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qemu/migration.c

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/*
* QEMU live migration
*
* Copyright IBM, Corp. 2008
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*
* Contributions after 2012-01-13 are licensed under the terms of the
* GNU GPL, version 2 or (at your option) any later version.
*/
#include "qemu-common.h"
#include "migration/migration.h"
#include "monitor/monitor.h"
#include "migration/qemu-file.h"
#include "sysemu/sysemu.h"
#include "block/block.h"
#include "qemu/sockets.h"
#include "migration/block.h"
#include "qemu/thread.h"
#include "qmp-commands.h"
//#define DEBUG_MIGRATION
#ifdef DEBUG_MIGRATION
#define DPRINTF(fmt, ...) \
do { printf("migration: " fmt, ## __VA_ARGS__); } while (0)
#else
#define DPRINTF(fmt, ...) \
do { } while (0)
#endif
enum {
MIG_STATE_ERROR,
MIG_STATE_SETUP,
MIG_STATE_CANCELLED,
MIG_STATE_ACTIVE,
MIG_STATE_COMPLETED,
};
#define MAX_THROTTLE (32 << 20) /* Migration speed throttling */
/* Amount of time to allocate to each "chunk" of bandwidth-throttled
* data. */
#define BUFFER_DELAY 100
#define XFER_LIMIT_RATIO (1000 / BUFFER_DELAY)
/* Migration XBZRLE default cache size */
#define DEFAULT_MIGRATE_CACHE_SIZE (64 * 1024 * 1024)
static NotifierList migration_state_notifiers =
NOTIFIER_LIST_INITIALIZER(migration_state_notifiers);
/* When we add fault tolerance, we could have several
migrations at once. For now we don't need to add
dynamic creation of migration */
MigrationState *migrate_get_current(void)
{
static MigrationState current_migration = {
.state = MIG_STATE_SETUP,
.bandwidth_limit = MAX_THROTTLE,
.xbzrle_cache_size = DEFAULT_MIGRATE_CACHE_SIZE,
};
return &current_migration;
}
void qemu_start_incoming_migration(const char *uri, Error **errp)
{
const char *p;
if (strstart(uri, "tcp:", &p))
tcp_start_incoming_migration(p, errp);
#if !defined(WIN32)
else if (strstart(uri, "exec:", &p))
exec_start_incoming_migration(p, errp);
else if (strstart(uri, "unix:", &p))
unix_start_incoming_migration(p, errp);
else if (strstart(uri, "fd:", &p))
fd_start_incoming_migration(p, errp);
#endif
else {
error_setg(errp, "unknown migration protocol: %s", uri);
}
}
static void process_incoming_migration_co(void *opaque)
{
QEMUFile *f = opaque;
int ret;
ret = qemu_loadvm_state(f);
qemu_fclose(f);
if (ret < 0) {
fprintf(stderr, "load of migration failed\n");
exit(0);
}
qemu_announce_self();
DPRINTF("successfully loaded vm state\n");
bdrv_clear_incoming_migration_all();
/* Make sure all file formats flush their mutable metadata */
bdrv_invalidate_cache_all();
if (autostart) {
vm_start();
} else {
runstate_set(RUN_STATE_PAUSED);
}
}
void process_incoming_migration(QEMUFile *f)
{
Coroutine *co = qemu_coroutine_create(process_incoming_migration_co);
int fd = qemu_get_fd(f);
assert(fd != -1);
socket_set_nonblock(fd);
qemu_coroutine_enter(co, f);
}
/* amount of nanoseconds we are willing to wait for migration to be down.
