kvm.c

#include "kvm/kvm.h"
#include "kvm/read-write.h"
#include "kvm/util.h"
#include "kvm/mutex.h"
#include "kvm/kvm-cpu.h"
#include "kvm/kvm-ipc.h"

#include <linux/kvm.h>
#include <linux/err.h>

#include <sys/un.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <stdbool.h>
#include <limits.h>
#include <signal.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <time.h>
#include <sys/eventfd.h>
#include <asm/unistd.h>
#include <dirent.h>

#define DEFINE_KVM_EXIT_REASON(reason) [reason] = #reason

const char *kvm_exit_reasons[] = {
	DEFINE_KVM_EXIT_REASON(KVM_EXIT_UNKNOWN),
	DEFINE_KVM_EXIT_REASON(KVM_EXIT_EXCEPTION),
	DEFINE_KVM_EXIT_REASON(KVM_EXIT_IO),
	DEFINE_KVM_EXIT_REASON(KVM_EXIT_HYPERCALL),
	DEFINE_KVM_EXIT_REASON(KVM_EXIT_DEBUG),
	DEFINE_KVM_EXIT_REASON(KVM_EXIT_HLT),
	DEFINE_KVM_EXIT_REASON(KVM_EXIT_MMIO),
	DEFINE_KVM_EXIT_REASON(KVM_EXIT_IRQ_WINDOW_OPEN),
	DEFINE_KVM_EXIT_REASON(KVM_EXIT_SHUTDOWN),
	DEFINE_KVM_EXIT_REASON(KVM_EXIT_FAIL_ENTRY),
	DEFINE_KVM_EXIT_REASON(KVM_EXIT_INTR),
	DEFINE_KVM_EXIT_REASON(KVM_EXIT_SET_TPR),
	DEFINE_KVM_EXIT_REASON(KVM_EXIT_TPR_ACCESS),
	DEFINE_KVM_EXIT_REASON(KVM_EXIT_S390_SIEIC),
	DEFINE_KVM_EXIT_REASON(KVM_EXIT_S390_RESET),
	DEFINE_KVM_EXIT_REASON(KVM_EXIT_DCR),
	DEFINE_KVM_EXIT_REASON(KVM_EXIT_NMI),
	DEFINE_KVM_EXIT_REASON(KVM_EXIT_INTERNAL_ERROR),
#ifdef CONFIG_PPC64
	DEFINE_KVM_EXIT_REASON(KVM_EXIT_PAPR_HCALL),
#endif
};

extern struct kvm *kvm;
extern struct kvm_cpu **kvm_cpus;
static int pause_event;
static DEFINE_MUTEX(pause_lock);
extern struct kvm_ext kvm_req_ext[];

static char kvm_dir[PATH_MAX];

static int set_dir(const char *fmt, va_list args)
{
	char tmp[PATH_MAX];

	vsnprintf(tmp, sizeof(tmp), fmt, args);

	mkdir(tmp, 0777);

	if (!realpath(tmp, kvm_dir))
		return -errno;

	strcat(kvm_dir, "/");

	return 0;
}

void kvm__set_dir(const char *fmt, ...)
{
	va_list args;

	va_start(args, fmt);
	set_dir(fmt, args);
	va_end(args);
}

const char *kvm__get_dir(void)
{
	return kvm_dir;
}

bool kvm__supports_extension(struct kvm *kvm, unsigned int extension)
{
	int ret;

	ret = ioctl(kvm->sys_fd, KVM_CHECK_EXTENSION, extension);
	if (ret < 0)
		return false;

	return ret;
}

static int kvm__check_extensions(struct kvm *kvm)
{
	int i;

	for (i = 0; ; i++) {
		if (!kvm_req_ext[i].name)
			break;
		if (!kvm__supports_extension(kvm, kvm_req_ext[i].code)) {
			pr_err("Unsuppored KVM extension detected: %s",
				kvm_req_ext[i].name);
			return -i;
		}
	}

	return 0;
}

static struct kvm *kvm__new(void)
{
	struct kvm *kvm = calloc(1, sizeof(*kvm));

	if (!kvm)
		return ERR_PTR(-ENOMEM);

	return kvm;
}

#define KVM_SOCK_SUFFIX		".sock"
#define KVM_SOCK_SUFFIX_LEN	((ssize_t)sizeof(KVM_SOCK_SUFFIX) - 1)

