[PATCH v2 2/7] Fixed qemu crash when guest power off in COLO mode

["Rao, Lei" <lei.rao@intel.com>]

From: "Rao, Lei" <lei.rao@intel.com>

This patch fixes the following:
qemu-system-x86_64: invalid runstate transition: 'shutdown' -> 'running'
Aborted (core dumped)
The gdb bt as following:
0  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50
1  0x00007faa3d613859 in __GI_abort () at abort.c:79
2  0x000055c5a21268fd in runstate_set (new_state=RUN_STATE_RUNNING) at vl.c:723
3  0x000055c5a1f8cae4 in vm_prepare_start () at /home/workspace/colo-qemu/cpus.c:2206
4  0x000055c5a1f8cb1b in vm_start () at /home/workspace/colo-qemu/cpus.c:2213
5  0x000055c5a2332bba in migration_iteration_finish (s=0x55c5a4658810) at migration/migration.c:3376
6  0x000055c5a2332f3b in migration_thread (opaque=0x55c5a4658810) at migration/migration.c:3527
7  0x000055c5a251d68a in qemu_thread_start (args=0x55c5a5491a70) at util/qemu-thread-posix.c:519
8  0x00007faa3d7e9609 in start_thread (arg=<optimized out>) at pthread_create.c:477
9  0x00007faa3d710293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Signed-off-by: Lei Rao <lei.rao@intel.com>
---
 migration/migration.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/migration/migration.c b/migration/migration.c
index 9172686b89..e5b38a492f 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -3616,7 +3616,9 @@ static void migration_iteration_finish(MigrationState *s)
     case MIGRATION_STATUS_CANCELLED:
     case MIGRATION_STATUS_CANCELLING:
         if (s->vm_was_running) {
-            vm_start();
+            if (!runstate_check(RUN_STATE_SHUTDOWN)) {
+                vm_start();
+            }
         } else {
             if (runstate_check(RUN_STATE_FINISH_MIGRATE)) {
                 runstate_set(RUN_STATE_POSTMIGRATE);
-- 
2.30.2