_null_feature(fixed_event) || !this_pmu_has(fixed_event))
+		goto done;
+
+	i = fixed_event.f.bit;
+
+	wrmsr(MSR_CORE_PERF_FIXED_CTR0 + i, 0);
+	wrmsr(MSR_CORE_PERF_FIXED_CTR_CTRL, BIT_ULL(4 * i));
+
+	wrmsr(MSR_CORE_PERF_GLOBAL_CTRL, BIT_ULL(PMC_IDX_FIXED + i));
+	__asm__ __volatile__("loop ." : "+c"((int){NUM_BRANCHES}));
+	wrmsr(MSR_CORE_PERF_GLOBAL_CTRL, 0);
+
+	if (pmu_is_intel_event_stable(idx))
+		GUEST_ASSERT_NE(_rdpmc(PMC_FIXED_RDPMC_BASE | i), 0);
+
+done:
 	GUEST_DONE();
 }
 
-- 
2.42.0.758.gaed0368e0e-goog