/* * 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 ¤t_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(¶ms); 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); }