i40e: add XDP support for pass and drop actions

This commit adds basic XDP support for i40e derived NICs. All XDP
actions will end up in XDP_DROP.
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/i40e/i40e.h

@@ -645,6 +645,8 @@ struct i40e_vsi {
 	u16 max_frame;
 	u16 rx_buf_len;
 
+	struct bpf_prog *xdp_prog;
+
 	/* List of q_vectors allocated to this VSI */
 	struct i40e_q_vector **q_vectors;
 	int num_q_vectors;
@@ -972,4 +974,9 @@ i40e_status i40e_get_npar_bw_setting(struct i40e_pf *pf);
 i40e_status i40e_set_npar_bw_setting(struct i40e_pf *pf);
 i40e_status i40e_commit_npar_bw_setting(struct i40e_pf *pf);
 void i40e_print_link_message(struct i40e_vsi *vsi, bool isup);
+
+static inline bool i40e_enabled_xdp_vsi(struct i40e_vsi *vsi)
+{
+	return !!vsi->xdp_prog;
+}
 #endif /* _I40E_H_ */

drivers/net/ethernet/intel/i40e/i40e_main.c

@@ -27,6 +27,7 @@
 #include <linux/etherdevice.h>
 #include <linux/of_net.h>
 #include <linux/pci.h>
+#include <linux/bpf.h>
 
 /* Local includes */
 #include "i40e.h"
@@ -2395,6 +2396,18 @@ static void i40e_sync_filters_subtask(struct i40e_pf *pf)
 	}
 }
 
+/**
+ * i40e_max_xdp_frame_size - returns the maximum allowed frame size for XDP
+ * @vsi: the vsi
+ **/
+static int i40e_max_xdp_frame_size(struct i40e_vsi *vsi)
+{
+	if (PAGE_SIZE >= 8192 || (vsi->back->flags & I40E_FLAG_LEGACY_RX))
+		return I40E_RXBUFFER_2048;
+	else
+		return I40E_RXBUFFER_3072;
+}
+
 /**
  * i40e_change_mtu - NDO callback to change the Maximum Transfer Unit
  * @netdev: network interface device structure
@@ -2408,6 +2421,13 @@ static int i40e_change_mtu(struct net_device *netdev, int new_mtu)
 	struct i40e_vsi *vsi = np->vsi;
 	struct i40e_pf *pf = vsi->back;
 
+	if (i40e_enabled_xdp_vsi(vsi)) {
+		int frame_size = new_mtu + ETH_HLEN + ETH_FCS_LEN + VLAN_HLEN;
+
+		if (frame_size > i40e_max_xdp_frame_size(vsi))
+			return -EINVAL;
+	}
+
 	netdev_info(netdev, "changing MTU from %d to %d\n",
 		    netdev->mtu, new_mtu);
 	netdev->mtu = new_mtu;
@@ -9311,6 +9331,72 @@ static netdev_features_t i40e_features_check(struct sk_buff *skb,
 	return features & ~(NETIF_F_CSUM_MASK | NETIF_F_GSO_MASK);
 }
 
