text: /*
   * 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/osdep.h"
  #include "qemu/cutils.h"
  #include "qemu/error-report.h"
  #include "migration/blocker.h"
  #include "exec.h"
  #include "fd.h"
  #include "socket.h"
  #include "rdma.h"
  #include "ram.h"
  #include "migration/global_state.h"
  #include "migration/misc.h"
  #include "migration.h"
  #include "savevm.h"
  #include "qemu-file-channel.h"
  #include "qemu-file.h"
  #include "migration/vmstate.h"
  #include "block/block.h"
  #include "qapi/error.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 "migration/colo.h"
  #include "hw/boards.h"
  #include "monitor/monitor.h"
  
  #define MAX_THROTTLE  (32 << 20)      /* Migration transfer 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)
  
  /* Time in milliseconds we are allowed to stop the source,
   * for sending the last part */
  #define DEFAULT_MIGRATE_SET_DOWNTIME 300
  
  /* Maximum migrate downtime set to 2000 seconds */
  #define MAX_MIGRATE_DOWNTIME_SECONDS 2000
  #define MAX_MIGRATE_DOWNTIME (MAX_MIGRATE_DOWNTIME_SECONDS * 1000)
  
  /* Default compression thread count */
  #define DEFAULT_MIGRATE_COMPRESS_THREAD_COUNT 8
  /* Default decompression thread count, usually decompression is at
   * least 4 times as fast as compression.*/
  #define DEFAULT_MIGRATE_DECOMPRESS_THREAD_COUNT 2
  /*0: means nocompress, 1: best speed, ... 9: best compress ratio */
  #define DEFAULT_MIGRATE_COMPRESS_LEVEL 1
  /* Define default autoconverge cpu throttle migration parameters */
  #define DEFAULT_MIGRATE_CPU_THROTTLE_INITIAL 20
  #define DEFAULT_MIGRATE_CPU_THROTTLE_INCREMENT 10
  
  /* Migration XBZRLE default cache size */
  #define DEFAULT_MIGRATE_XBZRLE_CACHE_SIZE (64 * 1024 * 1024)
  
  /* The delay time (in ms) between two COLO checkpoints
   * Note: Please change this default value to 10000 when we support hybrid mode.
   */
  #define DEFAULT_MIGRATE_X_CHECKPOINT_DELAY 200
  #define DEFAULT_MIGRATE_MULTIFD_CHANNELS 2
  #define DEFAULT_MIGRATE_MULTIFD_PAGE_COUNT 16
  
  /* Background transfer rate for postcopy, 0 means unlimited, note
   * that page requests can still exceed this limit.
   */
  #define DEFAULT_MIGRATE_MAX_POSTCOPY_BANDWIDTH 0
  
  static NotifierList migration_state_notifiers =
      NOTIFIER_LIST_INITIALIZER(migration_state_notifiers);
  
  static bool deferred_incoming;
  
  /* 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 bool migration_object_check(MigrationState *ms, Error **errp);
  static int migration_maybe_pause(MigrationState *s,
                                   int *current_active_state,
                                   int new_state);
  
  void migration_object_init(void)
  {
      MachineState *ms = MACHINE(qdev_get_machine());
      Error *err = NULL;
  
      /* 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(&current_incoming->rp_mutex);
      qemu_event_init(&current_incoming->main_thread_load_event, false);
      qemu_sem_init(&current_incoming->postcopy_pause_sem_dst, 0);
      qemu_sem_init(&current_incoming->postcopy_pause_sem_fault, 0);
  
      init_dirty_bitmap_incoming_migration();
  
      if (!migration_object_check(current_migration, &err)) {
          error_report_err(err);
          exit(1);
      }
  
      /*
       * We cannot really do this in migration_instance_init() since at
       * that time global properties are not yet applied, then this
       * value will be definitely replaced by something else.
       */
      if (ms->enforce_config_section) {
          current_migration->send_configuration = true;
      }
  }
  
  void migration_object_finalize(void)
  {
      object_unref(OBJECT(current_migration));
  }
  
  /* 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_state_destroy(void)
  {
      struct MigrationIncomingState *mis = migration_incoming_get_current();
  
      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) {
          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;
      }
  
      qemu_event_reset(&mis->main_thread_load_event);
  }
  
  static void migrate_generate_event(int new_state)
  {
      if (migrate_use_events()) {
          qapi_event_send_migration(new_state, &error_abort);
      }
  }
  
  static bool migrate_late_block_activate(void)
  {
      MigrationState *s;
  
      s = migrate_get_current();
  
      return s->enabled_capabilities[
          MIGRATION_CAPABILITY_LATE_BLOCK_ACTIVATE];
  }
  
  /*
   * Called on -incoming with a defer: uri.
   * The migration can be started later after any parameters have been
   * changed.
   */
  static void deferred_incoming_migration(Error **errp)
  {
      if (deferred_incoming) {
          error_setg(errp, "Incoming migration already deferred");
      }
      deferred_incoming = true;
  }
  
  /*
   * 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_mutex_lock(&mis->rp_mutex);
  
      /*
       * It's possible that the file handle got lost due to network
       * failures.
       */
      if (!mis->to_src_file) {
          ret = -EIO;
          goto error;
      }
  
      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);
  
  error:
      qemu_mutex_unlock(&mis->rp_mutex);
      return ret;
  }
  
  /* Request a range of pages from the source VM at the given
   * start address.
   *   rbname: Name of the RAMBlock to request the page in, if NULL it's the same
   *           as the last request (a name must have been given previously)
   *   Start: Address offset within the RB
   *   Len: Length in bytes required - must be a multiple of pagesize
   */
  int migrate_send_rp_req_pages(MigrationIncomingState *mis, const char *rbname,
                                ram_addr_t start, size_t len)
  {
      uint8_t bufc[12 + 1 + 255]; /* start (8), len (4), rbname up to 256 */
      size_t msglen = 12; /* start + len */
      enum mig_rp_message_type msg_type;
  
      *(uint64_t *)bufc = cpu_to_be64((uint64_t)start);
      *(uint32_t *)(bufc + 8) = cpu_to_be32((uint32_t)len);
  
      if (rbname) {
          int 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);
  }
  
  void qemu_start_incoming_migration(const char *uri, Error **errp)
  {
      const char *p;
  
      qapi_event_send_migration(MIGRATION_STATUS_SETUP, &error_abort);
      if (!strcmp(uri, "defer")) {
          deferred_incoming_migration(errp);
      } else if (strstart(uri, "tcp:", &p)) {
          tcp_start_incoming_migration(p, 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, "unix:", &p)) {
          unix_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 flush their mutable metadata.
           * If we get an error here, just don't restart the VM yet. */
          bdrv_invalidate_cache_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();
  
      if (multifd_load_cleanup(&local_err) != 0) {
          error_report_err(local_err);
          autostart = false;
      }
      /* If global state section was not received or we are in running
         state, we need to obey autostart. Any other state is set with
         runstate_set. */
  
