/* * QEMU live migration * * Copyright IBM, Corp. 2008 * * Authors: * Anthony Liguori * * 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/osdep.h" #include "qemu/cutils.h" #include "qemu/error-report.h" #include "qemu/main-loop.h" #include "migration/blocker.h" #include "exec.h" #include "fd.h" #include "socket.h" #include "sysemu/runstate.h" #include "sysemu/sysemu.h" #include "sysemu/cpu-throttle.h" #include "rdma.h" #include "ram.h" #include "migration/global_state.h" #include "migration/misc.h" #include "migration.h" #include "migration-stats.h" #include "savevm.h" #include "qemu-file.h" #include "channel.h" #include "migration/vmstate.h" #include "block/block.h" #include "qapi/error.h" #include "qapi/clone-visitor.h" #include "qapi/qapi-visit-migration.h" #include "qapi/qapi-visit-sockets.h" #include "qapi/qapi-commands-migration.h" #include "qapi/qapi-events-migration.h" #include "qapi/qmp/qerror.h" #include "qapi/qmp/qnull.h" #include "qemu/rcu.h" #include "block.h" #include "postcopy-ram.h" #include "qemu/thread.h" #include "trace.h" #include "exec/target_page.h" #include "io/channel-buffer.h" #include "io/channel-tls.h" #include "migration/colo.h" #include "hw/boards.h" #include "monitor/monitor.h" #include "net/announce.h" #include "qemu/queue.h" #include "multifd.h" #include "threadinfo.h" #include "qemu/yank.h" #include "sysemu/cpus.h" #include "yank_functions.h" #include "sysemu/qtest.h" #include "options.h" static NotifierList migration_state_notifiers = NOTIFIER_LIST_INITIALIZER(migration_state_notifiers); /* Messages sent on the return path from destination to source */ enum mig_rp_message_type { MIG_RP_MSG_INVALID = 0, /* Must be 0 */ MIG_RP_MSG_SHUT, /* sibling will not send any more RP messages */ MIG_RP_MSG_PONG, /* Response to a PING; data (seq: be32 ) */ MIG_RP_MSG_REQ_PAGES_ID, /* data (start: be64, len: be32, id: string) */ MIG_RP_MSG_REQ_PAGES, /* data (start: be64, len: be32) */ MIG_RP_MSG_RECV_BITMAP, /* send recved_bitmap back to source */ MIG_RP_MSG_RESUME_ACK, /* tell source that we are ready to resume */ MIG_RP_MSG_MAX }; /* When we add fault tolerance, we could have several migrations at once. For now we don't need to add dynamic creation of migration */ static MigrationState *current_migration; static MigrationIncomingState *current_incoming; static GSList *migration_blockers; static bool migration_object_check(MigrationState *ms, Error **errp); static int migration_maybe_pause(MigrationState *s, int *current_active_state, int new_state); static void migrate_fd_cancel(MigrationState *s); static bool migration_needs_multiple_sockets(void) { return migrate_multifd() || migrate_postcopy_preempt(); } static bool uri_supports_multi_channels(const char *uri) { return strstart(uri, "tcp:", NULL) || strstart(uri, "unix:", NULL) || strstart(uri, "vsock:", NULL); } static bool migration_channels_and_uri_compatible(const char *uri, Error **errp) { if (migration_needs_multiple_sockets() && !uri_supports_multi_channels(uri)) { error_setg(errp, "Migration requires multi-channel URIs (e.g. tcp)"); return false; } return true; } static gint page_request_addr_cmp(gconstpointer ap, gconstpointer bp) { uintptr_t a = (uintptr_t) ap, b = (uintptr_t) bp; return (a > b) - (a < b); } void migration_object_init(void) { /* This can only be called once. */ assert(!current_migration); current_migration = MIGRATION_OBJ(object_new(TYPE_MIGRATION)); /* * Init the migrate incoming object as well no matter whether * we'll use it or not. */ assert(!current_incoming); current_incoming = g_new0(MigrationIncomingState, 1); current_incoming->state = MIGRATION_STATUS_NONE; current_incoming->postcopy_remote_fds = g_array_new(FALSE, TRUE, sizeof(struct PostCopyFD)); qemu_mutex_init(¤t_incoming->rp_mutex); qemu_mutex_init(¤t_incoming->postcopy_prio_thread_mutex); qemu_event_init(¤t_incoming->main_thread_load_event, false); qemu_sem_init(¤t_incoming->postcopy_pause_sem_dst, 0); qemu_sem_init(¤t_incoming->postcopy_pause_sem_fault, 0); qemu_sem_init(¤t_incoming->postcopy_pause_sem_fast_load, 0); qemu_sem_init(¤t_incoming->postcopy_qemufile_dst_done, 0); qemu_mutex_init(¤t_incoming->page_request_mutex); current_incoming->page_requested = g_tree_new(page_request_addr_cmp); migration_object_check(current_migration, &error_fatal); blk_mig_init(); ram_mig_init(); dirty_bitmap_mig_init(); } void migration_cancel(const Error *error) { if (error) { migrate_set_error(current_migration, error); } migrate_fd_cancel(current_migration); } void migration_shutdown(void) { /* * When the QEMU main thread exit, the COLO thread * may wait a semaphore. So, we should wakeup the * COLO thread before migration shutdown. */ colo_shutdown(); /* * Cancel the current migration - that will (eventually) * stop the migration using this structure */ migration_cancel(NULL); object_unref(OBJECT(current_migration)); /* * Cancel outgoing migration of dirty bitmaps. It should * at least unref used block nodes. */ dirty_bitmap_mig_cancel_outgoing(); /* * Cancel incoming migration of dirty bitmaps. Dirty bitmaps * are non-critical data, and their loss never considered as * something serious. */ dirty_bitmap_mig_cancel_incoming(); } /* For outgoing */ MigrationState *migrate_get_current(void) { /* This can only be called after the object created. */ assert(current_migration); return current_migration; } MigrationIncomingState *migration_incoming_get_current(void) { assert(current_incoming); return current_incoming; } void migration_incoming_transport_cleanup(MigrationIncomingState *mis) { if (mis->socket_address_list) { qapi_free_SocketAddressList(mis->socket_address_list); mis->socket_address_list = NULL; } if (mis->transport_cleanup) { mis->transport_cleanup(mis->transport_data); mis->transport_data = mis->transport_cleanup = NULL; } } void migration_incoming_state_destroy(void) { struct MigrationIncomingState *mis = migration_incoming_get_current(); multifd_load_cleanup(); if (mis->to_src_file) { /* Tell source that we are done */ migrate_send_rp_shut(mis, qemu_file_get_error(mis->from_src_file) != 0); qemu_fclose(mis->to_src_file); mis->to_src_file = NULL; } if (mis->from_src_file) { migration_ioc_unregister_yank_from_file(mis->from_src_file); qemu_fclose(mis->from_src_file); mis->from_src_file = NULL; } if (mis->postcopy_remote_fds) { g_array_free(mis->postcopy_remote_fds, TRUE); mis->postcopy_remote_fds = NULL; } migration_incoming_transport_cleanup(mis); qemu_event_reset(&mis->main_thread_load_event); if (mis->page_requested) { g_tree_destroy(mis->page_requested); mis->page_requested = NULL; } if (mis->postcopy_qemufile_dst) { migration_ioc_unregister_yank_from_file(mis->postcopy_qemufile_dst); qemu_fclose(mis->postcopy_qemufile_dst); mis->postcopy_qemufile_dst = NULL; } yank_unregister_instance(MIGRATION_YANK_INSTANCE); } static void migrate_generate_event(int new_state) { if (migrate_events()) { qapi_event_send_migration(new_state); } } /* * Send a message on the return channel back to the source * of the migration. */ static int migrate_send_rp_message(MigrationIncomingState *mis, enum mig_rp_message_type message_type, uint16_t len, void *data) { int ret = 0; trace_migrate_send_rp_message((int)message_type, len); QEMU_LOCK_GUARD(&mis->rp_mutex); /* * It's possible that the file handle got lost due to network * failures. */ if (!mis->to_src_file) { ret = -EIO; return ret; } qemu_put_be16(mis->to_src_file, (unsigned int)message_type); qemu_put_be16(mis->to_src_file, len); qemu_put_buffer(mis->to_src_file, data, len); qemu_fflush(mis->to_src_file); /* It's possible that qemu file got error during sending */ ret = qemu_file_get_error(mis->to_src_file); return ret; } /* Request one page from the source VM at the given start address. * rb: the RAMBlock to request the page in * Start: Address offset within the RB * Len: Length in bytes required - must be a multiple of pagesize */ int migrate_send_rp_message_req_pages(MigrationIncomingState *mis, RAMBlock *rb, ram_addr_t start) { uint8_t bufc[12 + 1 + 255]; /* start (8), len (4), rbname up to 256 */ size_t msglen = 12; /* start + len */ size_t len = qemu_ram_pagesize(rb); enum mig_rp_message_type msg_type; const char *rbname; int rbname_len; *(uint64_t *)bufc = cpu_to_be64((uint64_t)start); *(uint32_t *)(bufc + 8) = cpu_to_be32((uint32_t)len); /* * We maintain the last ramblock that we requested for page. Note that we * don't need locking because this function will only be called within the * postcopy ram fault thread. */ if (rb != mis->last_rb) { mis->last_rb = rb; rbname = qemu_ram_get_idstr(rb); rbname_len = strlen(rbname); assert(rbname_len < 256); bufc[msglen++] = rbname_len; memcpy(bufc + msglen, rbname, rbname_len); msglen += rbname_len; msg_type = MIG_RP_MSG_REQ_PAGES_ID; } else { msg_type = MIG_RP_MSG_REQ_PAGES; } return migrate_send_rp_message(mis, msg_type, msglen, bufc); } int migrate_send_rp_req_pages(MigrationIncomingState *mis, RAMBlock *rb, ram_addr_t start, uint64_t haddr) { void *aligned = (void *)(uintptr_t)ROUND_DOWN(haddr, qemu_ram_pagesize(rb)); bool received = false; WITH_QEMU_LOCK_GUARD(&mis->page_request_mutex) { received = ramblock_recv_bitmap_test_byte_offset(rb, start); if (!received && !g_tree_lookup(mis->page_requested, aligned)) { /* * The page has not been received, and it's not yet in the page * request list. Queue it. Set the value of element to 1, so that * things like g_tree_lookup() will return TRUE (1) when found. */ g_tree_insert(mis->page_requested, aligned, (gpointer)1); mis->page_requested_count++; trace_postcopy_page_req_add(aligned, mis->page_requested_count); } } /* * If the page is there, skip sending the message. We don't even need the * lock because as long as the page arrived, it'll be there forever. */ if (received) { return 0; } return migrate_send_rp_message_req_pages(mis, rb, start); } static bool migration_colo_enabled; bool migration_incoming_colo_enabled(void) { return migration_colo_enabled; } void migration_incoming_disable_colo(void) { ram_block_discard_disable(false); migration_colo_enabled = false; } int migration_incoming_enable_colo(void) { if (ram_block_discard_disable(true)) { error_report("COLO: cannot disable RAM discard"); return -EBUSY; } migration_colo_enabled = true; return 0; } void migrate_add_address(SocketAddress *address) { MigrationIncomingState *mis = migration_incoming_get_current(); QAPI_LIST_PREPEND(mis->socket_address_list, QAPI_CLONE(SocketAddress, address)); } static void qemu_start_incoming_migration(const char *uri, Error **errp) { const char *p = NULL; /* URI is not suitable for migration? */ if (!migration_channels_and_uri_compatible(uri, errp)) { return; } qapi_event_send_migration(MIGRATION_STATUS_SETUP); if (strstart(uri, "tcp:", &p) || strstart(uri, "unix:", NULL) || strstart(uri, "vsock:", NULL)) { socket_start_incoming_migration(p ? p : uri, errp); #ifdef CONFIG_RDMA } else if (strstart(uri, "rdma:", &p)) { rdma_start_incoming_migration(p, errp); #endif } else if (strstart(uri, "exec:", &p)) { exec_start_incoming_migration(p, errp); } else if (strstart(uri, "fd:", &p)) { fd_start_incoming_migration(p, errp); } else { error_setg(errp, "unknown migration protocol: %s", uri); } } static void process_incoming_migration_bh(void *opaque) { Error *local_err = NULL; MigrationIncomingState *mis = opaque; /* If capability late_block_activate is set: * Only fire up the block code now if we're going to restart the * VM, else 'cont' will do it. * This causes file locking to happen; so we don't want it to happen * unless we really are starting the VM. */ if (!migrate_late_block_activate() || (autostart && (!global_state_received() || global_state_get_runstate() == RUN_STATE_RUNNING))) { /* Make sure all file formats throw away their mutable metadata. * If we get an error here, just don't restart the VM yet. */ bdrv_activate_all(&local_err); if (local_err) { error_report_err(local_err); local_err = NULL; autostart = false; } } /* * This must happen after all error conditions are dealt with and * we're sure the VM is going to be running on this host. */ qemu_announce_self(&mis->announce_timer, migrate_announce_params()); multifd_load_shutdown(); dirty_bitmap_mig_before_vm_start(); if (!global_state_received() || global_state_get_runstate() == RUN_STATE_RUNNING) { if (autostart) { vm_start(); } else { runstate_set(RUN_STATE_PAUSED); } } else if (migration_incoming_colo_enabled()) { migration_incoming_disable_colo(); vm_start(); } else { runstate_set(global_state_get_runstate()); } /* * This must happen after any state changes since as soon as an external * observer sees this event they might start to prod at the VM assuming * it's ready to use. */ migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE, MIGRATION_STATUS_COMPLETED); qemu_bh_delete(mis->bh); migration_incoming_state_destroy(); } static void coroutine_fn process_incoming_migration_co(void *opaque) { MigrationIncomingState *mis = migration_incoming_get_current(); PostcopyState ps; int ret; Error *local_err = NULL; assert(mis->from_src_file); mis->migration_incoming_co = qemu_coroutine_self(); mis->largest_page_size = qemu_ram_pagesize_largest(); postcopy_state_set(POSTCOPY_INCOMING_NONE); migrate_set_state(&mis->state, MIGRATION_STATUS_NONE, MIGRATION_STATUS_ACTIVE); ret = qemu_loadvm_state(mis->from_src_file); ps = postcopy_state_get(); trace_process_incoming_migration_co_end(ret, ps); if (ps != POSTCOPY_INCOMING_NONE) { if (ps == POSTCOPY_INCOMING_ADVISE) { /* * Where a migration had postcopy enabled (and thus went to advise) * but managed to complete within the precopy period, we can use * the normal exit. */ postcopy_ram_incoming_cleanup(mis); } else if (ret >= 0) { /* * Postcopy was started, cleanup should happen at the end of the * postcopy thread. */ trace_process_incoming_migration_co_postcopy_end_main(); return; } /* Else if something went wrong then just fall out of the normal exit */ } /* we get COLO info, and know if we are in COLO mode */ if (!ret && migration_incoming_colo_enabled()) { /* Make sure all file formats throw away their mutable metadata */ bdrv_activate_all(&local_err); if (local_err) { error_report_err(local_err); goto fail; } qemu_thread_create(&mis->colo_incoming_thread, "COLO incoming", colo_process_incoming_thread, mis, QEMU_THREAD_JOINABLE); mis->have_colo_incoming_thread = true; qemu_coroutine_yield(); qemu_mutex_unlock_iothread(); /* Wait checkpoint incoming thread exit before free resource */ qemu_thread_join(&mis->colo_incoming_thread); qemu_mutex_lock_iothread(); /* We hold the global iothread lock, so it is safe here */ colo_release_ram_cache(); } if (ret < 0) { error_report("load of migration failed: %s", strerror(-ret)); goto fail; } mis->bh = qemu_bh_new(process_incoming_migration_bh, mis); qemu_bh_schedule(mis->bh); mis->migration_incoming_co = NULL; return; fail: local_err = NULL; migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE, MIGRATION_STATUS_FAILED); qemu_fclose(mis->from_src_file); multifd_load_cleanup(); exit(EXIT_FAILURE); } /** * migration_incoming_setup: Setup incoming migration * @f: file for main migration channel * @errp: where to put errors * * Returns: %true on success, %false on error. */ static bool migration_incoming_setup(QEMUFile *f, Error **errp) { MigrationIncomingState *mis = migration_incoming_get_current(); if (!mis->from_src_file) { mis->from_src_file = f; } qemu_file_set_blocking(f, false); return true; } void migration_incoming_process(void) { Coroutine *co = qemu_coroutine_create(process_incoming_migration_co, NULL); qemu_coroutine_enter(co); } /* Returns true if recovered from a paused migration, otherwise false */ static bool postcopy_try_recover(void) { MigrationIncomingState *mis = migration_incoming_get_current(); if (mis->state == MIGRATION_STATUS_POSTCOPY_PAUSED) { /* Resumed from a paused postcopy migration */ /* This should be set already in migration_incoming_setup() */ assert(mis->from_src_file); /* Postcopy has standalone thread to do vm load */ qemu_file_set_blocking(mis->from_src_file, true); /* Re-configure the return path */ mis->to_src_file = qemu_file_get_return_path(mis->from_src_file); migrate_set_state(&mis->state, MIGRATION_STATUS_POSTCOPY_PAUSED, MIGRATION_STATUS_POSTCOPY_RECOVER); /* * Here, we only wake up the main loading thread (while the * rest threads will still be waiting), so that we can receive * commands from source now, and answer it if needed. The * rest threads will be woken up afterwards until we are sure * that source is ready to reply to page requests. */ qemu_sem_post(&mis->postcopy_pause_sem_dst); return true; } return false; } void migration_fd_process_incoming(QEMUFile *f, Error **errp) { if (!migration_incoming_setup(f, errp)) { return; } if (postcopy_try_recover()) { return; } migration_incoming_process(); } /* * Returns true when we want to start a new incoming migration process, * false otherwise. */ static bool migration_should_start_incoming(bool main_channel) { /* Multifd doesn't start unless all channels are established */ if (migrate_multifd()) { return migration_has_all_channels(); } /* Preempt channel only starts when the main channel is created */ if (migrate_postcopy_preempt()) { return main_channel; } /* * For all the rest types of migration, we should only reach here when * it's the main channel that's being created, and we should always * proceed with this channel. */ assert(main_channel); return true; } void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp) { MigrationIncomingState *mis = migration_incoming_get_current(); Error *local_err = NULL; QEMUFile *f; bool default_channel = true; uint32_t channel_magic = 0; int ret = 0; if (migrate_multifd() && !migrate_postcopy_ram() && qio_channel_has_feature(ioc, QIO_CHANNEL_FEATURE_READ_MSG_PEEK)) { /* * With multiple channels, it is possible that we receive channels * out of order on destination side, causing incorrect mapping of * source channels on destination side. Check channel MAGIC to * decide type of channel. Please note this is best effort, postcopy * preempt channel does not send any magic number so avoid it for * postcopy live migration. Also tls live migration already does * tls handshake while initializing main channel so with tls this * issue is not possible. */ ret = migration_channel_read_peek(ioc, (void *)&channel_magic, sizeof(channel_magic), &local_err); if (ret != 0) { error_propagate(errp, local_err); return; } default_channel = (channel_magic == cpu_to_be32(QEMU_VM_FILE_MAGIC)); } else { default_channel = !mis->from_src_file; } if (multifd_load_setup(errp) != 0) { error_setg(errp, "Failed to setup multifd channels"); return; } if (default_channel) { f = qemu_file_new_input(ioc); if (!migration_incoming_setup(f, errp)) { return; } } else { /* Multiple connections */ assert(migration_needs_multiple_sockets()); if (migrate_multifd()) { multifd_recv_new_channel(ioc, &local_err); } else { assert(migrate_postcopy_preempt()); f = qemu_file_new_input(ioc); postcopy_preempt_new_channel(mis, f); } if (local_err) { error_propagate(errp, local_err); return; } } if (migration_should_start_incoming(default_channel)) { /* If it's a recovery, we're done */ if (postcopy_try_recover()) { return; } migration_incoming_process(); } } /** * @migration_has_all_channels: We have received all channels that we need * * Returns true when we have got connections to all the channels that * we need for migration. */ bool migration_has_all_channels(void) { MigrationIncomingState *mis = migration_incoming_get_current(); if (!mis->from_src_file) { return false; } if (migrate_multifd()) { return multifd_recv_all_channels_created(); } if (migrate_postcopy_preempt()) { return mis->postcopy_qemufile_dst != NULL; } return true; } /* * Send a 'SHUT' message on the return channel with the given value * to indicate that we've finished with the RP. Non-0 value indicates * error. */ void migrate_send_rp_shut(MigrationIncomingState *mis, uint32_t value) { uint32_t buf; buf = cpu_to_be32(value); migrate_send_rp_message(mis, MIG_RP_MSG_SHUT, sizeof(buf), &buf); } /* * Send a 'PONG' message on the return channel with the given value * (normally in response to a 'PING') */ void migrate_send_rp_pong(MigrationIncomingState *mis, uint32_t value) { uint32_t buf; buf = cpu_to_be32(value); migrate_send_rp_message(mis, MIG_RP_MSG_PONG, sizeof(buf), &buf); } void migrate_send_rp_recv_bitmap(MigrationIncomingState *mis, char *block_name) { char buf[512]; int len; int64_t res; /* * First, we send the header part. It contains only the len of * idstr, and the idstr itself. */ len = strlen(block_name); buf[0] = len; memcpy(buf + 1, block_name, len); if (mis->state != MIGRATION_STATUS_POSTCOPY_RECOVER) { error_report("%s: MSG_RP_RECV_BITMAP only used for recovery", __func__); return; } migrate_send_rp_message(mis, MIG_RP_MSG_RECV_BITMAP, len + 1, buf); /* * Next, we dump the received bitmap to the stream. * * TODO: currently we are safe since we are the only one that is * using the to_src_file handle (fault thread is still paused), * and it's ok even not taking the mutex. However the best way is * to take the lock before sending the message header, and release * the lock after sending the bitmap. */ qemu_mutex_lock(&mis->rp_mutex); res = ramblock_recv_bitmap_send(mis->to_src_file, block_name); qemu_mutex_unlock(&mis->rp_mutex); trace_migrate_send_rp_recv_bitmap(block_name, res); } void migrate_send_rp_resume_ack(MigrationIncomingState *mis, uint32_t value) { uint32_t buf; buf = cpu_to_be32(value); migrate_send_rp_message(mis, MIG_RP_MSG_RESUME_ACK, sizeof(buf), &buf); } /* * Return true if we're already in the middle of a migration * (i.e. any of the active or