[Qemu-block] [RFC PATCH 1/2] migrate: Allow incoming migration without defer

[Richard Palethorpe]

Allow a QEMU instance which has been started and used without the "-incoming"
flag to accept an incoming migration with the "migrate-incoming" QMP
command. This allows the user to dump the VM state to an external file then
revert to that state at a later time without restarting QEMU.
---
 migration/migration.c | 12 +++++-------
 vl.c                  |  2 ++
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/migration/migration.c b/migration/migration.c
index 0aa596f867..05595a4cec 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1321,14 +1321,14 @@ void migrate_del_blocker(Error *reason)
 void qmp_migrate_incoming(const char *uri, Error **errp)
 {
     Error *local_err = NULL;
-    static bool once = true;
 
-    if (!deferred_incoming) {
-        error_setg(errp, "For use with '-incoming defer'");
+    if (runstate_check(RUN_STATE_INMIGRATE)) {
+        error_setg(errp, "The incoming migration has already been started");
         return;
     }
-    if (!once) {
-        error_setg(errp, "The incoming migration has already been started");
+
+    if (!deferred_incoming) {
+        vm_stop(RUN_STATE_INMIGRATE);
     }
 
     qemu_start_incoming_migration(uri, &local_err);
@@ -1337,8 +1337,6 @@ void qmp_migrate_incoming(const char *uri, Error **errp)
         error_propagate(errp, local_err);
         return;
     }
-
-    once = false;
 }
 
 bool migration_is_blocked(Error **errp)
diff --git a/vl.c b/vl.c
index 9e7235df6d..a91eda039e 100644
--- a/vl.c
+++ b/vl.c
@@ -634,6 +634,7 @@ static const RunStateTransition runstate_transitions_def[] 
= {
     { RUN_STATE_PAUSED, RUN_STATE_POSTMIGRATE },
     { RUN_STATE_PAUSED, RUN_STATE_PRELAUNCH },
     { RUN_STATE_PAUSED, RUN_STATE_COLO},
+    { RUN_STATE_PAUSED, RUN_STATE_INMIGRATE },
 
     { RUN_STATE_POSTMIGRATE, RUN_STATE_RUNNING },
     { RUN_STATE_POSTMIGRATE, RUN_STATE_FINISH_MIGRATE },
@@ -665,6 +666,7 @@ static const RunStateTransition runstate_transitions_def[] 
= {
     { RUN_STATE_RUNNING, RUN_STATE_WATCHDOG },
     { RUN_STATE_RUNNING, RUN_STATE_GUEST_PANICKED },
     { RUN_STATE_RUNNING, RUN_STATE_COLO},
+    { RUN_STATE_RUNNING, RUN_STATE_INMIGRATE },
 
     { RUN_STATE_SAVE_VM, RUN_STATE_RUNNING },
 
-- 
2.16.2