From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [net-next PATCH v3 5/6] virtio_net: add XDP_TX support Date: Wed, 30 Nov 2016 20:45:20 +0200 Message-ID: <20161130204250-mutt-send-email-mst@kernel.org> References: <20161129200933.26851.41883.stgit@john-Precision-Tower-5810> <20161129201108.26851.1114.stgit@john-Precision-Tower-5810> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: eric.dumazet@gmail.com, daniel@iogearbox.net, shm@cumulusnetworks.com, davem@davemloft.net, tgraf@suug.ch, alexei.starovoitov@gmail.com, john.r.fastabend@intel.com, netdev@vger.kernel.org, bblanco@plumgrid.com, brouer@redhat.com To: John Fastabend Return-path: Received: from mx1.redhat.com ([209.132.183.28]:58602 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758779AbcK3SpZ (ORCPT ); Wed, 30 Nov 2016 13:45:25 -0500 Content-Disposition: inline In-Reply-To: <20161129201108.26851.1114.stgit@john-Precision-Tower-5810> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, Nov 29, 2016 at 12:11:08PM -0800, John Fastabend wrote: > This adds support for the XDP_TX action to virtio_net. When an XDP > program is run and returns the XDP_TX action the virtio_net XDP > implementation will transmit the packet on a TX queue that aligns > with the current CPU that the XDP packet was processed on. > > Before sending the packet the header is zeroed. Also XDP is expected > to handle checksum correctly so no checksum offload support is > provided. > > Signed-off-by: John Fastabend > --- > drivers/net/virtio_net.c | 59 ++++++++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 56 insertions(+), 3 deletions(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index a1bfa99..9604e55 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -330,12 +330,40 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi, > return skb; > } > > +static void virtnet_xdp_xmit(struct virtnet_info *vi, > + unsigned int qnum, struct xdp_buff *xdp) > +{ > + struct send_queue *sq = &vi->sq[qnum]; > + struct virtio_net_hdr_mrg_rxbuf *hdr; > + unsigned int num_sg, len; > + void *xdp_sent; > + > + /* Free up any pending old buffers before queueing new ones. */ > + while ((xdp_sent = virtqueue_get_buf(sq->vq, &len)) != NULL) { > + struct page *page = virt_to_head_page(xdp_sent); > + > + put_page(page); > + } > + > + /* Zero header and leave csum up to XDP layers */ > + hdr = xdp->data; > + memset(hdr, 0, vi->hdr_len); > + hdr->hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE; > + hdr->hdr.flags = VIRTIO_NET_HDR_F_DATA_VALID; Do we really want this? This is CHECKSUM_UNNECESSARY. Does not XDP pass checksummed packets? > + > + num_sg = 1; > + sg_init_one(sq->sg, xdp->data, xdp->data_end - xdp->data); > + virtqueue_add_outbuf(sq->vq, sq->sg, num_sg, xdp->data, GFP_ATOMIC); This might fail. If it does, you want to at least free up the memory. > + virtqueue_kick(sq->vq); > +} > + > static u32 do_xdp_prog(struct virtnet_info *vi, > struct bpf_prog *xdp_prog, > struct page *page, int offset, int len) > { > int hdr_padded_len; > struct xdp_buff xdp; > + unsigned int qp; > u32 act; > u8 *buf; > > @@ -353,9 +381,15 @@ static u32 do_xdp_prog(struct virtnet_info *vi, > switch (act) { > case XDP_PASS: > return XDP_PASS; > + case XDP_TX: > + qp = vi->curr_queue_pairs - > + vi->xdp_queue_pairs + > + smp_processor_id(); > + xdp.data = buf + (vi->mergeable_rx_bufs ? 0 : 4); > + virtnet_xdp_xmit(vi, qp, &xdp); > + return XDP_TX; > default: > bpf_warn_invalid_xdp_action(act); > - case XDP_TX: > case XDP_ABORTED: > case XDP_DROP: > return XDP_DROP; > @@ -387,8 +421,16 @@ static struct sk_buff *receive_big(struct net_device *dev, > if (xdp_prog) { > u32 act = do_xdp_prog(vi, xdp_prog, page, 0, len); > > - if (act == XDP_DROP) > + switch (act) { > + case XDP_PASS: > + break; > + case XDP_TX: > + rcu_read_unlock(); > + goto xdp_xmit; > + case XDP_DROP: > + default: > goto err_xdp; > + } > } > rcu_read_unlock(); > > @@ -403,6 +445,7 @@ static struct sk_buff *receive_big(struct net_device *dev, > err: > dev->stats.rx_dropped++; > give_pages(rq, page); > +xdp_xmit: > return NULL; > } > > @@ -421,6 +464,8 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, > struct sk_buff *head_skb, *curr_skb; > struct bpf_prog *xdp_prog; > > + head_skb = NULL; > + > rcu_read_lock(); > xdp_prog = rcu_dereference(rq->xdp_prog); > if (xdp_prog) { > @@ -432,8 +477,15 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, > } > > act = do_xdp_prog(vi, xdp_prog, page, offset, len); > - if (act == XDP_DROP) > + switch (act) { > + case XDP_PASS: > + break; > + case XDP_TX: > + goto xdp_xmit; > + case XDP_DROP: > + default: > goto err_xdp; > + } > } > rcu_read_unlock(); > > @@ -510,6 +562,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, > err_buf: > dev->stats.rx_dropped++; > dev_kfree_skb(head_skb); > +xdp_xmit: > return NULL; > } >