* the choice of nanoseconds is because it is the maximum resolution that
* get_clock() can achieve. It is an internal measure. All user-visible
* units must be in seconds */
static uint64_t max_downtime = 30000000;
uint64_t migrate_max_downtime(void)
{
return max_downtime;
}
MigrationCapabilityStatusList *qmp_query_migrate_capabilities(Error **errp)
{
MigrationCapabilityStatusList *head = NULL;
MigrationCapabilityStatusList *caps;
MigrationState *s = migrate_get_current();
int i;
for (i = 0; i < MIGRATION_CAPABILITY_MAX; i++) {
if (head == NULL) {
head = g_malloc0(sizeof(*caps));
caps = head;
} else {
caps->next = g_malloc0(sizeof(*caps));
caps = caps->next;
}
caps->value =
g_malloc(sizeof(*caps->value));
caps->value->capability = i;
caps->value->state = s->enabled_capabilities[i];
}
return head;
}
static void get_xbzrle_cache_stats(MigrationInfo *info)
{
if (migrate_use_xbzrle()) {
info->has_xbzrle_cache = true;
info->xbzrle_cache = g_malloc0(sizeof(*info->xbzrle_cache));
info->xbzrle_cache->cache_size = migrate_xbzrle_cache_size();
info->xbzrle_cache->bytes = xbzrle_mig_bytes_transferred();
info->xbzrle_cache->pages = xbzrle_mig_pages_transferred();
info->xbzrle_cache->cache_miss = xbzrle_mig_pages_cache_miss();
info->xbzrle_cache->overflow = xbzrle_mig_pages_overflow();
}
}
MigrationInfo *qmp_query_migrate(Error **errp)
{
MigrationInfo *info = g_malloc0(sizeof(*info));
MigrationState *s = migrate_get_current();
switch (s->state) {
case MIG_STATE_SETUP:
/* no migration has happened ever */
break;
case MIG_STATE_ACTIVE:
info->has_status = true;
info->status = g_strdup("active");
info->has_total_time = true;
info->total_time = qemu_get_clock_ms(rt_clock)
- s->total_time;
info->has_expected_downtime = true;
info->expected_downtime = s->expected_downtime;
info->has_ram = true;
info->ram = g_malloc0(sizeof(*info->ram));
info->ram->transferred = ram_bytes_transferred();
info->ram->remaining = ram_bytes_remaining();
info->ram->total = ram_bytes_total();
info->ram->duplicate = dup_mig_pages_transferred();
info->ram->normal = norm_mig_pages_transferred();
info->ram->normal_bytes = norm_mig_bytes_transferred();
info->ram->dirty_pages_rate = s->dirty_pages_rate;
if (blk_mig_active()) {
info->has_disk = true;
info->disk = g_malloc0(sizeof(*info->disk));
info->disk->transferred = blk_mig_bytes_transferred();
info->disk->remaining = blk_mig_bytes_remaining();
info->disk->total = blk_mig_bytes_total();
}
get_xbzrle_cache_stats(info);
break;
case MIG_STATE_COMPLETED:
get_xbzrle_cache_stats(info);
info->has_status = true;
info->status = g_strdup("completed");
info->total_time = s->total_time;
info->has_downtime = true;
info->downtime = s->downtime;
info->has_ram = true;
info->ram = g_malloc0(sizeof(*info->ram));
info->ram->transferred = ram_bytes_transferred();
info->ram->remaining = 0;
info->ram->total = ram_bytes_total();
info->ram->duplicate = dup_mig_pages_transferred();
info->ram->normal = norm_mig_pages_transferred();
info->ram->normal_bytes = norm_mig_bytes_transferred();
break;
case MIG_STATE_ERROR:
info->has_status = true;
info->status = g_strdup("failed");
break;
case MIG_STATE_CANCELLED:
info->has_status = true;
info->status = g_strdup("cancelled");
break;
}
return info;
}
void qmp_migrate_set_capabilities(MigrationCapabilityStatusList *params,
Error **errp)
{
MigrationState *s = migrate_get_current();
MigrationCapabilityStatusList *cap;
if (s->state == MIG_STATE_ACTIVE) {
error_set(errp, QERR_MIGRATION_ACTIVE);
return;
}
for (cap = params; cap; cap = cap->next) {
s->enabled_capabilities[cap->value->capability] = cap->value->state;
}
}
/* shared migration helpers */
static int migrate_fd_cleanup(MigrationState *s)
{
int ret = 0;
if (s->file) {
