netdevsim: add NAPI support

Add NAPI support to netdevim, similar to veth.

* Add a nsim_rq rx queue structure to hold a NAPI instance and a skb
  queue.
* During xmit, store the skb in the peer skb queue and schedule NAPI.
* During napi_poll(), drain the skb queue and pass up the stack.
* Add assoc between rxq and NAPI instance using netif_queue_set_napi().

Signed-off-by: David Wei <dw@davidwei.uk>
Link: https://lore.kernel.org/r/20240507163228.2066817-2-dw@davidwei.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/netdevsim/netdev.c b/drivers/net/netdevsim/netdev.c
index e3a385a322695fc79693a8fb134c37142e769cde..c22897bf5509cad18a208cc41e25aa53d22ba2be 100644 (file)
--- a/drivers/net/netdevsim/netdev.c
+++ b/drivers/net/netdevsim/netdev.c
@@ -28,11 +28,33 @@
 
 #include "netdevsim.h"
 
+#define NSIM_RING_SIZE         256
+
+static int nsim_napi_rx(struct nsim_rq *rq, struct sk_buff *skb)
+{
+       if (skb_queue_len(&rq->skb_queue) > NSIM_RING_SIZE) {
+               dev_kfree_skb_any(skb);
+               return NET_RX_DROP;
+       }
+
+       skb_queue_tail(&rq->skb_queue, skb);
+       return NET_RX_SUCCESS;
+}
+
+static int nsim_forward_skb(struct net_device *dev, struct sk_buff *skb,
+                           struct nsim_rq *rq)
+{
+       return __dev_forward_skb(dev, skb) ?: nsim_napi_rx(rq, skb);
+}
+
 static netdev_tx_t nsim_start_xmit(struct sk_buff *skb, struct net_device *dev)
 {
        struct netdevsim *ns = netdev_priv(dev);
+       struct net_device *peer_dev;
        unsigned int len = skb->len;
        struct netdevsim *peer_ns;
+       struct nsim_rq *rq;
+       int rxq;
 
        rcu_read_lock();
        if (!nsim_ipsec_tx(ns, skb))
@@ -42,10 +64,18 @@ static netdev_tx_t nsim_start_xmit(struct sk_buff *skb, struct net_device *dev)
        if (!peer_ns)
                goto out_drop_free;
 
+       peer_dev = peer_ns->netdev;
+       rxq = skb_get_queue_mapping(skb);
+       if (rxq >= peer_dev->num_rx_queues)
+               rxq = rxq % peer_dev->num_rx_queues;
+       rq = &peer_ns->rq[rxq];
+
        skb_tx_timestamp(skb);
-       if (unlikely(dev_forward_skb(peer_ns->netdev, skb) == NET_RX_DROP))
+       if (unlikely(nsim_forward_skb(peer_dev, skb, rq) == NET_RX_DROP))
                goto out_drop_cnt;
 
+       napi_schedule(&rq->napi);
+
        rcu_read_unlock();
        u64_stats_update_begin(&ns->syncp);
        ns->tx_packets++;
@@ -300,25 +330,146 @@ static int nsim_get_iflink(const struct net_device *dev)
        return iflink;
 }
 
