Start migrating migration code into a migration directory

The migration code now occupies a fair chunk of the top level .c
files, it seems time to give it it's own directory.

I've not touched:
   arch_init.c - that's mostly RAM migration but has a few random other
                 bits
   savevm.c    - because it's built target specific

This is purely a code move; no code has changed.
   - it fails checkpatch because of old violations, it feels safer
     to keep this as purely a move and fix those at some mythical future
     date.

The xbzrle and vmstate tests are now only run for softmmu builds
since they require files in the migrate/ directory which is only built
for softmmu.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>

1 files changed, 700 insertions, 0 deletions

diff --git a/migration/migration.c b/migration/migration.c
new file mode 100644
index 0000000000..c49a05a165
--- /dev/null
+++ b/migration/migration.c
@@ -0,0 +1,700 @@
+/*
+ * QEMU live migration
+ *
+ * Copyright IBM, Corp. 2008
+ *
+ * Authors:
+ *  Anthony Liguori   <aliguori@us.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ * Contributions after 2012-01-13 are licensed under the terms of the
+ * GNU GPL, version 2 or (at your option) any later version.
+ */
+
+#include "qemu-common.h"
+#include "qemu/main-loop.h"
+#include "migration/migration.h"
+#include "monitor/monitor.h"
+#include "migration/qemu-file.h"
+#include "sysemu/sysemu.h"
+#include "block/block.h"
+#include "qemu/sockets.h"
+#include "migration/block.h"
+#include "qemu/thread.h"
+#include "qmp-commands.h"
+#include "trace.h"
+
+enum {
+    MIG_STATE_ERROR = -1,
+    MIG_STATE_NONE,
+    MIG_STATE_SETUP,
+    MIG_STATE_CANCELLING,
+    MIG_STATE_CANCELLED,
+    MIG_STATE_ACTIVE,
+    MIG_STATE_COMPLETED,
+};
+
+#define MAX_THROTTLE  (32 << 20)      /* Migration speed throttling */
+
+/* Amount of time to allocate to each "chunk" of bandwidth-throttled
+ * data. */
+#define BUFFER_DELAY     100
+#define XFER_LIMIT_RATIO (1000 / BUFFER_DELAY)
+
+/* Migration XBZRLE default cache size */
+#define DEFAULT_MIGRATE_CACHE_SIZE (64 * 1024 * 1024)
+
+static NotifierList migration_state_notifiers =
+    NOTIFIER_LIST_INITIALIZER(migration_state_notifiers);
+
+/* When we add fault tolerance, we could have several
+   migrations at once.  For now we don't need to add
+   dynamic creation of migration */
+
+MigrationState *migrate_get_current(void)
+{
+    static MigrationState current_migration = {
+        .state = MIG_STATE_NONE,
+        .bandwidth_limit = MAX_THROTTLE,
+        .xbzrle_cache_size = DEFAULT_MIGRATE_CACHE_SIZE,
+        .mbps = -1,
+    };
+
+    return &current_migration;
+}
+
+void qemu_start_incoming_migration(const char *uri, Error **errp)
+{
+    const char *p;
+
+    if (strstart(uri, "tcp:", &p))
+        tcp_start_incoming_migration(p, errp);
+#ifdef CONFIG_RDMA
+    else if (strstart(uri, "rdma:", &p))
+        rdma_start_incoming_migration(p, errp);
+#endif
+#if !defined(WIN32)
+    else if (strstart(uri, "exec:", &p))
+        exec_start_incoming_migration(p, errp);
+    else if (strstart(uri, "unix:", &p))
+        unix_start_incoming_migration(p, errp);
+    else if (strstart(uri, "fd:", &p))
+        fd_start_incoming_migration(p, errp);
+#endif
+    else {
+        error_setg(errp, "unknown migration protocol: %s", uri);
+    }
+}
+
+static void process_incoming_migration_co(void *opaque)
+{
+    QEMUFile *f = opaque;
+    Error *local_err = NULL;
+    int ret;
+
+    ret = qemu_loadvm_state(f);
+    qemu_fclose(f);
+    free_xbzrle_decoded_buf();
+    if (ret < 0) {
+        error_report("load of migration failed: %s", strerror(-ret));
+        exit(EXIT_FAILURE);
+    }
+    qemu_announce_self();
+
+    /* Make sure all file formats flush their mutable metadata */
+    bdrv_invalidate_cache_all(&local_err);
+    if (local_err) {
+        qerror_report_err(local_err);
+        error_free(local_err);
+        exit(EXIT_FAILURE);
+    }
+
+    if (autostart) {
+        vm_start();
+    } else {
+        runstate_set(RUN_STATE_PAUSED);
+    }
+}
+
+void process_incoming_migration(QEMUFile *f)
+{
+    Coroutine *co = qemu_coroutine_create(process_incoming_migration_co);
+    int fd = qemu_get_fd(f);
+
+    assert(fd != -1);
+    qemu_set_nonblock(fd);
+    qemu_coroutine_enter(co, f);
+}
+
+/* amount of nanoseconds we are willing to wait for migration to be down.
