1 files changed, 100 insertions, 0 deletions
diff --git a/tools/testing/selftests/kvm/x86/cr4_cpuid_sync_test.c b/tools/testing/selftests/kvm/x86/cr4_cpuid_sync_test.c
new file mode 100644
index 000000000000..28cc66454601
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86/cr4_cpuid_sync_test.c
@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * CR4 and CPUID sync test
+ *
+ * Copyright 2018, Red Hat, Inc. and/or its affiliates.
+ *
+ * Author:
+ *   Wei Huang <wei@redhat.com>
+ */
+
+#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"
+
+#define MAGIC_HYPERCALL_PORT	0x80
+
+static void guest_code(void)
+{
+	u32 regs[4] = {
+		[KVM_CPUID_EAX] = X86_FEATURE_OSXSAVE.function,
+		[KVM_CPUID_ECX] = X86_FEATURE_OSXSAVE.index,
+	};
+
+	/* CR4.OSXSAVE should be enabled by default (for selftests vCPUs). */
+	GUEST_ASSERT(get_cr4() & X86_CR4_OSXSAVE);
+
+	/* verify CR4.OSXSAVE == CPUID.OSXSAVE */
+	GUEST_ASSERT(this_cpu_has(X86_FEATURE_OSXSAVE));
+
+	/*
+	 * Notify hypervisor to clear CR4.0SXSAVE, do CPUID and save output,
+	 * and then restore CR4.  Do this all in  assembly to ensure no AVX
+	 * instructions are executed while OSXSAVE=0.
+	 */
+	asm volatile (
+		"out %%al, $" __stringify(MAGIC_HYPERCALL_PORT) "\n\t"
+		"cpuid\n\t"
+		"mov %%rdi, %%cr4\n\t"
+		: "+a" (regs[KVM_CPUID_EAX]),
+		  "=b" (regs[KVM_CPUID_EBX]),
+		  "+c" (regs[KVM_CPUID_ECX]),
+		  "=d" (regs[KVM_CPUID_EDX])
+		: "D" (get_cr4())
+	);
+
+	/* Verify KVM cleared OSXSAVE in CPUID when it was cleared in CR4. */
+	GUEST_ASSERT(!(regs[X86_FEATURE_OSXSAVE.reg] & BIT(X86_FEATURE_OSXSAVE.bit)));
+
+	/* Verify restoring CR4 also restored OSXSAVE in CPUID. */
+	GUEST_ASSERT(this_cpu_has(X86_FEATURE_OSXSAVE));
+
+	GUEST_DONE();
+}
+
+int main(int argc, char *argv[])
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm;
+	struct kvm_sregs sregs;
+	struct ucall uc;
+
+	TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_XSAVE));
+
+	vm = vm_create_with_one_vcpu(&vcpu, guest_code);
+
+	while (1) {
+		vcpu_run(vcpu);
+		TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
+
+		if (vcpu->run->io.port == MAGIC_HYPERCALL_PORT &&
+		    vcpu->run->io.direction == KVM_EXIT_IO_OUT) {
+			/* emulate hypervisor clearing CR4.OSXSAVE */
+			vcpu_sregs_get(vcpu, &sregs);
+			sregs.cr4 &= ~X86_CR4_OSXSAVE;
+			vcpu_sregs_set(vcpu, &sregs);
+			continue;
+		}
+
+		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;
+}