DPRINTF("closing file\n");
ret = qemu_fclose(s->file);
s->file = NULL;
}
assert(s->fd == -1);
return ret;
}
void migrate_fd_error(MigrationState *s)
{
DPRINTF("setting error state\n");
s->state = MIG_STATE_ERROR;
notifier_list_notify(&migration_state_notifiers, s);
migrate_fd_cleanup(s);
}
static void migrate_fd_completed(MigrationState *s)
{
DPRINTF("setting completed state\n");
if (migrate_fd_cleanup(s) < 0) {
s->state = MIG_STATE_ERROR;
} else {
s->state = MIG_STATE_COMPLETED;
runstate_set(RUN_STATE_POSTMIGRATE);
}
notifier_list_notify(&migration_state_notifiers, s);
}
static ssize_t migrate_fd_put_buffer(MigrationState *s, const void *data,
size_t size)
{
ssize_t ret;
if (s->state != MIG_STATE_ACTIVE) {
return -EIO;
}
do {
ret = s->write(s, data, size);
} while (ret == -1 && ((s->get_error(s)) == EINTR));
if (ret == -1)
ret = -(s->get_error(s));
return ret;
}
static void migrate_fd_cancel(MigrationState *s)
{
if (s->state != MIG_STATE_ACTIVE)
return;
DPRINTF("cancelling migration\n");
s->state = MIG_STATE_CANCELLED;
notifier_list_notify(&migration_state_notifiers, s);
qemu_savevm_state_cancel();
migrate_fd_cleanup(s);
}
int migrate_fd_close(MigrationState *s)
{
int rc = 0;
if (s->fd != -1) {
rc = s->close(s);
s->fd = -1;
}
return rc;
}
void add_migration_state_change_notifier(Notifier *notify)
{
notifier_list_add(&migration_state_notifiers, notify);
}
void remove_migration_state_change_notifier(Notifier *notify)
{
notifier_remove(notify);
}
bool migration_is_active(MigrationState *s)
{
return s->state == MIG_STATE_ACTIVE;
}
bool migration_has_finished(MigrationState *s)
{
return s->state == MIG_STATE_COMPLETED;
}
bool migration_has_failed(MigrationState *s)
{
return (s->state == MIG_STATE_CANCELLED ||
s->state == MIG_STATE_ERROR);
}
static MigrationState *migrate_init(const MigrationParams *params)
{
MigrationState *s = migrate_get_current();
int64_t bandwidth_limit = s->bandwidth_limit;
bool enabled_capabilities[MIGRATION_CAPABILITY_MAX];
int64_t xbzrle_cache_size = s->xbzrle_cache_size;
memcpy(enabled_capabilities, s->enabled_capabilities,
sizeof(enabled_capabilities));
memset(s, 0, sizeof(*s));
s->bandwidth_limit = bandwidth_limit;
s->params = *params;
memcpy(s->enabled_capabilities, enabled_capabilities,
sizeof(enabled_capabilities));
s->xbzrle_cache_size = xbzrle_cache_size;
s->bandwidth_limit = bandwidth_limit;
s->state = MIG_STATE_SETUP;
s->total_time = qemu_get_clock_ms(rt_clock);
return s;
}
static GSList *migration_blockers;
void migrate_add_blocker(Error *reason)
{
migration_blockers = g_slist_prepend(migration_blockers, reason);
}
void migrate_del_blocker(Error *reason)
{
migration_blockers = g_slist_remove(migration_blockers, reason);
}
void qmp_migrate(const char *uri, bool has_blk, bool blk,
bool has_inc, bool inc, bool has_detach, bool detach,
Error **errp)
{
Error *local_err = NULL;
MigrationState *s = migrate_get_current();
MigrationParams params;
const char *p;
params.blk = blk;
params.shared = inc;
if (s->state == MIG_STATE_ACTIVE) {
error_set(errp, QERR_MIGRATION_ACTIVE);
return;
}
if (qemu_savevm_state_blocked(errp)) {
return;
}
if (migration_blockers) {
*errp = error_copy(migration_blockers->data);
return;
}
s = migrate_init(&params);
if (strstart(uri, "tcp:", &p)) {
tcp_start_outgoing_migration(s, p, &local_err);
#if !defined(WIN32)
} else if (strstart(uri, "exec:", &p)) {
exec_start_outgoing_migration(s, p, &local_err);
} else if (strstart(uri, "unix:", &p)) {
unix_start_outgoing_migration(s, p, &local_err);
} else if (strstart(uri, "fd:", &p)) {
fd_start_outgoing_migration(s, p, &local_err);
#endif
} else {
error_set(errp, QERR_INVALID_PARAMETER_VALUE, "uri", "a valid migration protocol");
return;
}
if (local_err) {
