[Intel-wired-lan] [PATCH 6/9] igc: Add Initial XDP support

[Andre Guedes <andre.guedes@intel.com>]

This patch adds the initial XDP support to the igc driver. For now,
only XDP_PASS, XDP_DROP, XDP_ABORT actions are supported. Upcoming
patches will add support for the remaining XDP actions.

XDP-specific helpers are defined in a new file, igc_xdp.c. These
helpers are utilized in igc_main.c to implement the ndo_bpf callback
and to handle XDP programs execution in igc_clean_rx_irq(). The driver
doesn't support XDP functionality with frames that span over multiple
buffers so jumbo frames are not allowed for now.

The approach implemented by this patch follows the approach implemented
in other Intel drivers as much as possible for the sake of consistency
across the drivers.

Quick comment regarding igc_build_skb(): this patch doesn't touch it
because the function is never called. It seems its support is
incomplete/in progress. The function was added by commit 0507ef8a0372b
("igc: Add transmit and receive fastpath and interrupt handlers") but
ring_ uses_build_skb() always return False since the IGC_RING_FLAG_RX_
BUILD_SKB_ENABLED isn't set anywhere in the driver code.

This patch has been tested with the sample app "xdp1" located in
samples/bpf/ dir.

Signed-off-by: Andre Guedes <andre.guedes@intel.com>
---
 drivers/net/ethernet/intel/igc/Makefile   |  2 +-
 drivers/net/ethernet/intel/igc/igc.h      |  2 +
 drivers/net/ethernet/intel/igc/igc_main.c | 58 +++++++++++++++---
 drivers/net/ethernet/intel/igc/igc_xdp.c  | 75 +++++++++++++++++++++++
 drivers/net/ethernet/intel/igc/igc_xdp.h  | 18 ++++++
 5 files changed, 144 insertions(+), 11 deletions(-)
 create mode 100644 drivers/net/ethernet/intel/igc/igc_xdp.c
 create mode 100644 drivers/net/ethernet/intel/igc/igc_xdp.h

diff --git a/drivers/net/ethernet/intel/igc/Makefile b/drivers/net/ethernet/intel/igc/Makefile
index 1c3051db9085..95d1e8c490a4 100644
--- a/drivers/net/ethernet/intel/igc/Makefile
+++ b/drivers/net/ethernet/intel/igc/Makefile
@@ -8,4 +8,4 @@
 obj-$(CONFIG_IGC) += igc.o
 
 igc-objs := igc_main.o igc_mac.o igc_i225.o igc_base.o igc_nvm.o igc_phy.o \
-igc_diag.o igc_ethtool.o igc_ptp.o igc_dump.o igc_tsn.o
+igc_diag.o igc_ethtool.o igc_ptp.o igc_dump.o igc_tsn.o igc_xdp.o
diff --git a/drivers/net/ethernet/intel/igc/igc.h b/drivers/net/ethernet/intel/igc/igc.h
index b9d15e6f22f6..e013ac65001b 100644
--- a/drivers/net/ethernet/intel/igc/igc.h
+++ b/drivers/net/ethernet/intel/igc/igc.h
@@ -217,6 +217,8 @@ struct igc_adapter {
 	struct timecounter tc;
 	struct timespec64 prev_ptp_time; /* Pre-reset PTP clock */
 	ktime_t ptp_reset_start; /* Reset time in clock mono */
+
+	struct bpf_prog *xdp_prog;
 };
 
 void igc_up(struct igc_adapter *adapter);
diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index d026609eec4d..8cdd3a16e637 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -16,6 +16,7 @@
 #include "igc.h"
 #include "igc_hw.h"
 #include "igc_tsn.h"
+#include "igc_xdp.h"
 
 #define DRV_SUMMARY	"Intel(R) 2.5G Ethernet Linux Driver"
 
@@ -1592,11 +1593,11 @@ static struct sk_buff *igc_build_skb(struct igc_ring *rx_ring,
 
 static struct sk_buff *igc_construct_skb(struct igc_ring *rx_ring,
 					 struct igc_rx_buffer *rx_buffer,
-					 unsigned int size, int pkt_offset,
+					 struct xdp_buff *xdp,
 					 ktime_t timestamp)
 {
-	void *va = page_address(rx_buffer->page) + rx_buffer->page_offset +
-		   pkt_offset;
+	void *va = xdp->data;
+	unsigned int size = xdp->data_end - xdp->data;
 	unsigned int truesize = igc_get_rx_frame_truesize(rx_ring, size);
 	unsigned int headlen;
 	struct sk_buff *skb;
@@ -1746,6 +1747,10 @@ static bool igc_cleanup_headers(struct igc_ring *rx_ring,
 				union igc_adv_rx_desc *rx_desc,
 				struct sk_buff *skb)
 {
+	/* XDP packets use error pointer so abort at this point */
+	if (IS_ERR(skb))
+		return true;
+
 	if (unlikely(igc_test_staterr(rx_desc, IGC_RXDEXT_STATERR_RXE))) {
 		struct net_device *netdev = rx_ring->netdev;
 
@@ -1911,7 +1916,9 @@ static int igc_clean_rx_irq(struct igc_q_vector *q_vector, const int budget)
 		struct igc_rx_buffer *rx_buffer;
 		ktime_t timestamp = 0;
 		int pkt_offset = 0;
+		struct xdp_buff xdp;
 		unsigned int size;
+		void *pktbuf;
 
 		/* return some buffers to hardware, one at a time is too slow */
 		if (cleaned_count >= IGC_RX_BUFFER_WRITE) {
@@ -1932,24 +1939,37 @@ static int igc_clean_rx_irq(struct igc_q_vector *q_vector, const int budget)
 
 		rx_buffer = igc_get_rx_buffer(rx_ring, size);
 
-		if (igc_test_staterr(rx_desc, IGC_RXDADV_STAT_TSIP)) {
-			void *pktbuf = page_address(rx_buffer->page) +
-				       rx_buffer->page_offset;
+		pktbuf = page_address(rx_buffer->page) + rx_buffer->page_offset;
 
+		if (igc_test_staterr(rx_desc, IGC_RXDADV_STAT_TSIP)) {
 			timestamp = igc_ptp_rx_pktstamp(q_vector->adapter,
 							pktbuf);
 			pkt_offset = IGC_TS_HDR_LEN;
 			size -= IGC_TS_HDR_LEN;
 		}
 
-		/* retrieve a buffer from the ring */
-		if (skb)
+		if (!skb) {
+			struct igc_adapter *adapter = q_vector->adapter;
+
+			xdp.data = pktbuf + pkt_offset;
+			xdp.data_end = xdp.data + size;
+			xdp.data_hard_start = pktbuf - igc_rx_offset(rx_ring);
+			xdp_set_data_meta_invalid(&xdp);
+
+			skb = igc_xdp_run_prog(adapter, &xdp);
+		}
+
+		if (IS_ERR(skb)) {
+			rx_buffer->pagecnt_bias++;
+			total_packets++;
+			total_bytes += size;
+		} else if (skb)
 			igc_add_rx_frag(rx_ring, rx_buffer, skb, size);
 		else if (ring_uses_build_skb(rx_ring))
 			skb = igc_build_skb(rx_ring, rx_buffer, rx_desc, size);
 		else
-			skb = igc_construct_skb(rx_ring, rx_buffer, size,
-						pkt_offset, timestamp);
+			skb = igc_construct_skb(rx_ring, rx_buffer, &xdp,
+						timestamp);
 
 		/* exit if we failed to retrieve a buffer */
 		if (!skb) {
@@ -3881,6 +3901,11 @@ static int igc_change_mtu(struct net_device *netdev, int new_mtu)
 	int max_frame = new_mtu + ETH_HLEN + ETH_FCS_LEN + VLAN_HLEN;
 	struct igc_adapter *adapter = netdev_priv(netdev);
 
+	if (igc_xdp_is_enabled(adapter) && new_mtu > ETH_DATA_LEN) {
+		netdev_dbg(netdev, "Jumbo frames not supported with XDP");
+		return -EINVAL;
+	}
+
 	/* adjust max frame to be at least the size of a standard frame */
 	if (max_frame < (ETH_FRAME_LEN + ETH_FCS_LEN))
 		max_frame = ETH_FRAME_LEN + ETH_FCS_LEN;
@@ -4867,6 +4892,18 @@ static int igc_setup_tc(struct net_device *dev, enum tc_setup_type type,
 	}
 }
 
