migration: create migration event

We have one argument that tells us what event has happened.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

docs/qmp/qmp-events.txt

@@ -473,6 +473,20 @@ Example:
 { "timestamp": {"seconds": 1290688046, "microseconds": 417172},
   "event": "SPICE_MIGRATE_COMPLETED" }
 
+MIGRATION
+---------
+
+Emitted when a migration event happens
+
+Data: None.
+
+ - "status": migration status
+     See MigrationStatus in ~/qapi-schema.json for possible values
+
+Example:
+
+{"timestamp": {"seconds": 1432121972, "microseconds": 744001},
+ "event": "MIGRATION", "data": {"status": "completed"}}
 
 STOP
 ----

migration/migration.c

@@ -27,6 +27,7 @@
 #include "qmp-commands.h"
 #include "trace.h"
 #include "qapi/util.h"
+#include "qapi-event.h"
 
 #define MAX_THROTTLE  (32 << 20)      /* Migration speed throttling */
 
@@ -510,6 +511,7 @@ void qmp_migrate_set_parameters(bool has_compress_level,
 static void migrate_set_state(MigrationState *s, int old_state, int new_state)
 {
     if (atomic_cmpxchg(&s->state, old_state, new_state) == old_state) {
+        qapi_event_send_migration(new_state, &error_abort);
         trace_migrate_set_state(new_state);
     }
 }

qapi/event.json

@@ -242,6 +242,18 @@
 ##
 { 'event': 'SPICE_MIGRATE_COMPLETED' }
 
+##
+# @MIGRATION
+#
+# Emitted when a migration event happens
+#
+# @status: @MigrationStatus describing the current migration status.
+#
+# Since: 2.4
+##
+{ 'event': 'MIGRATION',
+  'data': {'status': 'MigrationStatus'}}
+
 ##
 # @ACPI_DEVICE_OST
 #