migrate_fd_error(s);
error_propagate(errp, local_err);
return;
}
}
void qmp_migrate_cancel(Error **errp)
{
migrate_fd_cancel(migrate_get_current());
}
void qmp_migrate_set_cache_size(int64_t value, Error **errp)
{
MigrationState *s = migrate_get_current();
/* Check for truncation */
if (value != (size_t)value) {
error_set(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
"exceeding address space");
return;
}
s->xbzrle_cache_size = xbzrle_cache_resize(value);
}
int64_t qmp_query_migrate_cache_size(Error **errp)
{
return migrate_xbzrle_cache_size();
}
void qmp_migrate_set_speed(int64_t value, Error **errp)
{
MigrationState *s;
if (value < 0) {
value = 0;
}
s = migrate_get_current();
s->bandwidth_limit = value;
qemu_file_set_rate_limit(s->file, s->bandwidth_limit);
}
void qmp_migrate_set_downtime(double value, Error **errp)
{
value *= 1e9;
value = MAX(0, MIN(UINT64_MAX, value));
max_downtime = (uint64_t)value;
}
int migrate_use_xbzrle(void)
{
MigrationState *s;
s = migrate_get_current();
return s->enabled_capabilities[MIGRATION_CAPABILITY_XBZRLE];
}
int64_t migrate_xbzrle_cache_size(void)
{
MigrationState *s;
s = migrate_get_current();
return s->xbzrle_cache_size;
}
/* migration thread support */
static ssize_t buffered_flush(MigrationState *s)
{
size_t offset = 0;
ssize_t ret = 0;
DPRINTF("flushing %zu byte(s) of data\n", s->buffer_size);
while (s->bytes_xfer < s->xfer_limit && offset < s->buffer_size) {
size_t to_send = MIN(s->buffer_size - offset, s->xfer_limit - s->bytes_xfer);
ret = migrate_fd_put_buffer(s, s->buffer + offset, to_send);
if (ret <= 0) {
DPRINTF("error flushing data, %zd\n", ret);
break;
} else {
DPRINTF("flushed %zd byte(s)\n", ret);
offset += ret;
s->bytes_xfer += ret;
}
}
DPRINTF("flushed %zu of %zu byte(s)\n", offset, s->buffer_size);
memmove(s->buffer, s->buffer + offset, s->buffer_size - offset);
s->buffer_size -= offset;
if (ret < 0) {
return ret;
}
return offset;
}
static int buffered_put_buffer(void *opaque, const uint8_t *buf,
int64_t pos, int size)
{
MigrationState *s = opaque;
ssize_t error;
DPRINTF("putting %d bytes at %" PRId64 "\n", size, pos);
error = qemu_file_get_error(s->file);
if (error) {
DPRINTF("flush when error, bailing: %s\n", strerror(-error));
return error;
}
if (size <= 0) {
return size;
}
if (size > (s->buffer_capacity - s->buffer_size)) {
DPRINTF("increasing buffer capacity from %zu by %zu\n",
s->buffer_capacity, size + 1024);
s->buffer_capacity += size + 1024;
s->buffer = g_realloc(s->buffer, s->buffer_capacity);
}
memcpy(s->buffer + s->buffer_size, buf, size);
s->buffer_size += size;
return size;
}
static int buffered_close(void *opaque)
{
MigrationState *s = opaque;
ssize_t ret = 0;
int ret2;
DPRINTF("closing\n");
s->xfer_limit = INT_MAX;
while (!qemu_file_get_error(s->file) && s->buffer_size) {
ret = buffered_flush(s);
if (ret < 0) {
break;
}
}
ret2 = migrate_fd_close(s);
if (ret >= 0) {
ret = ret2;
}
s->complete = true;
return ret;
}
static int buffered_get_fd(void *opaque)
{
MigrationState *s = opaque;
return s->fd;
}
/*
* The meaning of the return values is:
* 0: We can continue sending
* 1: Time to stop
* negative: There has been an error
*/
static int buffered_rate_limit(void *opaque)
{
MigrationState *s = opaque;
int ret;
ret = qemu_file_get_error(s->file);
if (ret) {
return ret;
}
if (s->bytes_xfer >= s->xfer_limit) {
return 1;
}
return 0;
}
static int64_t buffered_set_rate_limit(void *opaque, int64_t new_rate)
{
MigrationState *s = opaque;
if (qemu_file_get_error(s->file)) {
goto out;
}
if (new_rate > SIZE_MAX) {
new_rate = SIZE_MAX;
}
s->xfer_limit = new_rate / XFER_LIMIT_RATIO;
out:
return s->xfer_limit;
}
static int64_t buffered_get_rate_limit(void *opaque)
{