setup states) */ bool migration_is_setup_or_active(int state) { switch (state) { case MIGRATION_STATUS_ACTIVE: case MIGRATION_STATUS_POSTCOPY_ACTIVE: case MIGRATION_STATUS_POSTCOPY_PAUSED: case MIGRATION_STATUS_POSTCOPY_RECOVER: case MIGRATION_STATUS_SETUP: case MIGRATION_STATUS_PRE_SWITCHOVER: case MIGRATION_STATUS_DEVICE: case MIGRATION_STATUS_WAIT_UNPLUG: case MIGRATION_STATUS_COLO: return true; default: return false; } } bool migration_is_running(int state) { switch (state) { case MIGRATION_STATUS_ACTIVE: case MIGRATION_STATUS_POSTCOPY_ACTIVE: case MIGRATION_STATUS_POSTCOPY_PAUSED: case MIGRATION_STATUS_POSTCOPY_RECOVER: case MIGRATION_STATUS_SETUP: case MIGRATION_STATUS_PRE_SWITCHOVER: case MIGRATION_STATUS_DEVICE: case MIGRATION_STATUS_WAIT_UNPLUG: case MIGRATION_STATUS_CANCELLING: return true; default: return false; } } static bool migrate_show_downtime(MigrationState *s) { return (s->state == MIGRATION_STATUS_COMPLETED) || migration_in_postcopy(); } static void populate_time_info(MigrationInfo *info, MigrationState *s) { info->has_status = true; info->has_setup_time = true; info->setup_time = s->setup_time; if (s->state == MIGRATION_STATUS_COMPLETED) { info->has_total_time = true; info->total_time = s->total_time; } else { info->has_total_time = true; info->total_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME) - s->start_time; } if (migrate_show_downtime(s)) { info->has_downtime = true; info->downtime = s->downtime; } else { info->has_expected_downtime = true; info->expected_downtime = s->expected_downtime; } } static void populate_ram_info(MigrationInfo *info, MigrationState *s) { size_t page_size = qemu_target_page_size(); info->ram = g_malloc0(sizeof(*info->ram)); info->ram->transferred = stat64_get(&mig_stats.transferred); info->ram->total = ram_bytes_total(); info->ram->duplicate = stat64_get(&mig_stats.zero_pages); /* legacy value. It is not used anymore */ info->ram->skipped = 0; info->ram->normal = stat64_get(&mig_stats.normal_pages); info->ram->normal_bytes = info->ram->normal * page_size; info->ram->mbps = s->mbps; info->ram->dirty_sync_count = stat64_get(&mig_stats.dirty_sync_count); info->ram->dirty_sync_missed_zero_copy = stat64_get(&mig_stats.dirty_sync_missed_zero_copy); info->ram->postcopy_requests = stat64_get(&mig_stats.postcopy_requests); info->ram->page_size = page_size; info->ram->multifd_bytes = stat64_get(&mig_stats.multifd_bytes); info->ram->pages_per_second = s->pages_per_second; info->ram->precopy_bytes = stat64_get(&mig_stats.precopy_bytes); info->ram->downtime_bytes = stat64_get(&mig_stats.downtime_bytes); info->ram->postcopy_bytes = stat64_get(&mig_stats.postcopy_bytes); if (migrate_xbzrle()) { info->xbzrle_cache = g_malloc0(sizeof(*info->xbzrle_cache)); info->xbzrle_cache->cache_size = migrate_xbzrle_cache_size(); info->xbzrle_cache->bytes = xbzrle_counters.bytes; info->xbzrle_cache->pages = xbzrle_counters.pages; info->xbzrle_cache->cache_miss = xbzrle_counters.cache_miss; info->xbzrle_cache->cache_miss_rate = xbzrle_counters.cache_miss_rate; info->xbzrle_cache->encoding_rate = xbzrle_counters.encoding_rate; info->xbzrle_cache->overflow = xbzrle_counters.overflow; } if (migrate_compress()) { info->compression = g_malloc0(sizeof(*info->compression)); info->compression->pages = compression_counters.pages; info->compression->busy = compression_counters.busy; info->compression->busy_rate = compression_counters.busy_rate; info->compression->compressed_size = compression_counters.compressed_size; info->compression->compression_rate = compression_counters.compression_rate; } if (cpu_throttle_active()) { info->has_cpu_throttle_percentage = true; info->cpu_throttle_percentage = cpu_throttle_get_percentage(); } if (s->state != MIGRATION_STATUS_COMPLETED) { info->ram->remaining = ram_bytes_remaining(); info->ram->dirty_pages_rate = stat64_get(&mig_stats.dirty_pages_rate); } } static void populate_disk_info(MigrationInfo *info) { if (blk_mig_active()) { 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(); } } static void fill_source_migration_info(MigrationInfo *info) { MigrationState *s = migrate_get_current(); int state = qatomic_read(&s->state); GSList *cur_blocker = migration_blockers; info->blocked_reasons = NULL; /* * There are two types of reasons a migration might be blocked; * a) devices marked in VMState as non-migratable, and * b) Explicit migration blockers * We need to add both of them here. */ qemu_savevm_non_migratable_list(&info->blocked_reasons); while (cur_blocker) { QAPI_LIST_PREPEND(info->blocked_reasons, g_strdup(error_get_pretty(cur_blocker->data))); cur_blocker = g_slist_next(cur_blocker); } info->has_blocked_reasons = info->blocked_reasons != NULL; switch (state) { case MIGRATION_STATUS_NONE: /* no migration has happened ever */ /* do not overwrite destination migration status */ return; case MIGRATION_STATUS_SETUP: info->has_status = true; info->has_total_time = false; break; case MIGRATION_STATUS_ACTIVE: case MIGRATION_STATUS_CANCELLING: case MIGRATION_STATUS_POSTCOPY_ACTIVE: case MIGRATION_STATUS_PRE_SWITCHOVER: case MIGRATION_STATUS_DEVICE: case MIGRATION_STATUS_POSTCOPY_PAUSED: case MIGRATION_STATUS_POSTCOPY_RECOVER: /* TODO add some postcopy stats */ populate_time_info(info, s); populate_ram_info(info, s); populate_disk_info(info); populate_vfio_info(info); break; case MIGRATION_STATUS_COLO: info->has_status = true; /* TODO: display COLO specific information (checkpoint info etc.) */ break; case MIGRATION_STATUS_COMPLETED: populate_time_info(info, s); populate_ram_info(info, s); populate_vfio_info(info); break; case MIGRATION_STATUS_FAILED: info->has_status = true; if (s->error) { info->error_desc = g_strdup(error_get_pretty(s->error)); } break; case MIGRATION_STATUS_CANCELLED: info->has_status = true; break; case MIGRATION_STATUS_WAIT_UNPLUG: info->has_status = true; break; } info->status = state; } static void fill_destination_migration_info(MigrationInfo *info) { MigrationIncomingState *mis = migration_incoming_get_current(); if (mis->socket_address_list) { info->has_socket_address = true; info->socket_address = QAPI_CLONE(SocketAddressList, mis->socket_address_list); } switch (mis->state) { case MIGRATION_STATUS_NONE: return; case MIGRATION_STATUS_SETUP: case MIGRATION_STATUS_CANCELLING: case MIGRATION_STATUS_CANCELLED: case MIGRATION_STATUS_ACTIVE: case MIGRATION_STATUS_POSTCOPY_ACTIVE: case MIGRATION_STATUS_POSTCOPY_PAUSED: case MIGRATION_STATUS_POSTCOPY_RECOVER: case MIGRATION_STATUS_FAILED: case MIGRATION_STATUS_COLO: info->has_status = true; break; case MIGRATION_STATUS_COMPLETED: info->has_status = true; fill_destination_postcopy_migration_info(info); break; } info->status = mis->state; } MigrationInfo *qmp_query_migrate(Error **errp) { MigrationInfo *info = g_malloc0(sizeof(*info)); fill_destination_migration_info(info); fill_source_migration_info(info); return info; } void qmp_migrate_start_postcopy(Error **errp) { MigrationState *s = migrate_get_current(); if (!migrate_postcopy()) { error_setg(errp, "Enable postcopy with migrate_set_capability before" " the start of migration"); return; } if (s->state == MIGRATION_STATUS_NONE) { error_setg(errp, "Postcopy must be started after migration has been" " started"); return; } /* * we don't error if migration has finished since that would be racy * with issuing this command. */ qatomic_set(&s->start_postcopy, true); } /* shared migration helpers */ void migrate_set_state(int *state, int old_state, int new_state) { assert(new_state < MIGRATION_STATUS__MAX); if (qatomic_cmpxchg(state, old_state, new_state) == old_state) { trace_migrate_set_state(MigrationStatus_str(new_state)); migrate_generate_event(new_state); } } static void migrate_fd_cleanup(MigrationState *s) { qemu_bh_delete(s->cleanup_bh); s->cleanup_bh = NULL; g_free(s->hostname); s->hostname = NULL; json_writer_free(s->vmdesc); s->vmdesc = NULL; qemu_savevm_state_cleanup(); if (s->to_dst_file) { QEMUFile *tmp; trace_migrate_fd_cleanup(); qemu_mutex_unlock_iothread(); if (s->migration_thread_running) { qemu_thread_join(&s->thread); s->migration_thread_running = false; } qemu_mutex_lock_iothread(); multifd_save_cleanup(); qemu_mutex_lock(&s->qemu_file_lock); tmp = s->to_dst_file; s->to_dst_file = NULL; qemu_mutex_unlock(&s->qemu_file_lock); /* * Close the file handle without the lock to make sure the * critical section won't block for long. */ migration_ioc_unregister_yank_from_file(tmp); qemu_fclose(tmp); } if (s->postcopy_qemufile_src) { migration_ioc_unregister_yank_from_file(s->postcopy_qemufile_src); qemu_fclose(s->postcopy_qemufile_src); s->postcopy_qemufile_src = NULL; } assert(!migration_is_active(s)); if (s->state == MIGRATION_STATUS_CANCELLING) { migrate_set_state(&s->state, MIGRATION_STATUS_CANCELLING, MIGRATION_STATUS_CANCELLED); } if (s->error) { /* It is used on info migrate. We can't free it */ error_report_err(error_copy(s->error)); } notifier_list_notify(&migration_state_notifiers, s); block_cleanup_parameters(); yank_unregister_instance(MIGRATION_YANK_INSTANCE); } static void migrate_fd_cleanup_schedule(MigrationState *s) { /* * Ref the state for bh, because it may be called when * there're already no other refs */ object_ref(OBJECT(s)); qemu_bh_schedule(s->cleanup_bh); } static void migrate_fd_cleanup_bh(void *opaque) { MigrationState *s = opaque; migrate_fd_cleanup(s); object_unref(OBJECT(s)); } void migrate_set_error(MigrationState *s, const Error *error) { QEMU_LOCK_GUARD(&s->error_mutex); if (!s->error) { s->error = error_copy(error); } } static void migrate_error_free(MigrationState *s) { QEMU_LOCK_GUARD(&s->error_mutex); if (s->error) { error_free(s->error); s->error = NULL; } } void migrate_fd_error(MigrationState *s, const Error *error) { trace_migrate_fd_error(error_get_pretty(error)); assert(s->to_dst_file == NULL); migrate_set_state(&s->state, MIGRATION_STATUS_SETUP, MIGRATION_STATUS_FAILED); migrate_set_error(s, error); } static void migrate_fd_cancel(MigrationState *s) { int old_state ; QEMUFile *f = migrate_get_current()->to_dst_file; trace_migrate_fd_cancel(); WITH_QEMU_LOCK_GUARD(&s->qemu_file_lock) { if (s->rp_state.from_dst_file) { /* shutdown the rp socket, so causing the rp thread to shutdown */ qemu_file_shutdown(s->rp_state.from_dst_file); } } do { old_state = s->state; if (!migration_is_running(old_state)) { break; } /* If the migration is paused, kick it out of the pause */ if (old_state == MIGRATION_STATUS_PRE_SWITCHOVER) { qemu_sem_post(&s->pause_sem); } migrate_set_state(&s->state, old_state, MIGRATION_STATUS_CANCELLING); } while (s->state != MIGRATION_STATUS_CANCELLING); /* * If we're unlucky the migration code might be stuck somewhere in a * send/write while the network has failed and is waiting to timeout; * if we've got shutdown(2) available then we can force it to quit. * The outgoing qemu file gets