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virtio-net: support XDP when not more queues
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 <xuanzhuo@linux.alibaba.com> Reviewed-by: Dust Li <dust.li@linux.alibaba.com> Acked-by: Jason Wang <jasowang@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
parent
0bb3262c02
commit
97c2c69e19
1 changed files with 48 additions and 12 deletions
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@ -195,6 +195,9 @@ struct virtnet_info {
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/* # of XDP queue pairs currently used by the driver */
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/* # of XDP queue pairs currently used by the driver */
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u16 xdp_queue_pairs;
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u16 xdp_queue_pairs;
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/* xdp_queue_pairs may be 0, when xdp is already loaded. So add this. */
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bool xdp_enabled;
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/* I like... big packets and I cannot lie! */
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/* I like... big packets and I cannot lie! */
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bool big_packets;
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bool big_packets;
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@ -481,12 +484,41 @@ static int __virtnet_xdp_xmit_one(struct virtnet_info *vi,
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return 0;
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return 0;
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}
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}
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static struct send_queue *virtnet_xdp_sq(struct virtnet_info *vi)
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/* when vi->curr_queue_pairs > nr_cpu_ids, the txq/sq is only used for xdp tx on
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{
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* the current cpu, so it does not need to be locked.
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unsigned int qp;
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*
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* Here we use marco instead of inline functions because we have to deal with
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* three issues at the same time: 1. the choice of sq. 2. judge and execute the
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* lock/unlock of txq 3. make sparse happy. It is difficult for two inline
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* functions to perfectly solve these three problems at the same time.
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*/
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#define virtnet_xdp_get_sq(vi) ({ \
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struct netdev_queue *txq; \
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typeof(vi) v = (vi); \
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unsigned int qp; \
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\
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if (v->curr_queue_pairs > nr_cpu_ids) { \
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qp = v->curr_queue_pairs - v->xdp_queue_pairs; \
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qp += smp_processor_id(); \
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txq = netdev_get_tx_queue(v->dev, qp); \
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__netif_tx_acquire(txq); \
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} else { \
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qp = smp_processor_id() % v->curr_queue_pairs; \
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txq = netdev_get_tx_queue(v->dev, qp); \
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__netif_tx_lock(txq, raw_smp_processor_id()); \
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} \
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v->sq + qp; \
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})
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qp = vi->curr_queue_pairs - vi->xdp_queue_pairs + smp_processor_id();
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#define virtnet_xdp_put_sq(vi, q) { \
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return &vi->sq[qp];
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struct netdev_queue *txq; \
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typeof(vi) v = (vi); \
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\
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txq = netdev_get_tx_queue(v->dev, (q) - v->sq); \
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if (v->curr_queue_pairs > nr_cpu_ids) \
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__netif_tx_release(txq); \
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else \
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__netif_tx_unlock(txq); \
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}
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}
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static int virtnet_xdp_xmit(struct net_device *dev,
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static int virtnet_xdp_xmit(struct net_device *dev,
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@ -512,7 +544,7 @@ static int virtnet_xdp_xmit(struct net_device *dev,
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if (!xdp_prog)
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if (!xdp_prog)
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return -ENXIO;
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return -ENXIO;
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sq = virtnet_xdp_sq(vi);
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sq = virtnet_xdp_get_sq(vi);
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if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK)) {
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if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK)) {
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ret = -EINVAL;
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ret = -EINVAL;
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@ -560,12 +592,13 @@ static int virtnet_xdp_xmit(struct net_device *dev,
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sq->stats.kicks += kicks;
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sq->stats.kicks += kicks;
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u64_stats_update_end(&sq->stats.syncp);
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u64_stats_update_end(&sq->stats.syncp);
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virtnet_xdp_put_sq(vi, sq);
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return ret;
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return ret;
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}
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}
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static unsigned int virtnet_get_headroom(struct virtnet_info *vi)
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static unsigned int virtnet_get_headroom(struct virtnet_info *vi)
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{
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{
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return vi->xdp_queue_pairs ? VIRTIO_XDP_HEADROOM : 0;
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return vi->xdp_enabled ? VIRTIO_XDP_HEADROOM : 0;
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}
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}
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/* We copy the packet for XDP in the following cases:
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/* We copy the packet for XDP in the following cases:
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@ -1458,12 +1491,13 @@ static int virtnet_poll(struct napi_struct *napi, int budget)
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xdp_do_flush();
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xdp_do_flush();
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if (xdp_xmit & VIRTIO_XDP_TX) {
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if (xdp_xmit & VIRTIO_XDP_TX) {
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sq = virtnet_xdp_sq(vi);
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sq = virtnet_xdp_get_sq(vi);
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if (virtqueue_kick_prepare(sq->vq) && virtqueue_notify(sq->vq)) {
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if (virtqueue_kick_prepare(sq->vq) && virtqueue_notify(sq->vq)) {
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u64_stats_update_begin(&sq->stats.syncp);
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u64_stats_update_begin(&sq->stats.syncp);
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sq->stats.kicks++;
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sq->stats.kicks++;
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u64_stats_update_end(&sq->stats.syncp);
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u64_stats_update_end(&sq->stats.syncp);
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}
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}
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virtnet_xdp_put_sq(vi, sq);
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}
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}
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return received;
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return received;
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@ -2418,10 +2452,9 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog,
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/* XDP requires extra queues for XDP_TX */
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/* XDP requires extra queues for XDP_TX */
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if (curr_qp + xdp_qp > vi->max_queue_pairs) {
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if (curr_qp + xdp_qp > vi->max_queue_pairs) {
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NL_SET_ERR_MSG_MOD(extack, "Too few free TX rings available");
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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",
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netdev_warn(dev, "request %i queues but max is %i\n",
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curr_qp + xdp_qp, vi->max_queue_pairs);
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curr_qp + xdp_qp, vi->max_queue_pairs);
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return -ENOMEM;
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xdp_qp = 0;
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}
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}
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old_prog = rtnl_dereference(vi->rq[0].xdp_prog);
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old_prog = rtnl_dereference(vi->rq[0].xdp_prog);
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@ -2455,11 +2488,14 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog,
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vi->xdp_queue_pairs = xdp_qp;
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vi->xdp_queue_pairs = xdp_qp;
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if (prog) {
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if (prog) {
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vi->xdp_enabled = true;
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for (i = 0; i < vi->max_queue_pairs; i++) {
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for (i = 0; i < vi->max_queue_pairs; i++) {
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rcu_assign_pointer(vi->rq[i].xdp_prog, prog);
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rcu_assign_pointer(vi->rq[i].xdp_prog, prog);
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if (i == 0 && !old_prog)
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if (i == 0 && !old_prog)
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virtnet_clear_guest_offloads(vi);
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virtnet_clear_guest_offloads(vi);
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}
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}
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} else {
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vi->xdp_enabled = false;
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}
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}
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for (i = 0; i < vi->max_queue_pairs; i++) {
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for (i = 0; i < vi->max_queue_pairs; i++) {
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@ -2527,7 +2563,7 @@ static int virtnet_set_features(struct net_device *dev,
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int err;
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int err;
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if ((dev->features ^ features) & NETIF_F_LRO) {
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if ((dev->features ^ features) & NETIF_F_LRO) {
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if (vi->xdp_queue_pairs)
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if (vi->xdp_enabled)
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return -EBUSY;
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return -EBUSY;
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if (features & NETIF_F_LRO)
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if (features & NETIF_F_LRO)
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