static int kvm__create_socket(struct kvm *kvm)
{
	char full_name[PATH_MAX];
	unsigned int s;
	struct sockaddr_un local;
	int len, r;

	if (!kvm->name)
		return -EINVAL;

	sprintf(full_name, "%s/%s%s", kvm__get_dir(), kvm->name,
			KVM_SOCK_SUFFIX);
	if (access(full_name, F_OK) == 0) {
		pr_err("Socket file %s already exist", full_name);
		return -EEXIST;
	}

	s = socket(AF_UNIX, SOCK_STREAM, 0);
	if (s < 0)
		return s;
	local.sun_family = AF_UNIX;
	strcpy(local.sun_path, full_name);
	len = strlen(local.sun_path) + sizeof(local.sun_family);
	r = bind(s, (struct sockaddr *)&local, len);
	if (r < 0)
		goto fail;

	r = listen(s, 5);
	if (r < 0)
		goto fail;

	return s;

fail:
	close(s);
	return r;
}

void kvm__remove_socket(const char *name)
{
	char full_name[PATH_MAX];

	sprintf(full_name, "%s/%s%s", kvm__get_dir(), name, KVM_SOCK_SUFFIX);
	unlink(full_name);
}

int kvm__get_sock_by_instance(const char *name)
{
	int s, len, r;
	char sock_file[PATH_MAX];
	struct sockaddr_un local;

	sprintf(sock_file, "%s/%s%s", kvm__get_dir(), name, KVM_SOCK_SUFFIX);
	s = socket(AF_UNIX, SOCK_STREAM, 0);

	local.sun_family = AF_UNIX;
	strcpy(local.sun_path, sock_file);
	len = strlen(local.sun_path) + sizeof(local.sun_family);

	r = connect(s, &local, len);
	if (r < 0 && errno == ECONNREFUSED) {
		/* Tell the user clean ghost socket file */
		pr_err("\"%s\" could be a ghost socket file, please remove it",
				sock_file);
		return r;
	} else if (r < 0) {
		return r;
	}

	return s;
}

int kvm__enumerate_instances(int (*callback)(const char *name, int fd))
{
	int sock;
	DIR *dir;
	struct dirent entry, *result;
	int ret = 0;

	dir = opendir(kvm__get_dir());
	if (!dir)
		return -errno;

	for (;;) {
		readdir_r(dir, &entry, &result);
		if (result == NULL)
			break;
		if (entry.d_type == DT_SOCK) {
			ssize_t name_len = strlen(entry.d_name);
			char *p;

			if (name_len <= KVM_SOCK_SUFFIX_LEN)
				continue;

			p = &entry.d_name[name_len - KVM_SOCK_SUFFIX_LEN];
			if (memcmp(KVM_SOCK_SUFFIX, p, KVM_SOCK_SUFFIX_LEN))
				continue;

			*p = 0;
			sock = kvm__get_sock_by_instance(entry.d_name);
			if (sock < 0)
				continue;
			ret = callback(entry.d_name, sock);
			close(sock);
			if (ret < 0)
				break;
		}
	}

	closedir(dir);

	return ret;
}

int kvm__exit(struct kvm *kvm)
{
	kvm__stop_timer(kvm);

	kvm__arch_delete_ram(kvm);
	kvm_ipc__stop();
	kvm__remove_socket(kvm->name);
	free(kvm);

	return 0;
}

/*
 * Note: KVM_SET_USER_MEMORY_REGION assumes that we don't pass overlapping
 * memory regions to it. Therefore, be careful if you use this function for
 * registering memory regions for emulating hardware.
 */
int kvm__register_mem(struct kvm *kvm, u64 guest_phys, u64 size, void *userspace_addr)
{
	struct kvm_userspace_memory_region mem;
	int ret;

	mem = (struct kvm_userspace_memory_region) {
		.slot			= kvm->mem_slots++,
		.guest_phys_addr	= guest_phys,
		.memory_size		= size,
		.userspace_addr		= (unsigned long)userspace_addr,
	};

	ret = ioctl(kvm->vm_fd, KVM_SET_USER_MEMORY_REGION, &mem);
	if (ret < 0)
		return -errno;

	return 0;
}

int kvm__recommended_cpus(struct kvm *kvm)
{
	int ret;

