1 files changed, 256 insertions, 0 deletions
diff --git a/tools/testing/selftests/kvm/x86_64/vmx_pmu_caps_test.c b/tools/testing/selftests/kvm/x86_64/vmx_pmu_caps_test.c
new file mode 100644
index 0000000000..ebbcb0a3f7
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/vmx_pmu_caps_test.c
@@ -0,0 +1,256 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Test for VMX-pmu perf capability msr
+ *
+ * Copyright (C) 2021 Intel Corporation
+ *
+ * Test to check the effect of various CPUID settings on
+ * MSR_IA32_PERF_CAPABILITIES MSR, and check that what
+ * we write with KVM_SET_MSR is _not_ modified by the guest
+ * and check it can be retrieved with KVM_GET_MSR, also test
+ * the invalid LBR formats are rejected.
+ */
+#define _GNU_SOURCE /* for program_invocation_short_name */
+#include <sys/ioctl.h>
+
+#include <linux/bitmap.h>
+
+#include "kvm_util.h"
+#include "vmx.h"
+
+union perf_capabilities {
+	struct {
+		u64	lbr_format:6;
+		u64	pebs_trap:1;
+		u64	pebs_arch_reg:1;
+		u64	pebs_format:4;
+		u64	smm_freeze:1;
+		u64	full_width_write:1;
+		u64 pebs_baseline:1;
+		u64	perf_metrics:1;
+		u64	pebs_output_pt_available:1;
+		u64	anythread_deprecated:1;
+	};
+	u64	capabilities;
+};
+
+/*
+ * The LBR format and most PEBS features are immutable, all other features are
+ * fungible (if supported by the host and KVM).
+ */
+static const union perf_capabilities immutable_caps = {
+	.lbr_format = -1,
+	.pebs_trap  = 1,
+	.pebs_arch_reg = 1,
+	.pebs_format = -1,
+	.pebs_baseline = 1,
+};
+
+static const union perf_capabilities format_caps = {
+	.lbr_format = -1,
+	.pebs_format = -1,
+};
+
+static void guest_test_perf_capabilities_gp(uint64_t val)
+{
+	uint8_t vector = wrmsr_safe(MSR_IA32_PERF_CAPABILITIES, val);
+
+	__GUEST_ASSERT(vector == GP_VECTOR,
+		       "Expected #GP for value '0x%llx', got vector '0x%x'",
+		       val, vector);
+}
+
+static void guest_code(uint64_t current_val)
+{
+	int i;
+
+	guest_test_perf_capabilities_gp(current_val);
+	guest_test_perf_capabilities_gp(0);
+
+	for (i = 0; i < 64; i++)
+		guest_test_perf_capabilities_gp(current_val ^ BIT_ULL(i));
+
+	GUEST_DONE();
+}
+
+/*
+ * Verify that guest WRMSRs to PERF_CAPABILITIES #GP regardless of the value
+ * written, that the guest always sees the userspace controlled value, and that
+ * PERF_CAPABILITIES is immutable after KVM_RUN.
+ */
+static void test_guest_wrmsr_perf_capabilities(union perf_capabilities host_cap)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm = vm_create_with_one_vcpu(&vcpu, guest_code);
+	struct ucall uc;
+	int r, i;
+
+	vm_init_descriptor_tables(vm);
+	vcpu_init_descriptor_tables(vcpu);
+
+	vcpu_set_msr(vcpu, MSR_IA32_PERF_CAPABILITIES, host_cap.capabilities);
+
+	vcpu_args_set(vcpu, 1, host_cap.capabilities);
+	vcpu_run(vcpu);
+
+	switch (get_ucall(vcpu, &uc)) {
+	case UCALL_ABORT:
+		REPORT_GUEST_ASSERT(uc);
+		break;
+	case UCALL_DONE:
+		break;
+	default:
+		TEST_FAIL("Unexpected ucall: %lu", uc.cmd);
+	}
+
+	TEST_ASSERT_EQ(vcpu_get_msr(vcpu, MSR_IA32_PERF_CAPABILITIES),
+			host_cap.capabilities);
+
+	vcpu_set_msr(vcpu, MSR_IA32_PERF_CAPABILITIES, host_cap.capabilities);
+
+	r = _vcpu_set_msr(vcpu, MSR_IA32_PERF_CAPABILITIES, 0);
+	TEST_ASSERT(!r, "Post-KVM_RUN write '0' didn't fail");
+
+	for (i = 0; i < 64; i++) {
+		r = _vcpu_set_msr(vcpu, MSR_IA32_PERF_CAPABILITIES,
+				  host_cap.capabilities ^ BIT_ULL(i));
+		TEST_ASSERT(!r, "Post-KVM_RUN write '0x%llx'didn't fail",
+			    host_cap.capabilities ^ BIT_ULL(i));
+	}
+
+	kvm_vm_free(vm);
+}
+
+/*
+ * Verify KVM allows writing PERF_CAPABILITIES with all KVM-supported features
+ * enabled, as well as '0' (to disable all features).
