linux-kernel - [PATCH v5 11/13] KVM: selftests: Test consistency of CPUID with num of fixed counters

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Date:   Mon, 23 Oct 2023 17:26:31 -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 11/13] KVM: selftests: Test consistency of CPUID with num
 of fixed counters

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

Extend the PMU counters test to verify KVM emulation of fixed counters in
addition to general purpose counters.  Fixed counters add an extra wrinkle
in the form of an extra supported bitmask.  Thus quoth the SDM:

  fixed-function performance counter 'i' is supported if ECX[i] || (EDX[4:0] > i)

Test that KVM handles a counter being available through either method.

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  | 58 ++++++++++++++++++-
 1 file changed, 55 insertions(+), 3 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 274b7f4d4b53..f1d9cdd69a17 100644
--- a/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c
+++ b/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c
@@ -227,13 +227,19 @@ __GUEST_ASSERT(expect_gp ? vector == GP_VECTOR : !vector,			\
 	       expect_gp ? "#GP" : "no fault", msr, vector)			\
 
 static void guest_rd_wr_counters(uint32_t base_msr, uint8_t nr_possible_counters,
-				 uint8_t nr_counters)
+				 uint8_t nr_counters, uint32_t or_mask)
 {
 	uint8_t i;
 
 	for (i = 0; i < nr_possible_counters; i++) {
 		const uint32_t msr = base_msr + i;
-		const bool expect_success = i < nr_counters;
+
+		/*
+		 * Fixed counters are supported if the counter is less than the
+		 * number of enumerated contiguous counters *or* the counter is
+		 * explicitly enumerated in the supported counters mask.
+		 */
+		const bool expect_success = i < nr_counters || (or_mask & BIT(i));
 
 		/*
 		 * KVM drops writes to MSR_P6_PERFCTR[0|1] if the counters are
@@ -273,7 +279,7 @@ static void guest_test_gp_counters(void)
 	else
 		base_msr = MSR_IA32_PERFCTR0;
 
-	guest_rd_wr_counters(base_msr, MAX_NR_GP_COUNTERS, nr_gp_counters);
+	guest_rd_wr_counters(base_msr, MAX_NR_GP_COUNTERS, nr_gp_counters, 0);
 }
 
 static void test_gp_counters(uint8_t nr_gp_counters, uint64_t perf_cap)
@@ -292,10 +298,51 @@ static void test_gp_counters(uint8_t nr_gp_counters, uint64_t perf_cap)
 	kvm_vm_free(vm);
 }
 
+static void guest_test_fixed_counters(void)
+{
+	uint64_t supported_bitmask = 0;
+	uint8_t nr_fixed_counters = 0;
+
+	/* KVM provides fixed counters iff the vPMU version is 2+. */
+	if (this_cpu_property(X86_PROPERTY_PMU_VERSION) >= 2)
+		nr_fixed_counters = this_cpu_property(X86_PROPERTY_PMU_NR_FIXED_COUNTERS);
+
+	/*
+	 * The supported bitmask for fixed counters was introduced in PMU
+	 * version 5.
+	 */
+	if (this_cpu_property(X86_PROPERTY_PMU_VERSION) >= 5)
+		supported_bitmask = this_cpu_property(X86_PROPERTY_PMU_FIXED_COUNTERS_BITMASK);
+
+	guest_rd_wr_counters(MSR_CORE_PERF_FIXED_CTR0, MAX_NR_FIXED_COUNTERS,
+			     nr_fixed_counters, supported_bitmask);
+}
+
+static void test_fixed_counters(uint8_t nr_fixed_counters,
+				uint32_t supported_bitmask, uint64_t perf_cap)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm;
+
+	vm = pmu_vm_create_with_one_vcpu(&vcpu, guest_test_fixed_counters);
+
+	vcpu_set_cpuid_property(vcpu, X86_PROPERTY_PMU_FIXED_COUNTERS_BITMASK,
+				supported_bitmask);
+	vcpu_set_cpuid_property(vcpu, X86_PROPERTY_PMU_NR_FIXED_COUNTERS,
+				nr_fixed_counters);
+	vcpu_set_msr(vcpu, MSR_IA32_PERF_CAPABILITIES, perf_cap);
+
+	run_vcpu(vcpu);
+
+	kvm_vm_free(vm);
+}
+
 static void test_intel_counters(void)
 {
+	uint8_t nr_fixed_counters = kvm_cpu_property(X86_PROPERTY_PMU_NR_FIXED_COUNTERS);
 	uint8_t nr_gp_counters = kvm_cpu_property(X86_PROPERTY_PMU_NR_GP_COUNTERS);
 	unsigned int i;
+	uint32_t k;
 	uint8_t j;
 
 	const uint64_t perf_caps[] = {
@@ -306,6 +353,11 @@ static void test_intel_counters(void)
 	for (i = 0; i < ARRAY_SIZE(perf_caps); i++) {
 		for (j = 0; j <= nr_gp_counters; j++)
 			test_gp_counters(j, perf_caps[i]);
+
+		for (j = 0; j <= nr_fixed_counters; j++) {
+			for (k = 0; k <= (BIT(nr_fixed_counters) - 1); k++)
+				test_fixed_counters(j, k, perf_caps[i]);
+		}
 	}
 }
 
-- 
2.42.0.758.gaed0368e0e-goog