On Fri, 12 Dec 2014 11:55:38 +0100
Thomas Huth <thuth@xxxxxxxxxxxxxxxxxx> wrote:
> On Thu, 11 Dec 2014 14:25:14 +0100
> Cornelia Huck <cornelia.huck@xxxxxxxxxx> wrote:
>
> > For virtio-1 devices, the driver must not attempt to set feature bits
> > after it set FEATURES_OK in the device status. Simply reject it in
> > that case.
> >
> > Signed-off-by: Cornelia Huck <cornelia.huck@xxxxxxxxxx>
> > ---
> > hw/virtio/virtio.c | 16 ++++++++++++++--
> > include/hw/virtio/virtio.h | 2 ++
> > 2 files changed, 16 insertions(+), 2 deletions(-)
> >
> > diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> > index 57190ba..a3dd67b 100644
> > --- a/hw/virtio/virtio.c
> > +++ b/hw/virtio/virtio.c
> > @@ -978,7 +978,7 @@ void virtio_save(VirtIODevice *vdev, QEMUFile *f)
> > vmstate_save_state(f, &vmstate_virtio, vdev);
> > }
> >
> > -int virtio_set_features(VirtIODevice *vdev, uint64_t val)
> > +static int __virtio_set_features(VirtIODevice *vdev, uint64_t val)
>
> Maybe avoid the double underscores here? But unfortunately, I also fail
> to come up with a better suggestion for a name here ...
virtio_set_features_nocheck()?
This function is only called within virtio.c anyway...
>
> > {
> > BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
> > VirtioBusClass *vbusk = VIRTIO_BUS_GET_CLASS(qbus);
> > @@ -994,6 +994,18 @@ int virtio_set_features(VirtIODevice *vdev, uint64_t val)
> > return bad ? -1 : 0;
> > }
> >
> > +int virtio_set_features(VirtIODevice *vdev, uint64_t val)
> > +{
> > + /*
> > + * The driver must not attempt to set features after feature negotiation
> > + * has finished.
> > + */
> > + if (vdev->status & VIRTIO_CONFIG_S_FEATURES_OK) {
> > + return -EINVAL;
> > + }
>
> Hmm, according to your patch description, the FEATURES_OK check only
> applies to virtio-1.0 devices ... so shouldn't there be a check for
> virtio-1 here? Or did I miss something?
A device in legacy mode will never have FEATURES_OK set. But it is a
bit non-obvious - maybe adding a check for VERSION_1 does not hurt.
>
> > + return __virtio_set_features(vdev, val);
> > +}
>
> Thomas
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