strace/tests/ioctl_kvm_run.c

/*
 * Check decoding of KVM_* commands of ioctl syscall using /dev/kvm API.
 * Based on kvmtest.c from https://lwn.net/Articles/658512/
 *
 * kvmtest.c author: Josh Triplett <josh@joshtriplett.org>
 * Copyright (c) 2015 Intel Corporation
 * Copyright (c) 2017 The strace developers.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
 * deal in the Software without restriction, including without limitation the
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

#include "tests.h"

#if defined HAVE_LINUX_KVM_H				\
 && defined HAVE_STRUCT_KVM_REGS			\
 && defined HAVE_STRUCT_KVM_SREGS			\
 && defined HAVE_STRUCT_KVM_USERSPACE_MEMORY_REGION	\
 &&(defined __x86_64__ || defined __i386__)

# include <fcntl.h>
# include <stdint.h>
# include <stdio.h>
# include <stdlib.h>
# include <string.h>
# include <sys/ioctl.h>
# include <sys/mman.h>
# include <linux/kvm.h>

static int
kvm_ioctl(int fd, unsigned long cmd, const char *cmd_str, void *arg)
{
	int rc = ioctl(fd, cmd, arg);
	if (rc < 0)
		perror_msg_and_skip("%s", cmd_str);
	return rc;
}

#define KVM_IOCTL(fd_, cmd_, arg_)	\
	kvm_ioctl((fd_), (cmd_), #cmd_, (arg_))

static const char dev[] = "/dev/kvm";
static const char vm_dev[] = "anon_inode:kvm-vm";
static const char vcpu_dev[] = "anon_inode:kvm-vcpu";
static size_t page_size;

static void
code(void)
{
	__asm__("mov $0xd80003f8, %edx; mov $'\n', %al; out %al, (%dx); hlt");
}

static void
run_kvm(const int vcpu_fd, struct kvm_run *const run, const size_t mmap_size,
	void *const mem)
{
	/* Initialize CS to point at 0, via a read-modify-write of sregs. */
	struct kvm_sregs sregs;
	KVM_IOCTL(vcpu_fd, KVM_GET_SREGS, &sregs);
	printf("ioctl(%d<%s>, KVM_GET_SREGS, {cs={base=%#jx, limit=%u, selector=%u"
	       ", type=%u, present=%u, dpl=%u, db=%u, s=%u, l=%u, g=%u, avl=%u}"
	       ", ...}) = 0\n", vcpu_fd, vcpu_dev, (uintmax_t) sregs.cs.base,
	       sregs.cs.limit, sregs.cs.selector, sregs.cs.type,
	       sregs.cs.present, sregs.cs.dpl, sregs.cs.db, sregs.cs.s,
	       sregs.cs.l, sregs.cs.g, sregs.cs.avl);

	sregs.cs.base = 0;
	sregs.cs.selector = 0;
	KVM_IOCTL(vcpu_fd, KVM_SET_SREGS, &sregs);
	printf("ioctl(%d<%s>, KVM_SET_SREGS, {cs={base=%#jx, limit=%u"
	       ", selector=%u, type=%u, present=%u, dpl=%u, db=%u, s=%u"
	       ", l=%u, g=%u, avl=%u}, ...}) = 0\n",
	       vcpu_fd, vcpu_dev, (uintmax_t) sregs.cs.base,
	       sregs.cs.limit, sregs.cs.selector, sregs.cs.type,
	       sregs.cs.present, sregs.cs.dpl, sregs.cs.db, sregs.cs.s,
	       sregs.cs.l, sregs.cs.g, sregs.cs.avl);

	/*
	 * Initialize registers: instruction pointer for our code, addends,
	 * and initial flags required by x86 architecture.
	 */
	struct kvm_regs regs = {
		.rip = page_size,
		.rax = 2,
		.rbx = 2,
		.rflags = 0x2,
	};
	KVM_IOCTL(vcpu_fd, KVM_SET_REGS, &regs);
	printf("ioctl(%d<%s>, KVM_SET_REGS, {rax=%#jx, ..."
	       ", rsp=%#jx, rbp=%#jx, ..., rip=%#jx, rflags=%#jx}) = 0\n",
	       vcpu_fd, vcpu_dev, (uintmax_t) regs.rax,
	       (uintmax_t) regs.rsp, (uintmax_t) regs.rbp,
	       (uintmax_t) regs.rip, (uintmax_t) regs.rflags);

	/* Copy the code till the end of page */
	size_t code_size = page_size - ((uintptr_t) code & (page_size - 1));
	if (code_size < 16)
		code_size = 16;
	memcpy(mem, code, code_size);

	const char *p = "\n";

