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

["Michael S. Tsirkin" <mst@redhat.com>]

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.

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