      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 {
          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 process_incoming_migration_co(void *opaque)
  {
      MigrationIncomingState *mis = migration_incoming_get_current();
      PostcopyState ps;
      int ret;
  
      assert(mis->from_src_file);
      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_enable_colo()) {
          mis->migration_incoming_co = qemu_coroutine_self();
          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();
  
          /* Wait checkpoint incoming thread exit before free resource */
          qemu_thread_join(&mis->colo_incoming_thread);
      }
  
      if (ret < 0) {
          Error *local_err = NULL;
  
          migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE,
                            MIGRATION_STATUS_FAILED);
          error_report("load of migration failed: %s", strerror(-ret));
          qemu_fclose(mis->from_src_file);
          if (multifd_load_cleanup(&local_err) != 0) {
              error_report_err(local_err);
          }
          exit(EXIT_FAILURE);
      }
      mis->bh = qemu_bh_new(process_incoming_migration_bh, mis);
      qemu_bh_schedule(mis->bh);
  }
  
  static void migration_incoming_setup(QEMUFile *f)
  {
      MigrationIncomingState *mis = migration_incoming_get_current();
  
      if (multifd_load_setup() != 0) {
          /* We haven't been able to create multifd threads
             nothing better to do */
          exit(EXIT_FAILURE);
      }
  
      if (!mis->from_src_file) {
          mis->from_src_file = f;
      }
      qemu_file_set_blocking(f, false);
  }
  
  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(QEMUFile *f)
  {
      MigrationIncomingState *mis = migration_incoming_get_current();
  
      if (mis->state == MIGRATION_STATUS_POSTCOPY_PAUSED) {
          /* Resumed from a paused postcopy migration */
  
          mis->from_src_file = f;
          /* Postcopy has standalone thread to do vm load */
          qemu_file_set_blocking(f, true);
  
          /* Re-configure the return path */
          mis->to_src_file = qemu_file_get_return_path(f);
  
          migrate_set_state(&mis->state, MIGRATION_STATUS_POSTCOPY_PAUSED,
                            MIGRATION_STATUS_POSTCOPY_RECOVER);
  
          /*
           * Here, we only wake up the main loading thread (while the
           * fault thread will still be waiting), so that we can receive
           * commands from source now, and answer it if needed. The
           * fault thread 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)
  {
      if (postcopy_try_recover(f)) {
          return;
      }
  
      migration_incoming_setup(f);
      migration_incoming_process();
  }
  
  void migration_ioc_process_incoming(QIOChannel *ioc)
  {
      MigrationIncomingState *mis = migration_incoming_get_current();
      bool start_migration;
  
      if (!mis->from_src_file) {
          /* The first connection (multifd may have multiple) */
          QEMUFile *f = qemu_fopen_channel_input(ioc);
  
          /* If it's a recovery, we're done */
          if (postcopy_try_recover(f)) {
              return;
          }
  
          migration_incoming_setup(f);
  
          /*
           * Common migration only needs one channel, so we can start
           * right now.  Multifd needs more than one channel, we wait.
           */
          start_migration = !migrate_use_multifd();
      } else {
          /* Multiple connections */
          assert(migrate_use_multifd());
          start_migration = multifd_recv_new_channel(ioc);
      }
  
      if (start_migration) {
          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();
      bool all_channels;
  
      all_channels = multifd_recv_all_channels_created();
  
      return all_channels && mis->from_src_file != NULL;
  }
  
  /*
   * 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);
  }
  
  MigrationCapabilityStatusList *qmp_query_migrate_capabilities(Error **errp)
  {
      MigrationCapabilityStatusList *head = NULL;
      MigrationCapabilityStatusList *caps;
      MigrationState *s = migrate_get_current();
      int i;
  
      caps = NULL; /* silence compiler warning */
      for (i = 0; i < MIGRATION_CAPABILITY__MAX; i++) {
  #ifndef CONFIG_LIVE_BLOCK_MIGRATION
          if (i == MIGRATION_CAPABILITY_BLOCK) {
              continue;
          }
  #endif
          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;
  }
  
  MigrationParameters *qmp_query_migrate_parameters(Error **errp)
  {
      MigrationParameters *params;
      MigrationState *s = migrate_get_current();
  
      /* TODO use QAPI_CLONE() instead of duplicating it inline */
      params = g_malloc0(sizeof(*params));
      params->has_compress_level = true;
      params->compress_level = s->parameters.compress_level;
      params->has_compress_threads = true;
      params->compress_threads = s->parameters.compress_threads;
      params->has_decompress_threads = true;
      params->decompress_threads = s->parameters.decompress_threads;
      params->has_cpu_throttle_initial = true;
      params->cpu_throttle_initial = s->parameters.cpu_throttle_initial;
      params->has_cpu_throttle_increment = true;
      params->cpu_throttle_increment = s->parameters.cpu_throttle_increment;
      params->has_tls_creds = true;
      params->tls_creds = g_strdup(s->parameters.tls_creds);
      params->has_tls_hostname = true;
      params->tls_hostname = g_strdup(s->parameters.tls_hostname);
      params->has_max_bandwidth = true;
      params->max_bandwidth = s->parameters.max_bandwidth;
      params->has_downtime_limit = true;
      params->downtime_limit = s->parameters.downtime_limit;
      params->has_x_checkpoint_delay = true;
      params->x_checkpoint_delay = s->parameters.x_checkpoint_delay;
      params->has_block_incremental = true;
      params->block_incremental = s->parameters.block_incremental;
      params->has_x_multifd_channels = true;
      params->x_multifd_channels = s->parameters.x_multifd_channels;
      params->has_x_multifd_page_count = true;
      params->x_multifd_page_count = s->parameters.x_multifd_page_count;
      params->has_xbzrle_cache_size = true;
      params->xbzrle_cache_size = s->parameters.xbzrle_cache_size;
      params->has_max_postcopy_bandwidth = true;
      params->max_postcopy_bandwidth = s->parameters.max_postcopy_bandwidth;
  
      return params;
  }
  
  /*
   * Return true if we're already in the middle of a migration
   * (i.e. any of the active or setup states)
   */
  static 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:
          return true;
  
      default:
          return false;
  
      }
  }
  
  static void populate_ram_info(MigrationInfo *info, MigrationState *s)
  {
      info->has_ram = true;
      info->ram = g_malloc0(sizeof(*info->ram));
      info->ram->transferred = ram_counters.transferred;
      info->ram->total = ram_bytes_total();
      info->ram->duplicate = ram_counters.duplicate;
      /* legacy value.  It is not used anymore */
      info->ram->skipped = 0;
      info->ram->normal = ram_counters.normal;
      info->ram->normal_bytes = ram_counters.normal *
          qemu_target_page_size();
      info->ram->mbps = s->mbps;
      info->ram->dirty_sync_count = ram_counters.dirty_sync_count;
      info->ram->postcopy_requests = ram_counters.postcopy_requests;
      info->ram->page_size = qemu_target_page_size();
      info->ram->multifd_bytes = ram_counters.multifd_bytes;
  