	/* Repeatedly run code and handle VM exits. */
	for (;;) {
		KVM_IOCTL(vcpu_fd, KVM_RUN, NULL);
		printf("ioctl(%d<%s>, KVM_RUN, 0) = 0\n", vcpu_fd, vcpu_dev);

		switch (run->exit_reason) {
		case KVM_EXIT_HLT:
			if (p)
				error_msg_and_fail("premature KVM_EXIT_HLT");
			return;
		case KVM_EXIT_IO:
			if (run->io.direction == KVM_EXIT_IO_OUT
			    && run->io.size == 1
			    && run->io.port == 0x03f8
			    && run->io.count == 1
			    && run->io.data_offset < mmap_size
			    && p && *p == ((char *) run)[run->io.data_offset])
				p = NULL;
			else
				error_msg_and_fail("unhandled KVM_EXIT_IO");
			break;
		default:
			error_msg_and_fail("exit_reason = %#x",
					   run->exit_reason);
		}
	}
}

int
main(void)
{
	skip_if_unavailable("/proc/self/fd/");

	int kvm = open(dev, O_RDWR);
	if (kvm < 0)
		perror_msg_and_skip("open: %s", dev);

	/* Make sure we have the stable version of the API */
	int ret = KVM_IOCTL(kvm, KVM_GET_API_VERSION, 0);
	if (ret != KVM_API_VERSION)
		error_msg_and_skip("KVM_GET_API_VERSION returned %d"
				   ", KVM_API_VERSION is %d",
				   kvm, KVM_API_VERSION);
	printf("ioctl(%d<%s>, KVM_GET_API_VERSION, 0) = %d\n",
	       kvm, dev, ret);

	int vm_fd = KVM_IOCTL(kvm, KVM_CREATE_VM, 0);
	printf("ioctl(%d<%s>, KVM_CREATE_VM, 0) = %d<%s>\n",
	       kvm, dev, vm_fd, vm_dev);

	/* Allocate one aligned page of guest memory to hold the code. */
	page_size = get_page_size();
	void *const mem = mmap(NULL, page_size, PROT_READ | PROT_WRITE,
				  MAP_SHARED | MAP_ANONYMOUS, -1, 0);
	if (mem == MAP_FAILED)
		perror_msg_and_fail("mmap page");

	/* Map it to the second page frame (to avoid the real-mode IDT at 0). */
	struct kvm_userspace_memory_region region = {
		.slot = 0,
		.guest_phys_addr = page_size,
		.memory_size = page_size,
		.userspace_addr = (uintptr_t) mem,
	};
	KVM_IOCTL(vm_fd, KVM_SET_USER_MEMORY_REGION, &region);
	printf("ioctl(%d<%s>, KVM_SET_USER_MEMORY_REGION"
	       ", {slot=0, flags=0, guest_phys_addr=%#lx, memory_size=%lu"
	       ", userspace_addr=%p}) = 0\n", vm_fd, vm_dev,
	       (unsigned long) page_size, (unsigned long) page_size, mem);

	int vcpu_fd = KVM_IOCTL(vm_fd, KVM_CREATE_VCPU, NULL);
	printf("ioctl(%d<%s>, KVM_CREATE_VCPU, 0) = %d<%s>\n",
	       vm_fd, vm_dev, vcpu_fd, vcpu_dev);

	/* Map the shared kvm_run structure and following data. */
	ret = KVM_IOCTL(kvm, KVM_GET_VCPU_MMAP_SIZE, NULL);
	struct kvm_run *run;
	if (ret < (int) sizeof(*run))
		error_msg_and_fail("KVM_GET_VCPU_MMAP_SIZE returned %d < %d",
				   ret, (int) sizeof(*run));
	printf("ioctl(%d<%s>, KVM_GET_VCPU_MMAP_SIZE, 0) = %d\n",
	       kvm, dev, ret);

	const size_t mmap_size = (ret + page_size - 1) & -page_size;
	run = mmap(NULL, mmap_size, PROT_READ | PROT_WRITE,
		   MAP_SHARED, vcpu_fd, 0);
	if (run == MAP_FAILED)
		perror_msg_and_fail("mmap vcpu");

	run_kvm(vcpu_fd, run, mmap_size, mem);

	puts("+++ exited with 0 +++");
	return 0;
}

#else /* !HAVE_LINUX_KVM_H */

SKIP_MAIN_UNDEFINED("HAVE_LINUX_KVM_H && HAVE_STRUCT_KVM_REGS && "
		    "HAVE_STRUCT_KVM_SREGS && "
		    "HAVE_STRUCT_KVM_USERSPACE_MEMORY_REGION && "
		    "(__x86_64__ || __i386__)")

#endif