+/**
+ * i40e_xdp_setup - add/remove an XDP program
+ * @vsi: VSI to changed
+ * @prog: XDP program
+ **/
+static int i40e_xdp_setup(struct i40e_vsi *vsi,
+			  struct bpf_prog *prog)
+{
+	int frame_size = vsi->netdev->mtu + ETH_HLEN + ETH_FCS_LEN + VLAN_HLEN;
+	struct i40e_pf *pf = vsi->back;
+	struct bpf_prog *old_prog;
+	bool need_reset;
+	int i;
+
+	/* Don't allow frames that span over multiple buffers */
+	if (frame_size > vsi->rx_buf_len)
+		return -EINVAL;
+
+	if (!i40e_enabled_xdp_vsi(vsi) && !prog)
+		return 0;
+
+	/* When turning XDP on->off/off->on we reset and rebuild the rings. */
+	need_reset = (i40e_enabled_xdp_vsi(vsi) != !!prog);
+
+	if (need_reset)
+		i40e_prep_for_reset(pf, true);
+
+	old_prog = xchg(&vsi->xdp_prog, prog);
+
+	if (need_reset)
+		i40e_reset_and_rebuild(pf, true, true);
+
+	for (i = 0; i < vsi->num_queue_pairs; i++)
+		WRITE_ONCE(vsi->rx_rings[i]->xdp_prog, vsi->xdp_prog);
+
+	if (old_prog)
+		bpf_prog_put(old_prog);
+
+	return 0;
+}
+
+/**
+ * i40e_xdp - implements ndo_xdp for i40e
+ * @dev: netdevice
+ * @xdp: XDP command
+ **/
+static int i40e_xdp(struct net_device *dev,
+		    struct netdev_xdp *xdp)
+{
+	struct i40e_netdev_priv *np = netdev_priv(dev);
+	struct i40e_vsi *vsi = np->vsi;
+
+	if (vsi->type != I40E_VSI_MAIN)
+		return -EINVAL;
+
+	switch (xdp->command) {
+	case XDP_SETUP_PROG:
+		return i40e_xdp_setup(vsi, xdp->prog);
+	case XDP_QUERY_PROG:
+		xdp->prog_attached = i40e_enabled_xdp_vsi(vsi);
+		return 0;
+	default:
+		return -EINVAL;
+	}
+}
+
 static const struct net_device_ops i40e_netdev_ops = {
 	.ndo_open		= i40e_open,
 	.ndo_stop		= i40e_close,
@@ -9343,6 +9429,7 @@ static const struct net_device_ops i40e_netdev_ops = {
 	.ndo_features_check	= i40e_features_check,
 	.ndo_bridge_getlink	= i40e_ndo_bridge_getlink,
 	.ndo_bridge_setlink	= i40e_ndo_bridge_setlink,
+	.ndo_xdp		= i40e_xdp,
 };
 
 /**

drivers/net/ethernet/intel/i40e/i40e_txrx.c

@@ -26,6 +26,7 @@
 
 #include <linux/prefetch.h>
 #include <net/busy_poll.h>
+#include <linux/bpf_trace.h>
 #include "i40e.h"
 #include "i40e_trace.h"
 #include "i40e_prototype.h"
@@ -1195,6 +1196,7 @@ void i40e_clean_rx_ring(struct i40e_ring *rx_ring)
 void i40e_free_rx_resources(struct i40e_ring *rx_ring)
 {
 	i40e_clean_rx_ring(rx_ring);
+	rx_ring->xdp_prog = NULL;
 	kfree(rx_ring->rx_bi);
 	rx_ring->rx_bi = NULL;
 
@@ -1241,6 +1243,8 @@ int i40e_setup_rx_descriptors(struct i40e_ring *rx_ring)
 	rx_ring->next_to_clean = 0;
 	rx_ring->next_to_use = 0;
 
+	rx_ring->xdp_prog = rx_ring->vsi->xdp_prog;
+
 	return 0;
 err:
 	kfree(rx_ring->rx_bi);
@@ -1593,6 +1597,7 @@ void i40e_process_skb_fields(struct i40e_ring *rx_ring,
  * i40e_cleanup_headers - Correct empty headers
  * @rx_ring: rx descriptor ring packet is being transacted on
  * @skb: pointer to current skb being fixed
+ * @rx_desc: pointer to the EOP Rx descriptor
  *
  * Also address the case where we are pulling data in on pages only
  * and as such no data is present in the skb header.
@@ -1602,8 +1607,25 @@ void i40e_process_skb_fields(struct i40e_ring *rx_ring,
  *
  * Returns true if an error was encountered and skb was freed.
  **/
-static bool i40e_cleanup_headers(struct i40e_ring *rx_ring, struct sk_buff *skb)
+static bool i40e_cleanup_headers(struct i40e_ring *rx_ring, struct sk_buff *skb,
+				 union i40e_rx_desc *rx_desc)
+
 {
+	/* XDP packets use error pointer so abort at this point */
+	if (IS_ERR(skb))
+		return true;
+
+	/* ERR_MASK will only have valid bits if EOP set, and
+	 * what we are doing here is actually checking
+	 * I40E_RX_DESC_ERROR_RXE_SHIFT, since it is the zeroth bit in
+	 * the error field
+	 */
+	if (unlikely(i40e_test_staterr(rx_desc,
+				       BIT(I40E_RXD_QW1_ERROR_SHIFT)))) {
+		dev_kfree_skb_any(skb);
+		return true;
+	}
+
 	/* if eth_skb_pad returns an error the skb was freed */
 	if (eth_skb_pad(skb))
 		return true;
@@ -1776,7 +1798,7 @@ static struct i40e_rx_buffer *i40e_get_rx_buffer(struct i40e_ring *rx_ring,
  * i40e_construct_skb - Allocate skb and populate it
  * @rx_ring: rx descriptor ring to transact packets on
  * @rx_buffer: rx buffer to pull data from
- * @size: size of buffer to add to skb
+ * @xdp: xdp_buff pointing to the data
  *
  * This function allocates an skb.  It then populates it with the page
  * data from the current receive descriptor, taking care to set up the
@@ -1784,9 +1806,9 @@ static struct i40e_rx_buffer *i40e_get_rx_buffer(struct i40e_ring *rx_ring,
  */
 static struct sk_buff *i40e_construct_skb(struct i40e_ring *rx_ring,
 					  struct i40e_rx_buffer *rx_buffer,
-					  unsigned int size)
+					  struct xdp_buff *xdp)
 {
-	void *va = page_address(rx_buffer->page) + rx_buffer->page_offset;
+	unsigned int size = xdp->data_end - xdp->data;
 #if (PAGE_SIZE < 8192)
 	unsigned int truesize = i40e_rx_pg_size(rx_ring) / 2;
 #else
@@ -1796,9 +1818,9 @@ static struct sk_buff *i40e_construct_skb(struct i40e_ring *rx_ring,
 	struct sk_buff *skb;
 