      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_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->overflow = xbzrle_counters.overflow;
      }
  
      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 = ram_counters.dirty_pages_rate;
      }
  }
  
  static void populate_disk_info(MigrationInfo *info)
  {
      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();
      }
  }
  
  static void fill_source_migration_info(MigrationInfo *info)
  {
      MigrationState *s = migrate_get_current();
  
      switch (s->state) {
      case MIGRATION_STATUS_NONE:
          /* no migration has happened ever */
          /* do not overwrite destination migration status */
          return;
          break;
      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 */
          info->has_status = true;
          info->has_total_time = true;
          info->total_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME)
              - s->start_time;
          info->has_expected_downtime = true;
          info->expected_downtime = s->expected_downtime;
          info->has_setup_time = true;
          info->setup_time = s->setup_time;
  
          populate_ram_info(info, s);
          populate_disk_info(info);
          break;
      case MIGRATION_STATUS_COLO:
          info->has_status = true;
          /* TODO: display COLO specific information (checkpoint info etc.) */
          break;
      case MIGRATION_STATUS_COMPLETED:
          info->has_status = true;
          info->has_total_time = true;
          info->total_time = s->total_time;
          info->has_downtime = true;
          info->downtime = s->downtime;
          info->has_setup_time = true;
          info->setup_time = s->setup_time;
  
          populate_ram_info(info, s);
          break;
      case MIGRATION_STATUS_FAILED:
          info->has_status = true;
          if (s->error) {
              info->has_error_desc = true;
              info->error_desc = g_strdup(error_get_pretty(s->error));
          }
          break;
      case MIGRATION_STATUS_CANCELLED:
          info->has_status = true;
          break;
      }
      info->status = s->state;
  }
  
  /**
   * @migration_caps_check - check capability validity
   *
   * @cap_list: old capability list, array of bool
   * @params: new capabilities to be applied soon
   * @errp: set *errp if the check failed, with reason
   *
   * Returns true if check passed, otherwise false.
   */
  static bool migrate_caps_check(bool *cap_list,
                                 MigrationCapabilityStatusList *params,
                                 Error **errp)
  {
      MigrationCapabilityStatusList *cap;
      bool old_postcopy_cap;
      MigrationIncomingState *mis = migration_incoming_get_current();
  
      old_postcopy_cap = cap_list[MIGRATION_CAPABILITY_POSTCOPY_RAM];
  
      for (cap = params; cap; cap = cap->next) {
          cap_list[cap->value->capability] = cap->value->state;
      }
  
  #ifndef CONFIG_LIVE_BLOCK_MIGRATION
      if (cap_list[MIGRATION_CAPABILITY_BLOCK]) {
          error_setg(errp, "QEMU compiled without old-style (blk/-b, inc/-i) "
                     "block migration");
          error_append_hint(errp, "Use drive_mirror+NBD instead.\n");
          return false;
      }
  #endif
  
      if (cap_list[MIGRATION_CAPABILITY_POSTCOPY_RAM]) {
          if (cap_list[MIGRATION_CAPABILITY_COMPRESS]) {
              /* The decompression threads asynchronously write into RAM
               * rather than use the atomic copies needed to avoid
               * userfaulting.  It should be possible to fix the decompression
               * threads for compatibility in future.
               */
              error_setg(errp, "Postcopy is not currently compatible "
                         "with compression");
              return false;
          }
  
          /* This check is reasonably expensive, so only when it's being
           * set the first time, also it's only the destination that needs
           * special support.
           */
          if (!old_postcopy_cap && runstate_check(RUN_STATE_INMIGRATE) &&
              !postcopy_ram_supported_by_host(mis)) {
              /* postcopy_ram_supported_by_host will have emitted a more
               * detailed message
               */
              error_setg(errp, "Postcopy is not supported");
              return false;
          }
      }
  
      return true;
  }
  
  static void fill_destination_migration_info(MigrationInfo *info)
  {
      MigrationIncomingState *mis = migration_incoming_get_current();
  
      switch (mis->state) {
      case MIGRATION_STATUS_NONE:
          return;
          break;
      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_set_capabilities(MigrationCapabilityStatusList *params,
                                    Error **errp)
  {
      MigrationState *s = migrate_get_current();
      MigrationCapabilityStatusList *cap;
      bool cap_list[MIGRATION_CAPABILITY__MAX];
  
      if (migration_is_setup_or_active(s->state)) {
          error_setg(errp, QERR_MIGRATION_ACTIVE);
          return;
      }
  
      memcpy(cap_list, s->enabled_capabilities, sizeof(cap_list));
      if (!migrate_caps_check(cap_list, params, errp)) {
          return;
      }
  
      for (cap = params; cap; cap = cap->next) {
          s->enabled_capabilities[cap->value->capability] = cap->value->state;
      }
  }
  
  /*
   * Check whether the parameters are valid. Error will be put into errp
   * (if provided). Return true if valid, otherwise false.
   */
  static bool migrate_params_check(MigrationParameters *params, Error **errp)
  {
      if (params->has_compress_level &&
          (params->compress_level > 9)) {
          error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "compress_level",
                     "is invalid, it should be in the range of 0 to 9");
          return false;
      }
  
      if (params->has_compress_threads && (params->compress_threads < 1)) {
          error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
                     "compress_threads",
                     "is invalid, it should be in the range of 1 to 255");
          return false;
      }
  
      if (params->has_decompress_threads && (params->decompress_threads < 1)) {
          error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
                     "decompress_threads",
                     "is invalid, it should be in the range of 1 to 255");
          return false;
      }
  
      if (params->has_cpu_throttle_initial &&
          (params->cpu_throttle_initial < 1 ||
           params->cpu_throttle_initial > 99)) {
          error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
                     "cpu_throttle_initial",
                     "an integer in the range of 1 to 99");
          return false;
      }
  
      if (params->has_cpu_throttle_increment &&
          (params->cpu_throttle_increment < 1 ||
           params->cpu_throttle_increment > 99)) {
          error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
                     "cpu_throttle_increment",
                     "an integer in the range of 1 to 99");
          return false;
      }
  
      if (params->has_max_bandwidth && (params->max_bandwidth > SIZE_MAX)) {
          error_setg(errp, "Parameter 'max_bandwidth' expects an integer in the"
                           " range of 0 to %zu bytes/second", SIZE_MAX);
          return false;
      }
  
      if (params->has_downtime_limit &&
          (params->downtime_limit > MAX_MIGRATE_DOWNTIME)) {
          error_setg(errp, "Parameter 'downtime_limit' expects an integer in "
                           "the range of 0 to %d milliseconds",
                           MAX_MIGRATE_DOWNTIME);
          return false;
      }
  