MigrationState *s = opaque;
return s->xfer_limit;
}
static void *buffered_file_thread(void *opaque)
{
MigrationState *s = opaque;
int64_t initial_time = qemu_get_clock_ms(rt_clock);
int64_t sleep_time = 0;
int64_t max_size = 0;
bool last_round = false;
int ret;
qemu_mutex_lock_iothread();
DPRINTF("beginning savevm\n");
ret = qemu_savevm_state_begin(s->file, &s->params);
if (ret < 0) {
DPRINTF("failed, %d\n", ret);
qemu_mutex_unlock_iothread();
goto out;
}
qemu_mutex_unlock_iothread();
while (true) {
int64_t current_time;
uint64_t pending_size;
qemu_mutex_lock_iothread();
if (s->state != MIG_STATE_ACTIVE) {
DPRINTF("put_ready returning because of non-active state\n");
qemu_mutex_unlock_iothread();
break;
}
if (s->complete) {
qemu_mutex_unlock_iothread();
break;
}
if (s->bytes_xfer < s->xfer_limit) {
DPRINTF("iterate\n");
pending_size = qemu_savevm_state_pending(s->file, max_size);
DPRINTF("pending size %lu max %lu\n", pending_size, max_size);
if (pending_size && pending_size >= max_size) {
ret = qemu_savevm_state_iterate(s->file);
if (ret < 0) {
qemu_mutex_unlock_iothread();
break;
}
} else {
int old_vm_running = runstate_is_running();
int64_t start_time, end_time;
DPRINTF("done iterating\n");
start_time = qemu_get_clock_ms(rt_clock);
qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER);
if (old_vm_running) {
vm_stop(RUN_STATE_FINISH_MIGRATE);
} else {
vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
}
ret = qemu_savevm_state_complete(s->file);
if (ret < 0) {
qemu_mutex_unlock_iothread();
break;
} else {
migrate_fd_completed(s);
}
end_time = qemu_get_clock_ms(rt_clock);
s->total_time = end_time - s->total_time;
s->downtime = end_time - start_time;
if (s->state != MIG_STATE_COMPLETED) {
if (old_vm_running) {
vm_start();
}
}
last_round = true;
}
}
qemu_mutex_unlock_iothread();
current_time = qemu_get_clock_ms(rt_clock);
if (current_time >= initial_time + BUFFER_DELAY) {
uint64_t transferred_bytes = s->bytes_xfer;
uint64_t time_spent = current_time - initial_time - sleep_time;
double bandwidth = transferred_bytes / time_spent;
max_size = bandwidth * migrate_max_downtime() / 1000000;
DPRINTF("transferred %" PRIu64 " time_spent %" PRIu64
" bandwidth %g max_size %" PRId64 "\n",
transferred_bytes, time_spent, bandwidth, max_size);
/* if we haven't sent anything, we don't want to recalculate
10000 is a small enough number for our purposes */
if (s->dirty_bytes_rate && transferred_bytes > 10000) {
s->expected_downtime = s->dirty_bytes_rate / bandwidth;
}
s->bytes_xfer = 0;
sleep_time = 0;
initial_time = current_time;
}
if (!last_round && (s->bytes_xfer >= s->xfer_limit)) {
/* usleep expects microseconds */
g_usleep((initial_time + BUFFER_DELAY - current_time)*1000);
sleep_time += qemu_get_clock_ms(rt_clock) - current_time;
}
ret = buffered_flush(s);
if (ret < 0) {
break;
}
}
out:
if (ret < 0) {
migrate_fd_error(s);
}
g_free(s->buffer);
return NULL;
}
static const QEMUFileOps buffered_file_ops = {
.get_fd = buffered_get_fd,
.put_buffer = buffered_put_buffer,
.close = buffered_close,
.rate_limit = buffered_rate_limit,
.get_rate_limit = buffered_get_rate_limit,
.set_rate_limit = buffered_set_rate_limit,
};
void migrate_fd_connect(MigrationState *s)
{
s->state = MIG_STATE_ACTIVE;
s->bytes_xfer = 0;
s->buffer = NULL;
s->buffer_size = 0;
s->buffer_capacity = 0;
/* This is a best 1st approximation. ns to ms */
s->expected_downtime = max_downtime/1000000;
s->xfer_limit = s->bandwidth_limit / XFER_LIMIT_RATIO;
s->complete = false;
s->file = qemu_fopen_ops(s, &buffered_file_ops);
qemu_thread_create(&s->thread, buffered_file_thread, s,
QEMU_THREAD_DETACHED);
notifier_list_notify(&migration_state_notifiers, s);
}
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