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net: xdp: support xdp generic on virtual devices
XDP generic allows users to test XDP programs and/or run them with degraded performance on devices that do not yet support XDP. For testing I typically test eBPF programs using a set of veth devices. This allows testing topologies that would otherwise be difficult to setup especially in the early stages of development. This patch adds a xdp generic hook to the netif_rx_internal() function which is called from dev_forward_skb(). With this addition attaching XDP programs to veth devices works as expected! Also I noticed multiple drivers using netif_rx(). These devices will also benefit and generic XDP will work for them as well. Signed-off-by: John Fastabend <john.fastabend@gmail.com> Tested-by: Andy Gospodarek <andy@greyhouse.net> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
John Fastabend
David S. Miller
parent
90382dca61
commit
d445516966
208
net/core/dev.c
208
net/core/dev.c
@ -3865,6 +3865,107 @@ drop:
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return NET_RX_DROP;
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}
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static u32 netif_receive_generic_xdp(struct sk_buff *skb,
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struct bpf_prog *xdp_prog)
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{
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struct xdp_buff xdp;
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u32 act = XDP_DROP;
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void *orig_data;
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int hlen, off;
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u32 mac_len;
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/* Reinjected packets coming from act_mirred or similar should
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* not get XDP generic processing.
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*/
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if (skb_cloned(skb))
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return XDP_PASS;
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if (skb_linearize(skb))
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goto do_drop;
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/* The XDP program wants to see the packet starting at the MAC
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* header.
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*/
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mac_len = skb->data - skb_mac_header(skb);
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hlen = skb_headlen(skb) + mac_len;
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xdp.data = skb->data - mac_len;
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xdp.data_end = xdp.data + hlen;
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xdp.data_hard_start = skb->data - skb_headroom(skb);
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orig_data = xdp.data;
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act = bpf_prog_run_xdp(xdp_prog, &xdp);
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off = xdp.data - orig_data;
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if (off > 0)
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__skb_pull(skb, off);
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else if (off < 0)
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__skb_push(skb, -off);
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switch (act) {
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case XDP_TX:
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__skb_push(skb, mac_len);
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/* fall through */
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case XDP_PASS:
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break;
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default:
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bpf_warn_invalid_xdp_action(act);
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/* fall through */
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case XDP_ABORTED:
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trace_xdp_exception(skb->dev, xdp_prog, act);
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/* fall through */
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case XDP_DROP:
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do_drop:
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kfree_skb(skb);
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break;
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}
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return act;
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}
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/* When doing generic XDP we have to bypass the qdisc layer and the
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* network taps in order to match in-driver-XDP behavior.
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*/
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static void generic_xdp_tx(struct sk_buff *skb, struct bpf_prog *xdp_prog)
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{
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struct net_device *dev = skb->dev;
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struct netdev_queue *txq;
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bool free_skb = true;
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int cpu, rc;
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txq = netdev_pick_tx(dev, skb, NULL);
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cpu = smp_processor_id();
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HARD_TX_LOCK(dev, txq, cpu);
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if (!netif_xmit_stopped(txq)) {
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rc = netdev_start_xmit(skb, dev, txq, 0);
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if (dev_xmit_complete(rc))
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free_skb = false;
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}
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HARD_TX_UNLOCK(dev, txq);
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if (free_skb) {
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trace_xdp_exception(dev, xdp_prog, XDP_TX);
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kfree_skb(skb);
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}
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}
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static struct static_key generic_xdp_needed __read_mostly;
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static int do_xdp_generic(struct sk_buff *skb)
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{
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struct bpf_prog *xdp_prog = rcu_dereference(skb->dev->xdp_prog);
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if (xdp_prog) {
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u32 act = netif_receive_generic_xdp(skb, xdp_prog);
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if (act != XDP_PASS) {
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if (act == XDP_TX)
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generic_xdp_tx(skb, xdp_prog);
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return XDP_DROP;
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}
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}
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return XDP_PASS;
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}
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static int netif_rx_internal(struct sk_buff *skb)
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{
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int ret;
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@ -3872,6 +3973,14 @@ static int netif_rx_internal(struct sk_buff *skb)
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net_timestamp_check(netdev_tstamp_prequeue, skb);
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trace_netif_rx(skb);
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if (static_key_false(&generic_xdp_needed)) {
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int ret = do_xdp_generic(skb);
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if (ret != XDP_PASS)
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return NET_RX_DROP;
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}
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#ifdef CONFIG_RPS
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if (static_key_false(&rps_needed)) {
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struct rps_dev_flow voidflow, *rflow = &voidflow;
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@ -4338,8 +4447,6 @@ static int __netif_receive_skb(struct sk_buff *skb)
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return ret;
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}
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static struct static_key generic_xdp_needed __read_mostly;
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static int generic_xdp_install(struct net_device *dev, struct netdev_xdp *xdp)
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{
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struct bpf_prog *old = rtnl_dereference(dev->xdp_prog);
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@ -4373,89 +4480,6 @@ static int generic_xdp_install(struct net_device *dev, struct netdev_xdp *xdp)
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return ret;
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}
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static u32 netif_receive_generic_xdp(struct sk_buff *skb,
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struct bpf_prog *xdp_prog)
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{
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struct xdp_buff xdp;
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u32 act = XDP_DROP;
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void *orig_data;
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int hlen, off;
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u32 mac_len;
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/* Reinjected packets coming from act_mirred or similar should
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* not get XDP generic processing.
