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Re: [Qemu-devel] [PATCH V3 2/3] virtio-blk: fail get_features when both
From: |
Cornelia Huck |
Subject: |
Re: [Qemu-devel] [PATCH V3 2/3] virtio-blk: fail get_features when both scsi and 1.0 were set |
Date: |
Wed, 22 Jul 2015 12:25:31 +0200 |
On Wed, 22 Jul 2015 12:21:32 +0300
"Michael S. Tsirkin" <address@hidden> wrote:
> On Wed, Jul 22, 2015 at 10:58:43AM +0200, Cornelia Huck wrote:
> > On Wed, 22 Jul 2015 13:59:51 +0800
> > Jason Wang <address@hidden> 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!");
> > > + 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.
And I still think requiring user action and not having this work
transparently is a bad idea...
Moreover, I will need a revision-fencing mechanism in any case, when we
introduce further revisions.
- [Qemu-devel] [PATCH V3 0/3] Set correct blk feature for virtio 1.0, Jason Wang, 2015/07/22
- [Qemu-devel] [PATCH V3 1/3] virtio: get_features() can fail, Jason Wang, 2015/07/22
- [Qemu-devel] [PATCH V3 2/3] virtio-blk: fail get_features when both scsi and 1.0 were set, Jason Wang, 2015/07/22
- Re: [Qemu-devel] [PATCH V3 2/3] virtio-blk: fail get_features when both scsi and 1.0 were set, Cornelia Huck, 2015/07/22
- Re: [Qemu-devel] [PATCH V3 2/3] virtio-blk: fail get_features when both scsi and 1.0 were set, Michael S. Tsirkin, 2015/07/22
- Re: [Qemu-devel] [PATCH V3 2/3] virtio-blk: fail get_features when both scsi and 1.0 were set,
Cornelia Huck <=
- Re: [Qemu-devel] [PATCH V3 2/3] virtio-blk: fail get_features when both scsi and 1.0 were set, Michael S. Tsirkin, 2015/07/22
- Re: [Qemu-devel] [PATCH V3 2/3] virtio-blk: fail get_features when both scsi and 1.0 were set, Cornelia Huck, 2015/07/22
- Re: [Qemu-devel] [PATCH V3 2/3] virtio-blk: fail get_features when both scsi and 1.0 were set, Michael S. Tsirkin, 2015/07/22
- Re: [Qemu-devel] [PATCH V3 2/3] virtio-blk: fail get_features when both scsi and 1.0 were set, Cornelia Huck, 2015/07/22
- Re: [Qemu-devel] [PATCH V3 2/3] virtio-blk: fail get_features when both scsi and 1.0 were set, Michael S. Tsirkin, 2015/07/22
- Re: [Qemu-devel] [PATCH V3 2/3] virtio-blk: fail get_features when both scsi and 1.0 were set, Cornelia Huck, 2015/07/22
- Re: [Qemu-devel] [PATCH V3 2/3] virtio-blk: fail get_features when both scsi and 1.0 were set, Michael S. Tsirkin, 2015/07/22
- Re: [Qemu-devel] [PATCH V3 2/3] virtio-blk: fail get_features when both scsi and 1.0 were set, Cornelia Huck, 2015/07/23
- Re: [Qemu-devel] [PATCH V3 2/3] virtio-blk: fail get_features when both scsi and 1.0 were set, Paolo Bonzini, 2015/07/23
- Re: [Qemu-devel] [PATCH V3 2/3] virtio-blk: fail get_features when both scsi and 1.0 were set, Cornelia Huck, 2015/07/23