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@@ -105,7 +105,7 @@ static MigrationIncomingState *current_incoming;
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static GSList *migration_blockers[MIG_MODE__MAX];
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static bool migration_object_check(MigrationState *ms, Error **errp);
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-static int migration_maybe_pause(MigrationState *s, int new_state);
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+static bool migration_switchover_start(MigrationState *s);
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static void migrate_fd_cancel(MigrationState *s);
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static bool close_return_path_on_source(MigrationState *s);
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static void migration_completion_end(MigrationState *s);
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@@ -2657,11 +2657,6 @@ static int postcopy_start(MigrationState *ms, Error **errp)
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}
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}
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- if (!migrate_pause_before_switchover()) {
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- migrate_set_state(&ms->state, MIGRATION_STATUS_ACTIVE,
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- MIGRATION_STATUS_POSTCOPY_ACTIVE);
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- }
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-
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trace_postcopy_start();
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bql_lock();
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trace_postcopy_start_set_run();
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@@ -2672,10 +2667,8 @@ static int postcopy_start(MigrationState *ms, Error **errp)
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goto fail;
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}
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- ret = migration_maybe_pause(ms, MIGRATION_STATUS_POSTCOPY_ACTIVE);
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- if (ret < 0) {
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- error_setg_errno(errp, -ret, "%s: Failed in migration_maybe_pause()",
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- __func__);
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+ if (!migration_switchover_start(ms)) {
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+ error_setg(errp, "migration_switchover_start() failed");
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goto fail;
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}
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@@ -2800,6 +2793,10 @@ static int postcopy_start(MigrationState *ms, Error **errp)
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*/
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migration_rate_set(migrate_max_postcopy_bandwidth());
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+ /* Now, switchover looks all fine, switching to postcopy-active */
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+ migrate_set_state(&ms->state, MIGRATION_STATUS_DEVICE,
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+ MIGRATION_STATUS_POSTCOPY_ACTIVE);
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+
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bql_unlock();
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return ret;
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@@ -2816,14 +2813,39 @@ fail:
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}
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/**
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- * migration_maybe_pause: Pause if required to by
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- * migrate_pause_before_switchover called with the BQL locked
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- * Returns: 0 on success
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+ * @migration_switchover_start: Start VM switchover procedure
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+ *
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+ * @s: The migration state object pointer
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+ *
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+ * Prepares for the switchover, depending on "pause-before-switchover"
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+ * capability.
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+ *
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+ * If cap set, state machine goes like:
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+ * [postcopy-]active -> pre-switchover -> device
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+ *
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+ * If cap not set:
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+ * [postcopy-]active -> device
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+ *
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+ * Returns: true on success, false on interruptions.
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*/
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-static int migration_maybe_pause(MigrationState *s, int new_state)
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+static bool migration_switchover_start(MigrationState *s)
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{
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+ /* Concurrent cancellation? Quit */
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+ if (s->state == MIGRATION_STATUS_CANCELLING) {
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+ return false;
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+ }
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+
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+ /*
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+ * No matter precopy or postcopy, since we still hold BQL it must not
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+ * change concurrently to CANCELLING, so it must be either ACTIVE or
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+ * POSTCOPY_ACTIVE.
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+ */
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+ assert(migration_is_active());
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+
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+ /* If the pre stage not requested, directly switch to DEVICE */
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if (!migrate_pause_before_switchover()) {
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- return 0;
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+ migrate_set_state(&s->state, s->state, MIGRATION_STATUS_DEVICE);
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+ return true;
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}
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/* Since leaving this state is not atomic with posting the semaphore
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@@ -2836,23 +2858,22 @@ static int migration_maybe_pause(MigrationState *s, int new_state)
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/* This block intentionally left blank */
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}
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+ /* Update [POSTCOPY_]ACTIVE to PRE_SWITCHOVER */
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+ migrate_set_state(&s->state, s->state, MIGRATION_STATUS_PRE_SWITCHOVER);
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+ bql_unlock();
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+
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+ qemu_sem_wait(&s->pause_sem);
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+
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+ bql_lock();
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/*
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- * If the migration is cancelled when it is in the completion phase,
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- * the migration state is set to MIGRATION_STATUS_CANCELLING.
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- * So we don't need to wait a semaphore, otherwise we would always
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- * wait for the 'pause_sem' semaphore.
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+ * After BQL released and retaken, the state can be CANCELLING if it
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+ * happend during sem_wait().. Only change the state if it's still
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+ * pre-switchover.
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*/
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- if (s->state != MIGRATION_STATUS_CANCELLING) {
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- migrate_set_state(&s->state, s->state,
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- MIGRATION_STATUS_PRE_SWITCHOVER);
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- bql_unlock();
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- qemu_sem_wait(&s->pause_sem);
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- bql_lock();
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- migrate_set_state(&s->state, MIGRATION_STATUS_PRE_SWITCHOVER,
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- new_state);
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- }
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+ migrate_set_state(&s->state, MIGRATION_STATUS_PRE_SWITCHOVER,
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+ MIGRATION_STATUS_DEVICE);
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- return s->state == new_state ? 0 : -EINVAL;
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+ return s->state == MIGRATION_STATUS_DEVICE;
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}
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static int migration_completion_precopy(MigrationState *s)
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@@ -2868,8 +2889,7 @@ static int migration_completion_precopy(MigrationState *s)
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}
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}
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- ret = migration_maybe_pause(s, MIGRATION_STATUS_DEVICE);
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- if (ret < 0) {
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+ if (!migration_switchover_start(s)) {
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goto out_unlock;
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}
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Peter Xu