 	/* prefetch first cache line of first page */
-	prefetch(va);
+	prefetch(xdp->data);
 #if L1_CACHE_BYTES < 128
-	prefetch(va + L1_CACHE_BYTES);
+	prefetch(xdp->data + L1_CACHE_BYTES);
 #endif
 
 	/* allocate a skb to store the frags */
@@ -1811,10 +1833,11 @@ static struct sk_buff *i40e_construct_skb(struct i40e_ring *rx_ring,
 	/* Determine available headroom for copy */
 	headlen = size;
 	if (headlen > I40E_RX_HDR_SIZE)
-		headlen = eth_get_headlen(va, I40E_RX_HDR_SIZE);
+		headlen = eth_get_headlen(xdp->data, I40E_RX_HDR_SIZE);
 
 	/* align pull length to size of long to optimize memcpy performance */
-	memcpy(__skb_put(skb, headlen), va, ALIGN(headlen, sizeof(long)));
+	memcpy(__skb_put(skb, headlen), xdp->data,
+	       ALIGN(headlen, sizeof(long)));
 
 	/* update all of the pointers */
 	size -= headlen;
@@ -1841,16 +1864,16 @@ static struct sk_buff *i40e_construct_skb(struct i40e_ring *rx_ring,
  * i40e_build_skb - Build skb around an existing buffer
  * @rx_ring: Rx descriptor ring to transact packets on
  * @rx_buffer: Rx buffer to pull data from
- * @size: size of buffer to add to skb
+ * @xdp: xdp_buff pointing to the data
  *
  * This function builds an skb around an existing Rx buffer, taking care
  * to set up the skb correctly and avoid any memcpy overhead.
  */
 static struct sk_buff *i40e_build_skb(struct i40e_ring *rx_ring,
 				      struct i40e_rx_buffer *rx_buffer,
-				      unsigned int size)
+				      struct xdp_buff *xdp)
 {
-	void *va = page_address(rx_buffer->page) + rx_buffer->page_offset;
+	unsigned int size = xdp->data_end - xdp->data;
 #if (PAGE_SIZE < 8192)
 	unsigned int truesize = i40e_rx_pg_size(rx_ring) / 2;
 #else
@@ -1860,12 +1883,12 @@ static struct sk_buff *i40e_build_skb(struct i40e_ring *rx_ring,
 	struct sk_buff *skb;
 
 	/* prefetch first cache line of first page */
-	prefetch(va);
+	prefetch(xdp->data);
 #if L1_CACHE_BYTES < 128
-	prefetch(va + L1_CACHE_BYTES);
+	prefetch(xdp->data + L1_CACHE_BYTES);
 #endif
 	/* build an skb around the page buffer */
-	skb = build_skb(va - I40E_SKB_PAD, truesize);
+	skb = build_skb(xdp->data_hard_start, truesize);
 	if (unlikely(!skb))
 		return NULL;
 
@@ -1944,6 +1967,46 @@ static bool i40e_is_non_eop(struct i40e_ring *rx_ring,
 	return true;
 }
 
