Re: [PATCH 2/6] migration/colo.c: Use cpu_synchronize_all_states()

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Lukas Straub (lukasstraub2@web.de) wrote:
> cpu_synchronize_all_pre_loadvm() marks all vcpus as dirty, so the
> registers are loaded from CPUState before we continue running
> the vm. However if we failover during checkpoint, CPUState is not
> initialized and the registers are loaded with garbage. This causes
> guest hangs and crashes.
> 
> Fix this by using cpu_synchronize_all_states(), which initializes
> CPUState from the current cpu registers additionally to marking
> the vcpus as dirty.
> 
> Signed-off-by: Lukas Straub <lukasstraub2@web.de>

OK, so I think you're saying that if the qemu_loadvm_state_main fails
because we failover, we now have duff CPU state, where we should just
carry on running on the secondary with the current state, so yes


Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> ---
>  migration/colo.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/migration/colo.c b/migration/colo.c
> index 09168627bc..6b2ad35aa4 100644
> --- a/migration/colo.c
> +++ b/migration/colo.c
> @@ -696,7 +696,7 @@ static void colo_incoming_process_checkpoint(MigrationIncomingState *mis,
>      }
>  
>      qemu_mutex_lock_iothread();
> -    cpu_synchronize_all_pre_loadvm();
> +    cpu_synchronize_all_states();
>      ret = qemu_loadvm_state_main(mis->from_src_file, mis);
>      qemu_mutex_unlock_iothread();
>  
> -- 
> 2.20.1
> 


--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK