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

[Eli Cohen <elic@nvidia.com>]

On Wed, Jun 02, 2021 at 03:07:00PM +0800, Jason Wang wrote:
> 
> 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@nvidia.com>
> > > 
> > > 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@nvidia.com>
> > > Signed-off-by: Jason Wang <jasowang@redhat.com>
> > > ---
> > >   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.
> 

OK.

> 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
> > > 
>