On Mon, Jan 9, 2023 at 10:48 AM Heng Qi <hengqi@xxxxxxxxxxxxxxxxx> wrote:
>
>
>
> 在 2023/1/3 下午2:40, Heng Qi 写道:
> > When the xdp program sets xdp.frags, which means it can process
> > multi-buffer packets over larger MTU, so we continue to support xdp.
> > But for single-buffer xdp, we should keep checking for MTU.
> >
> > Signed-off-by: Heng Qi <hengqi@xxxxxxxxxxxxxxxxx>
> > Reviewed-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
> > ---
> > drivers/net/virtio_net.c | 10 ++++++----
> > 1 file changed, 6 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > index 443aa7b8f0ad..60e199811212 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -3074,7 +3074,9 @@ static int virtnet_restore_guest_offloads(struct virtnet_info *vi)
> > static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog,
> > struct netlink_ext_ack *extack)
> > {
> > - unsigned long int max_sz = PAGE_SIZE - sizeof(struct padded_vnet_hdr);
> > + unsigned int room = SKB_DATA_ALIGN(VIRTIO_XDP_HEADROOM +
> > + sizeof(struct skb_shared_info));
> > + unsigned int max_sz = PAGE_SIZE - room - ETH_HLEN;
>
> Hi Jason, I've updated the calculation of 'max_sz' in this patch instead
> of a separate bugfix, since doing so also seemed clear.
Sure, I will review it with this series no later than the end of this week.
Thanks
>
> Thanks.
>
> > struct virtnet_info *vi = netdev_priv(dev);
> > struct bpf_prog *old_prog;
> > u16 xdp_qp = 0, curr_qp;
> > @@ -3095,9 +3097,9 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog,
> > return -EINVAL;
> > }
> >
> > - if (dev->mtu > max_sz) {
> > - NL_SET_ERR_MSG_MOD(extack, "MTU too large to enable XDP");
> > - netdev_warn(dev, "XDP requires MTU less than %lu\n", max_sz);
> > + if (prog && !prog->aux->xdp_has_frags && dev->mtu > max_sz) {
> > + NL_SET_ERR_MSG_MOD(extack, "MTU too large to enable XDP without frags");
> > + netdev_warn(dev, "single-buffer XDP requires MTU less than %u\n", max_sz);
> > return -EINVAL;
> > }
> >
>