      /* x_checkpoint_delay is now always positive */
  
      if (params->has_x_multifd_channels && (params->x_multifd_channels < 1)) {
          error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
                     "multifd_channels",
                     "is invalid, it should be in the range of 1 to 255");
          return false;
      }
      if (params->has_x_multifd_page_count &&
          (params->x_multifd_page_count < 1 ||
           params->x_multifd_page_count > 10000)) {
          error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
                     "multifd_page_count",
                     "is invalid, it should be in the range of 1 to 10000");
          return false;
      }
  
      if (params->has_xbzrle_cache_size &&
          (params->xbzrle_cache_size < qemu_target_page_size() ||
           !is_power_of_2(params->xbzrle_cache_size))) {
          error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
                     "xbzrle_cache_size",
                     "is invalid, it should be bigger than target page size"
                     " and a power of two");
          return false;
      }
  
      return true;
  }
  
  static void migrate_params_test_apply(MigrateSetParameters *params,
                                        MigrationParameters *dest)
  {
      *dest = migrate_get_current()->parameters;
  
      /* TODO use QAPI_CLONE() instead of duplicating it inline */
  
      if (params->has_compress_level) {
          dest->compress_level = params->compress_level;
      }
  
      if (params->has_compress_threads) {
          dest->compress_threads = params->compress_threads;
      }
  
      if (params->has_decompress_threads) {
          dest->decompress_threads = params->decompress_threads;
      }
  
      if (params->has_cpu_throttle_initial) {
          dest->cpu_throttle_initial = params->cpu_throttle_initial;
      }
  
      if (params->has_cpu_throttle_increment) {
          dest->cpu_throttle_increment = params->cpu_throttle_increment;
      }
  
      if (params->has_tls_creds) {
          assert(params->tls_creds->type == QTYPE_QSTRING);
          dest->tls_creds = g_strdup(params->tls_creds->u.s);
      }
  
      if (params->has_tls_hostname) {
          assert(params->tls_hostname->type == QTYPE_QSTRING);
          dest->tls_hostname = g_strdup(params->tls_hostname->u.s);
      }
  
      if (params->has_max_bandwidth) {
          dest->max_bandwidth = params->max_bandwidth;
      }
  
      if (params->has_downtime_limit) {
          dest->downtime_limit = params->downtime_limit;
      }
  
      if (params->has_x_checkpoint_delay) {
          dest->x_checkpoint_delay = params->x_checkpoint_delay;
      }
  
      if (params->has_block_incremental) {
          dest->block_incremental = params->block_incremental;
      }
      if (params->has_x_multifd_channels) {
          dest->x_multifd_channels = params->x_multifd_channels;
      }
      if (params->has_x_multifd_page_count) {
          dest->x_multifd_page_count = params->x_multifd_page_count;
      }
      if (params->has_xbzrle_cache_size) {
          dest->xbzrle_cache_size = params->xbzrle_cache_size;
      }
      if (params->has_max_postcopy_bandwidth) {
          dest->max_postcopy_bandwidth = params->max_postcopy_bandwidth;
      }
  }
  
  static void migrate_params_apply(MigrateSetParameters *params, Error **errp)
  {
      MigrationState *s = migrate_get_current();
  
      /* TODO use QAPI_CLONE() instead of duplicating it inline */
  
      if (params->has_compress_level) {
          s->parameters.compress_level = params->compress_level;
      }
  
      if (params->has_compress_threads) {
          s->parameters.compress_threads = params->compress_threads;
      }
  
      if (params->has_decompress_threads) {
          s->parameters.decompress_threads = params->decompress_threads;
      }
  
      if (params->has_cpu_throttle_initial) {
          s->parameters.cpu_throttle_initial = params->cpu_throttle_initial;
      }
  
      if (params->has_cpu_throttle_increment) {
          s->parameters.cpu_throttle_increment = params->cpu_throttle_increment;
      }
  
      if (params->has_tls_creds) {
          g_free(s->parameters.tls_creds);
          assert(params->tls_creds->type == QTYPE_QSTRING);
          s->parameters.tls_creds = g_strdup(params->tls_creds->u.s);
      }
  
      if (params->has_tls_hostname) {
          g_free(s->parameters.tls_hostname);
          assert(params->tls_hostname->type == QTYPE_QSTRING);
          s->parameters.tls_hostname = g_strdup(params->tls_hostname->u.s);
      }
  
      if (params->has_max_bandwidth) {
          s->parameters.max_bandwidth = params->max_bandwidth;
          if (s->to_dst_file) {
              qemu_file_set_rate_limit(s->to_dst_file,
                                  s->parameters.max_bandwidth / XFER_LIMIT_RATIO);
          }
      }
  
      if (params->has_downtime_limit) {
          s->parameters.downtime_limit = params->downtime_limit;
      }
  
      if (params->has_x_checkpoint_delay) {
          s->parameters.x_checkpoint_delay = params->x_checkpoint_delay;
          if (migration_in_colo_state()) {
              colo_checkpoint_notify(s);
          }
      }
  
      if (params->has_block_incremental) {
          s->parameters.block_incremental = params->block_incremental;
      }
      if (params->has_x_multifd_channels) {
          s->parameters.x_multifd_channels = params->x_multifd_channels;
      }
      if (params->has_x_multifd_page_count) {
          s->parameters.x_multifd_page_count = params->x_multifd_page_count;
      }
      if (params->has_xbzrle_cache_size) {
          s->parameters.xbzrle_cache_size = params->xbzrle_cache_size;
          xbzrle_cache_resize(params->xbzrle_cache_size, errp);
      }
      if (params->has_max_postcopy_bandwidth) {
          s->parameters.max_postcopy_bandwidth = params->max_postcopy_bandwidth;
      }
  }
  
  void qmp_migrate_set_parameters(MigrateSetParameters *params, Error **errp)
  {
      MigrationParameters tmp;
  
      /* TODO Rewrite "" to null instead */
      if (params->has_tls_creds
          && params->tls_creds->type == QTYPE_QNULL) {
          qobject_unref(params->tls_creds->u.n);
          params->tls_creds->type = QTYPE_QSTRING;
          params->tls_creds->u.s = strdup("");
      }
      /* TODO Rewrite "" to null instead */
      if (params->has_tls_hostname
          && params->tls_hostname->type == QTYPE_QNULL) {
          qobject_unref(params->tls_hostname->u.n);
          params->tls_hostname->type = QTYPE_QSTRING;
          params->tls_hostname->u.s = strdup("");
      }
  
      migrate_params_test_apply(params, &tmp);
  
      if (!migrate_params_check(&tmp, errp)) {
          /* Invalid parameter */
          return;
      }
  
      migrate_params_apply(params, errp);
  }
  
  
  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.
       */
      atomic_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 (atomic_cmpxchg(state, old_state, new_state) == old_state) {
          trace_migrate_set_state(MigrationStatus_str(new_state));
          migrate_generate_event(new_state);
      }
  }
  
  static MigrationCapabilityStatusList *migrate_cap_add(
      MigrationCapabilityStatusList *list,
      MigrationCapability index,
      bool state)
  {
      MigrationCapabilityStatusList *cap;
  