closed in migrate_fd_cleanup that is * called in a bh, so there is no race against this cancel. */ if (s->state == MIGRATION_STATUS_CANCELLING && f) { qemu_file_shutdown(f); } if (s->state == MIGRATION_STATUS_CANCELLING && s->block_inactive) { Error *local_err = NULL; bdrv_activate_all(&local_err); if (local_err) { error_report_err(local_err); } else { s->block_inactive = false; } } } 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_in_setup(MigrationState *s) { return s->state == MIGRATION_STATUS_SETUP; } bool migration_has_finished(MigrationState *s) { return s->state == MIGRATION_STATUS_COMPLETED; } bool migration_has_failed(MigrationState *s) { return (s->state == MIGRATION_STATUS_CANCELLED || s->state == MIGRATION_STATUS_FAILED); } bool migration_in_postcopy(void) { MigrationState *s = migrate_get_current(); switch (s->state) { case MIGRATION_STATUS_POSTCOPY_ACTIVE: case MIGRATION_STATUS_POSTCOPY_PAUSED: case MIGRATION_STATUS_POSTCOPY_RECOVER: return true; default: return false; } } bool migration_in_postcopy_after_devices(MigrationState *s) { return migration_in_postcopy() && s->postcopy_after_devices; } bool migration_in_incoming_postcopy(void) { PostcopyState ps = postcopy_state_get(); return ps >= POSTCOPY_INCOMING_DISCARD && ps < POSTCOPY_INCOMING_END; } bool migration_incoming_postcopy_advised(void) { PostcopyState ps = postcopy_state_get(); return ps >= POSTCOPY_INCOMING_ADVISE && ps < POSTCOPY_INCOMING_END; } bool migration_in_bg_snapshot(void) { MigrationState *s = migrate_get_current(); return migrate_background_snapshot() && migration_is_setup_or_active(s->state); } bool migration_is_idle(void) { MigrationState *s = current_migration; if (!s) { return true; } switch (s->state) { case MIGRATION_STATUS_NONE: case MIGRATION_STATUS_CANCELLED: case MIGRATION_STATUS_COMPLETED: case MIGRATION_STATUS_FAILED: return true; case MIGRATION_STATUS_SETUP: case MIGRATION_STATUS_CANCELLING: case MIGRATION_STATUS_ACTIVE: case MIGRATION_STATUS_POSTCOPY_ACTIVE: case MIGRATION_STATUS_COLO: case MIGRATION_STATUS_PRE_SWITCHOVER: case MIGRATION_STATUS_DEVICE: case MIGRATION_STATUS_WAIT_UNPLUG: return false; case MIGRATION_STATUS__MAX: g_assert_not_reached(); } return false; } bool migration_is_active(MigrationState *s) { return (s->state == MIGRATION_STATUS_ACTIVE || s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE); } void migrate_init(MigrationState *s) { /* * Reinitialise all migration state, except * parameters/capabilities that the user set, and * locks. */ s->cleanup_bh = 0; s->vm_start_bh = 0; s->to_dst_file = NULL; s->state = MIGRATION_STATUS_NONE; s->rp_state.from_dst_file = NULL; s->rp_state.error = false; s->mbps = 0.0; s->pages_per_second = 0.0; s->downtime = 0; s->expected_downtime = 0; s->setup_time = 0; s->start_postcopy = false; s->postcopy_after_devices = false; s->migration_thread_running = false; error_free(s->error); s->error = NULL; s->hostname = NULL; migrate_set_state(&s->state, MIGRATION_STATUS_NONE, MIGRATION_STATUS_SETUP); s->start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME); s->total_time = 0; s->vm_was_running = false; s->iteration_initial_bytes = 0; s->threshold_size = 0; } int migrate_add_blocker_internal(Error *reason, Error **errp) { /* Snapshots are similar to migrations, so check RUN_STATE_SAVE_VM too. */ if (runstate_check(RUN_STATE_SAVE_VM) || !migration_is_idle()) { error_propagate_prepend(errp, error_copy(reason), "disallowing migration blocker " "(migration/snapshot in progress) for: "); return -EBUSY; } migration_blockers = g_slist_prepend(migration_blockers, reason); return 0; } int migrate_add_blocker(Error *reason, Error **errp) { if (only_migratable) { error_propagate_prepend(errp, error_copy(reason), "disallowing migration blocker " "(--only-migratable) for: "); return -EACCES; } return migrate_add_blocker_internal(reason, errp); } void migrate_del_blocker(Error *reason) { migration_blockers = g_slist_remove(migration_blockers, reason); } void qmp_migrate_incoming(const char *uri, Error **errp) { Error *local_err = NULL; static bool once = true; if (!once) { error_setg(errp, "The incoming migration has already been started"); return; } if (!runstate_check(RUN_STATE_INMIGRATE)) { error_setg(errp, "'-incoming' was not specified on the command line"); return; } if (!yank_register_instance(MIGRATION_YANK_INSTANCE, errp)) { return; } qemu_start_incoming_migration(uri, &local_err); if (local_err) { yank_unregister_instance(MIGRATION_YANK_INSTANCE); error_propagate(errp, local_err); return; } once = false; } void qmp_migrate_recover(const char *uri, Error **errp) { MigrationIncomingState *mis = migration_incoming_get_current(); /* * Don't even bother to use ERRP_GUARD() as it _must_ always be set by * callers (no one should ignore a recover failure); if there is, it's a * programming error. */ assert(errp); if (mis->state != MIGRATION_STATUS_POSTCOPY_PAUSED) { error_setg(errp, "Migrate recover can only be run " "when postcopy is paused."); return; } /* If there's an existing transport, release it */ migration_incoming_transport_cleanup(mis); /* * Note that this call will never start a real migration; it will * only re-setup the migration stream and poke existing migration * to continue using that newly established channel. */ qemu_start_incoming_migration(uri, errp); } void qmp_migrate_pause(Error **errp) { MigrationState *ms = migrate_get_current(); MigrationIncomingState *mis = migration_incoming_get_current(); int ret; if (ms->state == MIGRATION_STATUS_POSTCOPY_ACTIVE) { /* Source side, during postcopy */ qemu_mutex_lock(&ms->qemu_file_lock); ret = qemu_file_shutdown(ms->to_dst_file); qemu_mutex_unlock(&ms->qemu_file_lock); if (ret) { error_setg(errp, "Failed to pause source migration"); } return; } if (mis->state == MIGRATION_STATUS_POSTCOPY_ACTIVE) { ret = qemu_file_shutdown(mis->from_src_file); if (ret) { error_setg(errp, "Failed to pause destination migration"); } return; } error_setg(errp, "migrate-pause is currently only supported " "during postcopy-active state"); } bool migration_is_blocked(Error **errp) { if (qemu_savevm_state_blocked(errp)) { return true; } if (migration_blockers) { error_propagate(errp, error_copy(migration_blockers->data)); return true; } return false; } /* Returns true if continue to migrate, or false if error detected */ static bool migrate_prepare(MigrationState *s, bool blk, bool blk_inc, bool resume, Error **errp) { Error *local_err = NULL; if (resume) { if (s->state != MIGRATION_STATUS_POSTCOPY_PAUSED) { error_setg(errp, "Cannot resume if there is no " "paused migration"); return false; } /* * Postcopy recovery won't work well with release-ram * capability since release-ram will drop the page buffer as * long as the page is put into the send buffer. So if there * is a network failure happened, any page buffers that have * not yet reached the destination VM but have already been * sent from the source VM will be lost forever. Let's refuse * the client from resuming such a postcopy migration. * Luckily release-ram was designed to only be used when src * and destination VMs are on the same host, so it should be * fine. */ if (migrate_release_ram()) { error_setg(errp, "Postcopy recovery cannot work " "when release-ram capability is set"); return false; } /* This is a resume, skip init status */ return true; } if (migration_is_running(s->state)) { error_setg(errp, QERR_MIGRATION_ACTIVE); return false; } if (runstate_check(RUN_STATE_INMIGRATE)) { error_setg(errp, "Guest is waiting for an incoming migration"); return false; } if (runstate_check(RUN_STATE_POSTMIGRATE)) { error_setg(errp, "Can't migrate the vm that was paused due to " "previous migration"); return false; } if (migration_is_blocked(errp)) { return false; } if (blk || blk_inc) { if (migrate_colo()) { error_setg(errp, "No disk migration is required in COLO mode"); return false; } if (migrate_block() || migrate_block_incremental()) { error_setg(errp, "Command options are incompatible with " "current migration capabilities"); return false; } if (!migrate_cap_set(MIGRATION_CAPABILITY_BLOCK, true, &local_err)) { error_propagate(errp, local_err); return false; } s->must_remove_block_options = true; } if (blk_inc) { migrate_set_block_incremental(true); } migrate_init(s); /* * set mig_stats compression_counters memory to zero for a * new migration */ memset(&mig_stats, 0, sizeof(mig_stats)); memset(&compression_counters, 0, sizeof(compression_counters)); return true; } void qmp_migrate(const char *uri, bool has_blk, bool blk, bool has_inc, bool inc, bool has_detach, bool detach, bool has_resume, bool resume, Error **errp) { Error *local_err = NULL; MigrationState *s = migrate_get_current(); const char *p = NULL; /* URI is not suitable for migration? */ if (!migration_channels_and_uri_compatible(uri, errp)) { return; } if (!migrate_prepare(s, has_blk && blk, has_inc && inc, has_resume && resume, errp)) { /* Error detected, put into errp */ return; } if (!(has_resume && resume)) { if (!yank_register_instance(MIGRATION_YANK_INSTANCE, errp)) { return; } } if (strstart(uri, "tcp:", &p) || strstart(uri, "unix:", NULL) || strstart(uri, "vsock:", NULL)) { socket_start_outgoing_migration(s, p ? p : uri, &local_err); #ifdef CONFIG_RDMA } else if (strstart(uri, "rdma:", &p)) { rdma_start_outgoing_migration(s, p, &local_err); #endif } else if (strstart(uri, "exec:", &p)) { exec_start_outgoing_migration(s, p, &local_err); } else if (strstart(uri, "fd:", &p)) { fd_start_outgoing_migration(s, p, &local_err); } else { if (!(has_resume && resume)) { yank_unregister_instance(MIGRATION_YANK_INSTANCE); } error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "uri", "a valid migration protocol"); migrate_set_state(&s->state, MIGRATION_STATUS_SETUP, MIGRATION_STATUS_FAILED); block_cleanup_parameters(); return; } if (local_err) { if (!