migration/qmp: add command migrate-pause

It pauses an ongoing migration.  Currently it only supports postcopy.
Note that this command will work on either side of the migration.
Basically when we trigger this on one side, it'll interrupt the other
side as well since the other side will get notified on the disconnect
event.

However, it's still possible that the other side is not notified, for
example, when the network is totally broken, or due to some firewall
configuration changes.  In that case, we will also need to run the same
command on the other side so both sides will go into the paused state.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-24-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
---
s/2.12/2.13/

diff --git a/migration/migration.c b/migration/migration.c
index 3deded90e5e7ccc028a9445909438be32ea6f091..05aec2c9050039038c99bcb28b99c3f6e66fad40 100644 (file)
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1507,6 +1507,35 @@ void qmp_migrate_recover(const char *uri, Error **errp)
     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)) {

diff --git a/qapi/migration.json b/qapi/migration.json
index da351d74217f7076ce22994b65a00d63864a8281..23ba85ed3a1d7cb40900c65fa6ef10fa11bc0687 100644 (file)
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -1211,3 +1211,19 @@
 ##
 { 'command': 'migrate-recover', 'data': { 'uri': 'str' },
   'allow-oob': true }
+
+##
+# @migrate-pause:
+#
+# Pause a migration.  Currently it only supports postcopy.
+#
+# Returns: nothing.
+#
+# Example:
+#
+# -> { "execute": "migrate-pause" }
+# <- { "return": {} }
+#
+# Since: 2.13
+##
+{ 'command': 'migrate-pause', 'allow-oob': true }