+static int nsim_rcv(struct nsim_rq *rq, int budget)
+{
+       struct sk_buff *skb;
+       int i;
+
+       for (i = 0; i < budget; i++) {
+               if (skb_queue_empty(&rq->skb_queue))
+                       break;
+
+               skb = skb_dequeue(&rq->skb_queue);
+               netif_receive_skb(skb);
+       }
+
+       return i;
+}
+
+static int nsim_poll(struct napi_struct *napi, int budget)
+{
+       struct nsim_rq *rq = container_of(napi, struct nsim_rq, napi);
+       int done;
+
+       done = nsim_rcv(rq, budget);
+       napi_complete(napi);
+
+       return done;
+}
+
+static int nsim_create_page_pool(struct nsim_rq *rq)
+{
+       struct page_pool_params p = {
+               .order = 0,
+               .pool_size = NSIM_RING_SIZE,
+               .nid = NUMA_NO_NODE,
+               .dev = &rq->napi.dev->dev,
+               .napi = &rq->napi,
+               .dma_dir = DMA_BIDIRECTIONAL,
+               .netdev = rq->napi.dev,
+       };
+
+       rq->page_pool = page_pool_create(&p);
+       if (IS_ERR(rq->page_pool)) {
+               int err = PTR_ERR(rq->page_pool);
+
+               rq->page_pool = NULL;
+               return err;
+       }
+       return 0;
+}
+
+static int nsim_init_napi(struct netdevsim *ns)
+{
+       struct net_device *dev = ns->netdev;
+       struct nsim_rq *rq;
+       int err, i;
+
+       for (i = 0; i < dev->num_rx_queues; i++) {
+               rq = &ns->rq[i];
+
+               netif_napi_add(dev, &rq->napi, nsim_poll);
+       }
+
+       for (i = 0; i < dev->num_rx_queues; i++) {
+               rq = &ns->rq[i];
+
+               err = nsim_create_page_pool(rq);
+               if (err)
+                       goto err_pp_destroy;
+       }
+
+       return 0;
+
+err_pp_destroy:
+       while (i--) {
+               page_pool_destroy(ns->rq[i].page_pool);
+               ns->rq[i].page_pool = NULL;
+       }
+
+       for (i = 0; i < dev->num_rx_queues; i++)
+               __netif_napi_del(&ns->rq[i].napi);
+
+       return err;
+}
+
+static void nsim_enable_napi(struct netdevsim *ns)
+{
+       struct net_device *dev = ns->netdev;
+       int i;
+
+       for (i = 0; i < dev->num_rx_queues; i++) {
+               struct nsim_rq *rq = &ns->rq[i];
+
+               netif_queue_set_napi(dev, i, NETDEV_QUEUE_TYPE_RX, &rq->napi);
+               napi_enable(&rq->napi);
+       }
+}
+
 static int nsim_open(struct net_device *dev)
 {
        struct netdevsim *ns = netdev_priv(dev);
-       struct page_pool_params pp = { 0 };
+       int err;
 
-       pp.pool_size = 128;
-       pp.dev = &dev->dev;
-       pp.dma_dir = DMA_BIDIRECTIONAL;
-       pp.netdev = dev;
+       err = nsim_init_napi(ns);
+       if (err)
+               return err;
 
-       ns->pp = page_pool_create(&pp);
-       return PTR_ERR_OR_ZERO(ns->pp);
+       nsim_enable_napi(ns);
+
+       return 0;
+}
+
+static void nsim_del_napi(struct netdevsim *ns)
+{
+       struct net_device *dev = ns->netdev;
+       int i;
+
+       for (i = 0; i < dev->num_rx_queues; i++) {
+               struct nsim_rq *rq = &ns->rq[i];
+
+               napi_disable(&rq->napi);
+               __netif_napi_del(&rq->napi);
+       }
+       synchronize_net();
+
+       for (i = 0; i < dev->num_rx_queues; i++) {
+               page_pool_destroy(ns->rq[i].page_pool);
+               ns->rq[i].page_pool = NULL;
+       }
 }
 
 static int nsim_stop(struct net_device *dev)
 {
        struct netdevsim *ns = netdev_priv(dev);
+       struct netdevsim *peer;
+
+       netif_carrier_off(dev);
+       peer = rtnl_dereference(ns->peer);
+       if (peer)
+               netif_carrier_off(peer->netdev);
 