(has_resume && resume)) { yank_unregister_instance(MIGRATION_YANK_INSTANCE); } migrate_fd_error(s, local_err); error_propagate(errp, local_err); return; } } void qmp_migrate_cancel(Error **errp) { migration_cancel(NULL); } void qmp_migrate_continue(MigrationStatus state, Error **errp) { MigrationState *s = migrate_get_current(); if (s->state != state) { error_setg(errp, "Migration not in expected state: %s", MigrationStatus_str(s->state)); return; } qemu_sem_post(&s->pause_sem); } /* migration thread support */ /* * Something bad happened to the RP stream, mark an error * The caller shall print or trace something to indicate why */ static void mark_source_rp_bad(MigrationState *s) { s->rp_state.error = true; } static struct rp_cmd_args { ssize_t len; /* -1 = variable */ const char *name; } rp_cmd_args[] = { [MIG_RP_MSG_INVALID] = { .len = -1, .name = "INVALID" }, [MIG_RP_MSG_SHUT] = { .len = 4, .name = "SHUT" }, [MIG_RP_MSG_PONG] = { .len = 4, .name = "PONG" }, [MIG_RP_MSG_REQ_PAGES] = { .len = 12, .name = "REQ_PAGES" }, [MIG_RP_MSG_REQ_PAGES_ID] = { .len = -1, .name = "REQ_PAGES_ID" }, [MIG_RP_MSG_RECV_BITMAP] = { .len = -1, .name = "RECV_BITMAP" }, [MIG_RP_MSG_RESUME_ACK] = { .len = 4, .name = "RESUME_ACK" }, [MIG_RP_MSG_MAX] = { .len = -1, .name = "MAX" }, }; /* * Process a request for pages received on the return path, * We're allowed to send more than requested (e.g. to round to our page size) * and we don't need to send pages that have already been sent. */ static void migrate_handle_rp_req_pages(MigrationState *ms, const char* rbname, ram_addr_t start, size_t len) { long our_host_ps = qemu_real_host_page_size(); trace_migrate_handle_rp_req_pages(rbname, start, len); /* * Since we currently insist on matching page sizes, just sanity check * we're being asked for whole host pages. */ if (!QEMU_IS_ALIGNED(start, our_host_ps) || !QEMU_IS_ALIGNED(len, our_host_ps)) { error_report("%s: Misaligned page request, start: " RAM_ADDR_FMT " len: %zd", __func__, start, len); mark_source_rp_bad(ms); return; } if (ram_save_queue_pages(rbname, start, len)) { mark_source_rp_bad(ms); } } /* Return true to retry, false to quit */ static bool postcopy_pause_return_path_thread(MigrationState *s) { trace_postcopy_pause_return_path(); qemu_sem_wait(&s->postcopy_pause_rp_sem); trace_postcopy_pause_return_path_continued(); return true; } static int migrate_handle_rp_recv_bitmap(MigrationState *s, char *block_name) { RAMBlock *block = qemu_ram_block_by_name(block_name); if (!block) { error_report("%s: invalid block name '%s'", __func__, block_name); return -EINVAL; } /* Fetch the received bitmap and refresh the dirty bitmap */ return ram_dirty_bitmap_reload(s, block); } static int migrate_handle_rp_resume_ack(MigrationState *s, uint32_t value) { trace_source_return_path_thread_resume_ack(value); if (value != MIGRATION_RESUME_ACK_VALUE) { error_report("%s: illegal resume_ack value %"PRIu32, __func__, value); return -1; } /* Now both sides are active. */ migrate_set_state(&s->state, MIGRATION_STATUS_POSTCOPY_RECOVER, MIGRATION_STATUS_POSTCOPY_ACTIVE); /* Notify send thread that time to continue send pages */ qemu_sem_post(&s->rp_state.rp_sem); return 0; } /* * Release ms->rp_state.from_dst_file (and postcopy_qemufile_src if * existed) in a safe way. */ static void migration_release_dst_files(MigrationState *ms) { QEMUFile *file; WITH_QEMU_LOCK_GUARD(&ms->qemu_file_lock) { /* * Reset the from_dst_file pointer first before releasing it, as we * can't block within lock section */ file = ms->rp_state.from_dst_file; ms->rp_state.from_dst_file = NULL; } /* * Do the same to postcopy fast path socket too if there is. No * locking needed because this qemufile should only be managed by * return path thread. */ if (ms->postcopy_qemufile_src) { migration_ioc_unregister_yank_from_file(ms->postcopy_qemufile_src); qemu_file_shutdown(ms->postcopy_qemufile_src); qemu_fclose(ms->postcopy_qemufile_src); ms->postcopy_qemufile_src = NULL; } qemu_fclose(file); } /* * Handles messages sent on the return path towards the source VM * */ static void *source_return_path_thread(void *opaque) { MigrationState *ms = opaque; QEMUFile *rp = ms->rp_state.from_dst_file; uint16_t header_len, header_type; uint8_t buf[512]; uint32_t tmp32, sibling_error; ram_addr_t start = 0; /* =0 to silence warning */ size_t len = 0, expected_len; int res; trace_source_return_path_thread_entry(); rcu_register_thread(); retry: while (!ms->rp_state.error && !qemu_file_get_error(rp) && migration_is_setup_or_active(ms->state)) { trace_source_return_path_thread_loop_top(); header_type = qemu_get_be16(rp); header_len = qemu_get_be16(rp); if (qemu_file_get_error(rp)) { mark_source_rp_bad(ms); goto out; } if (header_type >= MIG_RP_MSG_MAX || header_type == MIG_RP_MSG_INVALID) { error_report("RP: Received invalid message 0x%04x length 0x%04x", header_type, header_len); mark_source_rp_bad(ms); goto out; } if ((rp_cmd_args[header_type].len != -1 && header_len != rp_cmd_args[header_type].len) || header_len > sizeof(buf)) { error_report("RP: Received '%s' message (0x%04x) with" "incorrect length %d expecting %zu", rp_cmd_args[header_type].name, header_type, header_len, (size_t)rp_cmd_args[header_type].len); mark_source_rp_bad(ms); goto out; } /* We know we've got a valid header by this point */ res = qemu_get_buffer(rp, buf, header_len); if (res != header_len) { error_report("RP: Failed reading data for message 0x%04x" " read %d expected %d", header_type, res, header_len); mark_source_rp_bad(ms); goto out; } /* OK, we have the message and the data */ switch (header_type) { case MIG_RP_MSG_SHUT: sibling_error = ldl_be_p(buf); trace_source_return_path_thread_shut(sibling_error); if (sibling_error) { error_report("RP: Sibling indicated error %d", sibling_error); mark_source_rp_bad(ms); } /* * We'll let the main thread deal with closing the RP * we could do a shutdown(2) on it, but we're the only user * anyway, so there's nothing gained. */ goto out; case MIG_RP_MSG_PONG: tmp32 = ldl_be_p(buf); trace_source_return_path_thread_pong(tmp32); qemu_sem_post(&ms->rp_state.rp_pong_acks); break; case MIG_RP_MSG_REQ_PAGES: start = ldq_be_p(buf); len = ldl_be_p(buf + 8); migrate_handle_rp_req_pages(ms, NULL, start, len); break; case MIG_RP_MSG_REQ_PAGES_ID: expected_len = 12 + 1; /* header + termination */ if (header_len >= expected_len) { start = ldq_be_p(buf); len = ldl_be_p(buf + 8); /* Now we expect an idstr */ tmp32 = buf[12]; /* Length of the following idstr */ buf[13 + tmp32] = '\0'; expected_len += tmp32; } if (header_len != expected_len) { error_report("RP: Req_Page_id with length %d expecting %zd", header_len, expected_len); mark_source_rp_bad(ms); goto out; } migrate_handle_rp_req_pages(ms, (char *)&buf[13], start, len); break; case MIG_RP_MSG_RECV_BITMAP: if (header_len < 1) { error_report("%s: missing block name", __func__); mark_source_rp_bad(ms); goto out; } /* Format: len (1B) + idstr (<255B). This ends the idstr. */ buf[buf[0] + 1] = '\0'; if (migrate_handle_rp_recv_bitmap(ms, (char *)(buf + 1))) { mark_source_rp_bad(ms); goto out; } break; case MIG_RP_MSG_RESUME_ACK: tmp32 = ldl_be_p(buf); if (migrate_handle_rp_resume_ack(ms, tmp32)) { mark_source_rp_bad(ms); goto out; } break; default: break; } } out: res = qemu_file_get_error(rp); if (res) { if (res && migration_in_postcopy()) { /* * Maybe there is something we can do: it looks like a * network down issue, and we pause for a recovery. */ migration_release_dst_files(ms); rp = NULL; if (postcopy_pause_return_path_thread(ms)) { /* * Reload rp, reset the rest. Referencing it is safe since * it's reset only by us above, or when migration completes */ rp = ms->rp_state.from_dst_file; ms->rp_state.error = false; goto retry; } } trace_source_return_path_thread_bad_end(); mark_source_rp_bad(ms); } trace_source_return_path_thread_end(); migration_release_dst_files(ms); rcu_unregister_thread(); return NULL; } static int open_return_path_on_source(MigrationState *ms, bool create_thread) { ms->rp_state.from_dst_file = qemu_file_get_return_path(ms->to_dst_file); if (!ms->rp_state.from_dst_file) { return -1; } trace_open_return_path_on_source(); if (!create_thread) { /* We're done */ return 0; } qemu_thread_create(&ms->rp_state.rp_thread, "return path", source_return_path_thread, ms, QEMU_THREAD_JOINABLE); ms->rp_state.rp_thread_created = true; trace_open_return_path_on_source_continue(); return 0; } /* Returns 0 if the RP was ok, otherwise there was an error on the RP */ static int await_return_path_close_on_source(MigrationState *ms) { /* * If this is a normal exit then the destination will send a SHUT and the * rp_thread will exit, however if there's an error we need to cause * it to exit. */ if (qemu_file_get_error(ms->to_dst_file) && ms->rp_state.from_dst_file) { /* * shutdown(2), if we have it, will cause it to unblock if it's stuck * waiting for the destination. */ qemu_file_shutdown(ms->rp_state.from_dst_file); mark_source_rp_bad(ms); } trace_await_return_path_close_on_source_joining(); qemu_thread_join(&ms->rp_state.rp_thread); ms->rp_state.rp_thread_created = false; trace_await_return_path_close_on_source_close(); return ms->rp_state.error; } static inline void migration_wait_main_channel(MigrationState *ms) { /* Wait until one PONG message received */ qemu_sem_wait(&ms->rp_state.rp_pong_acks); } /* * Switch from normal iteration to postcopy * Returns non-0 on error */ static int postcopy_start(MigrationState *ms) { int ret; QIOChannelBuffer *bioc; QEMUFile *fb; int64_t time_at_stop = qemu_clock_get_ms(QEMU_CLOCK_REALTIME); int64_t bandwidth = migrate_max_postcopy_bandwidth(); bool restart_block = false; int cur_state = MIGRATION_STATUS_ACTIVE; if (migrate_postcopy_preempt()) { migration_wait_main_channel(ms); if (postcopy_preempt_establish_channel(ms)) { migrate_set_state(&ms->state, ms->state, MIGRATION_STATUS_FAILED); return -1; } } if (!migrate_pause_before_switchover()) { migrate_set_state(&ms->state, MIGRATION_STATUS_ACTIVE, MIGRATION_STATUS_POSTCOPY_ACTIVE); } trace_postcopy_start(); qemu_mutex_lock_iothread(); trace_postcopy_start_set_run(); qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER, NULL); global_state_store(); ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE); if (ret < 0) { goto fail; } ret = migration_maybe_pause(ms, &cur_state, MIGRATION_STATUS_POSTCOPY_ACTIVE); if (ret < 0) { goto fail; } ret = bdrv_inactivate_all(); if (ret < 0) { goto fail; } restart_block = true; /* * Cause any non-postcopiable, but iterative devices to * send out their final data. */ qemu_savevm_state_complete_precopy(ms->to_dst_file, true, false); /* * in Finish migrate and with the io-lock held everything should * be quiet, but we've potentially still got dirty pages and we * need to tell the destination to throw any pages it's already received * that are dirty */ if (migrate_postcopy_ram()) { ram_postcopy_send_discard_bitmap(ms); } /* * send rest of state - note things that are doing postcopy * will notice we're in POSTCOPY_ACTIVE and not actually * wrap their state up here */ /* 0 max-postcopy-bandwidth means unlimited */ if (!bandwidth) { qemu_file_set_rate_limit(ms->to_dst_file, INT64_MAX); } else { qemu_file_set_rate_limit(ms->to_dst_file, bandwidth / XFER_LIMIT_RATIO); } if (migrate_postcopy_ram()) { /* Ping just for debugging, helps line traces up */ qemu_savevm_send_ping(ms->to_dst_file, 2); } /* * While loading the device state we may trigger page transfer * requests and the fd must be free to process those, and thus * the destination must read the whole device state off the fd before * it starts processing it. Unfortunately the ad-hoc migration format * doesn't allow the destination to know the size to read without fully * parsing it through each devices load-state code (especially the open * coded devices that use get/put). * So