KVM: selftests: Introduce "struct __kvm_pmu_event_filter" to manipulate filter

Add custom "__kvm_pmu_event_filter" structure to improve pmu event
filter settings. Simplifies event filter setup by organizing event
filter parameters in a cleaner, more organized way.

Alternatively, selftests could use a struct overlay ala vcpu_set_msr()
to avoid dynamically allocating the array:

        struct {
                struct kvm_msrs header;
                struct kvm_msr_entry entry;
        } buffer = {};

        memset(&buffer, 0, sizeof(buffer));
        buffer.header.nmsrs = 1;
        buffer.entry.index = msr_index;
        buffer.entry.data = msr_value;

but the extra layer added by the nested structs is counterproductive
to writing efficient, clean code.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Jinrong Liang <cloudliang@tencent.com>
Link: https://lore.kernel.org/r/20230810090945.16053-4-cloudliang@tencent.com
[sean: massage changelog to explain alternative]
Signed-off-by: Sean Christopherson <seanjc@google.com>

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

@@ -28,6 +28,10 @@
 
 #define NUM_BRANCHES 42
 
+/* Matches KVM_PMU_EVENT_FILTER_MAX_EVENTS in pmu.c */
+#define MAX_FILTER_EVENTS		300
+#define MAX_TEST_EVENTS		10
+
 /*
  * This is how the event selector and unit mask are stored in an AMD
  * core performance event-select register. Intel's format is similar,
@@ -69,21 +73,33 @@
 
 #define INST_RETIRED EVENT(0xc0, 0)
 
+struct __kvm_pmu_event_filter {
+	__u32 action;
+	__u32 nevents;
+	__u32 fixed_counter_bitmap;
+	__u32 flags;
+	__u32 pad[4];
+	__u64 events[MAX_FILTER_EVENTS];
+};
+
 /*
  * This event list comprises Intel's eight architectural events plus
  * AMD's "retired branch instructions" for Zen[123] (and possibly
  * other AMD CPUs).
  */
-static const uint64_t event_list[] = {
-	EVENT(0x3c, 0),
-	INST_RETIRED,
-	EVENT(0x3c, 1),
-	EVENT(0x2e, 0x4f),
-	EVENT(0x2e, 0x41),
-	EVENT(0xc4, 0),
-	EVENT(0xc5, 0),
-	EVENT(0xa4, 1),
-	AMD_ZEN_BR_RETIRED,
+static const struct __kvm_pmu_event_filter base_event_filter = {
+	.nevents = ARRAY_SIZE(base_event_filter.events),
+	.events = {
+		EVENT(0x3c, 0),
+		INST_RETIRED,
+		EVENT(0x3c, 1),
+		EVENT(0x2e, 0x4f),
+		EVENT(0x2e, 0x41),
+		EVENT(0xc4, 0),
+		EVENT(0xc5, 0),
+		EVENT(0xa4, 1),
+		AMD_ZEN_BR_RETIRED,
+	},
 };
 
 struct {
@@ -225,47 +241,11 @@ static bool sanity_check_pmu(struct kvm_vcpu *vcpu)
 	return !r;
 }
 
-static struct kvm_pmu_event_filter *alloc_pmu_event_filter(uint32_t nevents)
-{
-	struct kvm_pmu_event_filter *f;
-	int size = sizeof(*f) + nevents * sizeof(f->events[0]);
-
-	f = malloc(size);
-	TEST_ASSERT(f, "Out of memory");
-	memset(f, 0, size);
-	f->nevents = nevents;
-	return f;
-}
-
-
-static struct kvm_pmu_event_filter *
-create_pmu_event_filter(const uint64_t event_list[], int nevents,
-			uint32_t action, uint32_t flags)
-{
-	struct kvm_pmu_event_filter *f;
-	int i;
-
-	f = alloc_pmu_event_filter(nevents);
-	f->action = action;
-	f->flags = flags;
-	for (i = 0; i < nevents; i++)
-		f->events[i] = event_list[i];
-
-	return f;
-}
-
-static struct kvm_pmu_event_filter *event_filter(uint32_t action)
-{
-	return create_pmu_event_filter(event_list,
-				       ARRAY_SIZE(event_list),
-				       action, 0);
-}
-
 /*
  * Remove the first occurrence of 'event' (if any) from the filter's
  * event list.
  */
-static void remove_event(struct kvm_pmu_event_filter *f, uint64_t event)
+static void remove_event(struct __kvm_pmu_event_filter *f, uint64_t event)
 {
 	bool found = false;
 	int i;
@@ -313,66 +293,73 @@ static void test_without_filter(struct kvm_vcpu *vcpu)
 }
 
