KVM: selftests: Test if event filter meets expectations on fixed counters

Add tests to cover that pmu event_filter works as expected when it's
applied to fixed performance counters, even if there is none fixed
counter exists (e.g. Intel guest pmu version=1 or AMD guest).

Signed-off-by: Jinrong Liang <cloudliang@tencent.com>
Reviewed-by: Isaku Yamahata <isaku.yamahata@intel.com>
Link: https://lore.kernel.org/r/20230810090945.16053-6-cloudliang@tencent.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: Jinrong Liang

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

@@ -27,6 +27,7 @@
 #define ARCH_PERFMON_BRANCHES_RETIRED		5
 
 #define NUM_BRANCHES 42
+#define INTEL_PMC_IDX_FIXED		32
 
 /* Matches KVM_PMU_EVENT_FILTER_MAX_EVENTS in pmu.c */
 #define MAX_FILTER_EVENTS		300
@@ -808,6 +809,84 @@ static void test_filter_ioctl(struct kvm_vcpu *vcpu)
 	TEST_ASSERT(!r, "Masking non-existent fixed counters should be allowed");
 }
 
+static void intel_run_fixed_counter_guest_code(uint8_t fixed_ctr_idx)
+{
+	for (;;) {
+		wrmsr(MSR_CORE_PERF_GLOBAL_CTRL, 0);
+		wrmsr(MSR_CORE_PERF_FIXED_CTR0 + fixed_ctr_idx, 0);
+
+		/* Only OS_EN bit is enabled for fixed counter[idx]. */
+		wrmsr(MSR_CORE_PERF_FIXED_CTR_CTRL, BIT_ULL(4 * fixed_ctr_idx));
+		wrmsr(MSR_CORE_PERF_GLOBAL_CTRL,
+		      BIT_ULL(INTEL_PMC_IDX_FIXED + fixed_ctr_idx));
+		__asm__ __volatile__("loop ." : "+c"((int){NUM_BRANCHES}));
+		wrmsr(MSR_CORE_PERF_GLOBAL_CTRL, 0);
+
+		GUEST_SYNC(rdmsr(MSR_CORE_PERF_FIXED_CTR0 + fixed_ctr_idx));
+	}
+}
+
+static uint64_t test_with_fixed_counter_filter(struct kvm_vcpu *vcpu,
+					       uint32_t action, uint32_t bitmap)
+{
+	struct __kvm_pmu_event_filter f = {
+		.action = action,
+		.fixed_counter_bitmap = bitmap,
+	};
+	set_pmu_event_filter(vcpu, &f);
+
+	return run_vcpu_to_sync(vcpu);
+}
+
+static void __test_fixed_counter_bitmap(struct kvm_vcpu *vcpu, uint8_t idx,
+					uint8_t nr_fixed_counters)
+{
+	unsigned int i;
+	uint32_t bitmap;
+	uint64_t count;
+
+	TEST_ASSERT(nr_fixed_counters < sizeof(bitmap) * 8,
+		    "Invalid nr_fixed_counters");
+
+	/*
+	 * Check the fixed performance counter can count normally when KVM
+	 * userspace doesn't set any pmu filter.
+	 */
+	count = run_vcpu_to_sync(vcpu);
+	TEST_ASSERT(count, "Unexpected count value: %ld\n", count);
+
+	for (i = 0; i < BIT(nr_fixed_counters); i++) {
+		bitmap = BIT(i);
+		count = test_with_fixed_counter_filter(vcpu, KVM_PMU_EVENT_ALLOW,
+						       bitmap);
+		TEST_ASSERT_EQ(!!count, !!(bitmap & BIT(idx)));
+
+		count = test_with_fixed_counter_filter(vcpu, KVM_PMU_EVENT_DENY,
+						       bitmap);
+		TEST_ASSERT_EQ(!!count, !(bitmap & BIT(idx)));
+	}
+}
+
+static void test_fixed_counter_bitmap(void)
+{
+	uint8_t nr_fixed_counters = kvm_cpu_property(X86_PROPERTY_PMU_NR_FIXED_COUNTERS);
+	struct kvm_vm *vm;
+	struct kvm_vcpu *vcpu;
+	uint8_t idx;
+
+	/*
+	 * Check that pmu_event_filter works as expected when it's applied to
+	 * fixed performance counters.
+	 */
+	for (idx = 0; idx < nr_fixed_counters; idx++) {
+		vm = vm_create_with_one_vcpu(&vcpu,
+					     intel_run_fixed_counter_guest_code);
+		vcpu_args_set(vcpu, 1, idx);
+		__test_fixed_counter_bitmap(vcpu, idx, nr_fixed_counters);
+		kvm_vm_free(vm);
+	}
+}
+
 int main(int argc, char *argv[])
 {
 	void (*guest_code)(void);
@@ -851,6 +930,7 @@ int main(int argc, char *argv[])
 	kvm_vm_free(vm);
 
 	test_pmu_config_disable(guest_code);
+	test_fixed_counter_bitmap();
 
 	return 0;
 }