On Mon, Sep 10, 2018 at 07:56:49PM +0900, Toshiaki Makita wrote:
> On 2018/09/10 17:24, Ilias Apalodimas wrote:
> > Add basic AF_XDP support without zero-copy
> >
> > Signed-off-by: Ilias Apalodimas <ilias.apalodi...@linaro.org>
> > ---
> ...
> > @@ -707,6 +731,26 @@ static int netsec_process_rx(struct netsec_priv *priv,
> > int budget)
> > if (unlikely(!buf_addr))
> > break;
> >
> > + if (xdp_prog) {
> > + xdp_result = netsec_run_xdp(desc, priv, xdp_prog,
> > + pkt_len);
> > + if (xdp_result != NETSEC_XDP_PASS) {
> > + xdp_flush |= xdp_result & NETSEC_XDP_REDIR;
> > +
> > + dma_unmap_single_attrs(priv->dev,
> > + desc->dma_addr,
> > + desc->len, DMA_TO_DEVICE,
> > + DMA_ATTR_SKIP_CPU_SYNC);
> > +
> > + desc->len = desc_len;
> > + desc->dma_addr = dma_handle;
> > + desc->addr = buf_addr;
> > + netsec_rx_fill(priv, idx, 1);
> > + nsetsec_adv_desc(&dring->tail);
> > + }
> > + continue;
>
> Continue even on XDP_PASS? Is this really correct?
>
> Also seems there is no handling of adjust_head/tail for XDP_PASS case.
No continue is wrong there, thanks for the catch. This should return the packet
to the network stack. I'll fix it on v2.
>
> > + }
> > +
> > skb = build_skb(desc->addr, desc->len);
> > if (unlikely(!skb)) {
> > dma_unmap_single(priv->dev, dma_handle, desc_len,
> > @@ -740,6 +784,9 @@ static int netsec_process_rx(struct netsec_priv *priv,
> > int budget)
> > nsetsec_adv_desc(&dring->tail);
> > }
> >
> > + if (xdp_flush & NETSEC_XDP_REDIR)
> > + xdp_do_flush_map();
> > +
> > return done;
> > }
> ...
> > +static u32 netsec_run_xdp(struct netsec_desc *desc, struct netsec_priv
> > *priv,
> > + struct bpf_prog *prog, u16 len)
> > +
> > +{
> > + struct netsec_desc_ring *dring = &priv->desc_ring[NETSEC_RING_RX];
> > + struct xdp_buff xdp;
> > + u32 ret = NETSEC_XDP_PASS;
> > + int err;
> > + u32 act;
> > +
> > + xdp.data_hard_start = desc->addr;
> > + xdp.data = desc->addr;
>
> There is no headroom. REDIRECT using devmap/cpumap will fail due to
> this. Generally we need XDP_PACKET_HEADROOM.
>
Ok, i'll modify the patch to include XDP_PACKET_HEADROOM
> > + xdp_set_data_meta_invalid(&xdp);
> > + xdp.data_end = xdp.data + len;
> > + xdp.rxq = &dring->xdp_rxq;
> > +
> > + rcu_read_lock();
> > + act = bpf_prog_run_xdp(prog, &xdp);
> > +
> > + switch (act) {
> > + case XDP_PASS:
> > + ret = NETSEC_XDP_PASS;
> > + break;
> > + case XDP_TX:
> > + ret = netsec_xmit_xdp(priv, &xdp, desc);
> > + break;
> > + case XDP_REDIRECT:
> > + err = xdp_do_redirect(priv->ndev, &xdp, prog);
> > + if (!err) {
> > + ret = NETSEC_XDP_REDIR;
> > + } else {
> > + ret = NETSEC_XDP_CONSUMED;
> > + xdp_return_buff(&xdp);
> > + }
> > + break;
> > + default:
> > + bpf_warn_invalid_xdp_action(act);
> > + /* fall through */
> > + case XDP_ABORTED:
> > + trace_xdp_exception(priv->ndev, prog, act);
> > + /* fall through -- handle aborts by dropping packet */
> > + case XDP_DROP:
> > + ret = NETSEC_XDP_CONSUMED;
> > + break;
> > + }
> > +
> > + rcu_read_unlock();
> > +
> > + return ret;
> > +}
> > +
> > +static int netsec_xdp_setup(struct netsec_priv *priv, struct bpf_prog
> > *prog)
> > +{
> > + struct net_device *dev = priv->ndev;
> > + struct bpf_prog *old_prog;
> > +
> > + /* For now just support only the usual MTU sized frames */
> > + if (prog && dev->mtu > 1500) {
> > + netdev_warn(dev, "Jumbo frames not yet supported with XDP\n");
>
> Why not using extack?
>
Wasn't aware that this should use the extack for errors. I just saw the same
check on an existing driver and thought that was the way to go
> > + return -EOPNOTSUPP;
> > + }
> > +
Thanks for having a look!
/Ilias