+ * the choice of nanoseconds is because it is the maximum resolution that
+ * get_clock() can achieve. It is an internal measure. All user-visible
+ * units must be in seconds */
+static uint64_t max_downtime = 300000000;
+
+uint64_t migrate_max_downtime(void)
+{
+    return max_downtime;
+}
+
+MigrationCapabilityStatusList *qmp_query_migrate_capabilities(Error **errp)
+{
+    MigrationCapabilityStatusList *head = NULL;
+    MigrationCapabilityStatusList *caps;
+    MigrationState *s = migrate_get_current();
+    int i;
+
+    caps = NULL; /* silence compiler warning */
+    for (i = 0; i < MIGRATION_CAPABILITY_MAX; i++) {
+        if (head == NULL) {
+            head = g_malloc0(sizeof(*caps));
+            caps = head;
+        } else {
+            caps->next = g_malloc0(sizeof(*caps));
+            caps = caps->next;
+        }
+        caps->value =
+            g_malloc(sizeof(*caps->value));
+        caps->value->capability = i;
+        caps->value->state = s->enabled_capabilities[i];
+    }
+
+    return head;
+}
+
+static void get_xbzrle_cache_stats(MigrationInfo *info)
+{
+    if (migrate_use_xbzrle()) {
+        info->has_xbzrle_cache = true;
+        info->xbzrle_cache = g_malloc0(sizeof(*info->xbzrle_cache));
+        info->xbzrle_cache->cache_size = migrate_xbzrle_cache_size();
+        info->xbzrle_cache->bytes = xbzrle_mig_bytes_transferred();
+        info->xbzrle_cache->pages = xbzrle_mig_pages_transferred();
+        info->xbzrle_cache->cache_miss = xbzrle_mig_pages_cache_miss();
+        info->xbzrle_cache->cache_miss_rate = xbzrle_mig_cache_miss_rate();
+        info->xbzrle_cache->overflow = xbzrle_mig_pages_overflow();
+    }
+}
+
+MigrationInfo *qmp_query_migrate(Error **errp)
+{
+    MigrationInfo *info = g_malloc0(sizeof(*info));
+    MigrationState *s = migrate_get_current();
+
+    switch (s->state) {
+    case MIG_STATE_NONE:
+        /* no migration has happened ever */
+        break;
+    case MIG_STATE_SETUP:
+        info->has_status = true;
+        info->status = g_strdup("setup");
+        info->has_total_time = false;
+        break;
+    case MIG_STATE_ACTIVE:
+    case MIG_STATE_CANCELLING:
+        info->has_status = true;
+        info->status = g_strdup("active");
+        info->has_total_time = true;
+        info->total_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME)
+            - s->total_time;
+        info->has_expected_downtime = true;
+        info->expected_downtime = s->expected_downtime;
+        info->has_setup_time = true;
+        info->setup_time = s->setup_time;
+
+        info->has_ram = true;
+        info->ram = g_malloc0(sizeof(*info->ram));
+        info->ram->transferred = ram_bytes_transferred();
+        info->ram->remaining = ram_bytes_remaining();
+        info->ram->total = ram_bytes_total();
+        info->ram->duplicate = dup_mig_pages_transferred();
+        info->ram->skipped = skipped_mig_pages_transferred();
+        info->ram->normal = norm_mig_pages_transferred();
+        info->ram->normal_bytes = norm_mig_bytes_transferred();
+        info->ram->dirty_pages_rate = s->dirty_pages_rate;
+        info->ram->mbps = s->mbps;
+        info->ram->dirty_sync_count = s->dirty_sync_count;
+
+        if (blk_mig_active()) {
+            info->has_disk = true;
+            info->disk = g_malloc0(sizeof(*info->disk));
