[PATCH 6/6] selftests: kvm/x86: Add test for KVM_SET_PMU_EVENT_FILTER

[Jim Mattson <jmattson@google.com>]

Verify that the PMU event filter works as expected.

Note that the virtual PMU doesn't work as expected on AMD Zen CPUs (an
intercepted rdmsr is counted as a retired branch instruction), but the
PMU event filter does work.

Signed-off-by: Jim Mattson <jmattson@google.com>
---
 tools/testing/selftests/kvm/.gitignore        |   1 +
 tools/testing/selftests/kvm/Makefile          |   1 +
 .../kvm/x86_64/pmu_event_filter_test.c        | 310 ++++++++++++++++++
 3 files changed, 312 insertions(+)
 create mode 100644 tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c

diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
index 8c129961accf..7834e03ab159 100644
--- a/tools/testing/selftests/kvm/.gitignore
+++ b/tools/testing/selftests/kvm/.gitignore
@@ -22,6 +22,7 @@
 /x86_64/mmio_warning_test
 /x86_64/mmu_role_test
 /x86_64/platform_info_test
+/x86_64/pmu_event_filter_test
 /x86_64/set_boot_cpu_id
 /x86_64/set_sregs_test
 /x86_64/sev_migrate_tests
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index c407ebbec2c1..899413a6588f 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -56,6 +56,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/kvm_pv_test
 TEST_GEN_PROGS_x86_64 += x86_64/mmio_warning_test
 TEST_GEN_PROGS_x86_64 += x86_64/mmu_role_test
 TEST_GEN_PROGS_x86_64 += x86_64/platform_info_test
+TEST_GEN_PROGS_x86_64 += x86_64/pmu_event_filter_test
 TEST_GEN_PROGS_x86_64 += x86_64/set_boot_cpu_id
 TEST_GEN_PROGS_x86_64 += x86_64/set_sregs_test
 TEST_GEN_PROGS_x86_64 += x86_64/smm_test
diff --git a/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c b/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c
new file mode 100644
index 000000000000..d879a4b92fae
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c
@@ -0,0 +1,310 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Test for x86 KVM_SET_PMU_EVENT_FILTER.
+ *
+ * Copyright (C) 2022, Google LLC.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.
+ *
+ * Verifies the expected behavior of allow lists and deny lists for
+ * virtual PMU events.
+ */
+
+#define _GNU_SOURCE /* for program_invocation_short_name */
+#include "test_util.h"
+#include "kvm_util.h"
+#include "processor.h"
+
+/*
+ * In lieue of copying perf_event.h into tools...
+ */
+#define ARCH_PERFMON_EVENTSEL_ENABLE	BIT(22)
+#define ARCH_PERFMON_EVENTSEL_OS	BIT(17)
+
+#define VCPU_ID 0
+#define NUM_BRANCHES 42
+
+/*
+ * This is how the event selector and unit mask are stored in an AMD
+ * core performance event-select register. Intel's format is similar,
+ * but the event selector is only 8 bits.
+ */
+#define EVENT(select, umask) ((select & 0xf00UL) << 24 | (select & 0xff) | \
+			      (umask & 0xff) << 8)
+
+/*
+ * "Branch instructions retired", from the Intel SDM, volume 3,
+ * "Pre-defined Architectural Performance Events."
+ */
+
+#define INTEL_BR_RETIRED EVENT(0xc4, 0)
+
+/*
+ * "Retired branch instructions", from Processor Programming Reference
+ * (PPR) for AMD Family 17h Model 01h, Revision B1 Processors,
+ * Preliminary Processor Programming Reference (PPR) for AMD Family
+ * 17h Model 31h, Revision B0 Processors, and Preliminary Processor
+ * Programming Reference (PPR) for AMD Family 19h Model 01h, Revision
