[v5,08/11] dump-guest-memory: add qmp event DUMP_COMPLETED

diff --git a/docs/qmp-events.txt b/docs/qmp-events.txt
index d2f1ce4..1f79588 100644
--- a/docs/qmp-events.txt
+++ b/docs/qmp-events.txt
@@ -220,6 +220,22 @@  Data:
   },
   "timestamp": { "seconds": 1265044230, "microseconds": 450486 } }
 
+DUMP_COMPLETED
+--------------
+
+Emitted when the guest has finished one memory dump.
+
+Data:
+
+- "error": Error message when dump failed. This is only a
+  human-readable string provided when dump failed. It should not be
+  parsed in any way (json-string, optional)
+
+Example:
+
+{ "event": "DUMP_COMPLETED",
+  "data": {} }
+
 GUEST_PANICKED
 --------------
 
diff --git a/dump.c b/dump.c
index 630c67c..1a65fcf 100644
--- a/dump.c
+++ b/dump.c
@@ -25,6 +25,7 @@ 
 #include "qapi/error.h"
 #include "qapi/qmp/qerror.h"
 #include "qmp-commands.h"
+#include "qapi-event.h"
 
 #include <zlib.h>
 #ifdef CONFIG_LZO
@@ -1609,8 +1610,13 @@  static void dump_process(DumpState *s, Error **errp)
     }
 
     s->status = (local_err ? DUMP_STATUS_FAILED : DUMP_STATUS_COMPLETED);
-    error_propagate(errp, local_err);
 
+    /* send DUMP_COMPLETED message (unconditionally) */
+    qapi_event_send_dump_completed(!!local_err, (local_err ? \
+                                   error_get_pretty(local_err) : NULL),
+                                   &error_abort);
+
+    error_propagate(errp, local_err);
     dump_cleanup(s);
 }
 
@@ -1618,13 +1624,8 @@  static void *dump_thread(void *data)
 {
     Error *err = NULL;
     DumpState *s = (DumpState *)data;
-
     dump_process(s, &err);
-
-    if (err) {
-        /* TODO: notify user the error */
-        error_free(err);
-    }
+    error_free(err);
     return NULL;
 }
 
diff --git a/qapi-schema.json b/qapi-schema.json
index 691a130..f0d3c4a 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -2116,7 +2116,8 @@ 
 #               is the fd's name.
 #
 # @detach: #optional if true, QMP will return immediately rather than
-#          waiting for the dump to finish. (since 2.6).
+#          waiting for the dump to finish. A DUMP_COMPLETED event will
+#          occur at the end. (since 2.6).
 #
 # @begin: #optional if specified, the starting physical address.
 #
diff --git a/qapi/event.json b/qapi/event.json
index f0cef01..b18ed66 100644
--- a/qapi/event.json
+++ b/qapi/event.json
@@ -356,3 +356,17 @@ 
 ##
 { 'event': 'MEM_UNPLUG_ERROR',
   'data': { 'device': 'str', 'msg': 'str' } }
+
+##
+# @DUMP_COMPLETED
+#
+# Emitted when background dump has completed
+#
+# @error: #optional human-readable error string that provides
+#         hint on why dump failed. Only presents on failure. The
+#         user should not try to interpret the error string.
+#
+# Since: 2.6
+##
+{ 'event': 'DUMP_COMPLETED' ,
+  'data': { '*error': 'str' } }
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 6b51585..7b6f915 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -857,8 +857,9 @@  Arguments:
 - "paging": do paging to get guest's memory mapping (json-bool)
 - "protocol": destination file(started with "file:") or destination file
               descriptor (started with "fd:") (json-string)
-- "detach": if specified, command will return immediately, without waiting
-            for the dump to finish (json-bool)
+- "detach": if specified, command will return immediately rather than waiting
+            for the dump completion. A DUMP_COMPLETED event will occur at
+            the end. (json-bool)
 - "begin": the starting physical address. It's optional, and should be specified
            with length together (json-int)
 - "length": the memory size, in bytes. It's optional, and should be specified