+ */
+static void test_basic_perf_capabilities(union perf_capabilities host_cap)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm = vm_create_with_one_vcpu(&vcpu, NULL);
+
+	vcpu_set_msr(vcpu, MSR_IA32_PERF_CAPABILITIES, 0);
+	vcpu_set_msr(vcpu, MSR_IA32_PERF_CAPABILITIES, host_cap.capabilities);
+
+	kvm_vm_free(vm);
+}
+
+static void test_fungible_perf_capabilities(union perf_capabilities host_cap)
+{
+	const uint64_t fungible_caps = host_cap.capabilities & ~immutable_caps.capabilities;
+
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm = vm_create_with_one_vcpu(&vcpu, NULL);
+	int bit;
+
+	for_each_set_bit(bit, &fungible_caps, 64) {
+		vcpu_set_msr(vcpu, MSR_IA32_PERF_CAPABILITIES, BIT_ULL(bit));
+		vcpu_set_msr(vcpu, MSR_IA32_PERF_CAPABILITIES,
+			     host_cap.capabilities & ~BIT_ULL(bit));
+	}
+	vcpu_set_msr(vcpu, MSR_IA32_PERF_CAPABILITIES, host_cap.capabilities);
+
+	kvm_vm_free(vm);
+}
+
+/*
+ * Verify KVM rejects attempts to set unsupported and/or immutable features in
+ * PERF_CAPABILITIES.  Note, LBR format and PEBS format need to be validated
+ * separately as they are multi-bit values, e.g. toggling or setting a single
+ * bit can generate a false positive without dedicated safeguards.
+ */
+static void test_immutable_perf_capabilities(union perf_capabilities host_cap)
+{
+	const uint64_t reserved_caps = (~host_cap.capabilities |
+					immutable_caps.capabilities) &
+				       ~format_caps.capabilities;
+
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm = vm_create_with_one_vcpu(&vcpu, NULL);
+	union perf_capabilities val = host_cap;
+	int r, bit;
+
+	for_each_set_bit(bit, &reserved_caps, 64) {
+		r = _vcpu_set_msr(vcpu, MSR_IA32_PERF_CAPABILITIES,
+				  host_cap.capabilities ^ BIT_ULL(bit));
+		TEST_ASSERT(!r, "%s immutable feature 0x%llx (bit %d) didn't fail",
+			    host_cap.capabilities & BIT_ULL(bit) ? "Setting" : "Clearing",
+			    BIT_ULL(bit), bit);
+	}
+
+	/*
+	 * KVM only supports the host's native LBR format, as well as '0' (to
+	 * disable LBR support).  Verify KVM rejects all other LBR formats.
+	 */
+	for (val.lbr_format = 1; val.lbr_format; val.lbr_format++) {
+		if (val.lbr_format == host_cap.lbr_format)
+			continue;
+
+		r = _vcpu_set_msr(vcpu, MSR_IA32_PERF_CAPABILITIES, val.capabilities);
+		TEST_ASSERT(!r, "Bad LBR FMT = 0x%x didn't fail, host = 0x%x",
+			    val.lbr_format, host_cap.lbr_format);
+	}
+
+	/* Ditto for the PEBS format. */
+	for (val.pebs_format = 1; val.pebs_format; val.pebs_format++) {
+		if (val.pebs_format == host_cap.pebs_format)
+			continue;
+
+		r = _vcpu_set_msr(vcpu, MSR_IA32_PERF_CAPABILITIES, val.capabilities);
+		TEST_ASSERT(!r, "Bad PEBS FMT = 0x%x didn't fail, host = 0x%x",
+			    val.pebs_format, host_cap.pebs_format);
+	}
+
+	kvm_vm_free(vm);
+}
+
+/*
+ * Test that LBR MSRs are writable when LBRs are enabled, and then verify that
+ * disabling the vPMU via CPUID also disables LBR support.  Set bits 2:0 of
+ * LBR_TOS as those bits are writable across all uarch implementations (arch
+ * LBRs will need to poke a different MSR).
+ */
+static void test_lbr_perf_capabilities(union perf_capabilities host_cap)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm;
+	int r;
+
+	if (!host_cap.lbr_format)
+		return;
+
+	vm = vm_create_with_one_vcpu(&vcpu, NULL);
+
+	vcpu_set_msr(vcpu, MSR_IA32_PERF_CAPABILITIES, host_cap.capabilities);
+	vcpu_set_msr(vcpu, MSR_LBR_TOS, 7);
+
+	vcpu_clear_cpuid_entry(vcpu, X86_PROPERTY_PMU_VERSION.function);
+
+	r = _vcpu_set_msr(vcpu, MSR_LBR_TOS, 7);
+	TEST_ASSERT(!r, "Writing LBR_TOS should fail after disabling vPMU");
+
+	kvm_vm_free(vm);
+}
+
+int main(int argc, char *argv[])
+{
+	union perf_capabilities host_cap;
+
+	TEST_REQUIRE(get_kvm_param_bool("enable_pmu"));
+	TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_PDCM));
+
+	TEST_REQUIRE(kvm_cpu_has_p(X86_PROPERTY_PMU_VERSION));
+	TEST_REQUIRE(kvm_cpu_property(X86_PROPERTY_PMU_VERSION) > 0);
+
+	host_cap.capabilities = kvm_get_feature_msr(MSR_IA32_PERF_CAPABILITIES);
+
+	TEST_ASSERT(host_cap.full_width_write,
+		    "Full-width writes should always be supported");
+
+	test_basic_perf_capabilities(host_cap);
+	test_fungible_perf_capabilities(host_cap);
+	test_immutable_perf_capabilities(host_cap);
+	test_guest_wrmsr_perf_capabilities(host_cap);
+	test_lbr_perf_capabilities(host_cap);
+}