KVM: selftests: Test consistency of CPUID with num of fixed counters

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.

Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Co-developed-by: Like Xu <likexu@tencent.com>
Signed-off-by: Like Xu <likexu@tencent.com>
Signed-off-by: Jinrong Liang <cloudliang@tencent.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Link: https://lore.kernel.org/r/20240109230250.424295-20-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

tools/testing/selftests/kvm/x86_64/pmu_counters_test.c

@@ -290,7 +290,7 @@ __GUEST_ASSERT(expect_gp ? vector == GP_VECTOR : !vector,			\
 		       msr, expected_val, val);
 
 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;
 
@@ -301,7 +301,13 @@ static void guest_rd_wr_counters(uint32_t base_msr, uint8_t nr_possible_counters
 		 */
 		const uint64_t test_val = 0xffff;
 		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
@@ -343,7 +349,7 @@ 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 pmu_version, uint64_t perf_capabilities,
@@ -363,9 +369,50 @@ static void test_gp_counters(uint8_t pmu_version, uint64_t perf_capabilities,
 	kvm_vm_free(vm);
 }
 
+static void guest_test_fixed_counters(void)
+{
+	uint64_t supported_bitmask = 0;
+	uint8_t nr_fixed_counters = 0;
+
+	/* Fixed counters require Architectural vPMU Version 2+. */
+	if (guest_get_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 (guest_get_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 pmu_version, uint64_t perf_capabilities,
+				uint8_t nr_fixed_counters,
+				uint32_t supported_bitmask)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm;
+
+	vm = pmu_vm_create_with_one_vcpu(&vcpu, guest_test_fixed_counters,
+					 pmu_version, perf_capabilities);
+
+	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);
+
+	run_vcpu(vcpu);
+
+	kvm_vm_free(vm);
+}
+
 static void test_intel_counters(void)
 {
 	uint8_t nr_arch_events = kvm_cpu_property(X86_PROPERTY_PMU_EBX_BIT_VECTOR_LENGTH);
+	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);
 	uint8_t pmu_version = kvm_cpu_property(X86_PROPERTY_PMU_VERSION);
 	unsigned int i;
@@ -435,6 +482,13 @@ static void test_intel_counters(void)
 				v, perf_caps[i]);
 			for (j = 0; j <= nr_gp_counters; j++)
 				test_gp_counters(v, perf_caps[i], j);
+
+			pr_info("Testing fixed counters, PMU version %u, perf_caps = %lx\n",
+				v, perf_caps[i]);
+			for (j = 0; j <= nr_fixed_counters; j++) {
+				for (k = 0; k <= (BIT(nr_fixed_counters) - 1); k++)
+					test_fixed_counters(v, perf_caps[i], j, k);
+			}
 		}
 	}
 }