migration: Add 'pause-before-switchover' capability

When 'pause-before-switchover' is enabled, the outgoing migration will pause before invalidating the block devices and serializing the device state. At this point the management layer gets the chance to clean up any device jobs or other device users before the migration completes. Signed-off-by: Dr. David Alan Gilbert <[email protected]> Reviewed-by: Peter Xu <[email protected]> Reviewed-by: Juan Quintela <[email protected]> Signed-off-by: Juan Quintela <[email protected]>
stefanha · Oct 23, 2017 · 93fbd03 · 93fbd03
1 parent 80f8dfd
commit 93fbd03
Show file tree

Hide file tree

Showing 3 changed files with 15 additions and 1 deletion.
diff --git a/migration/migration.c b/migration/migration.c
@@ -1511,6 +1511,16 @@ bool migrate_use_multifd(void)
     return s->enabled_capabilities[MIGRATION_CAPABILITY_X_MULTIFD];
 }
 
+bool migrate_pause_before_switchover(void)
+{
+    MigrationState *s;
+
+    s = migrate_get_current();
+
+    return s->enabled_capabilities[
+        MIGRATION_CAPABILITY_PAUSE_BEFORE_SWITCHOVER];
+}
+
 int migrate_multifd_channels(void)
 {
     MigrationState *s;

diff --git a/migration/migration.h b/migration/migration.h
@@ -177,6 +177,7 @@ bool migrate_zero_blocks(void);
 
 bool migrate_auto_converge(void);
 bool migrate_use_multifd(void);
+bool migrate_pause_before_switchover(void);
 int migrate_multifd_channels(void);
 int migrate_multifd_page_count(void);
 

diff --git a/qapi/migration.json b/qapi/migration.json
@@ -341,14 +341,17 @@
 # @return-path: If enabled, migration will use the return path even
 #               for precopy. (since 2.10)
 #
+# @pause-before-switchover: Pause outgoing migration before serialising device
+#          state and before disabling block IO (since 2.11)
+#
 # @x-multifd: Use more than one fd for migration (since 2.11)
 #
 # Since: 1.2
 ##
 { 'enum': 'MigrationCapability',
   'data': ['xbzrle', 'rdma-pin-all', 'auto-converge', 'zero-blocks',
            'compress', 'events', 'postcopy-ram', 'x-colo', 'release-ram',
-           'block', 'return-path', 'x-multifd' ] }
+           'block', 'return-path', 'pause-before-switchover', 'x-multifd' ] }
 
 ##
 # @MigrationCapabilityStatus: