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SubjectRe: [PATCH RFC 2/3] virtio_ccw: legacy: don't negotiate rev 1/features
On Thu, Dec 04, 2014 at 06:56:06PM +0100, Cornelia Huck wrote:
> On Thu, 4 Dec 2014 19:26:45 +0200
> "Michael S. Tsirkin" <mst@redhat.com> wrote:
>
> > Legacy balloon device doesn't pretend to support revision 1 or 64 bit
> > features.
> >
> > But just in case someone implements a broken one that does, let's not
> > even try to drive legacy only devices using revision 1, and let's not
> > give them a chance to say they support VIRTIO_F_VERSION_1 by not reading
> > high feature bits.
> >
> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > ---
> > drivers/s390/kvm/virtio_ccw.c | 13 ++++++++++---
> > 1 file changed, 10 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/s390/kvm/virtio_ccw.c b/drivers/s390/kvm/virtio_ccw.c
> > index 4a3e6e5..088bdf1 100644
> > --- a/drivers/s390/kvm/virtio_ccw.c
> > +++ b/drivers/s390/kvm/virtio_ccw.c
> > @@ -733,6 +733,9 @@ static u64 virtio_ccw_get_features(struct virtio_device *vdev)
> >
> > rc = le32_to_cpu(features->features);
> >
> > + if (vcdev->revision == 0)
> > + goto out_free;
> > +
> > /* Read second half of the feature bits from the host. */
> > features->index = 1;
> > ccw->cmd_code = CCW_CMD_READ_FEAT;
> > @@ -1182,9 +1185,13 @@ static int virtio_ccw_online(struct ccw_device *cdev)
> > vcdev->vdev.id.vendor = cdev->id.cu_type;
> > vcdev->vdev.id.device = cdev->id.cu_model;
> >
> > - ret = virtio_ccw_set_transport_rev(vcdev);
> > - if (ret)
> > - goto out_free;
> > + if (virtio_device_is_legacy_only(vcdev->vdev.id)) {
>
> Inverted logic?

Ugh, clearly.

> > + ret = virtio_ccw_set_transport_rev(vcdev);
> > + if (ret)
> > + goto out_free;
> > + } else {
> > + vcdev->revision = 0;
> > + }
> >
> > ret = register_virtio_device(&vcdev->vdev);
> > if (ret) {


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