From patchwork Fri Mar 5 10:29:10 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xuan Zhuo X-Patchwork-Id: 12118293 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8F25DC433DB for ; Fri, 5 Mar 2021 10:29:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 598806501C for ; Fri, 5 Mar 2021 10:29:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229672AbhCEK3V (ORCPT ); Fri, 5 Mar 2021 05:29:21 -0500 Received: from out30-42.freemail.mail.aliyun.com ([115.124.30.42]:56121 "EHLO out30-42.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229597AbhCEK3N (ORCPT ); Fri, 5 Mar 2021 05:29:13 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R161e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04394;MF=xuanzhuo@linux.alibaba.com;NM=1;PH=DS;RN=11;SR=0;TI=SMTPD_---0UQYffdz_1614940150; Received: from localhost(mailfrom:xuanzhuo@linux.alibaba.com fp:SMTPD_---0UQYffdz_1614940150) by smtp.aliyun-inc.com(127.0.0.1); Fri, 05 Mar 2021 18:29:10 +0800 From: Xuan Zhuo To: netdev@vger.kernel.org Cc: "Michael S. Tsirkin" , Jason Wang , "David S. Miller" , Jakub Kicinski , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , virtualization@lists.linux-foundation.org, bpf@vger.kernel.org Subject: [PATCH v6 net-next] virtio-net: support XDP when not more queues Date: Fri, 5 Mar 2021 18:29:10 +0800 Message-Id: <1614940150-38458-1-git-send-email-xuanzhuo@linux.alibaba.com> X-Mailer: git-send-email 1.8.3.1 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org The number of queues implemented by many virtio backends is limited, especially some machines have a large number of CPUs. In this case, it is often impossible to allocate a separate queue for XDP_TX/XDP_REDIRECT, then xdp cannot be loaded to work, even xdp does not use the XDP_TX/XDP_REDIRECT. This patch allows XDP_TX/XDP_REDIRECT to run by reuse the existing SQ with __netif_tx_lock() hold when there are not enough queues. Signed-off-by: Xuan Zhuo Reviewed-by: Dust Li --- v6: 1. use __netif_tx_acquire()/__netif_tx_release(). (suggested by Jason Wang) 2. add note for why not lock. (suggested by Jason Wang) 3. Use variable 'flag' to record with or without locked. It is not safe to use curr_queue_pairs in "virtnet_put_xdp_sq", because it may changed after "virtnet_get_xdp_sq". v5: change subject from 'support XDP_TX when not more queues' v4: make sparse happy suggested by Jakub Kicinski v3: add warning when no more queues suggested by Jesper Dangaard Brouer drivers/net/virtio_net.c | 63 ++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 53 insertions(+), 10 deletions(-) -- 1.8.3.1 diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index ba8e637..f9e024d 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -195,6 +195,9 @@ struct virtnet_info { /* # of XDP queue pairs currently used by the driver */ u16 xdp_queue_pairs; + /* xdp_queue_pairs may be 0, when xdp is already loaded. So add this. */ + bool xdp_enabled; + /* I like... big packets and I cannot lie! */ bool big_packets; @@ -481,14 +484,48 @@ static int __virtnet_xdp_xmit_one(struct virtnet_info *vi, return 0; } -static struct send_queue *virtnet_xdp_sq(struct virtnet_info *vi) +static struct send_queue *virtnet_get_xdp_sq(struct virtnet_info *vi, int *flag) + __acquires(txq->_xmit_lock) { + struct netdev_queue *txq; unsigned int qp; - qp = vi->curr_queue_pairs - vi->xdp_queue_pairs + smp_processor_id(); + if (vi->curr_queue_pairs > nr_cpu_ids) { + qp = vi->curr_queue_pairs - vi->xdp_queue_pairs + smp_processor_id(); + txq = netdev_get_tx_queue(vi->dev, qp); + + /* In this case, this txq is only used for xdp tx on the current + * cpu, so it does not need to be locked. + * __netif_tx_acquire is for sparse. + */ + __netif_tx_acquire(txq); + *flag = false; + } else { + qp = smp_processor_id() % vi->curr_queue_pairs; + txq = netdev_get_tx_queue(vi->dev, qp); + __netif_tx_lock(txq, raw_smp_processor_id()); + *flag = true; + } + return &vi->sq[qp]; } +static void virtnet_put_xdp_sq(struct virtnet_info *vi, struct send_queue *sq, + int flag) + __releases(txq->_xmit_lock) +{ + struct netdev_queue *txq; + unsigned int qp; + + qp = sq - vi->sq; + txq = netdev_get_tx_queue(vi->dev, qp); + + if (flag) + __netif_tx_unlock(txq); + else + __netif_tx_release(txq); +} + static int virtnet_xdp_xmit(struct net_device *dev, int n, struct xdp_frame **frames, u32 flags) { @@ -496,12 +533,12 @@ static int virtnet_xdp_xmit(struct net_device *dev, struct receive_queue *rq = vi->rq; struct bpf_prog *xdp_prog; struct send_queue *sq; + int ret, err, sq_flag; unsigned int len; int packets = 0; int bytes = 0; int drops = 0; int kicks = 0; - int ret, err; void *ptr; int i; @@ -512,7 +549,7 @@ static int virtnet_xdp_xmit(struct net_device *dev, if (!xdp_prog) return -ENXIO; - sq = virtnet_xdp_sq(vi); + sq = virtnet_get_xdp_sq(vi, &sq_flag); if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK)) { ret = -EINVAL; @@ -560,12 +597,13 @@ static int virtnet_xdp_xmit(struct net_device *dev, sq->stats.kicks += kicks; u64_stats_update_end(&sq->stats.syncp); + virtnet_put_xdp_sq(vi, sq, sq_flag); return ret; } static unsigned int virtnet_get_headroom(struct virtnet_info *vi) { - return vi->xdp_queue_pairs ? VIRTIO_XDP_HEADROOM : 0; + return vi->xdp_enabled ? VIRTIO_XDP_HEADROOM : 0; } /* We copy the packet for XDP in the following cases: @@ -1457,12 +1495,15 @@ static int virtnet_poll(struct napi_struct *napi, int budget) xdp_do_flush(); if (xdp_xmit & VIRTIO_XDP_TX) { - sq = virtnet_xdp_sq(vi); + int sq_flag; + + sq = virtnet_get_xdp_sq(vi, &sq_flag); if (virtqueue_kick_prepare(sq->vq) && virtqueue_notify(sq->vq)) { u64_stats_update_begin(&sq->stats.syncp); sq->stats.kicks++; u64_stats_update_end(&sq->stats.syncp); } + virtnet_put_xdp_sq(vi, sq, sq_flag); } return received; @@ -2417,10 +2458,9 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog, /* XDP requires extra queues for XDP_TX */ if (curr_qp + xdp_qp > vi->max_queue_pairs) { - NL_SET_ERR_MSG_MOD(extack, "Too few free TX rings available"); - netdev_warn(dev, "request %i queues but max is %i\n", + netdev_warn(dev, "XDP request %i queues but max is %i. XDP_TX and XDP_REDIRECT will operate in a slower locked tx mode.\n", curr_qp + xdp_qp, vi->max_queue_pairs); - return -ENOMEM; + xdp_qp = 0; } old_prog = rtnl_dereference(vi->rq[0].xdp_prog); @@ -2454,11 +2494,14 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog, vi->xdp_queue_pairs = xdp_qp; if (prog) { + vi->xdp_enabled = true; for (i = 0; i < vi->max_queue_pairs; i++) { rcu_assign_pointer(vi->rq[i].xdp_prog, prog); if (i == 0 && !old_prog) virtnet_clear_guest_offloads(vi); } + } else { + vi->xdp_enabled = false; } for (i = 0; i < vi->max_queue_pairs; i++) { @@ -2526,7 +2569,7 @@ static int virtnet_set_features(struct net_device *dev, int err; if ((dev->features ^ features) & NETIF_F_LRO) { - if (vi->xdp_queue_pairs) + if (vi->xdp_enabled) return -EBUSY; if (features & NETIF_F_LRO)