+ * B1 Processors Volume 1 of 2
+ */
+
+#define AMD_ZEN_BR_RETIRED EVENT(0xc2, 0)
+
+/*
+ * This event list comprises Intel's eight architectural events plus
+ * AMD's "branch instructions retired" for Zen[123].
+ */
+static const uint64_t event_list[] = {
+	EVENT(0x3c, 0),
+	EVENT(0xc0, 0),
+	EVENT(0x3c, 1),
+	EVENT(0x2e, 0x4f),
+	EVENT(0x2e, 0x41),
+	EVENT(0xc4, 0),
+	EVENT(0xc5, 0),
+	EVENT(0xa4, 1),
+	AMD_ZEN_BR_RETIRED,
+};
+
+static void intel_guest_code(void)
+{
+	uint64_t br0, br1;
+
+	for (;;) {
+		wrmsr(MSR_CORE_PERF_GLOBAL_CTRL, 0);
+		wrmsr(MSR_P6_EVNTSEL0, ARCH_PERFMON_EVENTSEL_ENABLE |
+		      ARCH_PERFMON_EVENTSEL_OS | INTEL_BR_RETIRED);
+		wrmsr(MSR_CORE_PERF_GLOBAL_CTRL, 1);
+		br0 = rdmsr(MSR_IA32_PMC0);
+		__asm__ __volatile__("loop ."
+				     : "=c"((int){0})
+				     : "0"(NUM_BRANCHES));
+		br1 = rdmsr(MSR_IA32_PMC0);
+		GUEST_SYNC(br1 - br0);
+	}
+}
+
+/*
+ * To avoid needing a check for CPUID.80000001:ECX.PerfCtrExtCore[bit
+ * 23], this code uses the always-available, legacy K7 PMU MSRs, which
+ * alias to the first four of the six extended core PMU MSRs.
+ */
+static void amd_guest_code(void)
+{
+	uint64_t br0, br1;
+
+	for (;;) {
+		wrmsr(MSR_K7_EVNTSEL0, 0);
+		wrmsr(MSR_K7_EVNTSEL0, ARCH_PERFMON_EVENTSEL_ENABLE |
+		      ARCH_PERFMON_EVENTSEL_OS | AMD_ZEN_BR_RETIRED);
+		br0 = rdmsr(MSR_K7_PERFCTR0);
+		__asm__ __volatile__("loop ."
+				     : "=c"((int){0})
+				     : "0"(NUM_BRANCHES));
+		br1 = rdmsr(MSR_K7_PERFCTR0);
+		GUEST_SYNC(br1 - br0);
+	}
+}
+
+static uint64_t test_branches_retired(struct kvm_vm *vm)
+{
+	struct kvm_run *run = vcpu_state(vm, VCPU_ID);
+	struct ucall uc;
+
+	vcpu_run(vm, VCPU_ID);
+	TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
+		    "Exit_reason other than KVM_EXIT_IO: %u (%s)\n",
+		    run->exit_reason,
+		    exit_reason_str(run->exit_reason));
+	get_ucall(vm, VCPU_ID, &uc);
+	TEST_ASSERT(uc.cmd == UCALL_SYNC,
+		    "Received ucall other than UCALL_SYNC: %lu", uc.cmd);
+	return uc.args[1];
+}
+
+static struct kvm_pmu_event_filter *make_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 *event_filter(uint32_t action)
+{
+	struct kvm_pmu_event_filter *f;
+	int i;
+
+	f = make_pmu_event_filter(ARRAY_SIZE(event_list));
+	f->action = action;
+	for (i = 0; i < ARRAY_SIZE(event_list); i++)
+		f->events[i] = event_list[i];
+
+	return f;
+}
+
+static struct kvm_pmu_event_filter *remove_event(struct kvm_pmu_event_filter *f,
+						 uint64_t event)
+{
+	bool found = false;
+	int i;
+
+	for (i = 0; i < f->nevents; i++) {
+		if (found)
+			f->events[i - 1] = f->events[i];
+		else
+			found = f->events[i] == event;
+	}
+	if (found)
+		f->nevents--;
+	return f;
+}
+
+static void test_no_filter(struct kvm_vm *vm)
+{
+	uint64_t count = test_branches_retired(vm);
+
+	if (count != NUM_BRANCHES)
+		pr_info("%s: Branch instructions retired = %lu (expected %u)\n",
+			__func__, count, NUM_BRANCHES);
+	TEST_ASSERT(count, "Allowed PMU event is not counting");
+}
+
+static uint64_t test_with_filter(struct kvm_vm *vm,
+				 struct kvm_pmu_event_filter *f)
+{
+	vm_ioctl(vm, KVM_SET_PMU_EVENT_FILTER, (void *)f);
+	return test_branches_retired(vm);
+}
+
+static void test_member_deny_list(struct kvm_vm *vm)
+{
+	struct kvm_pmu_event_filter *f = event_filter(KVM_PMU_EVENT_DENY);
