net: lan966x: Add basic XDP support

Introduce basic XDP support to lan966x driver. Currently the driver
supports only the actions XDP_PASS, XDP_DROP and XDP_ABORTED.
Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/microchip/lan966x/Makefile

@@ -11,4 +11,5 @@ lan966x-switch-objs  := lan966x_main.o lan966x_phylink.o lan966x_port.o \
 			lan966x_ptp.o lan966x_fdma.o lan966x_lag.o \
 			lan966x_tc.o lan966x_mqprio.o lan966x_taprio.o \
 			lan966x_tbf.o lan966x_cbs.o lan966x_ets.o \
-			lan966x_tc_matchall.o lan966x_police.o lan966x_mirror.o
+			lan966x_tc_matchall.o lan966x_police.o lan966x_mirror.o \
+			lan966x_xdp.o

drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c

@@ -423,6 +423,7 @@ static bool lan966x_fdma_rx_more_frames(struct lan966x_rx *rx)
 static int lan966x_fdma_rx_check_frame(struct lan966x_rx *rx, u64 *src_port)
 {
 	struct lan966x *lan966x = rx->lan966x;
+	struct lan966x_port *port;
 	struct lan966x_db *db;
 	struct page *page;
 
@@ -443,7 +444,11 @@ static int lan966x_fdma_rx_check_frame(struct lan966x_rx *rx, u64 *src_port)
 	if (WARN_ON(*src_port >= lan966x->num_phys_ports))
 		return FDMA_ERROR;
 
+	port = lan966x->ports[*src_port];
+	if (!lan966x_xdp_port_present(port))
 		return FDMA_PASS;
+
+	return lan966x_xdp_run(port, page, FDMA_DCB_STATUS_BLOCKL(db->status));
 }
 
 static struct sk_buff *lan966x_fdma_rx_get_frame(struct lan966x_rx *rx,
@@ -524,6 +529,10 @@ static int lan966x_fdma_napi_poll(struct napi_struct *napi, int weight)
 			lan966x_fdma_rx_free_page(rx);
 			lan966x_fdma_rx_advance_dcb(rx);
 			goto allocate_new;
+		case FDMA_DROP:
+			lan966x_fdma_rx_free_page(rx);
+			lan966x_fdma_rx_advance_dcb(rx);
+			continue;
 		}
 
 		skb = lan966x_fdma_rx_get_frame(rx, src_port);

drivers/net/ethernet/microchip/lan966x/lan966x_main.c

@@ -468,6 +468,7 @@ static const struct net_device_ops lan966x_port_netdev_ops = {
 	.ndo_get_port_parent_id		= lan966x_port_get_parent_id,
 	.ndo_eth_ioctl			= lan966x_port_ioctl,
 	.ndo_setup_tc			= lan966x_tc_setup,
+	.ndo_bpf			= lan966x_xdp,
 };
 
 bool lan966x_netdevice_check(const struct net_device *dev)
@@ -694,6 +695,7 @@ static void lan966x_cleanup_ports(struct lan966x *lan966x)
 		if (port->dev)
 			unregister_netdev(port->dev);
 
+		lan966x_xdp_port_deinit(port);
 		if (lan966x->fdma && lan966x->fdma_ndev == port->dev)
 			lan966x_fdma_netdev_deinit(lan966x, port->dev);
 
@@ -1136,6 +1138,9 @@ static int lan966x_probe(struct platform_device *pdev)
 		lan966x->ports[p]->serdes = serdes;
 
 		lan966x_port_init(lan966x->ports[p]);
+		err = lan966x_xdp_port_init(lan966x->ports[p]);
+		if (err)
+			goto cleanup_ports;
 	}
 
 	lan966x_mdb_init(lan966x);

drivers/net/ethernet/microchip/lan966x/lan966x_main.h

@@ -103,10 +103,12 @@ enum macaccess_entry_type {
 /* FDMA return action codes for checking if the frame is valid
  * FDMA_PASS, frame is valid and can be used
  * FDMA_ERROR, something went wrong, stop getting more frames
+ * FDMA_DROP, frame is dropped, but continue to get more frames
  */
 enum lan966x_fdma_action {
 	FDMA_PASS = 0,
 	FDMA_ERROR,
+	FDMA_DROP,
 };
 