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*/
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if (skb_cloned(skb))
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return XDP_PASS;
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if (skb_linearize(skb))
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goto do_drop;
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/* The XDP program wants to see the packet starting at the MAC
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* header.
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*/
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mac_len = skb->data - skb_mac_header(skb);
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hlen = skb_headlen(skb) + mac_len;
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xdp.data = skb->data - mac_len;
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xdp.data_end = xdp.data + hlen;
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xdp.data_hard_start = skb->data - skb_headroom(skb);
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orig_data = xdp.data;
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act = bpf_prog_run_xdp(xdp_prog, &xdp);
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off = xdp.data - orig_data;
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if (off > 0)
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__skb_pull(skb, off);
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else if (off < 0)
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__skb_push(skb, -off);
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switch (act) {
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case XDP_TX:
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__skb_push(skb, mac_len);
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/* fall through */
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case XDP_PASS:
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break;
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default:
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bpf_warn_invalid_xdp_action(act);
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/* fall through */
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case XDP_ABORTED:
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trace_xdp_exception(skb->dev, xdp_prog, act);
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/* fall through */
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case XDP_DROP:
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do_drop:
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kfree_skb(skb);
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break;
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}
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return act;
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}
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/* When doing generic XDP we have to bypass the qdisc layer and the
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* network taps in order to match in-driver-XDP behavior.
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*/
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static void generic_xdp_tx(struct sk_buff *skb, struct bpf_prog *xdp_prog)
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{
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struct net_device *dev = skb->dev;
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struct netdev_queue *txq;
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bool free_skb = true;
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int cpu, rc;
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txq = netdev_pick_tx(dev, skb, NULL);
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cpu = smp_processor_id();
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HARD_TX_LOCK(dev, txq, cpu);
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if (!netif_xmit_stopped(txq)) {
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rc = netdev_start_xmit(skb, dev, txq, 0);
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if (dev_xmit_complete(rc))
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free_skb = false;
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}
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HARD_TX_UNLOCK(dev, txq);
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if (free_skb) {
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trace_xdp_exception(dev, xdp_prog, XDP_TX);
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kfree_skb(skb);
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}
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}
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static int netif_receive_skb_internal(struct sk_buff *skb)
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{
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int ret;
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@ -4468,17 +4492,11 @@ static int netif_receive_skb_internal(struct sk_buff *skb)
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rcu_read_lock();
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if (static_key_false(&generic_xdp_needed)) {
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struct bpf_prog *xdp_prog = rcu_dereference(skb->dev->xdp_prog);
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int ret = do_xdp_generic(skb);
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if (xdp_prog) {
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u32 act = netif_receive_generic_xdp(skb, xdp_prog);
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if (act != XDP_PASS) {
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rcu_read_unlock();
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if (act == XDP_TX)
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generic_xdp_tx(skb, xdp_prog);
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return NET_RX_DROP;
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}
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if (ret != XDP_PASS) {
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rcu_read_unlock();
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return NET_RX_DROP;
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}
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}
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