Re: [PATCH V3] vdpa/mlx5: preserve CVQ vringh index

["Michael S. Tsirkin" <mst@redhat.com>]

It's in my tee and I'm sending it to Linus.

On Mon, Dec 04, 2023 at 08:33:22AM -0500, Steven Sistare wrote:
> What's the decision here, pull it, or do not fix it?
> 
> - Steve
> 
> On 11/3/2023 8:26 AM, Steve Sistare wrote:
> > mlx5_vdpa does not preserve userland's view of vring base for the control
> > queue in the following sequence:
> > 
> > ioctl VHOST_SET_VRING_BASE
> > ioctl VHOST_VDPA_SET_STATUS VIRTIO_CONFIG_S_DRIVER_OK
> >   mlx5_vdpa_set_status()
> >     setup_cvq_vring()
> >       vringh_init_iotlb()
> >         vringh_init_kern()
> >           vrh->last_avail_idx = 0;
> > ioctl VHOST_GET_VRING_BASE
> > 
> > To fix, restore the value of cvq->vring.last_avail_idx after calling
> > vringh_init_iotlb.
> > 
> > Fixes: 5262912ef3cf ("vdpa/mlx5: Add support for control VQ and MAC setting")
> > 
> > Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
> > Acked-by: Eugenio Pérez <eperezma@redhat.com>
> > Acked-by: Jason Wang <jasowang@redhat.com>
> > ---
> >  drivers/vdpa/mlx5/net/mlx5_vnet.c | 7 ++++++-
> >  1 file changed, 6 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > index 946488b8989f..ca972af3c89a 100644
> > --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > @@ -2795,13 +2795,18 @@ static int setup_cvq_vring(struct mlx5_vdpa_dev *mvdev)
> >  	struct mlx5_control_vq *cvq = &mvdev->cvq;
> >  	int err = 0;
> >  
> > -	if (mvdev->actual_features & BIT_ULL(VIRTIO_NET_F_CTRL_VQ))
> > +	if (mvdev->actual_features & BIT_ULL(VIRTIO_NET_F_CTRL_VQ)) {
> > +		u16 idx = cvq->vring.last_avail_idx;
> > +
> >  		err = vringh_init_iotlb(&cvq->vring, mvdev->actual_features,
> >  					MLX5_CVQ_MAX_ENT, false,
> >  					(struct vring_desc *)(uintptr_t)cvq->desc_addr,
> >  					(struct vring_avail *)(uintptr_t)cvq->driver_addr,
> >  					(struct vring_used *)(uintptr_t)cvq->device_addr);
> >  
> > +		if (!err)
> > +			cvq->vring.last_avail_idx = cvq->vring.last_used_idx = idx;
> > +	}
> >  	return err;
> >  }
> >