we wrap the device state up in a package with a length at the start; * to do this we use a qemu_buf to hold the whole of the device state. */ bioc = qio_channel_buffer_new(4096); qio_channel_set_name(QIO_CHANNEL(bioc), "migration-postcopy-buffer"); fb = qemu_file_new_output(QIO_CHANNEL(bioc)); object_unref(OBJECT(bioc)); /* * Make sure the receiver can get incoming pages before we send the rest * of the state */ qemu_savevm_send_postcopy_listen(fb); qemu_savevm_state_complete_precopy(fb, false, false); if (migrate_postcopy_ram()) { qemu_savevm_send_ping(fb, 3); } qemu_savevm_send_postcopy_run(fb); /* <><> end of stuff going into the package */ /* Last point of recovery; as soon as we send the package the destination * can open devices and potentially start running. * Lets just check again we've not got any errors. */ ret = qemu_file_get_error(ms->to_dst_file); if (ret) { error_report("postcopy_start: Migration stream errored (pre package)"); goto fail_closefb; } restart_block = false; /* Now send that blob */ if (qemu_savevm_send_packaged(ms->to_dst_file, bioc->data, bioc->usage)) { goto fail_closefb; } qemu_fclose(fb); /* Send a notify to give a chance for anything that needs to happen * at the transition to postcopy and after the device state; in particular * spice needs to trigger a transition now */ ms->postcopy_after_devices = true; notifier_list_notify(&migration_state_notifiers, ms); ms->downtime = qemu_clock_get_ms(QEMU_CLOCK_REALTIME) - time_at_stop; qemu_mutex_unlock_iothread(); if (migrate_postcopy_ram()) { /* * Although this ping is just for debug, it could potentially be * used for getting a better measurement of downtime at the source. */ qemu_savevm_send_ping(ms->to_dst_file, 4); } if (migrate_release_ram()) { ram_postcopy_migrated_memory_release(ms); } ret = qemu_file_get_error(ms->to_dst_file); if (ret) { error_report("postcopy_start: Migration stream errored"); migrate_set_state(&ms->state, MIGRATION_STATUS_POSTCOPY_ACTIVE, MIGRATION_STATUS_FAILED); } trace_postcopy_preempt_enabled(migrate_postcopy_preempt()); return ret; fail_closefb: qemu_fclose(fb); fail: migrate_set_state(&ms->state, MIGRATION_STATUS_POSTCOPY_ACTIVE, MIGRATION_STATUS_FAILED); if (restart_block) { /* A failure happened early enough that we know the destination hasn't * accessed block devices, so we're safe to recover. */ Error *local_err = NULL; bdrv_activate_all(&local_err); if (local_err) { error_report_err(local_err); } } qemu_mutex_unlock_iothread(); return -1; } /** * migration_maybe_pause: Pause if required to by * migrate_pause_before_switchover called with the iothread locked * Returns: 0 on success */ static int migration_maybe_pause(MigrationState *s, int *current_active_state, int new_state) { if (!migrate_pause_before_switchover()) { return 0; } /* Since leaving this state is not atomic with posting the semaphore * it's possible that someone could have issued multiple migrate_continue * and the semaphore is incorrectly positive at this point; * the docs say it's undefined to reinit a semaphore that's already * init'd, so use timedwait to eat up any existing posts. */ while (qemu_sem_timedwait(&s->pause_sem, 1) == 0) { /* This block intentionally left blank */ } /* * If the migration is cancelled when it is in the completion phase, * the migration state is set to MIGRATION_STATUS_CANCELLING. * So we don't need to wait a semaphore, otherwise we would always * wait for the 'pause_sem' semaphore. */ if (s->state != MIGRATION_STATUS_CANCELLING) { qemu_mutex_unlock_iothread(); migrate_set_state(&s->state, *current_active_state, MIGRATION_STATUS_PRE_SWITCHOVER); qemu_sem_wait(&s->pause_sem); migrate_set_state(&s->state, MIGRATION_STATUS_PRE_SWITCHOVER, new_state); *current_active_state = new_state; qemu_mutex_lock_iothread(); } return s->state == new_state ? 0 : -EINVAL; } /** * migration_completion: Used by migration_thread when there's not much left. * The caller 'breaks' the loop when this returns. * * @s: Current migration state */ static void migration_completion(MigrationState *s) { int ret; int current_active_state = s->state; if (s->state == MIGRATION_STATUS_ACTIVE) { qemu_mutex_lock_iothread(); s->downtime_start = qemu_clock_get_ms(QEMU_CLOCK_REALTIME); qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER, NULL); s->vm_was_running = runstate_is_running(); ret = global_state_store(); if (!ret) { ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE); trace_migration_completion_vm_stop(ret); if (ret >= 0) { ret = migration_maybe_pause(s, ¤t_active_state, MIGRATION_STATUS_DEVICE); } if (ret >= 0) { s->block_inactive = !migrate_colo(); qemu_file_set_rate_limit(s->to_dst_file, INT64_MAX); ret = qemu_savevm_state_complete_precopy(s->to_dst_file, false, s->block_inactive); } } qemu_mutex_unlock_iothread(); if (ret < 0) { goto fail; } } else if (s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE) { trace_migration_completion_postcopy_end(); qemu_mutex_lock_iothread(); qemu_savevm_state_complete_postcopy(s->to_dst_file); qemu_mutex_unlock_iothread(); /* * Shutdown the postcopy fast path thread. This is only needed * when dest QEMU binary is old (7.1/7.2). QEMU 8.0+ doesn't need * this. */ if (migrate_postcopy_preempt() && s->preempt_pre_7_2) { postcopy_preempt_shutdown_file(s); } trace_migration_completion_postcopy_end_after_complete(); } else { goto fail; } /* * If rp was opened we must clean up the thread before * cleaning everything else up (since if there are no failures * it will wait for the destination to send it's status in * a SHUT command). */ if (s->rp_state.rp_thread_created) { int rp_error; trace_migration_return_path_end_before(); rp_error = await_return_path_close_on_source(s); trace_migration_return_path_end_after(rp_error); if (rp_error) { goto fail_invalidate; } } if (qemu_file_get_error(s->to_dst_file)) { trace_migration_completion_file_err(); goto fail_invalidate; } if (migrate_colo() && s->state == MIGRATION_STATUS_ACTIVE) { /* COLO does not support postcopy */ migrate_set_state(&s->state, MIGRATION_STATUS_ACTIVE, MIGRATION_STATUS_COLO); } else { migrate_set_state(&s->state, current_active_state, MIGRATION_STATUS_COMPLETED); } return; fail_invalidate: /* If not doing postcopy, vm_start() will be called: let's regain * control on images. */ if (s->state == MIGRATION_STATUS_ACTIVE || s->state == MIGRATION_STATUS_DEVICE) { Error *local_err = NULL; qemu_mutex_lock_iothread(); bdrv_activate_all(&local_err); if (local_err) { error_report_err(local_err); s->block_inactive = true; } else { s->block_inactive = false; } qemu_mutex_unlock_iothread(); } fail: migrate_set_state(&s->state, current_active_state, MIGRATION_STATUS_FAILED); } /** * bg_migration_completion: Used by bg_migration_thread when after all the * RAM has been saved. The caller 'breaks' the loop when this returns. * * @s: Current migration state */ static void bg_migration_completion(MigrationState *s) { int current_active_state = s->state; /* * Stop tracking RAM writes - un-protect memory, un-register UFFD * memory ranges, flush kernel wait queues and wake up threads * waiting for write fault to be resolved. */ ram_write_tracking_stop(); if (s->state == MIGRATION_STATUS_ACTIVE) { /* * By this moment we have RAM content saved into the migration stream. * The next step is to flush the non-RAM content (device state) * right after the ram content. The device state has been stored into * the temporary buffer before RAM saving started. */ qemu_put_buffer(s->to_dst_file, s->bioc->data, s->bioc->usage); qemu_fflush(s->to_dst_file); } else if (s->state == MIGRATION_STATUS_CANCELLING) { goto fail; } if (qemu_file_get_error(s->to_dst_file)) { trace_migration_completion_file_err(); goto fail; } migrate_set_state(&s->state, current_active_state, MIGRATION_STATUS_COMPLETED); return; fail: migrate_set_state(&s->state, current_active_state, MIGRATION_STATUS_FAILED); } typedef enum MigThrError { /* No error detected */ MIG_THR_ERR_NONE = 0, /* Detected error, but resumed successfully */ MIG_THR_ERR_RECOVERED = 1, /* Detected fatal error, need to exit */ MIG_THR_ERR_FATAL = 2, } MigThrError; static int postcopy_resume_handshake(MigrationState *s) { qemu_savevm_send_postcopy_resume(s->to_dst_file); while (s->state == MIGRATION_STATUS_POSTCOPY_RECOVER) { qemu_sem_wait(&s->rp_state.rp_sem); } if (s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE) { return 0; } return -1; } /* Return zero if success, or <0 for error */ static int postcopy_do_resume(MigrationState *s) { int ret; /* * Call all the resume_prepare() hooks, so that modules can be * ready for the migration resume. */ ret = qemu_savevm_state_resume_prepare(s); if (ret) { error_report("%s: resume_prepare() failure detected: %d", __func__, ret); return ret; } /* * If preempt is enabled, re-establish the preempt channel. Note that * we do it after resume prepare to make sure the main channel will be * created before the preempt channel. E.g. with weak network, the * dest QEMU may get messed up with the preempt and main channels on * the order of connection setup. This guarantees the correct order. */ ret = postcopy_preempt_establish_channel(s); if (ret) { error_report("%s: postcopy_preempt_establish_channel(): %d", __func__, ret); return ret; } /* * Last handshake with destination on the resume (destination will * switch to postcopy-active afterwards) */ ret = postcopy_resume_handshake(s); if (ret) { error_report("%s: handshake failed: %d", __func__, ret); return ret; } return 0; } /* * We don't return until we are in a safe state to continue current * postcopy migration. Returns MIG_THR_ERR_RECOVERED if recovered, or * MIG_THR_ERR_FATAL if unrecovery failure happened. */ static MigThrError postcopy_pause(MigrationState *s) { assert(s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE); while (true) { QEMUFile *file; /* * Current channel is possibly broken. Release it. Note that this is * guaranteed even without lock because to_dst_file should only be * modified by the migration thread. That also guarantees that the * unregister of yank is safe too without the lock. It should be safe * even to be within the qemu_file_lock, but we didn't do that to avoid * taking more mutex (yank_lock) within qemu_file_lock. TL;DR: we make * the qemu_file_lock critical section as small as possible. */ assert(s->to_dst_file); migration_ioc_unregister_yank_from_file(s->to_dst_file); qemu_mutex_lock(&s->qemu_file_lock); file = s->to_dst_file; s->to_dst_file = NULL; qemu_mutex_unlock(&s->qemu_file_lock); qemu_file_shutdown(file); qemu_fclose(file); migrate_set_state(&s->state, s->state, MIGRATION_STATUS_POSTCOPY_PAUSED); error_report("Detected IO failure for postcopy. " "Migration paused."); /* * We wait until things fixed up. Then someone will setup the * status back for us. */ while (s->state == MIGRATION_STATUS_POSTCOPY_PAUSED) { qemu_sem_wait(&s->postcopy_pause_sem); } if (s->state == MIGRATION_STATUS_POSTCOPY_RECOVER) { /* Woken up by a recover procedure. Give it a shot */ /* * Firstly, let's wake up the return path now, with a new * return path channel. */ qemu_sem_post(&s->postcopy_pause_rp_sem); /* Do the resume logic */ if (postcopy_do_resume(s) == 0) { /* Let's continue! */ trace_postcopy_pause_continued(); return MIG_THR_ERR_RECOVERED; } else { /* * Something wrong happened during the recovery, let's * pause again. Pause is always better than throwing * data away. */ continue; } } else { /* This is not right... Time to quit. */ return MIG_THR_ERR_FATAL; } } } static MigThrError migration_detect_error(MigrationState *s) { int ret; int state = s->state; Error *local_error = NULL; if (state == MIGRATION_STATUS_CANCELLING || state == MIGRATION_STATUS_CANCELLED) { /* End the migration, but don't set the state to failed */ return MIG_THR_ERR_FATAL; } /* * Try to detect any file errors. Note that postcopy_qemufile_src will * be NULL when postcopy preempt is not enabled. */ ret = qemu_file_get_error_obj_any(s->to_dst_file, s->postcopy_qemufile_src, &local_error); if (!ret) { /* Everything is fine */ assert(!local_error); return MIG_THR_ERR_NONE; } if (local_error) { migrate_set_error(s, local_error); error_free(local_error); } if (state == MIGRATION_STATUS_POSTCOPY_ACTIVE && ret) { /* * For postcopy, we allow the network to be down for a * while. After that, it can be continued by a * recovery phase. */ return postcopy_pause(s); } else { /* * For precopy (or postcopy with error outside IO), we fail * with no time. */ migrate_set_state(&s->state, state, MIGRATION_STATUS_FAILED); trace_migration_thread_file_err(); /* Time to stop the migration, now. */ return MIG_THR_ERR_FATAL; } } /* How many bytes have we transferred since the beginning of the migration */ static uint64_t migration_total_bytes(MigrationState *s) { return qemu_file_total_transferred(s->to_dst_file) + stat64_get(&mig_stats.multifd_bytes); } static void migration_calculate_complete(MigrationState *s) { uint64_t bytes = migration_total_bytes(s); int64_t end_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME); int64_t transfer_time; s->total_time = end_time - s->start_time; if (!s->downtime) { /* * It's still not set, so we are precopy migration. For * postcopy, downtime is calculated during postcopy_start(). */ s->downtime = end_time - s->downtime_start; } transfer_time = s->total_time - s->setup_time; if (transfer_time) { s->mbps = ((double) bytes * 8.0) / transfer_time / 1000; } } static void update_iteration_initial_status(MigrationState *s) { /* * Update these three fields at the same time to avoid mismatch info lead * wrong speed calculation. */ s->iteration_start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME); s->iteration_initial_bytes = migration_total_bytes(s); s->iteration_initial_pages = ram_get_total_transferred_pages(); } static void migration_update_counters(MigrationState *s, int64_t current_time) { uint64_t transferred, transferred_pages, time_spent; uint64_t current_bytes; /* bytes transferred since the beginning */ double bandwidth; if (current_time < s->iteration_start_time + BUFFER_DELAY) { return; } current_bytes = migration_total_bytes(s); transferred = current_bytes - s->iteration_initial_bytes; time_spent = current_time - s->iteration_start_time; bandwidth = (double)transferred / time_spent; s->threshold_size = bandwidth * migrate_downtime_limit(); s->mbps = (((double) transferred * 8.0) / ((double) time_spent / 1000.0)) / 1000.0 / 1000.0; transferred_pages = ram_get_total_transferred_pages() - s->iteration_initial_pages; s->pages_per_second = (double) transferred_pages / (((double) time_spent / 1000.0)); /* * if we haven't sent anything, we don't want to * recalculate. 10000 is a small enough number for our purposes */ if (stat64_get(&mig_stats.dirty_pages_rate) && transferred > 10000) { s->expected_downtime = stat64_get(&mig_stats.dirty_bytes_last_sync) / bandwidth; } qemu_file_reset_rate_limit(s->to_dst_file); update_iteration_initial_status(s); trace_migrate_transferred(transferred, time_spent, bandwidth, s->threshold_size); } /* Migration thread iteration status */ typedef enum { MIG_ITERATE_RESUME, /* Resume current iteration */ MIG_ITERATE_SKIP, /* Skip current iteration */ MIG_ITERATE_BREAK, /* Break the loop */ } MigIterateState; /* * Return true if continue to the next iteration directly, false * otherwise. */ static MigIterateState migration_iteration_run(MigrationState *s) { uint64_t must_precopy, can_postcopy; bool in_postcopy = s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE; qemu_savevm_state_pending_estimate(&must_precopy, &can_postcopy); uint64_t pending_size = must_precopy + can_postcopy; trace_migrate_pending_estimate(pending_size, must_precopy, can_postcopy); if (must_precopy <= s->threshold_size) { qemu_savevm_state_pending_exact(&must_precopy, &can_postcopy); pending_size = must_precopy + can_postcopy; trace_migrate_pending_exact(pending_size, must_precopy, can_postcopy); } if (!pending_size || pending_size < s->threshold_size) { trace_migration_thread_low_pending(pending_size); migration_completion(s); return MIG_ITERATE_BREAK; } /* Still a significant amount to transfer */ if (!in_postcopy && must_precopy <= s->threshold_size && qatomic_read(&s->start_postcopy)) { if (postcopy_start(s)) { error_report("%s: postcopy failed to start", __func__); } return MIG_ITERATE_SKIP; } /* Just another iteration step */ qemu_savevm_state_iterate(s->to_dst_file, in_postcopy); return MIG_ITERATE_RESUME; } static void migration_iteration_finish(MigrationState *s) { /* If we enabled cpu throttling for auto-converge, turn it off. */ cpu_throttle_stop(); qemu_mutex_lock_iothread(); switch (s->state) { case MIGRATION_STATUS_COMPLETED: migration_calculate_complete(s); runstate_set(RUN_STATE_POSTMIGRATE); break; case MIGRATION_STATUS_COLO: if (!migrate_colo()) { error_report("%s: critical error: calling COLO code without " "COLO enabled", __func__); } migrate_start_colo_process(s); s->vm_was_running = true; /* Fallthrough */ case MIGRATION_STATUS_FAILED: case MIGRATION_STATUS_CANCELLED: case MIGRATION_STATUS_CANCELLING: if (s->vm_was_running) { if (!runstate_check(RUN_STATE_SHUTDOWN)) { vm_start(); } } else { if (runstate_check(RUN_STATE_FINISH_MIGRATE)) { runstate_set(RUN_STATE_POSTMIGRATE); } } break; default: /* Should not reach here, but if so, forgive the VM. */ error_report("%s: Unknown ending state %d", __func__, s->state); break; } migrate_fd_cleanup_schedule(s); qemu_mutex_unlock_iothread(); } static void bg_migration_iteration_finish(MigrationState *s) { qemu_mutex_lock_iothread(); switch (s->state) { case MIGRATION_STATUS_COMPLETED: migration_calculate_complete(s); break; case MIGRATION_STATUS_ACTIVE: case MIGRATION_STATUS_FAILED: case MIGRATION_STATUS_CANCELLED: case MIGRATION_STATUS_CANCELLING: break; default: /* Should not reach here, but if so, forgive the VM. */ error_report("%s: Unknown ending state %d", __func__, s->state); break; } migrate_fd_cleanup_schedule(s); qemu_mutex_unlock_iothread(); } /* * Return true if continue to the next iteration directly, false * otherwise. */ static MigIterateState bg_migration_iteration_run(MigrationState *s) { int res; res = qemu_savevm_state_iterate(s->to_dst_file, false); if (res > 0) { bg_migration_completion(s); return MIG_ITERATE_BREAK; } return MIG_ITERATE_RESUME; } void migration_make_urgent_request(void) { qemu_sem_post(&migrate_get_current()->rate_limit_sem); } void migration_consume_urgent_request(void) { qemu_sem_wait(&migrate_get_current()->rate_limit_sem); } /* Returns true if the rate limiting was broken by an urgent request */ bool migration_rate_limit(void) { int64_t now = qemu_clock_get_ms(QEMU_CLOCK_REALTIME); MigrationState *s = migrate_get_current(); bool urgent = false; migration_update_counters(s, now); if (qemu_file_rate_limit(s->to_dst_file)) { if (qemu_file_get_error(s->to_dst_file)) { return false; } /* * Wait for a delay to do rate limiting OR * something urgent to post the semaphore. */ int ms = s->iteration_start_time + BUFFER_DELAY - now; trace_migration_rate_limit_pre(ms); if (qemu_sem_timedwait(&s->rate_limit_sem, ms) == 0) { /* * We were woken by one or more urgent things but * the timedwait will have consumed one of them. * The service routine for the urgent wake will dec * the semaphore itself for each item it consumes, * so add this one we just eat back. */ qemu_sem_post(&s->rate_limit_sem); urgent = true; } trace_migration_rate_limit_post(urgent); } return urgent; } /* * if failover devices are present, wait they are completely * unplugged */ static void qemu_savevm_wait_unplug(MigrationState *s, int old_state, int new_state) { if (qemu_savevm_state_guest_unplug_pending()) { migrate_set_state(&s->state, old_state, MIGRATION_STATUS_WAIT_UNPLUG); while (s->state == MIGRATION_STATUS_WAIT_UNPLUG && qemu_savevm_state_guest_unplug_pending()) { qemu_sem_timedwait(&s->wait_unplug_sem, 250); } if (s->state != MIGRATION_STATUS_WAIT_UNPLUG) { int timeout = 120; /* 30 seconds */ /* * migration has been canceled * but as we have started an unplug we must wait the end * to be able to plug back the card */ while (timeout-- && qemu_savevm_state_guest_unplug_pending()) { qemu_sem_timedwait(&s->wait_unplug_sem, 250); } if (qemu_savevm_state_guest_unplug_pending() && !qtest_enabled()) { warn_report("migration: partially unplugged device on " "failure"); } } migrate_set_state(&s->state, MIGRATION_STATUS_WAIT_UNPLUG, new_state); } else { migrate_set_state(&s->state, old_state, new_state); } } /* * Master migration thread on the source VM. * It drives the migration and pumps the data down the outgoing channel. */ static void *migration_thread(void *opaque) { MigrationState *s = opaque; MigrationThread *thread = NULL; int64_t setup_start = qemu_clock_get_ms(QEMU_CLOCK_HOST); MigThrError thr_error; bool urgent = false; thread = MigrationThreadAdd("live_migration", qemu_get_thread_id()); rcu_register_thread(); object_ref(OBJECT(s)); update_iteration_initial_status(s); qemu_savevm_state_header(s->to_dst_file); /* * If we opened the return path, we need to make sure dst has it * opened as well. */ if (s->rp_state.rp_thread_created) { /* Now tell the dest that it should open its end so it can reply */ qemu_savevm_send_open_return_path(s->to_dst_file); /* And do a ping that will make stuff easier to debug */ qemu_savevm_send_ping(s->to_dst_file, 1); } if (migrate_postcopy()) { /* * Tell the destination that we *might* want to do postcopy later; * if the other end can't do postcopy it should fail now, nice and * early. */ qemu_savevm_send_postcopy_advise(s->to_dst_file); } if (migrate_colo()) { /* Notify migration destination that we enable COLO */ qemu_savevm_send_colo_enable(s->to_dst_file); } qemu_savevm_state_setup(s->to_dst_file); qemu_savevm_wait_unplug(s, MIGRATION_STATUS_SETUP, MIGRATION_STATUS_ACTIVE); s->setup_time = qemu_clock_get_ms(QEMU_CLOCK_HOST) - setup_start; trace_migration_thread_setup_complete(); while (migration_is_active(s)) { if (urgent || !qemu_file_rate_limit(s->to_dst_file)) { MigIterateState iter_state = migration_iteration_run(s); if (iter_state == MIG_ITERATE_SKIP) { continue; } else if (iter_state == MIG_ITERATE_BREAK) { break; } } /* * Try to detect any kind of failures, and see whether we * should stop the migration now. */ thr_error = migration_detect_error(s); if (thr_error == MIG_THR_ERR_FATAL) { /* Stop migration */ break; } else if (thr_error == MIG_THR_ERR_RECOVERED) { /* * Just recovered from a e.g. network failure, reset all * the local variables. This is important to avoid * breaking transferred_bytes and bandwidth calculation */ update_iteration_initial_status(s); } urgent = migration_rate_limit(); } trace_migration_thread_after_loop(); migration_iteration_finish(s); object_unref(OBJECT(s)); rcu_unregister_thread(); MigrationThreadDel(thread); return NULL; } static void bg_migration_vm_start_bh(void *opaque) { MigrationState *s = opaque; qemu_bh_delete(s->vm_start_bh); s->vm_start_bh = NULL; vm_start(); s->downtime = qemu_clock_get_ms(QEMU_CLOCK_REALTIME) - s->downtime_start; } /** * Background snapshot thread, based on live migration code. * This is an alternative implementation of live migration mechanism * introduced specifically to support background snapshots. * * It takes advantage of userfault_fd write protection mechanism introduced * in v5.7 kernel. Compared to existing dirty page logging migration much * lesser stream traffic is produced resulting in smaller snapshot images, * simply cause of no page duplicates can get into the stream. * * Another key point is that generated vmstate stream reflects machine state * 'frozen' at the beginning of snapshot creation compared to dirty page logging * mechanism, which effectively results in that saved snapshot is the state of VM * at the end of the process. */ static void *bg_migration_thread(void *opaque) { MigrationState *s = opaque; int64_t setup_start; MigThrError thr_error; QEMUFile *fb; bool early_fail = true; rcu_register_thread(); object_ref(OBJECT(s)); qemu_file_set_rate_limit(s->to_dst_file, INT64_MAX); setup_start = qemu_clock_get_ms(QEMU_CLOCK_HOST); /* * We want to save vmstate for the moment when migration has been * initiated but also we want to save RAM content while VM is running. * The RAM content should appear first in the vmstate. So, we first * stash the non-RAM part of the vmstate to the temporary buffer, * then write RAM part of the vmstate to the migration stream * with vCPUs running and, finally, write stashed non-RAM part of * the vmstate from the buffer to the migration stream. */ s->bioc = qio_channel_buffer_new(512 * 1024); qio_channel_set_name(QIO_CHANNEL(s->bioc), "vmstate-buffer"); fb = qemu_file_new_output(QIO_CHANNEL(s->bioc)); object_unref(OBJECT(s->bioc)); update_iteration_initial_status(s); /* * Prepare for tracking memory writes with UFFD-WP - populate * RAM pages before protecting. */ #ifdef __linux__ ram_write_tracking_prepare(); #endif qemu_savevm_state_header(s->to_dst_file); qemu_savevm_state_setup(s->to_dst_file); qemu_savevm_wait_unplug(s, MIGRATION_STATUS_SETUP, MIGRATION_STATUS_ACTIVE); s->setup_time = qemu_clock_get_ms(QEMU_CLOCK_HOST) - setup_start; trace_migration_thread_setup_complete(); s->downtime_start = qemu_clock_get_ms(QEMU_CLOCK_REALTIME); qemu_mutex_lock_iothread(); /* * If VM is currently in suspended state, then, to make a valid runstate * transition in vm_stop_force_state() we need to wakeup it up. */ qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER, NULL); s->vm_was_running = runstate_is_running(); if (global_state_store()) { goto fail; } /* Forcibly stop VM before saving state of vCPUs and devices */ if (vm_stop_force_state(RUN_STATE_PAUSED)) { goto fail; } /* * Put vCPUs in sync with shadow context structures, then * save their state to channel-buffer along with devices. */ cpu_synchronize_all_states(); if (qemu_savevm_state_complete_precopy_non_iterable(fb, false, false)) { goto fail; } /* * Since we are going to get non-iterable state data directly * from s->bioc->data, explicit flush is needed here. */ qemu_fflush(fb); /* Now initialize UFFD context and start tracking RAM writes */ if (ram_write_tracking_start()) { goto fail; } early_fail = false; /* * Start VM from BH handler to avoid write-fault lock here. * UFFD-WP protection for the whole RAM is already enabled so * calling VM state change notifiers from vm_start() would initiate * writes to virtio VQs memory which is in write-protected region. */ s->vm_start_bh = qemu_bh_new(bg_migration_vm_start_bh, s); qemu_bh_schedule(s->vm_start_bh); qemu_mutex_unlock_iothread(); while (migration_is_active(s)) { MigIterateState iter_state = bg_migration_iteration_run(s); if (iter_state == MIG_ITERATE_SKIP) { continue; } else if (iter_state == MIG_ITERATE_BREAK) { break; } /* * Try to detect any kind of failures, and see whether we * should stop the migration now. */ thr_error = migration_detect_error(s); if (thr_error == MIG_THR_ERR_FATAL) { /* Stop migration */ break; } migration_update_counters(s, qemu_clock_get_ms(QEMU_CLOCK_REALTIME)); } trace_migration_thread_after_loop(); fail: if (early_fail) { migrate_set_state(&s->state, MIGRATION_STATUS_ACTIVE, MIGRATION_STATUS_FAILED); qemu_mutex_unlock_iothread(); } bg_migration_iteration_finish(s); qemu_fclose(fb); object_unref(OBJECT(s)); rcu_unregister_thread(); return NULL; } void migrate_fd_connect(MigrationState *s, Error *error_in) { Error *local_err = NULL; int64_t rate_limit; bool resume = s->state == MIGRATION_STATUS_POSTCOPY_PAUSED; /* * If there's a previous error, free it and prepare for another one. * Meanwhile if migration completes successfully, there won't have an error * dumped when calling migrate_fd_cleanup(). */ migrate_error_free(s); s->expected_downtime = migrate_downtime_limit(); if (resume) { assert(s->cleanup_bh); } else { assert(!s->cleanup_bh); s->cleanup_bh = qemu_bh_new(migrate_fd_cleanup_bh, s); } if (error_in) { migrate_fd_error(s, error_in); if (resume) { /* * Don't do cleanup for resume if channel is invalid, but only dump * the error. We wait for another channel connect from the user. * The error_report still gives HMP user a hint on what failed. * It's normally done in migrate_fd_cleanup(), but call it here * explicitly. */ error_report_err(error_copy(s->error)); } else { migrate_fd_cleanup(s); } return; } if (resume) { /* This is a resumed migration */ rate_limit = migrate_max_postcopy_bandwidth() / XFER_LIMIT_RATIO; } else { /* This is a fresh new migration */ rate_limit = migrate_max_bandwidth() / XFER_LIMIT_RATIO; /* Notify before starting migration thread */ notifier_list_notify(&migration_state_notifiers, s); } qemu_file_set_rate_limit(s->to_dst_file, rate_limit); qemu_file_set_blocking(s->to_dst_file, true); /* * Open the return path. For postcopy, it is used exclusively. For * precopy, only if user specified "return-path" capability would * QEMU uses the return path. */ if (migrate_postcopy_ram() || migrate_return_path()) { if (open_return_path_on_source(s, !resume)) { error_report("Unable to open return-path for postcopy"); migrate_set_state(&s->state, s->state, MIGRATION_STATUS_FAILED); migrate_fd_cleanup(s); return; } } /* * This needs to be done before resuming a postcopy. Note: for newer * QEMUs we will delay the channel creation until postcopy_start(), to * avoid disorder of channel creations. */ if (migrate_postcopy_preempt() && s->preempt_pre_7_2) { postcopy_preempt_setup(s); } if (resume) { /* Wakeup the main migration thread to do the recovery */ migrate_set_state(&s->state, MIGRATION_STATUS_POSTCOPY_PAUSED, MIGRATION_STATUS_POSTCOPY_RECOVER); qemu_sem_post(&s->postcopy_pause_sem); return; } if (multifd_save_setup(&local_err) != 0) { error_report_err(local_err); migrate_set_state(&s->state, MIGRATION_STATUS_SETUP, MIGRATION_STATUS_FAILED); migrate_fd_cleanup(s); return; } if (migrate_background_snapshot()) { qemu_thread_create(&s->thread, "bg_snapshot", bg_migration_thread, s, QEMU_THREAD_JOINABLE); } else { qemu_thread_create(&s->thread, "live_migration", migration_thread, s, QEMU_THREAD_JOINABLE); } s->migration_thread_running = true; } static void migration_class_init(ObjectClass *klass, void *data) { DeviceClass *dc = DEVICE_CLASS(klass); dc->user_creatable = false; device_class_set_props(dc, migration_properties); } static void migration_instance_finalize(Object *obj) { MigrationState *ms = MIGRATION_OBJ(obj); qemu_mutex_destroy(&ms->error_mutex); qemu_mutex_destroy(&ms->qemu_file_lock); qemu_sem_destroy(&ms->wait_unplug_sem); qemu_sem_destroy(&ms->rate_limit_sem); qemu_sem_destroy(&ms->pause_sem); qemu_sem_destroy(&ms->postcopy_pause_sem); qemu_sem_destroy(&ms->postcopy_pause_rp_sem); qemu_sem_destroy(&ms->rp_state.rp_sem); qemu_sem_destroy(&ms->rp_state.rp_pong_acks); qemu_sem_destroy(&ms->postcopy_qemufile_src_sem); error_free(ms->error); } static void migration_instance_init(Object *obj) { MigrationState *ms = MIGRATION_OBJ(obj); ms->state = MIGRATION_STATUS_NONE; ms->mbps = -1; ms->pages_per_second = -1; qemu_sem_init(&ms->pause_sem, 0); qemu_mutex_init(&ms->error_mutex); migrate_params_init(&ms->parameters); qemu_sem_init(&ms->postcopy_pause_sem, 0); qemu_sem_init(&ms->postcopy_pause_rp_sem, 0); qemu_sem_init(&ms->rp_state.rp_sem, 0); qemu_sem_init(&ms->rp_state.rp_pong_acks, 0); qemu_sem_init(&ms->rate_limit_sem, 0); qemu_sem_init(&ms->wait_unplug_sem, 0); qemu_sem_init(&ms->postcopy_qemufile_src_sem, 0); qemu_mutex_init(&ms->qemu_file_lock); } /* * Return true if check pass, false otherwise. Error will be put * inside errp if provided. */ static bool migration_object_check(MigrationState *ms, Error **errp) { /* Assuming all off */ bool old_caps[MIGRATION_CAPABILITY__MAX] = { 0 }; if (!migrate_params_check(&ms->parameters, errp)) { return false; } return migrate_caps_check(old_caps, ms->capabilities, errp); } static const TypeInfo migration_type = { .name = TYPE_MIGRATION, /* * NOTE: TYPE_MIGRATION is not really a device, as the object is * not created using qdev_new(), it is not attached to the qdev * device tree, and it is never realized. * * TODO: Make this TYPE_OBJECT once QOM provides something like * TYPE_DEVICE's "-global" properties. */ .parent = TYPE_DEVICE, .class_init = migration_class_init, .class_size = sizeof(MigrationClass), .instance_size = sizeof(MigrationState), .instance_init = migration_instance_init, .instance_finalize = migration_instance_finalize, }; static void register_migration_types(void) { type_register_static(&migration_type); } type_init(register_migration_types);