kvm: tests: Add test to verify MSR_IA32_XSS

Ensure that IA32_XSS appears in KVM_GET_MSR_INDEX_LIST if it can be set
to a non-zero value.

Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Aaron Lewis <aaronlewis@google.com>
Change-Id: Ia2d644f69e2d6d8c27d7e0a7a45c2bf9c42bf5ff
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 76 insertions, 0 deletions

diff --git a/tools/testing/selftests/kvm/x86_64/xss_msr_test.c b/tools/testing/selftests/kvm/x86_64/xss_msr_test.c
new file mode 100644
index 000000000000..851ea81b9d9f
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/xss_msr_test.c
@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019, Google LLC.
+ *
+ * Tests for the IA32_XSS MSR.
+ */
+
+#define _GNU_SOURCE /* for program_invocation_short_name */
+#include <sys/ioctl.h>
+
+#include "test_util.h"
+#include "kvm_util.h"
+#include "vmx.h"
+
+#define VCPU_ID	      1
+#define MSR_BITS      64
+
+#define X86_FEATURE_XSAVES	(1<<3)
+
+bool is_supported_msr(u32 msr_index)
+{
+	struct kvm_msr_list *list;
+	bool found = false;
+	int i;
+
+	list = kvm_get_msr_index_list();
+	for (i = 0; i < list->nmsrs; ++i) {
+		if (list->indices[i] == msr_index) {
+			found = true;
+			break;
+		}
+	}
+
+	free(list);
+	return found;
+}
+
+int main(int argc, char *argv[])
+{
+	struct kvm_cpuid_entry2 *entry;
+	bool xss_supported = false;
+	struct kvm_vm *vm;
+	uint64_t xss_val;
+	int i, r;
+
+	/* Create VM */
+	vm = vm_create_default(VCPU_ID, 0, 0);
+
+	if (kvm_get_cpuid_max_basic() >= 0xd) {
+		entry = kvm_get_supported_cpuid_index(0xd, 1);
+		xss_supported = entry && !!(entry->eax & X86_FEATURE_XSAVES);
+	}
+	if (!xss_supported) {
+		printf("IA32_XSS is not supported by the vCPU.\n");
+		exit(KSFT_SKIP);
+	}
+
+	xss_val = vcpu_get_msr(vm, VCPU_ID, MSR_IA32_XSS);
+	TEST_ASSERT(xss_val == 0,
+		    "MSR_IA32_XSS should be initialized to zero\n");
+
+	vcpu_set_msr(vm, VCPU_ID, MSR_IA32_XSS, xss_val);
+	/*
+	 * At present, KVM only supports a guest IA32_XSS value of 0. Verify
+	 * that trying to set the guest IA32_XSS to an unsupported value fails.
+	 * Also, in the future when a non-zero value succeeds check that
+	 * IA32_XSS is in the KVM_GET_MSR_INDEX_LIST.
+	 */
+	for (i = 0; i < MSR_BITS; ++i) {
+		r = _vcpu_set_msr(vm, VCPU_ID, MSR_IA32_XSS, 1ull << i);
+		TEST_ASSERT(r == 0 || is_supported_msr(MSR_IA32_XSS),
+			    "IA32_XSS was able to be set, but was not found in KVM_GET_MSR_INDEX_LIST.\n");
+	}
+
+	kvm_vm_free(vm);
+}