      cap = g_new0(MigrationCapabilityStatusList, 1);
      cap->value = g_new0(MigrationCapabilityStatus, 1);
      cap->value->capability = index;
      cap->value->state = state;
      cap->next = list;
  
      return cap;
  }
  
  void migrate_set_block_enabled(bool value, Error **errp)
  {
      MigrationCapabilityStatusList *cap;
  
      cap = migrate_cap_add(NULL, MIGRATION_CAPABILITY_BLOCK, value);
      qmp_migrate_set_capabilities(cap, errp);
      qapi_free_MigrationCapabilityStatusList(cap);
  }
  
  static void migrate_set_block_incremental(MigrationState *s, bool value)
  {
      s->parameters.block_incremental = value;
  }
  
  static void block_cleanup_parameters(MigrationState *s)
  {
      if (s->must_remove_block_options) {
          /* setting to false can never fail */
          migrate_set_block_enabled(false, &error_abort);
          migrate_set_block_incremental(s, false);
          s->must_remove_block_options = false;
      }
  }
  
  static void migrate_fd_cleanup(void *opaque)
  {
      MigrationState *s = opaque;
  
      qemu_bh_delete(s->cleanup_bh);
      s->cleanup_bh = NULL;
  
      qemu_savevm_state_cleanup();
  
      if (s->to_dst_file) {
          Error *local_err = NULL;
          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();
  
          if (multifd_save_cleanup(&local_err) != 0) {
              error_report_err(local_err);
          }
          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.
           */
          qemu_fclose(tmp);
      }
  
      assert((s->state != MIGRATION_STATUS_ACTIVE) &&
             (s->state != MIGRATION_STATUS_POSTCOPY_ACTIVE));
  
      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(s);
  }
  
  void migrate_set_error(MigrationState *s, const Error *error)
  {
      qemu_mutex_lock(&s->error_mutex);
      if (!s->error) {
          s->error = error_copy(error);
      }
      qemu_mutex_unlock(&s->error_mutex);
  }
  
  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();
  
      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_setup_or_active(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_invalidate_cache_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();
  
      return (s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE);
  }
  
  bool migration_in_postcopy_after_devices(MigrationState *s)
  {
      return migration_in_postcopy() && s->postcopy_after_devices;
  }
  
  bool migration_is_idle(void)
  {
      MigrationState *s = migrate_get_current();
  
      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:
          return false;
      case MIGRATION_STATUS__MAX:
          g_assert_not_reached();
      }
  
      return false;
  }
  
  void migrate_init(MigrationState *s)
  {
      /*
       * Reinitialise all migration state, except
       * parameters/capabilities that the user set, and
       * locks.
       */
      s->bytes_xfer = 0;
      s->xfer_limit = 0;
      s->cleanup_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->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;
  
      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;
  }
  
  static GSList *migration_blockers;
  
  int migrate_add_blocker(Error *reason, Error **errp)
  {
      if (migrate_get_current()->only_migratable) {
          error_propagate(errp, error_copy(reason));
          error_prepend(errp, "disallowing migration blocker "
                            "(--only_migratable) for: ");
          return -EACCES;
      }
  
      if (migration_is_idle()) {
          migration_blockers = g_slist_prepend(migration_blockers, reason);
          return 0;
      }
  
      error_propagate(errp, error_copy(reason));
      error_prepend(errp, "disallowing migration blocker (migration in "
                        "progress) for: ");
      return -EBUSY;
  }
  
  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 (!deferred_incoming) {
          error_setg(errp, "For use with '-incoming defer'");
          return;
      }
      if (!once) {
          error_setg(errp, "The incoming migration has already been started");
      }
  
      qemu_start_incoming_migration(uri, &local_err);
  
      if (local_err) {
          error_propagate(errp, local_err);
          return;
      }
  
      once = false;
  }
  
  void qmp_migrate_recover(const char *uri, Error **errp)
  {
      MigrationIncomingState *mis = migration_incoming_get_current();
  
      if (mis->state != MIGRATION_STATUS_POSTCOPY_PAUSED) {
          error_setg(errp, "Migrate recover can only be run "
                     "when postcopy is paused.");
          return;
      }
  
      if (atomic_cmpxchg(&mis->postcopy_recover_triggered,
                         false, true) == true) {
          error_setg(errp, "Migrate recovery is triggered already");
          return;
      }
  
      /*
       * 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_setup_or_active(s->state) ||
          s->state == MIGRATION_STATUS_CANCELLING ||
          s->state == MIGRATION_STATUS_COLO) {
          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 (migration_is_blocked(errp)) {
          return false;
      }
  
      if (blk || blk_inc) {
          if (migrate_use_block() || migrate_use_block_incremental()) {
              error_setg(errp, "Command options are incompatible with "
                         "current migration capabilities");
              return false;
          }
          migrate_set_block_enabled(true, &local_err);
          if (local_err) {
              error_propagate(errp, local_err);
              return false;
          }
          s->must_remove_block_options = true;
      }
  
      if (blk_inc) {
          migrate_set_block_incremental(s, true);
      }
  
      migrate_init(s);
  
      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;
  
      if (!migrate_prepare(s, has_blk && blk, has_inc && inc,
                           has_resume && resume, errp)) {
          /* Error detected, put into errp */
          return;
      }
  
      if (strstart(uri, "tcp:", &p)) {
          tcp_start_outgoing_migration(s, p, &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, "unix:", &p)) {
          unix_start_outgoing_migration(s, p, &local_err);
      } else if (strstart(uri, "fd:", &p)) {
          fd_start_outgoing_migration(s, p, &local_err);
      } else {
          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(s);
          return;
      }
  
      if (local_err) {
          migrate_fd_error(s, local_err);
          error_propagate(errp, local_err);
          return;
      }
  }
  
  void qmp_migrate_cancel(Error **errp)
  {
      migrate_fd_cancel(migrate_get_current());
  }
  
  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);
  }
  
  void qmp_migrate_set_cache_size(int64_t value, Error **errp)
  {
      MigrateSetParameters p = {
          .has_xbzrle_cache_size = true,
          .xbzrle_cache_size = value,
      };
  
      qmp_migrate_set_parameters(&p, errp);
  }
  
  int64_t qmp_query_migrate_cache_size(Error **errp)
  {
      return migrate_xbzrle_cache_size();
  }
  
  void qmp_migrate_set_speed(int64_t value, Error **errp)
  {
      MigrateSetParameters p = {
          .has_max_bandwidth = true,
          .max_bandwidth = value,
      };
  
      qmp_migrate_set_parameters(&p, errp);
  }
  
  void qmp_migrate_set_downtime(double value, Error **errp)
  {
      if (value < 0 || value > MAX_MIGRATE_DOWNTIME_SECONDS) {
          error_setg(errp, "Parameter 'downtime_limit' expects an integer in "
                           "the range of 0 to %d seconds",
                           MAX_MIGRATE_DOWNTIME_SECONDS);
          return;
      }
  
      value *= 1000; /* Convert to milliseconds */
      value = MAX(0, MIN(INT64_MAX, value));
  