+            info->disk->transferred = blk_mig_bytes_transferred();
+            info->disk->remaining = blk_mig_bytes_remaining();
+            info->disk->total = blk_mig_bytes_total();
+        }
+
+        get_xbzrle_cache_stats(info);
+        break;
+    case MIG_STATE_COMPLETED:
+        get_xbzrle_cache_stats(info);
+
+        info->has_status = true;
+        info->status = g_strdup("completed");
+        info->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;
+
+        info->has_ram = true;
+        info->ram = g_malloc0(sizeof(*info->ram));
+        info->ram->transferred = ram_bytes_transferred();
+        info->ram->remaining = 0;
+        info->ram->total = ram_bytes_total();
+        info->ram->duplicate = dup_mig_pages_transferred();
+        info->ram->skipped = skipped_mig_pages_transferred();
+        info->ram->normal = norm_mig_pages_transferred();
+        info->ram->normal_bytes = norm_mig_bytes_transferred();
+        info->ram->mbps = s->mbps;
+        info->ram->dirty_sync_count = s->dirty_sync_count;
+        break;
+    case MIG_STATE_ERROR:
+        info->has_status = true;
+        info->status = g_strdup("failed");
+        break;
+    case MIG_STATE_CANCELLED:
+        info->has_status = true;
+        info->status = g_strdup("cancelled");
+        break;
+    }
+
+    return info;
+}
+
+void qmp_migrate_set_capabilities(MigrationCapabilityStatusList *params,
+                                  Error **errp)
+{
+    MigrationState *s = migrate_get_current();
+    MigrationCapabilityStatusList *cap;
+
+    if (s->state == MIG_STATE_ACTIVE || s->state == MIG_STATE_SETUP) {
+        error_set(errp, QERR_MIGRATION_ACTIVE);
+        return;
+    }
+
+    for (cap = params; cap; cap = cap->next) {
+        s->enabled_capabilities[cap->value->capability] = cap->value->state;
+    }
+}
+
+/* shared migration helpers */
+
+static void migrate_set_state(MigrationState *s, int old_state, int new_state)
+{
+    if (atomic_cmpxchg(&s->state, old_state, new_state) == new_state) {
+        trace_migrate_set_state(new_state);
+    }
+}
+
+static void migrate_fd_cleanup(void *opaque)
+{
+    MigrationState *s = opaque;
+
+    qemu_bh_delete(s->cleanup_bh);
+    s->cleanup_bh = NULL;
+
+    if (s->file) {
+        trace_migrate_fd_cleanup();
+        qemu_mutex_unlock_iothread();
+        qemu_thread_join(&s->thread);
+        qemu_mutex_lock_iothread();
+
+        qemu_fclose(s->file);
+        s->file = NULL;
+    }
+
+    assert(s->state != MIG_STATE_ACTIVE);
+
+    if (s->state != MIG_STATE_COMPLETED) {
+        qemu_savevm_state_cancel();
+        if (s->state == MIG_STATE_CANCELLING) {
+            migrate_set_state(s, MIG_STATE_CANCELLING, MIG_STATE_CANCELLED);
+        }
+    }
+
+    notifier_list_notify(&migration_state_notifiers, s);
+}
+
+void migrate_fd_error(MigrationState *s)
+{
+    trace_migrate_fd_error();
+    assert(s->file == NULL);
+    s->state = MIG_STATE_ERROR;
+    trace_migrate_set_state(MIG_STATE_ERROR);
+    notifier_list_notify(&migration_state_notifiers, s);
+}
+
+static void migrate_fd_cancel(MigrationState *s)
+{
+    int old_state ;
+    trace_migrate_fd_cancel();
+
+    do {
+        old_state = s->state;
+        if (old_state != MIG_STATE_SETUP && old_state != MIG_STATE_ACTIVE) {
+            break;
+        }
+        migrate_set_state(s, old_state, MIG_STATE_CANCELLING);
