On Wed, Jul 22, 2015 at 10:58:43AM +0200, Cornelia Huck wrote:
> On Wed, 22 Jul 2015 13:59:51 +0800
> Jason Wang <jasow...@redhat.com> 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 <jasow...@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!");
> > + 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);
>
> Do we advertise F_SCSI even if scsi is not configured in order to keep
> the same bits as before? I'm afraid I don't remember, that thread was
> long :/
>
> I'm asking because I'd like to depend on that bit to decide whether I
> can negotiate revision 1 for ccw and subsequently offer VERSION_1. It
> would be an easy thing to do, and I'd like to avoid mucking around with
> device-specific configuration from the transport.
>
> To illustrate what I'm talking about, my current patchset for virtio-1
> on ccw is here:
>
> git://github.com/cohuck/qemu virtio-1-ccw-2.5
I still think you are over-engineering it.
Just add a property to disable the modern interface.
Anyone using scsi passthrough will have to set that,
if not - above patch will make initialization fail.
--
MST
