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Date: Mon, 3 Apr 2023 10:43:03 +0800
From: Jason Wang <jasowang@...hat.com>
To: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
Cc: netdev@...r.kernel.org, "Michael S. Tsirkin" <mst@...hat.com>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Jesper Dangaard Brouer <hawk@...nel.org>,
John Fastabend <john.fastabend@...il.com>,
virtualization@...ts.linux-foundation.org, bpf@...r.kernel.org
Subject: Re: [PATCH net-next 3/8] virtio_net: introduce virtnet_xdp_handler()
to seprate the logic of run xdp
On Tue, Mar 28, 2023 at 8:04 PM Xuan Zhuo <xuanzhuo@...ux.alibaba.com> wrote:
>
> At present, we have two similar logic to perform the XDP prog.
>
> Therefore, this PATCH separates the code of executing XDP, which is
> conducive to later maintenance.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
> ---
> drivers/net/virtio_net.c | 142 +++++++++++++++++++++------------------
> 1 file changed, 75 insertions(+), 67 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index bb426958cdd4..72b9d6ee4024 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -301,6 +301,15 @@ struct padded_vnet_hdr {
> char padding[12];
> };
>
> +enum {
> + /* xdp pass */
> + VIRTNET_XDP_RES_PASS,
> + /* drop packet. the caller needs to release the page. */
> + VIRTNET_XDP_RES_DROP,
> + /* packet is consumed by xdp. the caller needs to do nothing. */
> + VIRTNET_XDP_RES_CONSUMED,
> +};
I'd prefer this to be done on top unless it is a must. But I don't see
any advantage of introducing this, it's partial mapping of XDP action
and it needs to be extended when XDP action is extended. (And we've
already had: VIRTIO_XDP_REDIR and VIRTIO_XDP_TX ...)
> +
> static void virtnet_rq_free_unused_buf(struct virtqueue *vq, void *buf);
> static void virtnet_sq_free_unused_buf(struct virtqueue *vq, void *buf);
>
> @@ -789,6 +798,59 @@ static int virtnet_xdp_xmit(struct net_device *dev,
> return ret;
> }
>
> +static int virtnet_xdp_handler(struct bpf_prog *xdp_prog, struct xdp_buff *xdp,
> + struct net_device *dev,
> + unsigned int *xdp_xmit,
> + struct virtnet_rq_stats *stats)
> +{
> + struct xdp_frame *xdpf;
> + int err;
> + u32 act;
> +
> + act = bpf_prog_run_xdp(xdp_prog, xdp);
> + stats->xdp_packets++;
> +
> + switch (act) {
> + case XDP_PASS:
> + return VIRTNET_XDP_RES_PASS;
> +
> + case XDP_TX:
> + stats->xdp_tx++;
> + xdpf = xdp_convert_buff_to_frame(xdp);
> + if (unlikely(!xdpf))
> + return VIRTNET_XDP_RES_DROP;
> +
> + err = virtnet_xdp_xmit(dev, 1, &xdpf, 0);
> + if (unlikely(!err)) {
> + xdp_return_frame_rx_napi(xdpf);
> + } else if (unlikely(err < 0)) {
> + trace_xdp_exception(dev, xdp_prog, act);
> + return VIRTNET_XDP_RES_DROP;
> + }
> +
> + *xdp_xmit |= VIRTIO_XDP_TX;
> + return VIRTNET_XDP_RES_CONSUMED;
> +
> + case XDP_REDIRECT:
> + stats->xdp_redirects++;
> + err = xdp_do_redirect(dev, xdp, xdp_prog);
> + if (err)
> + return VIRTNET_XDP_RES_DROP;
> +
> + *xdp_xmit |= VIRTIO_XDP_REDIR;
> + return VIRTNET_XDP_RES_CONSUMED;
> +
> + default:
> + bpf_warn_invalid_xdp_action(dev, xdp_prog, act);
> + fallthrough;
> + case XDP_ABORTED:
> + trace_xdp_exception(dev, xdp_prog, act);
> + fallthrough;
> + case XDP_DROP:
> + return VIRTNET_XDP_RES_DROP;
> + }
> +}
> +
> static unsigned int virtnet_get_headroom(struct virtnet_info *vi)
> {
> return vi->xdp_enabled ? VIRTIO_XDP_HEADROOM : 0;
> @@ -876,7 +938,6 @@ static struct sk_buff *receive_small(struct net_device *dev,
> struct page *page = virt_to_head_page(buf);
> unsigned int delta = 0;
> struct page *xdp_page;
> - int err;
> unsigned int metasize = 0;
>
> len -= vi->hdr_len;