+    } while (s->state != MIG_STATE_CANCELLING);
+}
+
+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 == MIG_STATE_SETUP;
+}
+
+bool migration_has_finished(MigrationState *s)
+{
+    return s->state == MIG_STATE_COMPLETED;
+}
+
+bool migration_has_failed(MigrationState *s)
+{
+    return (s->state == MIG_STATE_CANCELLED ||
+            s->state == MIG_STATE_ERROR);
+}
+
+static MigrationState *migrate_init(const MigrationParams *params)
+{
+    MigrationState *s = migrate_get_current();
+    int64_t bandwidth_limit = s->bandwidth_limit;
+    bool enabled_capabilities[MIGRATION_CAPABILITY_MAX];
+    int64_t xbzrle_cache_size = s->xbzrle_cache_size;
+
+    memcpy(enabled_capabilities, s->enabled_capabilities,
+           sizeof(enabled_capabilities));
+
+    memset(s, 0, sizeof(*s));
+    s->params = *params;
+    memcpy(s->enabled_capabilities, enabled_capabilities,
+           sizeof(enabled_capabilities));
+    s->xbzrle_cache_size = xbzrle_cache_size;
+
+    s->bandwidth_limit = bandwidth_limit;
+    s->state = MIG_STATE_SETUP;
+    trace_migrate_set_state(MIG_STATE_SETUP);
+
+    s->total_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
+    return s;
+}
+
+static GSList *migration_blockers;
+
+void migrate_add_blocker(Error *reason)
+{
+    migration_blockers = g_slist_prepend(migration_blockers, reason);
+}
+
+void migrate_del_blocker(Error *reason)
+{
+    migration_blockers = g_slist_remove(migration_blockers, reason);
+}
+
+void qmp_migrate(const char *uri, bool has_blk, bool blk,
+                 bool has_inc, bool inc, bool has_detach, bool detach,
+                 Error **errp)
+{
+    Error *local_err = NULL;
+    MigrationState *s = migrate_get_current();
+    MigrationParams params;
+    const char *p;
+
+    params.blk = has_blk && blk;
+    params.shared = has_inc && inc;
+
+    if (s->state == MIG_STATE_ACTIVE || s->state == MIG_STATE_SETUP ||
+        s->state == MIG_STATE_CANCELLING) {
+        error_set(errp, QERR_MIGRATION_ACTIVE);
+        return;
+    }
+
+    if (runstate_check(RUN_STATE_INMIGRATE)) {
+        error_setg(errp, "Guest is waiting for an incoming migration");
+        return;
+    }
+
+    if (qemu_savevm_state_blocked(errp)) {
+        return;
+    }
+
+    if (migration_blockers) {
+        *errp = error_copy(migration_blockers->data);
+        return;
+    }
+
+    s = migrate_init(&params);
+
+    if (strstart(uri, "tcp:", &p)) {
+        tcp_start_outgoing_migration(s, p, &local_err);
+#ifdef CONFIG_RDMA
+    } else if (strstart(uri, "rdma:", &p)) {
+        rdma_start_outgoing_migration(s, p, &local_err);
+#endif
+#if !defined(WIN32)
+    } else if (strstart(uri, "exec:", &p)) {
+        exec_start_outgoing_migration(s, p, &local_err);
+    } else if (strstart(uri, "unix:", &p)) {
+        unix_start_outgoing_migration(s, p, &local_err);
+    } else if (strstart(uri, "fd:", &p)) {
+        fd_start_outgoing_migration(s, p, &local_err);
+#endif
+    } else {
+        error_set(errp, QERR_INVALID_PARAMETER_VALUE, "uri", "a valid migration protocol");
+        s->state = MIG_STATE_ERROR;
+        return;
+    }
+
+    if (local_err) {
+        migrate_fd_error(s);
+        error_propagate(errp, local_err);
+        return;
+    }
+}
+
+void qmp_migrate_cancel(Error **errp)
+{
+    migrate_fd_cancel(migrate_get_current());
+}
+
+void qmp_migrate_set_cache_size(int64_t value, Error **errp)