 static void test_with_filter(struct kvm_vcpu *vcpu,
-			     struct kvm_pmu_event_filter *f)
+			     struct __kvm_pmu_event_filter *__f)
 {
+	struct kvm_pmu_event_filter *f = (void *)__f;
+
 	vm_ioctl(vcpu->vm, KVM_SET_PMU_EVENT_FILTER, f);
 	run_vcpu_and_sync_pmc_results(vcpu);
 }
 
 static void test_amd_deny_list(struct kvm_vcpu *vcpu)
 {
-	uint64_t event = EVENT(0x1C2, 0);
-	struct kvm_pmu_event_filter *f;
+	struct __kvm_pmu_event_filter f = {
+		.action = KVM_PMU_EVENT_DENY,
+		.nevents = 1,
+		.events = {
+			EVENT(0x1C2, 0),
+		},
+	};
 
-	f = create_pmu_event_filter(&event, 1, KVM_PMU_EVENT_DENY, 0);
-	test_with_filter(vcpu, f);
-	free(f);
+	test_with_filter(vcpu, &f);
 
 	ASSERT_PMC_COUNTING_INSTRUCTIONS();
 }
 
 static void test_member_deny_list(struct kvm_vcpu *vcpu)
 {
-	struct kvm_pmu_event_filter *f = event_filter(KVM_PMU_EVENT_DENY);
+	struct __kvm_pmu_event_filter f = base_event_filter;
 
-	test_with_filter(vcpu, f);
-	free(f);
+	f.action = KVM_PMU_EVENT_DENY;
+	test_with_filter(vcpu, &f);
 
 	ASSERT_PMC_NOT_COUNTING_INSTRUCTIONS();
 }
 
 static void test_member_allow_list(struct kvm_vcpu *vcpu)
 {
-	struct kvm_pmu_event_filter *f = event_filter(KVM_PMU_EVENT_ALLOW);
+	struct __kvm_pmu_event_filter f = base_event_filter;
 
-	test_with_filter(vcpu, f);
-	free(f);
+	f.action = KVM_PMU_EVENT_ALLOW;
+	test_with_filter(vcpu, &f);
 
 	ASSERT_PMC_COUNTING_INSTRUCTIONS();
 }
 
 static void test_not_member_deny_list(struct kvm_vcpu *vcpu)
 {
-	struct kvm_pmu_event_filter *f = event_filter(KVM_PMU_EVENT_DENY);
+	struct __kvm_pmu_event_filter f = base_event_filter;
 
-	remove_event(f, INST_RETIRED);
-	remove_event(f, INTEL_BR_RETIRED);
-	remove_event(f, AMD_ZEN_BR_RETIRED);
-	test_with_filter(vcpu, f);
-	free(f);
+	f.action = KVM_PMU_EVENT_DENY;
+
+	remove_event(&f, INST_RETIRED);
+	remove_event(&f, INTEL_BR_RETIRED);
+	remove_event(&f, AMD_ZEN_BR_RETIRED);
+	test_with_filter(vcpu, &f);
 
 	ASSERT_PMC_COUNTING_INSTRUCTIONS();
 }
 
 static void test_not_member_allow_list(struct kvm_vcpu *vcpu)
 {
-	struct kvm_pmu_event_filter *f = event_filter(KVM_PMU_EVENT_ALLOW);
+	struct __kvm_pmu_event_filter f = base_event_filter;
+
+	f.action = KVM_PMU_EVENT_ALLOW;
 
-	remove_event(f, INST_RETIRED);
-	remove_event(f, INTEL_BR_RETIRED);
-	remove_event(f, AMD_ZEN_BR_RETIRED);
-	test_with_filter(vcpu, f);
-	free(f);
+	remove_event(&f, INST_RETIRED);
+	remove_event(&f, INTEL_BR_RETIRED);
+	remove_event(&f, AMD_ZEN_BR_RETIRED);
+	test_with_filter(vcpu, &f);
 