+	uint64_t count = test_with_filter(vm, f);
+
+	free(f);
+	if (count)
+		pr_info("%s: Branch instructions retired = %lu (expected 0)\n",
+			__func__, count);
+	TEST_ASSERT(!count, "Disallowed PMU Event is counting");
+}
+
+static void test_member_allow_list(struct kvm_vm *vm)
+{
+	struct kvm_pmu_event_filter *f = event_filter(KVM_PMU_EVENT_ALLOW);
+	uint64_t count = test_with_filter(vm, f);
+
+	free(f);
+	if (count != NUM_BRANCHES)
+		pr_info("%s: Branch instructions retired = %lu (expected %u)\n",
+			__func__, count, NUM_BRANCHES);
+	TEST_ASSERT(count, "Allowed PMU event is not counting");
+}
+
+static void test_not_member_deny_list(struct kvm_vm *vm)
+{
+	struct kvm_pmu_event_filter *f = event_filter(KVM_PMU_EVENT_DENY);
+	uint64_t count;
+
+	remove_event(f, INTEL_BR_RETIRED);
+	remove_event(f, AMD_ZEN_BR_RETIRED);
+	count = test_with_filter(vm, f);
+	free(f);
+	if (count != NUM_BRANCHES)
+		pr_info("%s: Branch instructions retired = %lu (expected %u)\n",
+			__func__, count, NUM_BRANCHES);
+	TEST_ASSERT(count, "Allowed PMU event is not counting");
+}
+
+static void test_not_member_allow_list(struct kvm_vm *vm)
+{
+	struct kvm_pmu_event_filter *f = event_filter(KVM_PMU_EVENT_ALLOW);
+	uint64_t count;
+
+	remove_event(f, INTEL_BR_RETIRED);
+	remove_event(f, AMD_ZEN_BR_RETIRED);
+	count = test_with_filter(vm, f);
+	free(f);
+	if (count)
+		pr_info("%s: Branch instructions retired = %lu (expected 0)\n",
+			__func__, count);
+	TEST_ASSERT(!count, "Disallowed PMU Event is counting");
+}
+
+/*
+ * Note that CPUID leaf 0xa is Intel-specific. This leaf should be
+ * clear on AMD hardware.
+ */
+static bool vcpu_supports_intel_br_retired(void)
+{
+	struct kvm_cpuid_entry2 *entry;
+	struct kvm_cpuid2 *cpuid;
+
+	cpuid = kvm_get_supported_cpuid();
+	entry = kvm_get_supported_cpuid_index(0xa, 0);
+	return entry &&
+		(entry->eax & 0xff) &&
+		(entry->eax >> 24) > 5 &&
+		!(entry->ebx & BIT(5));
+}
+
+/*
+ * Determining AMD support for a PMU event requires consulting the AMD
+ * PPR for the CPU or reference material derived therefrom.
+ */
+static bool vcpu_supports_amd_zen_br_retired(void)
+{
+	struct kvm_cpuid_entry2 *entry;
+	struct kvm_cpuid2 *cpuid;
+
+	cpuid = kvm_get_supported_cpuid();
+	entry = kvm_get_supported_cpuid_index(1, 0);
+	return entry &&
+		((x86_family(entry->eax) == 0x17 &&
+		  (x86_model(entry->eax) == 1 ||
+		   x86_model(entry->eax) == 0x31)) ||
+		 (x86_family(entry->eax) == 0x19 &&
+		  x86_model(entry->eax) == 1));
+}
+
+int main(int argc, char *argv[])
+{
+	void (*guest_code)(void) = NULL;
+	struct kvm_vm *vm;
+	int r;
+
+	/* Tell stdout not to buffer its content */
+	setbuf(stdout, NULL);
+
+	r = kvm_check_cap(KVM_CAP_PMU_EVENT_FILTER);
+	if (!r) {
+		print_skip("KVM_CAP_PMU_EVENT_FILTER not supported");
+		exit(KSFT_SKIP);
+	}
+
+	if (vcpu_supports_intel_br_retired())
+		guest_code = intel_guest_code;
+	else if (vcpu_supports_amd_zen_br_retired())
+		guest_code = amd_guest_code;
+
+	if (!guest_code) {
+		print_skip("Branch instructions retired not supported");
+		exit(KSFT_SKIP);
+	}
+
+	vm = vm_create_default(VCPU_ID, 0, guest_code);
+
+	test_no_filter(vm);
+	test_member_deny_list(vm);
+	test_member_allow_list(vm);
+	test_not_member_deny_list(vm);
+	test_not_member_allow_list(vm);
+
+	kvm_vm_free(vm);
+
+	return 0;
+}
-- 
2.34.1.575.g55b058a8bb-goog