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

[Michael S. Tsirkin]

On Wed, Jul 22, 2015 at 01:12:45PM +0300, Michael S. Tsirkin wrote:
> On Wed, Jul 22, 2015 at 05:52:29PM +0800, Jason Wang wrote:
> > 
> > 
> > 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 <address@hidden>
> > >> ---
> > >>  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!
> 
> Cool, then the message I suggested will contain all the
> necessary information.

Maybe add "or switch to virtio-scsi".

> > >
> > > 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