      MigrateSetParameters p = {
          .has_downtime_limit = true,
          .downtime_limit = value,
      };
  
      qmp_migrate_set_parameters(&p, errp);
  }
  
  bool migrate_release_ram(void)
  {
      MigrationState *s;
  
      s = migrate_get_current();
  
      return s->enabled_capabilities[MIGRATION_CAPABILITY_RELEASE_RAM];
  }
  
  bool migrate_postcopy_ram(void)
  {
      MigrationState *s;
  
      s = migrate_get_current();
  
      return s->enabled_capabilities[MIGRATION_CAPABILITY_POSTCOPY_RAM];
  }
  
  bool migrate_postcopy(void)
  {
      return migrate_postcopy_ram() || migrate_dirty_bitmaps();
  }
  
  bool migrate_auto_converge(void)
  {
      MigrationState *s;
  
      s = migrate_get_current();
  
      return s->enabled_capabilities[MIGRATION_CAPABILITY_AUTO_CONVERGE];
  }
  
  bool migrate_zero_blocks(void)
  {
      MigrationState *s;
  
      s = migrate_get_current();
  
      return s->enabled_capabilities[MIGRATION_CAPABILITY_ZERO_BLOCKS];
  }
  
  bool migrate_postcopy_blocktime(void)
  {
      MigrationState *s;
  
      s = migrate_get_current();
  
      return s->enabled_capabilities[MIGRATION_CAPABILITY_POSTCOPY_BLOCKTIME];
  }
  
  bool migrate_use_compression(void)
  {
      MigrationState *s;
  
      s = migrate_get_current();
  
      return s->enabled_capabilities[MIGRATION_CAPABILITY_COMPRESS];
  }
  
  int migrate_compress_level(void)
  {
      MigrationState *s;
  
      s = migrate_get_current();
  
      return s->parameters.compress_level;
  }
  
  int migrate_compress_threads(void)
  {
      MigrationState *s;
  
      s = migrate_get_current();
  
      return s->parameters.compress_threads;
  }
  
  int migrate_decompress_threads(void)
  {
      MigrationState *s;
  
      s = migrate_get_current();
  
      return s->parameters.decompress_threads;
  }
  
  bool migrate_dirty_bitmaps(void)
  {
      MigrationState *s;
  
      s = migrate_get_current();
  
      return s->enabled_capabilities[MIGRATION_CAPABILITY_DIRTY_BITMAPS];
  }
  
  bool migrate_use_events(void)
  {
      MigrationState *s;
  
      s = migrate_get_current();
  
      return s->enabled_capabilities[MIGRATION_CAPABILITY_EVENTS];
  }
  
  bool migrate_use_multifd(void)
  {
      MigrationState *s;
  
      s = migrate_get_current();
  
      return s->enabled_capabilities[MIGRATION_CAPABILITY_X_MULTIFD];
  }
  
  bool migrate_pause_before_switchover(void)
  {
      MigrationState *s;
  
      s = migrate_get_current();
  
      return s->enabled_capabilities[
          MIGRATION_CAPABILITY_PAUSE_BEFORE_SWITCHOVER];
  }
  
  int migrate_multifd_channels(void)
  {
      MigrationState *s;
  
      s = migrate_get_current();
  
      return s->parameters.x_multifd_channels;
  }
  
  int migrate_multifd_page_count(void)
  {
      MigrationState *s;
  
      s = migrate_get_current();
  
      return s->parameters.x_multifd_page_count;
  }
  
  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->parameters.xbzrle_cache_size;
  }
  
  static int64_t migrate_max_postcopy_bandwidth(void)
  {
      MigrationState *s;
  
      s = migrate_get_current();
  
      return s->parameters.max_postcopy_bandwidth;
  }
  
  
  bool migrate_use_block(void)
  {
      MigrationState *s;
  
      s = migrate_get_current();
  
      return s->enabled_capabilities[MIGRATION_CAPABILITY_BLOCK];
  }
  
  bool migrate_use_return_path(void)
  {
      MigrationState *s;
  
      s = migrate_get_current();
  
      return s->enabled_capabilities[MIGRATION_CAPABILITY_RETURN_PATH];
  }
  
  bool migrate_use_block_incremental(void)
  {
      MigrationState *s;
  
      s = migrate_get_current();
  
      return s->parameters.block_incremental;
  }
  
  /* 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 = getpagesize();
  
      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 (start & (our_host_ps-1) ||
         (len & (our_host_ps-1))) {
          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;
  }
  
  /*
   * 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();
  
  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);
              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 == -EIO) {
              /*
               * Maybe there is something we can do: it looks like a
               * network down issue, and we pause for a recovery.
               */
              if (postcopy_pause_return_path_thread(ms)) {
                  /* Reload rp, reset the rest */
                  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();
      ms->rp_state.from_dst_file = NULL;
      qemu_fclose(rp);
      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);
  
      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);
      trace_await_return_path_close_on_source_close();
      return ms->rp_state.error;
  }
  
  /*
   * 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_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);
      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()) {
          if (ram_postcopy_send_discard_bitmap(ms)) {
              error_report("postcopy send discard bitmap failed");
              goto fail;
          }
      }
  
      /*
       * 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_fopen_channel_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);
      }
  
      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_invalidate_cache_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 */
      }
  
      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);
          s->vm_was_running = runstate_is_running();
          ret = global_state_store();
  
          if (!ret) {
              bool inactivate = !migrate_colo_enabled();
              ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
              if (ret >= 0) {
                  ret = migration_maybe_pause(s, &current_active_state,
                                              MIGRATION_STATUS_DEVICE);
              }
              if (ret >= 0) {
                  qemu_file_set_rate_limit(s->to_dst_file, INT64_MAX);
                  ret = qemu_savevm_state_complete_precopy(s->to_dst_file, false,
                                                           inactivate);
              }
              if (inactivate && ret >= 0) {
                  s->block_inactive = true;
              }
          }
          qemu_mutex_unlock_iothread();
  
          if (ret < 0) {
              goto fail;
          }
      } else if (s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE) {
          trace_migration_completion_postcopy_end();
  
          qemu_savevm_state_complete_postcopy(s->to_dst_file);
          trace_migration_completion_postcopy_end_after_complete();
      }
  
      /*
       * 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.from_dst_file) {
          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_enabled()) {
          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_invalidate_cache_all(&local_err);
          if (local_err) {
              error_report_err(local_err);
          } else {
              s->block_inactive = false;
          }
          qemu_mutex_unlock_iothread();
      }
  
  fail:
      migrate_set_state(&s->state, current_active_state,
                        MIGRATION_STATUS_FAILED);
  }
  
  bool migrate_colo_enabled(void)
  {
      MigrationState *s = migrate_get_current();
      return s->enabled_capabilities[MIGRATION_CAPABILITY_X_COLO];
  }
  