> @@ -898,7 +959,6 @@ static struct sk_buff *receive_small(struct net_device *dev,
> xdp_prog = rcu_dereference(rq->xdp_prog);
> if (xdp_prog) {
> struct virtio_net_hdr_mrg_rxbuf *hdr = buf + header_offset;
> - struct xdp_frame *xdpf;
> struct xdp_buff xdp;
> void *orig_data;
> u32 act;
> @@ -931,46 +991,22 @@ static struct sk_buff *receive_small(struct net_device *dev,
> xdp_prepare_buff(&xdp, buf + VIRTNET_RX_PAD + vi->hdr_len,
> xdp_headroom, len, true);
> orig_data = xdp.data;
> - act = bpf_prog_run_xdp(xdp_prog, &xdp);
> - stats->xdp_packets++;
> +
> + act = virtnet_xdp_handler(xdp_prog, &xdp, dev, xdp_xmit, stats);
>
> switch (act) {
> - case XDP_PASS:
> + case VIRTNET_XDP_RES_PASS:
> /* Recalculate length in case bpf program changed it */
> delta = orig_data - xdp.data;
> len = xdp.data_end - xdp.data;
> metasize = xdp.data - xdp.data_meta;
> break;
> - case XDP_TX:
> - stats->xdp_tx++;
> - xdpf = xdp_convert_buff_to_frame(&xdp);
> - if (unlikely(!xdpf))
> - goto err_xdp;
> - err = virtnet_xdp_xmit(dev, 1, &xdpf, 0);
> - if (unlikely(!err)) {
> - xdp_return_frame_rx_napi(xdpf);
> - } else if (unlikely(err < 0)) {
> - trace_xdp_exception(vi->dev, xdp_prog, act);
> - goto err_xdp;
> - }
> - *xdp_xmit |= VIRTIO_XDP_TX;
> - rcu_read_unlock();
> - goto xdp_xmit;
> - case XDP_REDIRECT:
> - stats->xdp_redirects++;
> - err = xdp_do_redirect(dev, &xdp, xdp_prog);
> - if (err)
> - goto err_xdp;
> - *xdp_xmit |= VIRTIO_XDP_REDIR;
> +
> + case VIRTNET_XDP_RES_CONSUMED:
> rcu_read_unlock();
> goto xdp_xmit;
> - default:
> - bpf_warn_invalid_xdp_action(vi->dev, xdp_prog, act);
> - fallthrough;
> - case XDP_ABORTED:
> - trace_xdp_exception(vi->dev, xdp_prog, act);
> - goto err_xdp;
> - case XDP_DROP:
> +
> + case VIRTNET_XDP_RES_DROP:
> goto err_xdp;
> }
> }
> @@ -1277,7 +1313,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
> if (xdp_prog) {
> unsigned int xdp_frags_truesz = 0;
> struct skb_shared_info *shinfo;
> - struct xdp_frame *xdpf;
> struct page *xdp_page;
> struct xdp_buff xdp;
> void *data;
> @@ -1294,49 +1329,22 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
> if (unlikely(err))
> goto err_xdp_frags;
>
> - act = bpf_prog_run_xdp(xdp_prog, &xdp);
> - stats->xdp_packets++;
> + act = virtnet_xdp_handler(xdp_prog, &xdp, dev, xdp_xmit, stats);
>
> switch (act) {
> - case XDP_PASS:
> + case VIRTNET_XDP_RES_PASS:
> head_skb = build_skb_from_xdp_buff(dev, vi, &xdp, xdp_frags_truesz);
> if (unlikely(!head_skb))
> goto err_xdp_frags;
>
> rcu_read_unlock();
> return head_skb;
> - case XDP_TX:
> - stats->xdp_tx++;
> - xdpf = xdp_convert_buff_to_frame(&xdp);
> - if (unlikely(!xdpf)) {
> - netdev_dbg(dev, "convert buff to frame failed for xdp\n");
Nit: This debug is lost after the conversion.
Thanks
> - goto err_xdp_frags;
> - }
> - err = virtnet_xdp_xmit(dev, 1, &xdpf, 0);
> - if (unlikely(!err)) {
> - xdp_return_frame_rx_napi(xdpf);
> - } else if (unlikely(err < 0)) {
> - trace_xdp_exception(vi->dev, xdp_prog, act);
> - goto err_xdp_frags;
> - }
> - *xdp_xmit |= VIRTIO_XDP_TX;
> - rcu_read_unlock();
> - goto xdp_xmit;
> - case XDP_REDIRECT:
> - stats->xdp_redirects++;
> - err = xdp_do_redirect(dev, &xdp, xdp_prog);
> - if (err)
> - goto err_xdp_frags;
> - *xdp_xmit |= VIRTIO_XDP_REDIR;
> +
> + case VIRTNET_XDP_RES_CONSUMED:
> rcu_read_unlock();
> goto xdp_xmit;
> - default:
> - bpf_warn_invalid_xdp_action(vi->dev, xdp_prog, act);
> - fallthrough;
> - case XDP_ABORTED:
> - trace_xdp_exception(vi->dev, xdp_prog, act);
> - fallthrough;
> - case XDP_DROP:
> +
> + case VIRTNET_XDP_RES_DROP:
> goto err_xdp_frags;
> }
> err_xdp_frags:
> --
> 2.32.0.3.g01195cf9f
>
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