Re: [Qemu-devel] qemu seabios issue with vhost-scsi

[Badari Pulavarty <pbadari@us.ibm.com>]

On 05/23/2013 07:58 AM, Paolo Bonzini wrote:
> Il 23/05/2013 16:48, Badari Pulavarty ha scritto:
>>> The common virtio-scsi code in QEMU should guard against this.  In
>>> virtio-blk data plane I hit a similar case and ended up starting the
>>> data plane thread (equivalent to vhost here) *before* the status
>>> register is set to DRIVER_OK.
>> Thats exactly what my debug in vhost_scsi_set_status() shows.
>>
>> set status started 0 val 0
>> set status started 0 val 0
>> set status started 0 val 0
>> set status started 0 val 0
>> set status started 0 val 0
>> set status started 0 val 3
>> Program received signal SIGSEGV, Segmentation fault.
>>
>> We never got a chance to call vhost_scsi_start() as we are waiting
>> for DRIVER_OK.
> This is the fix in SeaBIOS:
>
> commit 5a7730db57ab0715223421e65b54fb50d6fefe5c
> Author: Asias He <asias@redhat.com>
> Date:   Fri Mar 15 09:45:15 2013 +0800
>
>      virtio-scsi: Set _DRIVER_OK flag before scsi target scanning
>
>      Before we start scsi target scanning, we need to set the
>      VIRTIO_CONFIG_S_DRIVER_OK flag so the device can do setup properly.
>
>      This fix a bug when booting tcm_vhost with seabios.
>
>      Signed-off-by: Asias He <asias@redhat.com>
>      Acked-by: Paolo Bonzini <pbonzini@redhat.com>
>
>
>
> Still, Gleb is right that SeaBIOS should not be able to crash QEMU;
> exit(1) is fine, SIGSEGV is not.
>
> Paolo
>
This fixed the issue and makes the guest boot.

Thanks
Badari