Re: [Qemu-devel] [PATCH V3 2/3] virtio-blk: fail get_features when both scsi and 1.0 were set

[Jason Wang <jasowang@redhat.com>]

On 07/22/2015 05:25 PM, Michael S. Tsirkin wrote:
> On Wed, Jul 22, 2015 at 01:59:51PM +0800, Jason Wang wrote:
>> SCSI passthrough was no longer supported in virtio 1.0, so this patch
>> fail the get_features() when both 1.0 and scsi is set. And also only
>> advertise VIRTIO_BLK_F_SCSI for legacy virtio-blk device.
>>
>> Signed-off-by: Jason Wang <jasowang@redhat.com>
>> ---
>>  hw/block/virtio-blk.c | 9 ++++++++-
>>  1 file changed, 8 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
>> index 4c27974..4716c3e 100644
>> --- a/hw/block/virtio-blk.c
>> +++ b/hw/block/virtio-blk.c
>> @@ -731,7 +731,14 @@ static uint64_t virtio_blk_get_features(VirtIODevice *vdev, uint64_t features,
>>      virtio_add_feature(&features, VIRTIO_BLK_F_GEOMETRY);
>>      virtio_add_feature(&features, VIRTIO_BLK_F_TOPOLOGY);
>>      virtio_add_feature(&features, VIRTIO_BLK_F_BLK_SIZE);
>> -    virtio_add_feature(&features, VIRTIO_BLK_F_SCSI);
>> +    if (__virtio_has_feature(features, VIRTIO_F_VERSION_1)) {
>> +        if (s->conf.scsi) {
>> +            error_setg(errp, "Virtio 1.0 does not support scsi passthrough!");
> A bit better:
> "Virtio modern does not support scsi passthrough - please set disable-modern=on".
>
> It might be even better if we could specify the device that failed the
> initialization, but I don't know how to do that in a way that's
> helpful to the user.

Looks like current error prompt has contained the device?

qemu-system-x86_64: -device
virtio-blk-pci,id=v0,scsi=on,disable-modern=off,drive=img1: Virtio 1.0
does not support scsi passthrough!

>
> Markus?
>
>
>> +            return 0;
>> +        }
>> +    } else {
>> +        virtio_add_feature(&features, VIRTIO_BLK_F_SCSI);
>> +    }
>>  
>>      if (s->conf.config_wce) {
>>          virtio_add_feature(&features, VIRTIO_BLK_F_CONFIG_WCE);
>> -- 
>> 2.1.4