 struct lan966x_port;
@@ -329,6 +331,9 @@ struct lan966x_port {
 	enum netdev_lag_hash hash_type;
 
 	struct lan966x_port_tc tc;
+
+	struct bpf_prog *xdp_prog;
+	struct xdp_rxq_info xdp_rxq;
 };
 
 extern const struct phylink_mac_ops lan966x_phylink_mac_ops;
@@ -536,6 +541,17 @@ void lan966x_mirror_port_stats(struct lan966x_port *port,
 			       struct flow_stats *stats,
 			       bool ingress);
 
+int lan966x_xdp_port_init(struct lan966x_port *port);
+void lan966x_xdp_port_deinit(struct lan966x_port *port);
+int lan966x_xdp(struct net_device *dev, struct netdev_bpf *xdp);
+int lan966x_xdp_run(struct lan966x_port *port,
+		    struct page *page,
+		    u32 data_len);
+static inline bool lan966x_xdp_port_present(struct lan966x_port *port)
+{
+	return !!port->xdp_prog;
+}
+
 static inline void __iomem *lan_addr(void __iomem *base[],
 				     int id, int tinst, int tcnt,
 				     int gbase, int ginst,

drivers/net/ethernet/microchip/lan966x/lan966x_xdp.c

+// SPDX-License-Identifier: GPL-2.0+
+
+#include <linux/bpf.h>
+#include <linux/bpf_trace.h>
+#include <linux/filter.h>
+
+#include "lan966x_main.h"
+
+static int lan966x_xdp_setup(struct net_device *dev, struct netdev_bpf *xdp)
+{
+	struct lan966x_port *port = netdev_priv(dev);
+	struct lan966x *lan966x = port->lan966x;
+	struct bpf_prog *old_prog;
+
+	if (!lan966x->fdma) {
+		NL_SET_ERR_MSG_MOD(xdp->extack,
+				   "Allow to set xdp only when using fdma");
+		return -EOPNOTSUPP;
+	}
+
+	old_prog = xchg(&port->xdp_prog, xdp->prog);
+	if (old_prog)
+		bpf_prog_put(old_prog);
+
+	return 0;
+}
+
+int lan966x_xdp(struct net_device *dev, struct netdev_bpf *xdp)
+{
+	switch (xdp->command) {
+	case XDP_SETUP_PROG:
+		return lan966x_xdp_setup(dev, xdp);
+	default:
+		return -EINVAL;
+	}
+}
+
+int lan966x_xdp_run(struct lan966x_port *port, struct page *page, u32 data_len)
+{
+	struct bpf_prog *xdp_prog = port->xdp_prog;
+	struct lan966x *lan966x = port->lan966x;
+	struct xdp_buff xdp;
+	u32 act;
+
+	xdp_init_buff(&xdp, PAGE_SIZE << lan966x->rx.page_order,
+		      &port->xdp_rxq);
+	xdp_prepare_buff(&xdp, page_address(page), IFH_LEN_BYTES,
+			 data_len - IFH_LEN_BYTES, false);
+	act = bpf_prog_run_xdp(xdp_prog, &xdp);
+	switch (act) {
+	case XDP_PASS:
+		return FDMA_PASS;
+	default:
+		bpf_warn_invalid_xdp_action(port->dev, xdp_prog, act);
+		fallthrough;
+	case XDP_ABORTED:
+		trace_xdp_exception(port->dev, xdp_prog, act);
+		fallthrough;
+	case XDP_DROP:
+		return FDMA_DROP;
+	}
+}
+
+int lan966x_xdp_port_init(struct lan966x_port *port)
+{
+	struct lan966x *lan966x = port->lan966x;
+
+	return xdp_rxq_info_reg(&port->xdp_rxq, port->dev, 0,
+				lan966x->napi.napi_id);
+}
+
+void lan966x_xdp_port_deinit(struct lan966x_port *port)
+{
+	if (xdp_rxq_info_is_reg(&port->xdp_rxq))
+		xdp_rxq_info_unreg(&port->xdp_rxq);
+}