  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;
      }
  
      /*
       * 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;
  
          migrate_set_state(&s->state, s->state,
                            MIGRATION_STATUS_POSTCOPY_PAUSED);
  
          /* Current channel is possibly broken. Release it. */
          assert(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);
  
          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;
  
      /* Try to detect any file errors */
      ret = qemu_file_get_error(s->to_dst_file);
  
      if (!ret) {
          /* Everything is fine */
          return MIG_THR_ERR_NONE;
      }
  
      if (s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE && ret == -EIO) {
          /*
           * 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, s->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 beggining of the migration */
  static uint64_t migration_total_bytes(MigrationState *s)
  {
      return qemu_ftell(s->to_dst_file) + ram_counters.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 migration_update_counters(MigrationState *s,
                                        int64_t current_time)
  {
      uint64_t transferred, 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 * s->parameters.downtime_limit;
  
      s->mbps = (((double) transferred * 8.0) /
                 ((double) time_spent / 1000.0)) / 1000.0 / 1000.0;
  
      /*
       * if we haven't sent anything, we don't want to
       * recalculate. 10000 is a small enough number for our purposes
       */
      if (ram_counters.dirty_pages_rate && transferred > 10000) {
          s->expected_downtime = ram_counters.remaining / bandwidth;
      }
  
      qemu_file_reset_rate_limit(s->to_dst_file);
  
      s->iteration_start_time = current_time;
      s->iteration_initial_bytes = current_bytes;
  
      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 pending_size, pend_pre, pend_compat, pend_post;
      bool in_postcopy = s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE;
  
      qemu_savevm_state_pending(s->to_dst_file, s->threshold_size, &pend_pre,
                                &pend_compat, &pend_post);
      pending_size = pend_pre + pend_compat + pend_post;
  
      trace_migrate_pending(pending_size, s->threshold_size,
                            pend_pre, pend_compat, pend_post);
  
      if (pending_size && pending_size >= s->threshold_size) {
          /* Still a significant amount to transfer */
          if (migrate_postcopy() && !in_postcopy &&
              pend_pre <= s->threshold_size &&
              atomic_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,
              s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE);
      } else {
          trace_migration_thread_low_pending(pending_size);
          migration_completion(s);
          return MIG_ITERATE_BREAK;
      }
  
      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_ACTIVE:
          /*
           * We should really assert here, but since it's during
           * migration, let's try to reduce the usage of assertions.
           */
          if (!migrate_colo_enabled()) {
              error_report("%s: critical error: calling COLO code without "
                           "COLO enabled", __func__);
          }
          migrate_start_colo_process(s);
          /*
           * Fixme: we will run VM in COLO no matter its old running state.
           * After exited COLO, we will keep running.
           */
          s->vm_was_running = true;
          /* Fallthrough */
      case MIGRATION_STATUS_FAILED:
      case MIGRATION_STATUS_CANCELLED:
      case MIGRATION_STATUS_CANCELLING:
          if (s->vm_was_running) {
              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;
      }
      qemu_bh_schedule(s->cleanup_bh);
      qemu_mutex_unlock_iothread();
  }
  
  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);
  }
  
  /*
   * 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;
      int64_t setup_start = qemu_clock_get_ms(QEMU_CLOCK_HOST);
      MigThrError thr_error;
      bool urgent = false;
  
      rcu_register_thread();
  
      s->iteration_start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
  
      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.from_dst_file) {
          /* 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);
      }
  
      qemu_savevm_state_setup(s->to_dst_file);
  
      s->setup_time = qemu_clock_get_ms(QEMU_CLOCK_HOST) - setup_start;
      migrate_set_state(&s->state, MIGRATION_STATUS_SETUP,
                        MIGRATION_STATUS_ACTIVE);
  
      trace_migration_thread_setup_complete();
  
      while (s->state == MIGRATION_STATUS_ACTIVE ||
             s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE) {
          int64_t current_time;
  
          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
               */
              s->iteration_start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
              s->iteration_initial_bytes = 0;
          }
  
          current_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
  
          migration_update_counters(s, current_time);
  
          urgent = false;
          if (qemu_file_rate_limit(s->to_dst_file)) {
              /* Wait for a delay to do rate limiting OR
               * something urgent to post the semaphore.
               */
              int ms = s->iteration_start_time + BUFFER_DELAY - current_time;
              trace_migration_thread_ratelimit_pre(ms);
              if (qemu_sem_timedwait(&s->rate_limit_sem, ms) == 0) {
                  /* We were worken 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_thread_ratelimit_post(urgent);
          }
      }
  
      trace_migration_thread_after_loop();
      migration_iteration_finish(s);
      rcu_unregister_thread();
      return NULL;
  }
  
  void migrate_fd_connect(MigrationState *s, Error *error_in)
  {
      int64_t rate_limit;
      bool resume = s->state == MIGRATION_STATUS_POSTCOPY_PAUSED;
  
      s->expected_downtime = s->parameters.downtime_limit;
      s->cleanup_bh = qemu_bh_new(migrate_fd_cleanup, s);
      if (error_in) {
          migrate_fd_error(s, error_in);
          migrate_fd_cleanup(s);
          return;
      }
  
      if (resume) {
          /* This is a resumed migration */
          rate_limit = INT64_MAX;
      } else {
          /* This is a fresh new migration */
          rate_limit = s->parameters.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_use_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;
          }
      }
  
      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() != 0) {
          migrate_set_state(&s->state, MIGRATION_STATUS_SETUP,
                            MIGRATION_STATUS_FAILED);
          migrate_fd_cleanup(s);
          return;
      }
      qemu_thread_create(&s->thread, "live_migration", migration_thread, s,
                         QEMU_THREAD_JOINABLE);
      s->migration_thread_running = true;
  }
  
  void migration_global_dump(Monitor *mon)
  {
      MigrationState *ms = migrate_get_current();
  
      monitor_printf(mon, "globals:\n");
      monitor_printf(mon, "store-global-state: %s\n",
                     ms->store_global_state ? "on" : "off");
      monitor_printf(mon, "only-migratable: %s\n",
                     ms->only_migratable ? "on" : "off");
      monitor_printf(mon, "send-configuration: %s\n",
                     ms->send_configuration ? "on" : "off");
      monitor_printf(mon, "send-section-footer: %s\n",
                     ms->send_section_footer ? "on" : "off");
      monitor_printf(mon, "decompress-error-check: %s\n",
                     ms->decompress_error_check ? "on" : "off");
  }
  
  #define DEFINE_PROP_MIG_CAP(name, x)             \
      DEFINE_PROP_BOOL(name, MigrationState, enabled_capabilities[x], false)
  
  static Property migration_properties[] = {
      DEFINE_PROP_BOOL("store-global-state", MigrationState,
                       store_global_state, true),
      DEFINE_PROP_BOOL("only-migratable", MigrationState, only_migratable, false),
      DEFINE_PROP_BOOL("send-configuration", MigrationState,
                       send_configuration, true),
      DEFINE_PROP_BOOL("send-section-footer", MigrationState,
                       send_section_footer, true),
      DEFINE_PROP_BOOL("decompress-error-check", MigrationState,
                        decompress_error_check, true),
  
