1 files changed, 137 insertions, 0 deletions
diff --git a/tools/testing/selftests/kvm/x86_64/xcr0_cpuid_test.c b/tools/testing/selftests/kvm/x86_64/xcr0_cpuid_test.c
new file mode 100644
index 000000000000..25a0b0db5c3c
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/xcr0_cpuid_test.c
@@ -0,0 +1,137 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * XCR0 cpuid test
+ *
+ * Copyright (C) 2022, Google LLC.
+ */
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+
+#include "test_util.h"
+
+#include "kvm_util.h"
+#include "processor.h"
+
+/*
+ * Assert that architectural dependency rules are satisfied, e.g. that AVX is
+ * supported if and only if SSE is supported.
+ */
+#define ASSERT_XFEATURE_DEPENDENCIES(supported_xcr0, xfeatures, dependencies)		\
+do {											\
+	uint64_t __supported = (supported_xcr0) & ((xfeatures) | (dependencies));	\
+											\
+	__GUEST_ASSERT((__supported & (xfeatures)) != (xfeatures) ||			\
+		       __supported == ((xfeatures) | (dependencies)),			\
+		       "supported = 0x%lx, xfeatures = 0x%llx, dependencies = 0x%llx",	\
+		       __supported, (xfeatures), (dependencies));			\
+} while (0)
+
+/*
+ * Assert that KVM reports a sane, usable as-is XCR0.  Architecturally, a CPU
+ * isn't strictly required to _support_ all XFeatures related to a feature, but
+ * at the same time XSETBV will #GP if bundled XFeatures aren't enabled and
+ * disabled coherently.  E.g. a CPU can technically enumerate supported for
+ * XTILE_CFG but not XTILE_DATA, but attempting to enable XTILE_CFG without
+ * XTILE_DATA will #GP.
+ */
+#define ASSERT_ALL_OR_NONE_XFEATURE(supported_xcr0, xfeatures)		\
+do {									\
+	uint64_t __supported = (supported_xcr0) & (xfeatures);		\
+									\
+	__GUEST_ASSERT(!__supported || __supported == (xfeatures),	\
+		       "supported = 0x%lx, xfeatures = 0x%llx",		\
+		       __supported, (xfeatures));			\
+} while (0)
+
+static void guest_code(void)
+{
+	uint64_t xcr0_reset;
+	uint64_t supported_xcr0;
+	int i, vector;
+
+	set_cr4(get_cr4() | X86_CR4_OSXSAVE);
+
+	xcr0_reset = xgetbv(0);
+	supported_xcr0 = this_cpu_supported_xcr0();
+
+	GUEST_ASSERT(xcr0_reset == XFEATURE_MASK_FP);
+
+	/* Check AVX */
+	ASSERT_XFEATURE_DEPENDENCIES(supported_xcr0,
+				     XFEATURE_MASK_YMM,
+				     XFEATURE_MASK_SSE);
+
+	/* Check MPX */
+	ASSERT_ALL_OR_NONE_XFEATURE(supported_xcr0,
+				    XFEATURE_MASK_BNDREGS | XFEATURE_MASK_BNDCSR);
+
+	/* Check AVX-512 */
+	ASSERT_XFEATURE_DEPENDENCIES(supported_xcr0,
+				     XFEATURE_MASK_AVX512,
+				     XFEATURE_MASK_SSE | XFEATURE_MASK_YMM);
+	ASSERT_ALL_OR_NONE_XFEATURE(supported_xcr0,
+				    XFEATURE_MASK_AVX512);
+
+	/* Check AMX */
+	ASSERT_ALL_OR_NONE_XFEATURE(supported_xcr0,
+				    XFEATURE_MASK_XTILE);
+
+	vector = xsetbv_safe(0, supported_xcr0);
+	__GUEST_ASSERT(!vector,
+		       "Expected success on XSETBV(0x%lx), got vector '0x%x'",
+		       supported_xcr0, vector);
+
+	for (i = 0; i < 64; i++) {
+		if (supported_xcr0 & BIT_ULL(i))
+			continue;
+
+		vector = xsetbv_safe(0, supported_xcr0 | BIT_ULL(i));
+		__GUEST_ASSERT(vector == GP_VECTOR,
+			       "Expected #GP on XSETBV(0x%llx), supported XCR0 = %lx, got vector '0x%x'",
+			       BIT_ULL(i), supported_xcr0, vector);
+	}
+
+	GUEST_DONE();
+}
+
+int main(int argc, char *argv[])
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_run *run;
+	struct kvm_vm *vm;
+	struct ucall uc;
+
+	TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_XSAVE));
+
+	vm = vm_create_with_one_vcpu(&vcpu, guest_code);
+	run = vcpu->run;
+
+	vm_init_descriptor_tables(vm);
+	vcpu_init_descriptor_tables(vcpu);
+
+	while (1) {
+		vcpu_run(vcpu);
+
+		TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
+			    "Unexpected exit reason: %u (%s),",
+			    run->exit_reason,
+			    exit_reason_str(run->exit_reason));
+
+		switch (get_ucall(vcpu, &uc)) {
+		case UCALL_ABORT:
+			REPORT_GUEST_ASSERT(uc);
+			break;
+		case UCALL_DONE:
+			goto done;
+		default:
+			TEST_FAIL("Unknown ucall %lu", uc.cmd);
+		}
+	}
+
+done:
+	kvm_vm_free(vm);
+	return 0;
+}