Re: [Qemu-devel] [PULL for-2.4 2/3] migration: Fix global state with Xen.

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

* Amit Shah (amit.shah@redhat.com) wrote:
> From: Anthony PERARD <anthony.perard@gmail.com>
> 
> When doing migration via the QMP command xen_save_devices_state, the
> current runstate is not store into the global state section. Also the
> current runstate is not the one we want on the receiver side.
> 
> During migration, the Xen toolstack paused QEMU before save the devices
> state. Also, the toolstack expect QEMU to autostart when the migration is
> finished.
> So this patch store "running" as it's current runstate.
> 
> Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
> Message-Id: <1438098885-4339-3-git-send-email-anthony.perard@citrix.com>
> Signed-off-by: Amit Shah <amit.shah@redhat.com>
> ---
>  include/migration/migration.h | 1 +
>  migration/migration.c         | 7 +++++++
>  migration/savevm.c            | 1 +
>  3 files changed, 9 insertions(+)
> 
> diff --git a/include/migration/migration.h b/include/migration/migration.h
> index a2f8ed0..8334621 100644
> --- a/include/migration/migration.h
> +++ b/include/migration/migration.h
> @@ -203,4 +203,5 @@ void register_global_state(void);
>  void global_state_set_optional(void);
>  void savevm_skip_configuration(void);
>  int global_state_store(void);
> +void global_state_store_running(void);
>  #endif
> diff --git a/migration/migration.c b/migration/migration.c
> index fd4f99b..175a397 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -122,6 +122,13 @@ int global_state_store(void)
>      return 0;
>  }
>  
> +void global_state_store_running(void)
> +{
> +    const char *state = RunState_lookup[RUN_STATE_RUNNING];
> +    memcpy((char *)global_state.runstate,
> +           state, sizeof(global_state.runstate));
> +}

As mentioned previously, I think that needs to be a strcpy,
NOT a memcpy; the RuNState_lookup[] array isn't guaranteed to
be long enough to fulfill that memcpy.

Dave

> +
>  static bool global_state_received(void)
>  {
>      return global_state.received;
> diff --git a/migration/savevm.c b/migration/savevm.c
> index 81dbe58..6071215 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -1394,6 +1394,7 @@ void qmp_xen_save_devices_state(const char *filename, Error **errp)
>  
>      saved_vm_running = runstate_is_running();
>      vm_stop(RUN_STATE_SAVE_VM);
> +    global_state_store_running();
>  
>      f = qemu_fopen(filename, "wb");
>      if (!f) {
> -- 
> 2.4.3
> 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK