RE: [PATCH 02/10] Fix the qemu crash when guest shutdown during checkpoint

[Rao, Lei]

The Primary VM can be shut down when it is in COLO state, which may trigger 
this bug.
About 'shutdown' -> 'colo' -> 'running', I think you are right, I did have the 
problems you said. For 'shutdown'->'colo', The fixed 
patch(5647051f432b7c9b57525470b0a79a31339062d2) have been merged.
Recently, I found another bug as follows in the test.
        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

For the bug, I made the following changes:
        @@ -3379,7 +3379,9 @@ 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);
                                 
I will send the patch to community after more test.

Thanks,
Lei.

-----Original Message-----
From: Lukas Straub <lukasstraub2@web.de> 
Sent: Thursday, January 21, 2021 3:13 AM
To: Rao, Lei <lei.rao@intel.com>
Cc: Zhang, Chen <chen.zhang@intel.com>; lizhijian@cn.fujitsu.com; 
jasowang@redhat.com; zhang.zhanghailiang@huawei.com; quintela@redhat.com; 
dgilbert@redhat.com; qemu-devel@nongnu.org
Subject: Re: [PATCH 02/10] Fix the qemu crash when guest shutdown during 
checkpoint

On Wed, 13 Jan 2021 10:46:27 +0800
leirao <lei.rao@intel.com> wrote:

> From: "Rao, Lei" <lei.rao@intel.com>
> 
> This patch fixes the following:
>     qemu-system-x86_64: invalid runstate transition: 'colo' ->'shutdown'
>     Aborted (core dumped)
> 
> Signed-off-by: Lei Rao <lei.rao@intel.com>

I wonder how that is possible, since the VM is stopped during 'colo' state.

Unrelated to this patch, I think this area needs some work since the following 
unintended runstate transition is possible:
'shutdown' -> 'colo' -> 'running'.

> ---
>  softmmu/runstate.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/softmmu/runstate.c b/softmmu/runstate.c index 
> 636aab0..455ad0d 100644
> --- a/softmmu/runstate.c
> +++ b/softmmu/runstate.c
> @@ -125,6 +125,7 @@ static const RunStateTransition 
> runstate_transitions_def[] = {
>      { RUN_STATE_RESTORE_VM, RUN_STATE_PRELAUNCH },
>  
>      { RUN_STATE_COLO, RUN_STATE_RUNNING },
> +    { RUN_STATE_COLO, RUN_STATE_SHUTDOWN},
>  
>      { RUN_STATE_RUNNING, RUN_STATE_DEBUG },
>      { RUN_STATE_RUNNING, RUN_STATE_INTERNAL_ERROR },



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