[PATCH V9 44/46] migration: fix suspended runstate

[Steve Sistare]

Migration of a guest in the suspended state is broken.  The incoming
migration code automatically tries to wake the guest, which IMO is
wrong -- the guest should end migration in the same state it started.
Further, the wakeup attempt merely sets state to running but does
not actually start the guest, as vm_start was never called during this
invocation of qemu.

To fix, leave the guest in the suspended state, but call
qemu_system_start_on_wakeup_request() so the guest is properly resumed
when the client sends a system_wakeup command.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
---
 migration/migration.c | 11 ++++-------
 softmmu/runstate.c    |  1 +
 2 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/migration/migration.c b/migration/migration.c
index e0fc2b8..45eebea 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -568,6 +568,10 @@ static void process_incoming_migration_bh(void *opaque)
         vm_start();
     } else {
         runstate_set(global_state_get_runstate());
+        if (runstate_check(RUN_STATE_SUSPENDED)) {
+            /* Force vm_start to be called later. */
+            qemu_system_start_on_wakeup_request();
+        }
     }
     /*
      * This must happen after any state changes since as soon as an external
@@ -3273,7 +3277,6 @@ static int postcopy_start(MigrationState *ms)
     qemu_mutex_lock_iothread();
     trace_postcopy_start_set_run();
 
-    qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER, NULL);
     global_state_store();
     ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
     if (ret < 0) {
@@ -3484,7 +3487,6 @@ static void migration_completion(MigrationState *s)
     if (s->state == MIGRATION_STATUS_ACTIVE) {
         qemu_mutex_lock_iothread();
         s->downtime_start = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
-        qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER, NULL);
         s->vm_was_running = runstate_is_running();
         ret = global_state_store();
 
@@ -4285,11 +4287,6 @@ static void *bg_migration_thread(void *opaque)
 
     qemu_mutex_lock_iothread();
 
-    /*
-     * If VM is currently in suspended state, then, to make a valid runstate
-     * transition in vm_stop_force_state() we need to wakeup it up.
-     */
-    qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER, NULL);
     s->vm_was_running = runstate_is_running();
 
     if (global_state_store()) {
diff --git a/softmmu/runstate.c b/softmmu/runstate.c
index c7db5ac..6ba0a4e 100644
--- a/softmmu/runstate.c
+++ b/softmmu/runstate.c
@@ -154,6 +154,7 @@ static const RunStateTransition runstate_transitions_def[] 
= {
     { RUN_STATE_RUNNING, RUN_STATE_SUSPENDED },
     { RUN_STATE_SUSPENDED, RUN_STATE_RUNNING },
     { RUN_STATE_SUSPENDED, RUN_STATE_FINISH_MIGRATE },
+    { RUN_STATE_SUSPENDED, RUN_STATE_PAUSED },
     { RUN_STATE_SUSPENDED, RUN_STATE_PRELAUNCH },
     { RUN_STATE_SUSPENDED, RUN_STATE_COLO},
 
-- 
1.8.3.1