+{
+    MigrationState *s = migrate_get_current();
+    int64_t new_size;
+
+    /* Check for truncation */
+    if (value != (size_t)value) {
+        error_set(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
+                  "exceeding address space");
+        return;
+    }
+
+    /* Cache should not be larger than guest ram size */
+    if (value > ram_bytes_total()) {
+        error_set(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
+                  "exceeds guest ram size ");
+        return;
+    }
+
+    new_size = xbzrle_cache_resize(value);
+    if (new_size < 0) {
+        error_set(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
+                  "is smaller than page size");
+        return;
+    }
+
+    s->xbzrle_cache_size = new_size;
+}
+
+int64_t qmp_query_migrate_cache_size(Error **errp)
+{
+    return migrate_xbzrle_cache_size();
+}
+
+void qmp_migrate_set_speed(int64_t value, Error **errp)
+{
+    MigrationState *s;
+
+    if (value < 0) {
+        value = 0;
+    }
+    if (value > SIZE_MAX) {
+        value = SIZE_MAX;
+    }
+
+    s = migrate_get_current();
+    s->bandwidth_limit = value;
+    if (s->file) {
+        qemu_file_set_rate_limit(s->file, s->bandwidth_limit / XFER_LIMIT_RATIO);
+    }
+}
+
+void qmp_migrate_set_downtime(double value, Error **errp)
+{
+    value *= 1e9;
+    value = MAX(0, MIN(UINT64_MAX, value));
+    max_downtime = (uint64_t)value;
+}
+
+bool migrate_rdma_pin_all(void)
+{
+    MigrationState *s;
+
+    s = migrate_get_current();
+
+    return s->enabled_capabilities[MIGRATION_CAPABILITY_RDMA_PIN_ALL];
+}
+
+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];
+}
+
+int migrate_use_xbzrle(void)
+{
+    MigrationState *s;
+
+    s = migrate_get_current();
+
+    return s->enabled_capabilities[MIGRATION_CAPABILITY_XBZRLE];
+}
+
+int64_t migrate_xbzrle_cache_size(void)
+{
+    MigrationState *s;
+
+    s = migrate_get_current();
+
+    return s->xbzrle_cache_size;
+}
+
+/* migration thread support */
+
+static void *migration_thread(void *opaque)
+{
+    MigrationState *s = opaque;
+    int64_t initial_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
+    int64_t setup_start = qemu_clock_get_ms(QEMU_CLOCK_HOST);
+    int64_t initial_bytes = 0;
+    int64_t max_size = 0;
+    int64_t start_time = initial_time;
+    bool old_vm_running = false;
+
+    qemu_savevm_state_begin(s->file, &s->params);
+
+    s->setup_time = qemu_clock_get_ms(QEMU_CLOCK_HOST) - setup_start;
+    migrate_set_state(s, MIG_STATE_SETUP, MIG_STATE_ACTIVE);
+
+    while (s->state == MIG_STATE_ACTIVE) {
+        int64_t current_time;
+        uint64_t pending_size;
+
+        if (!qemu_file_rate_limit(s->file)) {
+            pending_size = qemu_savevm_state_pending(s->file, max_size);
+            trace_migrate_pending(pending_size, max_size);
+            if (pending_size && pending_size >= max_size) {
+                qemu_savevm_state_iterate(s->file);
+            } else {
+                int ret;
+
+                qemu_mutex_lock_iothread();
+                start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
+                qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER);
+                old_vm_running = runstate_is_running();
+
+                ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
+                if (ret >= 0) {
