Re: [Qemu-devel] [PATCH 2/2] accel: Unbreak accelerator fallback

[Igor Mammedov]

On Wed, 27 Mar 2019 16:03:47 +0100
Markus Armbruster <address@hidden> wrote:

> When the user specifies a list of accelerators, we pick the first one
> that initializes successfully.  Recent commit 1a3ec8c1564 broke that.
> Reproducer:
> 
>     $ qemu-system-x86_64 --machine accel=xen:tcg
>     xencall: error: Could not obtain handle on privileged command interface: 
> No such file or directory
>     xen be core: xen be core: can't open xen interface
>     can't open xen interface
>     qemu-system-x86_64: failed to initialize Xen: Operation not permitted
>     qemu-system-x86_64: /home/armbru/work/qemu/qom/object.c:436: 
> object_set_accelerator_compat_props: Assertion `!object_compat_props[0]' 
> failed.
> 
> Root cause: we register accelerator compat properties even when the
> accelerator fails.  The failed assertion is
> object_set_accelerator_compat_props() telling us off.  Fix by calling
> it only for the accelerator that succeeded.
> 
> Fixes: 1a3ec8c1564f51628cce10d435a2e22559ea29fd
> Signed-off-by: Markus Armbruster <address@hidden>

Reviewed-by: Igor Mammedov <address@hidden>

> ---
>  accel/accel.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/accel/accel.c b/accel/accel.c
> index 8deb475b5d..454fef9d92 100644
> --- a/accel/accel.c
> +++ b/accel/accel.c
> @@ -65,8 +65,9 @@ static int accel_init_machine(AccelClass *acc, MachineState 
> *ms)
>          ms->accelerator = NULL;
>          *(acc->allowed) = false;
>          object_unref(OBJECT(accel));
> +    } else {
> +        object_set_accelerator_compat_props(acc->compat_props);
>      }
> -    object_set_accelerator_compat_props(acc->compat_props);
>      return ret;
>  }
>