	ret = ioctl(kvm->sys_fd, KVM_CHECK_EXTENSION, KVM_CAP_NR_VCPUS);
	if (ret <= 0)
		/*
		 * api.txt states that if KVM_CAP_NR_VCPUS does not exist,
		 * assume 4.
		 */
		return 4;

	return ret;
}

static void kvm__pid(int fd, u32 type, u32 len, u8 *msg)
{
	pid_t pid = getpid();
	int r = 0;

	if (type == KVM_IPC_PID)
		r = write(fd, &pid, sizeof(pid));

	if (r < 0)
		pr_warning("Failed sending PID");
}

/*
 * The following hack should be removed once 'x86: Raise the hard
 * VCPU count limit' makes it's way into the mainline.
 */
#ifndef KVM_CAP_MAX_VCPUS
#define KVM_CAP_MAX_VCPUS 66
#endif

int kvm__max_cpus(struct kvm *kvm)
{
	int ret;

	ret = ioctl(kvm->sys_fd, KVM_CHECK_EXTENSION, KVM_CAP_MAX_VCPUS);
	if (ret <= 0)
		ret = kvm__recommended_cpus(kvm);

	return ret;
}

struct kvm *kvm__init(const char *kvm_dev, const char *hugetlbfs_path, u64 ram_size, const char *name)
{
	struct kvm *kvm;
	int ret;

	if (!kvm__arch_cpu_supports_vm()) {
		pr_err("Your CPU does not support hardware virtualization");
		return ERR_PTR(-ENOSYS);
	}

	kvm = kvm__new();
	if (IS_ERR_OR_NULL(kvm))
		return kvm;

	kvm->sys_fd = open(kvm_dev, O_RDWR);
	if (kvm->sys_fd < 0) {
		if (errno == ENOENT) {
			pr_err("'%s' not found. Please make sure your kernel has CONFIG_KVM "
				"enabled and that the KVM modules are loaded.", kvm_dev);
			ret = -errno;
			goto cleanup;
		}
		if (errno == ENODEV) {
			die("'%s' KVM driver not available.\n  # (If the KVM "
				"module is loaded then 'dmesg' may offer further clues "
				"about the failure.)", kvm_dev);
			ret = -errno;
			goto cleanup;
		}

		pr_err("Could not open %s: ", kvm_dev);
		ret = -errno;
		goto cleanup;
	}

	ret = ioctl(kvm->sys_fd, KVM_GET_API_VERSION, 0);
	if (ret != KVM_API_VERSION) {
		pr_err("KVM_API_VERSION ioctl");
		ret = -errno;
		goto cleanup;
	}

	kvm->vm_fd = ioctl(kvm->sys_fd, KVM_CREATE_VM, 0);
	if (kvm->vm_fd < 0) {
		ret = kvm->vm_fd;
		goto cleanup;
	}

	if (kvm__check_extensions(kvm)) {
		pr_err("A required KVM extention is not supported by OS");
		ret = -ENOSYS;
	}

	kvm__arch_init(kvm, hugetlbfs_path, ram_size);

	kvm->name = name;

	kvm_ipc__start(kvm__create_socket(kvm));
	kvm_ipc__register_handler(KVM_IPC_PID, kvm__pid);
	return kvm;
cleanup:
	close(kvm->vm_fd);
	close(kvm->sys_fd);
	free(kvm);

	return ERR_PTR(ret);
}

/* RFC 1952 */
#define GZIP_ID1		0x1f
#define GZIP_ID2		0x8b
#define CPIO_MAGIC		"0707"
/* initrd may be gzipped, or a plain cpio */
static bool initrd_check(int fd)
{
	unsigned char id[4];

	if (read_in_full(fd, id, ARRAY_SIZE(id)) < 0)
		return false;

	if (lseek(fd, 0, SEEK_SET) < 0)
		die_perror("lseek");

	return (id[0] == GZIP_ID1 && id[1] == GZIP_ID2) ||
		!memcmp(id, CPIO_MAGIC, 4);
}

bool kvm__load_kernel(struct kvm *kvm, const char *kernel_filename,
		const char *initrd_filename, const char *kernel_cmdline, u16 vidmode)
{
	bool ret;
	int fd_kernel = -1, fd_initrd = -1;

	fd_kernel = open(kernel_filename, O_RDONLY);
	if (fd_kernel < 0)
		die("Unable to open kernel %s", kernel_filename);

	if (initrd_filename) {
		fd_initrd = open(initrd_filename, O_RDONLY);
		if (fd_initrd < 0)
			die("Unable to open initrd %s", initrd_filename);

		if (!initrd_check(fd_initrd))
			die("%s is not an initrd", initrd_filename);
	}

	ret = load_bzimage(kvm, fd_kernel, fd_initrd, kernel_cmdline, vidmode);

	if (ret)
		goto found_kernel;

	pr_warning("%s is not a bzImage. Trying to load it as a flat binary...", kernel_filename);

	ret = load_flat_binary(kvm, fd_kernel, fd_initrd, kernel_cmdline);

	if (ret)
		goto found_kernel;

	if (initrd_filename)
		close(fd_initrd);
	close(fd_kernel);

	die("%s is not a valid bzImage or flat binary", kernel_filename);

found_kernel:
	if (initrd_filename)
		close(fd_initrd);
	close(fd_kernel);

	return ret;
}

#define TIMER_INTERVAL_NS 1000000	/* 1 msec */

/*
 * This function sets up a timer that's used to inject interrupts from the
 * userspace hypervisor into the guest at periodical intervals. Please note
 * that clock interrupt, for example, is not handled here.
 */
void kvm__start_timer(struct kvm *kvm)
{
	struct itimerspec its;
	struct sigevent sev;

	memset(&sev, 0, sizeof(struct sigevent));
	sev.sigev_value.sival_int	= 0;
	sev.sigev_notify		= SIGEV_THREAD_ID;
	sev.sigev_signo			= SIGALRM;
	sev._sigev_un._tid		= syscall(__NR_gettid);

	if (timer_create(CLOCK_REALTIME, &sev, &kvm->timerid) < 0)
		die("timer_create()");

	its.it_value.tv_sec		= TIMER_INTERVAL_NS / 1000000000;
	its.it_value.tv_nsec		= TIMER_INTERVAL_NS % 1000000000;
	its.it_interval.tv_sec		= its.it_value.tv_sec;
	its.it_interval.tv_nsec		= its.it_value.tv_nsec;

	if (timer_settime(kvm->timerid, 0, &its, NULL) < 0)
		die("timer_settime()");
}

void kvm__stop_timer(struct kvm *kvm)
{
	if (kvm->timerid)
		if (timer_delete(kvm->timerid) < 0)
			die("timer_delete()");

	kvm->timerid = 0;
}

void kvm__dump_mem(struct kvm *kvm, unsigned long addr, unsigned long size)
{
	unsigned char *p;
	unsigned long n;

	size &= ~7; /* mod 8 */
	if (!size)
		return;

	p = guest_flat_to_host(kvm, addr);

	for (n = 0; n < size; n += 8) {
		if (!host_ptr_in_ram(kvm, p + n))
			break;

		printf("  0x%08lx: %02x %02x %02x %02x  %02x %02x %02x %02x\n",
			addr + n, p[n + 0], p[n + 1], p[n + 2], p[n + 3],
				  p[n + 4], p[n + 5], p[n + 6], p[n + 7]);
	}
}

void kvm__pause(void)
{
	int i, paused_vcpus = 0;

	/* Check if the guest is running */
	if (!kvm_cpus[0] || kvm_cpus[0]->thread == 0)
		return;

	mutex_lock(&pause_lock);

	pause_event = eventfd(0, 0);
	if (pause_event < 0)
		die("Failed creating pause notification event");
	for (i = 0; i < kvm->nrcpus; i++)
		pthread_kill(kvm_cpus[i]->thread, SIGKVMPAUSE);

	while (paused_vcpus < kvm->nrcpus) {
		u64 cur_read;

		if (read(pause_event, &cur_read, sizeof(cur_read)) < 0)
			die("Failed reading pause event");
		paused_vcpus += cur_read;
	}
	close(pause_event);
}

void kvm__continue(void)
{
	/* Check if the guest is running */
	if (!kvm_cpus[0] || kvm_cpus[0]->thread == 0)
		return;

	mutex_unlock(&pause_lock);
}

void kvm__notify_paused(void)
{
	u64 p = 1;

	if (write(pause_event, &p, sizeof(p)) < 0)
		die("Failed notifying of paused VCPU.");

	mutex_lock(&pause_lock);
	mutex_unlock(&pause_lock);
}