On Wed, Jun 02, 2021 at 03:05:35PM +0800, Jason Wang wrote:
>
> 在 2021/6/2 下午2:13, Eli Cohen 写道:
> > On Wed, Jun 02, 2021 at 10:10:42AM +0800, Jason Wang wrote:
> > > We used to fail the set_vq_state() since it was not supported yet by
> > > the virtio spec. But if the bus tries to set the state which is equal
> > > to the device initial state after reset, we can let it go.
> > >
> > > This is a must for virtio_vdpa() to set vq state during probe which is
> > > required for some vDPA parents.
> > >
> > > Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
> > > ---
> > > drivers/vdpa/virtio_pci/vp_vdpa.c | 42 ++++++++++++++++++++++++++++---
> > > 1 file changed, 39 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/vdpa/virtio_pci/vp_vdpa.c b/drivers/vdpa/virtio_pci/vp_vdpa.c
> > > index c76ebb531212..18bf4a422772 100644
> > > --- a/drivers/vdpa/virtio_pci/vp_vdpa.c
> > > +++ b/drivers/vdpa/virtio_pci/vp_vdpa.c
> > > @@ -210,13 +210,49 @@ static int vp_vdpa_get_vq_state(struct vdpa_device *vdpa, u16 qid,
> > > return -EOPNOTSUPP;
> > > }
> > > +static int vp_vdpa_set_vq_state_split(struct vdpa_device *vdpa,
> > > + const struct vdpa_vq_state *state)
> > > +{
> > > + const struct vdpa_vq_state_split *split = &state->split;
> > > +
> > > + if (split->avail_index == 0)
> > > + return 0;
> > > +
> > > + return -EOPNOTSUPP;
> > > +}
> > > +
> > > +static int vp_vdpa_set_vq_state_packed(struct vdpa_device *vdpa,
> > > + const struct vdpa_vq_state *state)
> > > +{
> > > + const struct vdpa_vq_state_packed *packed = &state->packed;
> > > +
> > > + if (packed->last_avail_counter == 1 &&
> > Can you elaborate on the requirement on last_avail_counter and
> > last_used_counter?
>
>
> This is required by the virtio spec:
>
> "
> 2.7.1 Driver and Device Ring Wrap Counters
> Each of the driver and the device are expected to maintain, internally, a
> single-bit ring wrap counter initialized to 1.
> "
>
> For virtio-pci device, since there's no way to assign the value of those
> counters, the counters will be reset to 1 after reset, otherwise the driver
> can't work.
I see, thanks for the explanation.
>
> Thanks
>
>
> >
> > > + packed->last_avail_idx == 0 &&
> > > + packed->last_used_counter == 1 &&
> > > + packed->last_used_idx == 0)
> > > + return 0;
> > > +
> > > + return -EOPNOTSUPP;
> > > +}
> > > +
> > > static int vp_vdpa_set_vq_state(struct vdpa_device *vdpa, u16 qid,
> > > const struct vdpa_vq_state *state)
> > > {
> > > - /* Note that this is not supported by virtio specification, so
> > > - * we return -ENOPOTSUPP here. This means we can't support live
> > > - * migration, vhost device start/stop.
> > > + struct virtio_pci_modern_device *mdev = vdpa_to_mdev(vdpa);
> > > +
> > > + /* Note that this is not supported by virtio specification.
> > > + * But if the state is by chance equal to the device initial
> > > + * state, we can let it go.
> > > */
> > > + if ((vp_modern_get_status(mdev) & VIRTIO_CONFIG_S_FEATURES_OK) &&
> > > + !vp_modern_get_queue_enable(mdev, qid)) {
> > > + if (vp_modern_get_driver_features(mdev) &
> > > + BIT_ULL(VIRTIO_F_RING_PACKED))
> > > + return vp_vdpa_set_vq_state_packed(vdpa, state);
> > > + else
> > > + return vp_vdpa_set_vq_state_split(vdpa, state);
> > > + }
> > > +
> > > return -EOPNOTSUPP;
> > > }
> > > --
> > > 2.25.1
> > >
>