-       page_pool_destroy(ns->pp);
+       nsim_del_napi(ns);
 
        return 0;
 }
@@ -437,7 +588,7 @@ nsim_pp_hold_write(struct file *file, const char __user *data,
        if (!netif_running(ns->netdev) && val) {
                ret = -ENETDOWN;
        } else if (val) {
-               ns->page = page_pool_dev_alloc_pages(ns->pp);
+               ns->page = page_pool_dev_alloc_pages(ns->rq[0].page_pool);
                if (!ns->page)
                        ret = -ENOMEM;
        } else {
@@ -477,6 +628,35 @@ static void nsim_setup(struct net_device *dev)
        dev->xdp_features = NETDEV_XDP_ACT_HW_OFFLOAD;
 }
 
+static int nsim_queue_init(struct netdevsim *ns)
+{
+       struct net_device *dev = ns->netdev;
+       int i;
+
+       ns->rq = kvcalloc(dev->num_rx_queues, sizeof(*ns->rq),
+                         GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL);
+       if (!ns->rq)
+               return -ENOMEM;
+
+       for (i = 0; i < dev->num_rx_queues; i++)
+               skb_queue_head_init(&ns->rq[i].skb_queue);
+
+       return 0;
+}
+
+static void nsim_queue_free(struct netdevsim *ns)
+{
+       struct net_device *dev = ns->netdev;
+       int i;
+
+       for (i = 0; i < dev->num_rx_queues; i++)
+               skb_queue_purge_reason(&ns->rq[i].skb_queue,
+                                      SKB_DROP_REASON_QUEUE_PURGE);
+
+       kvfree(ns->rq);
+       ns->rq = NULL;
+}
+
 static int nsim_init_netdevsim(struct netdevsim *ns)
 {
        struct mock_phc *phc;
@@ -495,10 +675,14 @@ static int nsim_init_netdevsim(struct netdevsim *ns)
                goto err_phc_destroy;
 
        rtnl_lock();
-       err = nsim_bpf_init(ns);
+       err = nsim_queue_init(ns);
        if (err)
                goto err_utn_destroy;
 
+       err = nsim_bpf_init(ns);
+       if (err)
+               goto err_rq_destroy;
+
        nsim_macsec_init(ns);
        nsim_ipsec_init(ns);
 
@@ -512,6 +696,8 @@ err_ipsec_teardown:
        nsim_ipsec_teardown(ns);
        nsim_macsec_teardown(ns);
        nsim_bpf_uninit(ns);
+err_rq_destroy:
+       nsim_queue_free(ns);
 err_utn_destroy:
        rtnl_unlock();
        nsim_udp_tunnels_info_destroy(ns->netdev);
@@ -593,6 +779,7 @@ void nsim_destroy(struct netdevsim *ns)
                nsim_macsec_teardown(ns);
                nsim_ipsec_teardown(ns);
                nsim_bpf_uninit(ns);
+               nsim_queue_free(ns);
        }
        rtnl_unlock();
        if (nsim_dev_port_is_pf(ns->nsim_dev_port))

diff --git a/drivers/net/netdevsim/netdevsim.h b/drivers/net/netdevsim/netdevsim.h
index 7664ab823e290a850f45d098b36867e5a9d72cc9..bf02efa10956a631adaafbd96c95b3f098d5092b 100644 (file)
--- a/drivers/net/netdevsim/netdevsim.h
+++ b/drivers/net/netdevsim/netdevsim.h
@@ -90,11 +90,18 @@ struct nsim_ethtool {
        struct ethtool_fecparam fec;
 };
 
+struct nsim_rq {
+       struct napi_struct napi;
+       struct sk_buff_head skb_queue;
+       struct page_pool *page_pool;
+};
+
 struct netdevsim {
        struct net_device *netdev;
        struct nsim_dev *nsim_dev;
        struct nsim_dev_port *nsim_dev_port;
        struct mock_phc *phc;
+       struct nsim_rq *rq;
 
        u64 tx_packets;
        u64 tx_bytes;
@@ -125,7 +132,6 @@ struct netdevsim {
                struct debugfs_u32_array dfs_ports[2];
        } udp_ports;
 
-       struct page_pool *pp;
        struct page *page;
        struct dentry *pp_dfs;