 	ASSERT_PMC_NOT_COUNTING_INSTRUCTIONS();
 }
@@ -567,19 +554,16 @@ static void run_masked_events_test(struct kvm_vcpu *vcpu,
 				   const uint64_t masked_events[],
 				   const int nmasked_events)
 {
-	struct kvm_pmu_event_filter *f;
+	struct __kvm_pmu_event_filter f = {
+		.nevents = nmasked_events,
+		.action = KVM_PMU_EVENT_ALLOW,
+		.flags = KVM_PMU_EVENT_FLAG_MASKED_EVENTS,
+	};
 
-	f = create_pmu_event_filter(masked_events, nmasked_events,
-				    KVM_PMU_EVENT_ALLOW,
-				    KVM_PMU_EVENT_FLAG_MASKED_EVENTS);
-	test_with_filter(vcpu, f);
-	free(f);
+	memcpy(f.events, masked_events, sizeof(uint64_t) * nmasked_events);
+	test_with_filter(vcpu, &f);
 }
 
-/* Matches KVM_PMU_EVENT_FILTER_MAX_EVENTS in pmu.c */
-#define MAX_FILTER_EVENTS	300
-#define MAX_TEST_EVENTS		10
-
 #define ALLOW_LOADS		BIT(0)
 #define ALLOW_STORES		BIT(1)
 #define ALLOW_LOADS_STORES	BIT(2)
@@ -751,17 +735,27 @@ static void test_masked_events(struct kvm_vcpu *vcpu)
 	run_masked_events_tests(vcpu, events, nevents);
 }
 
-static int run_filter_test(struct kvm_vcpu *vcpu, const uint64_t *events,
-			   int nevents, uint32_t flags)
+static int set_pmu_event_filter(struct kvm_vcpu *vcpu,
+				struct __kvm_pmu_event_filter *__f)
 {
-	struct kvm_pmu_event_filter *f;
-	int r;
+	struct kvm_pmu_event_filter *f = (void *)__f;
 
-	f = create_pmu_event_filter(events, nevents, KVM_PMU_EVENT_ALLOW, flags);
-	r = __vm_ioctl(vcpu->vm, KVM_SET_PMU_EVENT_FILTER, f);
-	free(f);
+	return __vm_ioctl(vcpu->vm, KVM_SET_PMU_EVENT_FILTER, f);
+}
+
+static int set_pmu_single_event_filter(struct kvm_vcpu *vcpu, uint64_t event,
+				       uint32_t flags, uint32_t action)
+{
+	struct __kvm_pmu_event_filter f = {
+		.nevents = 1,
+		.flags = flags,
+		.action = action,
+		.events = {
+			event,
+		},
+	};
 
-	return r;
+	return set_pmu_event_filter(vcpu, &f);
 }
 
 static void test_filter_ioctl(struct kvm_vcpu *vcpu)
@@ -773,14 +767,18 @@ static void test_filter_ioctl(struct kvm_vcpu *vcpu)
 	 * Unfortunately having invalid bits set in event data is expected to
 	 * pass when flags == 0 (bits other than eventsel+umask).
 	 */
-	r = run_filter_test(vcpu, &e, 1, 0);
+	r = set_pmu_single_event_filter(vcpu, e, 0, KVM_PMU_EVENT_ALLOW);
 	TEST_ASSERT(r == 0, "Valid PMU Event Filter is failing");
 
-	r = run_filter_test(vcpu, &e, 1, KVM_PMU_EVENT_FLAG_MASKED_EVENTS);
+	r = set_pmu_single_event_filter(vcpu, e,
+					KVM_PMU_EVENT_FLAG_MASKED_EVENTS,
+					KVM_PMU_EVENT_ALLOW);
 	TEST_ASSERT(r != 0, "Invalid PMU Event Filter is expected to fail");
 
 	e = KVM_PMU_ENCODE_MASKED_ENTRY(0xff, 0xff, 0xff, 0xf);
-	r = run_filter_test(vcpu, &e, 1, KVM_PMU_EVENT_FLAG_MASKED_EVENTS);
+	r = set_pmu_single_event_filter(vcpu, e,
+					KVM_PMU_EVENT_FLAG_MASKED_EVENTS,
+					KVM_PMU_EVENT_ALLOW);
 	TEST_ASSERT(r == 0, "Valid PMU Event Filter is failing");
 }