Re: [PATCH v5 22/22] virtio_net: support set_ringparam

[Xuan Zhuo <xuanzhuo@linux.alibaba.com>]

On Wed, 16 Feb 2022 12:14:39 +0800, Jason Wang <jasowang@redhat.com> wrote:
> On Mon, Feb 14, 2022 at 4:15 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote:
> >
> > Support set_ringparam based on virtio queue reset.
> >
> > The rx,tx_pending required to be passed must be power of 2.
> >
> > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> > ---
> >  drivers/net/virtio_net.c | 50 ++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 50 insertions(+)
> >
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > index f9bb760c6dbd..bf460ea87354 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -2308,6 +2308,55 @@ static void virtnet_get_ringparam(struct net_device *dev,
> >         ring->tx_pending = virtqueue_get_vring_size(vi->sq[0].vq);
> >  }
> >
> > +static int virtnet_set_ringparam(struct net_device *dev,
> > +                                struct ethtool_ringparam *ring,
> > +                                struct kernel_ethtool_ringparam *kernel_ring,
> > +                                struct netlink_ext_ack *extack)
> > +{
> > +       struct virtnet_info *vi = netdev_priv(dev);
> > +       u32 rx_pending, tx_pending;
> > +       int i, err;
> > +
> > +       if (ring->rx_mini_pending || ring->rx_jumbo_pending)
> > +               return -EINVAL;
> > +
> > +       rx_pending = virtqueue_get_vring_size(vi->rq[0].vq);
> > +       tx_pending = virtqueue_get_vring_size(vi->sq[0].vq);
> > +
> > +       if (ring->rx_pending == rx_pending &&
> > +           ring->tx_pending == tx_pending)
> > +               return 0;
> > +
> > +       if (ring->rx_pending > virtqueue_get_vring_max_size(vi->rq[0].vq))
> > +               return -EINVAL;
> > +
> > +       if (ring->tx_pending > virtqueue_get_vring_max_size(vi->sq[0].vq))
> > +               return -EINVAL;
> > +
> > +       if (!is_power_of_2(ring->rx_pending))
> > +               return -EINVAL;
> > +
> > +       if (!is_power_of_2(ring->tx_pending))
> > +               return -EINVAL;
>
> We'd better leave those checks to the virtio core where it knows
> packed virtqueue doesn't have this limitation.

OK.

>
> > +
> > +       for (i = 0; i < vi->max_queue_pairs; i++) {
> > +               if (ring->tx_pending != tx_pending) {
> > +                       virtio_set_max_ring_num(vi->vdev, ring->tx_pending);
>
> The name is kind of confusing, I guess it should not be the maximum
> ring. And this needs to be done after the reset, and it would be even
> better to disallow such change when virtqueue is not resetted.

OK.

Thanks.

>
> > +                       err = virtnet_tx_vq_reset(vi, i);
> > +                       if (err)
> > +                               return err;
> > +               }
> > +
> > +               if (ring->rx_pending != rx_pending) {
> > +                       virtio_set_max_ring_num(vi->vdev, ring->rx_pending);
> > +                       err = virtnet_rx_vq_reset(vi, i);
> > +                       if (err)
> > +                               return err;
> > +               }
> > +       }
> > +
> > +       return 0;
> > +}
> >
> >  static void virtnet_get_drvinfo(struct net_device *dev,
> >                                 struct ethtool_drvinfo *info)
> > @@ -2541,6 +2590,7 @@ static const struct ethtool_ops virtnet_ethtool_ops = {
> >         .get_drvinfo = virtnet_get_drvinfo,
> >         .get_link = ethtool_op_get_link,
> >         .get_ringparam = virtnet_get_ringparam,
> > +       .set_ringparam = virtnet_set_ringparam,
> >         .get_strings = virtnet_get_strings,
> >         .get_sset_count = virtnet_get_sset_count,
> >         .get_ethtool_stats = virtnet_get_ethtool_stats,
> > --
> > 2.31.0
> >
>