netdev - [PATCH RFC 5/9] veth: Handle xdp

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Message-Id: <20180424143923.26519-6-toshiaki.makita1@gmail.com>
Date:   Tue, 24 Apr 2018 23:39:19 +0900
From:   Toshiaki Makita <toshiaki.makita1@...il.com>
To:     netdev@...r.kernel.org
Cc:     Toshiaki Makita <makita.toshiaki@....ntt.co.jp>
Subject: [PATCH RFC 5/9] veth: Handle xdp_frame in xdp napi ring

From: Toshiaki Makita <makita.toshiaki@....ntt.co.jp>

This is preparation for XDP TX and ndo_xdp_xmit.

Now the napi ring accepts both skb and xdp_frame. When xdp_frame is
enqueued, skb will not be allocated until XDP program on veth returns
PASS. This will speedup the XDP processing when ndo_xdp_xmit is
implemented and xdp_frame is enqueued by the peer device.

Signed-off-by: Toshiaki Makita <makita.toshiaki@....ntt.co.jp>
---
 drivers/net/veth.c | 79 ++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 77 insertions(+), 2 deletions(-)

diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index 452771f31c30..89c91c1c9935 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -27,6 +27,7 @@
 #define DRV_NAME	"veth"
 #define DRV_VERSION	"1.0"
 
+#define VETH_XDP_FLAG		0x1UL
 #define VETH_RING_SIZE		256
 #define VETH_XDP_HEADROOM	(XDP_PACKET_HEADROOM + NET_IP_ALIGN)
 
@@ -48,6 +49,16 @@ struct veth_priv {
 	struct xdp_rxq_info	xdp_rxq;
 };
 
+static bool veth_is_xdp_frame(void *ptr)
+{
+	return (unsigned long)ptr & VETH_XDP_FLAG;
+}
+
+static void *veth_ptr_to_xdp(void *ptr)
+{
+	return (void *)((unsigned long)ptr & ~VETH_XDP_FLAG);
+}
+
 /*
  * ethtool interface
  */
@@ -117,7 +128,14 @@ static void veth_ptr_free(void *ptr)
 {
 	if (!ptr)
 		return;
-	dev_kfree_skb_any(ptr);
+
+	if (veth_is_xdp_frame(ptr)) {
+		struct xdp_frame *frame = veth_ptr_to_xdp(ptr);
+
+		xdp_return_frame(frame);
+	} else {
+		dev_kfree_skb_any(ptr);
+	}
 }
 
 static void veth_xdp_flush(struct veth_priv *priv)
@@ -263,6 +281,60 @@ static struct sk_buff *veth_build_skb(void *head, int headroom, int len,
 	return skb;
 }
 
+static struct sk_buff *veth_xdp_rcv_one(struct veth_priv *priv,
+					struct xdp_frame *frame)
+{
+	struct bpf_prog *xdp_prog;
+	unsigned int headroom;
+	struct sk_buff *skb;
+	int len, delta = 0;
+
+	rcu_read_lock();
+	xdp_prog = rcu_dereference(priv->xdp_prog);
+	if (xdp_prog) {
+		struct xdp_buff xdp;
+		u32 act;
+
+		xdp.data_hard_start = frame->data - frame->headroom;
+		xdp.data = frame->data;
+		xdp.data_end = frame->data + frame->len;
+		xdp.data_meta = frame->data - frame->metasize;
+		xdp.rxq = &priv->xdp_rxq;
+
+		act = bpf_prog_run_xdp(xdp_prog, &xdp);
+
+		switch (act) {
+		case XDP_PASS:
+			delta = frame->data - xdp.data;
+			break;
+		default:
+			bpf_warn_invalid_xdp_action(act);
+		case XDP_ABORTED:
+			trace_xdp_exception(priv->dev, xdp_prog, act);
+		case XDP_DROP:
+			goto err_xdp;
+		}
+	}
+	rcu_read_unlock();
+
+	headroom = frame->data - delta - (void *)frame;
+	len = frame->len + delta;
+	skb = veth_build_skb(frame, headroom, len, 0);
+	if (!skb) {
+		xdp_return_frame(frame);
+		goto err;
+	}
+
+	skb->protocol = eth_type_trans(skb, priv->dev);
+err:
+	return skb;
+err_xdp:
+	rcu_read_unlock();
+	xdp_return_frame(frame);
+
+	return NULL;
+}
+
 static struct sk_buff *veth_xdp_rcv_skb(struct veth_priv *priv,
 					struct sk_buff *skb)
 {
@@ -372,7 +444,10 @@ static int veth_xdp_rcv(struct veth_priv *priv, int budget)
 		if (!ptr)
 			break;
 
-		skb = veth_xdp_rcv_skb(priv, ptr);
+		if (veth_is_xdp_frame(ptr))
+			skb = veth_xdp_rcv_one(priv, veth_ptr_to_xdp(ptr));
+		else
+			skb = veth_xdp_rcv_skb(priv, ptr);
 
 		if (skb)
 			napi_gro_receive(&priv->xdp_napi, skb);
-- 
2.14.3