+static int igc_bpf(struct net_device *dev, struct netdev_bpf *bpf)
+{
+	struct igc_adapter *adapter = netdev_priv(dev);
+
+	switch (bpf->command) {
+	case XDP_SETUP_PROG:
+		return igc_xdp_set_prog(adapter, bpf->prog, bpf->extack);
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
 static const struct net_device_ops igc_netdev_ops = {
 	.ndo_open		= igc_open,
 	.ndo_stop		= igc_close,
@@ -4880,6 +4917,7 @@ static const struct net_device_ops igc_netdev_ops = {
 	.ndo_features_check	= igc_features_check,
 	.ndo_do_ioctl		= igc_ioctl,
 	.ndo_setup_tc		= igc_setup_tc,
+	.ndo_bpf		= igc_bpf,
 };
 
 /* PCIe configuration access */
diff --git a/drivers/net/ethernet/intel/igc/igc_xdp.c b/drivers/net/ethernet/intel/igc/igc_xdp.c
new file mode 100644
index 000000000000..0085d8b85466
--- /dev/null
+++ b/drivers/net/ethernet/intel/igc/igc_xdp.c
@@ -0,0 +1,75 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020, Intel Corporation. */
+
+#include <linux/bpf_trace.h>
+
+#include "igc.h"
+#include "igc_xdp.h"
+
+int igc_xdp_set_prog(struct igc_adapter *adapter, struct bpf_prog *prog,
+		     struct netlink_ext_ack *extack)
+{
+	struct net_device *dev = adapter->netdev;
+	bool if_running = netif_running(dev);
+	struct bpf_prog *old_prog;
+
+	if (dev->mtu > ETH_DATA_LEN) {
+		/* For now, the driver doesn't support XDP functionality with
+		 * jumbo frames so we return error.
+		 */
+		NL_SET_ERR_MSG_MOD(extack, "Jumbo frames not supported");
+		return -EOPNOTSUPP;
+	}
+
+	if (if_running)
+		igc_close(dev);
+
+	old_prog = xchg(&adapter->xdp_prog, prog);
+	if (old_prog)
+		bpf_prog_put(old_prog);
+
+	if (if_running)
+		igc_open(dev);
+
+	netdev_dbg(dev, "XDP program set successfully");
+	return 0;
+}
+
+struct sk_buff *igc_xdp_run_prog(struct igc_adapter *adapter,
+				 struct xdp_buff *xdp)
+{
+	struct bpf_prog *prog;
+	int res;
+	u32 act;
+
+	rcu_read_lock();
+
+	prog = READ_ONCE(adapter->xdp_prog);
+	if (!prog)
+		goto unlock;
+
+	act = bpf_prog_run_xdp(prog, xdp);
+	switch (act) {
+	case XDP_PASS:
+		res = IGC_XDP_PASS;
+		break;
+	default:
+		bpf_warn_invalid_xdp_action(act);
+		fallthrough;
+	case XDP_ABORTED:
+		trace_xdp_exception(adapter->netdev, prog, act);
+		fallthrough;
+	case XDP_DROP:
+		res = IGC_XDP_CONSUMED;
+		break;
+	}
+
+unlock:
+	rcu_read_unlock();
+	return ERR_PTR(-res);
+}
+
+bool igc_xdp_is_enabled(struct igc_adapter *adapter)
+{
+	return !!adapter->xdp_prog;
+}
diff --git a/drivers/net/ethernet/intel/igc/igc_xdp.h b/drivers/net/ethernet/intel/igc/igc_xdp.h
new file mode 100644
index 000000000000..ab36ab4d48fd
--- /dev/null
+++ b/drivers/net/ethernet/intel/igc/igc_xdp.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2020, Intel Corporation. */
+
+#ifndef _IGC_XDP_H_
+#define _IGC_XDP_H_
+
+#define IGC_XDP_PASS		0
+#define IGC_XDP_CONSUMED	BIT(0)
+
+int igc_xdp_set_prog(struct igc_adapter *adapter, struct bpf_prog *prog,
+		     struct netlink_ext_ack *extack);
+
+struct sk_buff *igc_xdp_run_prog(struct igc_adapter *adapter,
+				 struct xdp_buff *xdp);
+
+bool igc_xdp_is_enabled(struct igc_adapter *adapter);
+
+#endif /* _IGC_XDP_H_ */
-- 
2.26.2