+#define I40E_XDP_PASS 0
+#define I40E_XDP_CONSUMED 1
+
+/**
+ * i40e_run_xdp - run an XDP program
+ * @rx_ring: Rx ring being processed
+ * @xdp: XDP buffer containing the frame
+ **/
+static struct sk_buff *i40e_run_xdp(struct i40e_ring *rx_ring,
+				    struct xdp_buff *xdp)
+{
+	int result = I40E_XDP_PASS;
+	struct bpf_prog *xdp_prog;
+	u32 act;
+
+	rcu_read_lock();
+	xdp_prog = READ_ONCE(rx_ring->xdp_prog);
+
+	if (!xdp_prog)
+		goto xdp_out;
+
+	act = bpf_prog_run_xdp(xdp_prog, xdp);
+	switch (act) {
+	case XDP_PASS:
+		break;
+	default:
+		bpf_warn_invalid_xdp_action(act);
+	case XDP_TX:
+	case XDP_ABORTED:
+		trace_xdp_exception(rx_ring->netdev, xdp_prog, act);
+		/* fallthrough -- handle aborts by dropping packet */
+	case XDP_DROP:
+		result = I40E_XDP_CONSUMED;
+		break;
+	}
+xdp_out:
+	rcu_read_unlock();
+	return ERR_PTR(-result);
+}
+
 /**
  * i40e_clean_rx_irq - Clean completed descriptors from Rx ring - bounce buf
  * @rx_ring: rx descriptor ring to transact packets on
@@ -1966,6 +2029,7 @@ static int i40e_clean_rx_irq(struct i40e_ring *rx_ring, int budget)
 	while (likely(total_rx_packets < budget)) {
 		struct i40e_rx_buffer *rx_buffer;
 		union i40e_rx_desc *rx_desc;
+		struct xdp_buff xdp;
 		unsigned int size;
 		u16 vlan_tag;
 		u8 rx_ptype;
@@ -2006,12 +2070,27 @@ static int i40e_clean_rx_irq(struct i40e_ring *rx_ring, int budget)
 		rx_buffer = i40e_get_rx_buffer(rx_ring, size);
 
 		/* retrieve a buffer from the ring */
-		if (skb)
+		if (!skb) {
+			xdp.data = page_address(rx_buffer->page) +
+				   rx_buffer->page_offset;
+			xdp.data_hard_start = xdp.data -
+					      i40e_rx_offset(rx_ring);
+			xdp.data_end = xdp.data + size;
+
+			skb = i40e_run_xdp(rx_ring, &xdp);
+		}
+
+		if (IS_ERR(skb)) {
+			total_rx_bytes += size;
+			total_rx_packets++;
+			rx_buffer->pagecnt_bias++;
+		} else if (skb) {
 			i40e_add_rx_frag(rx_ring, rx_buffer, skb, size);
-		else if (ring_uses_build_skb(rx_ring))
-			skb = i40e_build_skb(rx_ring, rx_buffer, size);
-		else
-			skb = i40e_construct_skb(rx_ring, rx_buffer, size);
+		} else if (ring_uses_build_skb(rx_ring)) {
+			skb = i40e_build_skb(rx_ring, rx_buffer, &xdp);
+		} else {
+			skb = i40e_construct_skb(rx_ring, rx_buffer, &xdp);
+		}
 
 		/* exit if we failed to retrieve a buffer */
 		if (!skb) {
@@ -2026,18 +2105,7 @@ static int i40e_clean_rx_irq(struct i40e_ring *rx_ring, int budget)
 		if (i40e_is_non_eop(rx_ring, rx_desc, skb))
 			continue;
 
-		/* ERR_MASK will only have valid bits if EOP set, and
-		 * what we are doing here is actually checking
-		 * I40E_RX_DESC_ERROR_RXE_SHIFT, since it is the zeroth bit in
-		 * the error field
-		 */
-		if (unlikely(i40e_test_staterr(rx_desc, BIT(I40E_RXD_QW1_ERROR_SHIFT)))) {
-			dev_kfree_skb_any(skb);
-			skb = NULL;
-			continue;
-		}
-
-		if (i40e_cleanup_headers(rx_ring, skb)) {
+		if (i40e_cleanup_headers(rx_ring, skb, rx_desc)) {
 			skb = NULL;
 			continue;
 		}

drivers/net/ethernet/intel/i40e/i40e_txrx.h

@@ -360,6 +360,7 @@ struct i40e_ring {
 	void *desc;			/* Descriptor ring memory */
 	struct device *dev;		/* Used for DMA mapping */
 	struct net_device *netdev;	/* netdev ring maps to */
+	struct bpf_prog *xdp_prog;
 	union {
 		struct i40e_tx_buffer *tx_bi;
 		struct i40e_rx_buffer *rx_bi;