      /* Migration parameters */
      DEFINE_PROP_UINT8("x-compress-level", MigrationState,
                        parameters.compress_level,
                        DEFAULT_MIGRATE_COMPRESS_LEVEL),
      DEFINE_PROP_UINT8("x-compress-threads", MigrationState,
                        parameters.compress_threads,
                        DEFAULT_MIGRATE_COMPRESS_THREAD_COUNT),
      DEFINE_PROP_UINT8("x-decompress-threads", MigrationState,
                        parameters.decompress_threads,
                        DEFAULT_MIGRATE_DECOMPRESS_THREAD_COUNT),
      DEFINE_PROP_UINT8("x-cpu-throttle-initial", MigrationState,
                        parameters.cpu_throttle_initial,
                        DEFAULT_MIGRATE_CPU_THROTTLE_INITIAL),
      DEFINE_PROP_UINT8("x-cpu-throttle-increment", MigrationState,
                        parameters.cpu_throttle_increment,
                        DEFAULT_MIGRATE_CPU_THROTTLE_INCREMENT),
      DEFINE_PROP_SIZE("x-max-bandwidth", MigrationState,
                        parameters.max_bandwidth, MAX_THROTTLE),
      DEFINE_PROP_UINT64("x-downtime-limit", MigrationState,
                        parameters.downtime_limit,
                        DEFAULT_MIGRATE_SET_DOWNTIME),
      DEFINE_PROP_UINT32("x-checkpoint-delay", MigrationState,
                        parameters.x_checkpoint_delay,
                        DEFAULT_MIGRATE_X_CHECKPOINT_DELAY),
      DEFINE_PROP_UINT8("x-multifd-channels", MigrationState,
                        parameters.x_multifd_channels,
                        DEFAULT_MIGRATE_MULTIFD_CHANNELS),
      DEFINE_PROP_UINT32("x-multifd-page-count", MigrationState,
                        parameters.x_multifd_page_count,
                        DEFAULT_MIGRATE_MULTIFD_PAGE_COUNT),
      DEFINE_PROP_SIZE("xbzrle-cache-size", MigrationState,
                        parameters.xbzrle_cache_size,
                        DEFAULT_MIGRATE_XBZRLE_CACHE_SIZE),
      DEFINE_PROP_SIZE("max-postcopy-bandwidth", MigrationState,
                        parameters.max_postcopy_bandwidth,
                        DEFAULT_MIGRATE_MAX_POSTCOPY_BANDWIDTH),
  
      /* Migration capabilities */
      DEFINE_PROP_MIG_CAP("x-xbzrle", MIGRATION_CAPABILITY_XBZRLE),
      DEFINE_PROP_MIG_CAP("x-rdma-pin-all", MIGRATION_CAPABILITY_RDMA_PIN_ALL),
      DEFINE_PROP_MIG_CAP("x-auto-converge", MIGRATION_CAPABILITY_AUTO_CONVERGE),
      DEFINE_PROP_MIG_CAP("x-zero-blocks", MIGRATION_CAPABILITY_ZERO_BLOCKS),
      DEFINE_PROP_MIG_CAP("x-compress", MIGRATION_CAPABILITY_COMPRESS),
      DEFINE_PROP_MIG_CAP("x-events", MIGRATION_CAPABILITY_EVENTS),
      DEFINE_PROP_MIG_CAP("x-postcopy-ram", MIGRATION_CAPABILITY_POSTCOPY_RAM),
      DEFINE_PROP_MIG_CAP("x-colo", MIGRATION_CAPABILITY_X_COLO),
      DEFINE_PROP_MIG_CAP("x-release-ram", MIGRATION_CAPABILITY_RELEASE_RAM),
      DEFINE_PROP_MIG_CAP("x-block", MIGRATION_CAPABILITY_BLOCK),
      DEFINE_PROP_MIG_CAP("x-return-path", MIGRATION_CAPABILITY_RETURN_PATH),
      DEFINE_PROP_MIG_CAP("x-multifd", MIGRATION_CAPABILITY_X_MULTIFD),
  
      DEFINE_PROP_END_OF_LIST(),
  };
  
  static void migration_class_init(ObjectClass *klass, void *data)
  {
      DeviceClass *dc = DEVICE_CLASS(klass);
  
      dc->user_creatable = false;
      dc->props = migration_properties;
  }
  
  static void migration_instance_finalize(Object *obj)
  {
      MigrationState *ms = MIGRATION_OBJ(obj);
      MigrationParameters *params = &ms->parameters;
  
      qemu_mutex_destroy(&ms->error_mutex);
      qemu_mutex_destroy(&ms->qemu_file_lock);
      g_free(params->tls_hostname);
      g_free(params->tls_creds);
      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);
      error_free(ms->error);
  }
  
  static void migration_instance_init(Object *obj)
  {
      MigrationState *ms = MIGRATION_OBJ(obj);
      MigrationParameters *params = &ms->parameters;
  
      ms->state = MIGRATION_STATUS_NONE;
      ms->mbps = -1;
      qemu_sem_init(&ms->pause_sem, 0);
      qemu_mutex_init(&ms->error_mutex);
  
      params->tls_hostname = g_strdup("");
      params->tls_creds = g_strdup("");
  
      /* Set has_* up only for parameter checks */
      params->has_compress_level = true;
      params->has_compress_threads = true;
      params->has_decompress_threads = true;
      params->has_cpu_throttle_initial = true;
      params->has_cpu_throttle_increment = true;
      params->has_max_bandwidth = true;
      params->has_downtime_limit = true;
      params->has_x_checkpoint_delay = true;
      params->has_block_incremental = true;
      params->has_x_multifd_channels = true;
      params->has_x_multifd_page_count = true;
      params->has_xbzrle_cache_size = true;
      params->has_max_postcopy_bandwidth = true;
  
      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->rate_limit_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)
  {
      MigrationCapabilityStatusList *head = NULL;
      /* Assuming all off */
      bool cap_list[MIGRATION_CAPABILITY__MAX] = { 0 }, ret;
      int i;
  
      if (!migrate_params_check(&ms->parameters, errp)) {
          return false;
      }
  
      for (i = 0; i < MIGRATION_CAPABILITY__MAX; i++) {
          if (ms->enabled_capabilities[i]) {
              head = migrate_cap_add(head, i, true);
          }
      }
  
      ret = migrate_caps_check(cap_list, head, errp);
  
      /* It works with head == NULL */
      qapi_free_MigrationCapabilityStatusList(head);
  
      return ret;
  }
  
  static const TypeInfo migration_type = {
      .name = TYPE_MIGRATION,
      /*
       * NOTE: TYPE_MIGRATION is not really a device, as the object is
       * not created using qdev_create(), 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);
  