tools/testing/selftests/kvm/cr4_cpuid_sync_test.c

// 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 "x86.h"

#define X86_FEATURE_XSAVE	(1<<26)
#define X86_FEATURE_OSXSAVE	(1<<27)
#define VCPU_ID			1

static inline bool cr4_cpuid_is_sync(void)
{
	int func, subfunc;
	uint32_t eax, ebx, ecx, edx;
	uint64_t cr4;

	func = 0x1;
	subfunc = 0x0;
	__asm__ __volatile__("cpuid"
			     : "=a"(eax), "=b"(ebx), "=c"(ecx), "=d"(edx)
			     : "a"(func), "c"(subfunc));

	cr4 = get_cr4();

	return (!!(ecx & X86_FEATURE_OSXSAVE)) == (!!(cr4 & X86_CR4_OSXSAVE));
}

static void guest_code(void)
{
	uint64_t cr4;

	/* turn on CR4.OSXSAVE */
	cr4 = get_cr4();
	cr4 |= X86_CR4_OSXSAVE;
	set_cr4(cr4);

	/* verify CR4.OSXSAVE == CPUID.OSXSAVE */
	GUEST_ASSERT(cr4_cpuid_is_sync());

	/* notify hypervisor to change CR4 */
	GUEST_SYNC(0);

	/* check again */
	GUEST_ASSERT(cr4_cpuid_is_sync());

	GUEST_DONE();
}

int main(int argc, char *argv[])
{
	struct kvm_run *run;
	struct kvm_vm *vm;
	struct kvm_sregs sregs;
	struct kvm_cpuid_entry2 *entry;
	int rc;

	entry = kvm_get_supported_cpuid_entry(1);
	if (!(entry->ecx & X86_FEATURE_XSAVE)) {
		printf("XSAVE feature not supported, skipping test\n");
		return 0;
	}

	/* Tell stdout not to buffer its content */
	setbuf(stdout, NULL);

	/* Create VM */
	vm = vm_create_default(VCPU_ID, 0, guest_code);
	vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
	run = vcpu_state(vm, VCPU_ID);

	while (1) {
		rc = _vcpu_run(vm, VCPU_ID);

		if (run->exit_reason == KVM_EXIT_IO) {
			switch (run->io.port) {
			case GUEST_PORT_SYNC:
				/* emulate hypervisor clearing CR4.OSXSAVE */
				vcpu_sregs_get(vm, VCPU_ID, &sregs);
				sregs.cr4 &= ~X86_CR4_OSXSAVE;
				vcpu_sregs_set(vm, VCPU_ID, &sregs);
				break;
			case GUEST_PORT_ABORT:
				TEST_ASSERT(false, "Guest CR4 bit (OSXSAVE) unsynchronized with CPUID bit.");
				break;
			case GUEST_PORT_DONE:
				goto done;
			default:
				TEST_ASSERT(false, "Unknown port 0x%x.",
					    run->io.port);
			}
		}
	}

	kvm_vm_free(vm);

done:
	return 0;
}