+                    qemu_file_set_rate_limit(s->file, INT64_MAX);
+                    qemu_savevm_state_complete(s->file);
+                }
+                qemu_mutex_unlock_iothread();
+
+                if (ret < 0) {
+                    migrate_set_state(s, MIG_STATE_ACTIVE, MIG_STATE_ERROR);
+                    break;
+                }
+
+                if (!qemu_file_get_error(s->file)) {
+                    migrate_set_state(s, MIG_STATE_ACTIVE, MIG_STATE_COMPLETED);
+                    break;
+                }
+            }
+        }
+
+        if (qemu_file_get_error(s->file)) {
+            migrate_set_state(s, MIG_STATE_ACTIVE, MIG_STATE_ERROR);
+            break;
+        }
+        current_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
+        if (current_time >= initial_time + BUFFER_DELAY) {
+            uint64_t transferred_bytes = qemu_ftell(s->file) - initial_bytes;
+            uint64_t time_spent = current_time - initial_time;
+            double bandwidth = transferred_bytes / time_spent;
+            max_size = bandwidth * migrate_max_downtime() / 1000000;
+
+            s->mbps = time_spent ? (((double) transferred_bytes * 8.0) /
+                    ((double) time_spent / 1000.0)) / 1000.0 / 1000.0 : -1;
+
+            trace_migrate_transferred(transferred_bytes, time_spent,
+                                      bandwidth, max_size);
+            /* if we haven't sent anything, we don't want to recalculate
+               10000 is a small enough number for our purposes */
+            if (s->dirty_bytes_rate && transferred_bytes > 10000) {
+                s->expected_downtime = s->dirty_bytes_rate / bandwidth;
+            }
+
+            qemu_file_reset_rate_limit(s->file);
+            initial_time = current_time;
+            initial_bytes = qemu_ftell(s->file);
+        }
+        if (qemu_file_rate_limit(s->file)) {
+            /* usleep expects microseconds */
+            g_usleep((initial_time + BUFFER_DELAY - current_time)*1000);
+        }
+    }
+
+    qemu_mutex_lock_iothread();
+    if (s->state == MIG_STATE_COMPLETED) {
+        int64_t end_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
+        uint64_t transferred_bytes = qemu_ftell(s->file);
+        s->total_time = end_time - s->total_time;
+        s->downtime = end_time - start_time;
+        if (s->total_time) {
+            s->mbps = (((double) transferred_bytes * 8.0) /
+                       ((double) s->total_time)) / 1000;
+        }
+        runstate_set(RUN_STATE_POSTMIGRATE);
+    } else {
+        if (old_vm_running) {
+            vm_start();
+        }
+    }
+    qemu_bh_schedule(s->cleanup_bh);
+    qemu_mutex_unlock_iothread();
+
+    return NULL;
+}
+
+void migrate_fd_connect(MigrationState *s)
+{
+    s->state = MIG_STATE_SETUP;
+    trace_migrate_set_state(MIG_STATE_SETUP);
+
+    /* This is a best 1st approximation. ns to ms */
+    s->expected_downtime = max_downtime/1000000;
+    s->cleanup_bh = qemu_bh_new(migrate_fd_cleanup, s);
+
+    qemu_file_set_rate_limit(s->file,
+                             s->bandwidth_limit / XFER_LIMIT_RATIO);
+
+    /* Notify before starting migration thread */
+    notifier_list_notify(&migration_state_notifiers, s);
+
+    qemu_thread_create(&s->thread, "migration", migration_thread, s,
+                       QEMU_THREAD_JOINABLE);
+}