Re: [PATCH V2 4/4] virtio/vdpa: clear the virtqueue state during probe

[Jason Wang]

在 2021/6/2 下午2:17, Eli Cohen 写道:
> On Wed, Jun 02, 2021 at 10:10:43AM +0800, Jason Wang wrote:
> > From: Eli Cohen <elic@xxxxxxxxxx>
> >
> > Clear the available index as part of the initialization process to
> > clear and values that might be left from previous usage of the device.
> > For example, if the device was previously used by vhost_vdpa and now
> > probed by vhost_vdpa, you want to start with indices.
> >
> > Fixes: c043b4a8cf3b ("virtio: introduce a vDPA based transport")
> > Signed-off-by: Eli Cohen <elic@xxxxxxxxxx>
> > Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
> > ---
> >   drivers/virtio/virtio_vdpa.c | 15 +++++++++++++++
> >   1 file changed, 15 insertions(+)
> >
> > diff --git a/drivers/virtio/virtio_vdpa.c b/drivers/virtio/virtio_vdpa.c
> > index e28acf482e0c..e1a141135992 100644
> > --- a/drivers/virtio/virtio_vdpa.c
> > +++ b/drivers/virtio/virtio_vdpa.c
> > @@ -142,6 +142,8 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned int index,
> >   	struct vdpa_callback cb;
> >   	struct virtqueue *vq;
> >   	u64 desc_addr, driver_addr, device_addr;
> > +	/* Assume split virtqueue, switch to packed if necessary */
> > +	struct vdpa_vq_state state = {0};
> >   	unsigned long flags;
> >   	u32 align, num;
> >   	int err;
> > @@ -191,6 +193,19 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned int index,
> >   		goto err_vq;
> >   	}
> >   
> > +	/* reset virtqueue state index */
> > +	if (virtio_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
> > +		struct vdpa_vq_state_packed *s = &state.packed;
> > +
> > +		s->last_avail_counter = 1;
> > +		s->last_avail_idx = 0;
> It's already 0
>
> > +		s->last_used_counter = 1;
> > +		s->last_used_idx = 0;
> already 0


Yes, but for completeness and make code easy to read, it's no harm to 
keep them I think.

Thanks


> > +	}
> > +	err = ops->set_vq_state(vdpa, index, &state);
> > +	if (err)
> > +		goto err_vq;
> > +
> >   	ops->set_vq_ready(vdpa, index, 1);
> >   
> >   	vq->priv = info;
> > --
> > 2.25.1