Re: [PATCH v2 net-next 14/14] net: fec: add AF_XDP zero-copy support

Add AF_XDP zero-copy support for both TX and RX.

For RX, instead of allocating buffers from the page pool, the buffers
are allocated from xsk pool, so fec_alloc_rxq_buffers_zc() is added to
allocate RX buffers from xsk pool. And fec_enet_rx_queue_xsk() is used
to process the frames from the RX queue which is bound to the AF_XDP
socket. Similar to the XDP copy mode, the zero-copy mode also supports
XDP_TX, XDP_PASS, XDP_DROP and XDP_REDIRECT actions. In addition,
fec_enet_xsk_tx_xmit() is similar to fec_enet_xdp_tx_xmit() and is used
to handle XDP_TX action in zero-copy mode.

For TX, there are two cases, one is the frames from the AF_XDP socket,
so fec_enet_xsk_xmit() is added to directly transmit the frames from
the socket and the buffer type is marked as FEC_TXBUF_T_XSK_XMIT. The
other one is the frams from the RX queue (XDP_TX action), the buffer
type is marked as FEC_TXBUF_T_XSK_TX. Therefore, fec_enet_tx_queue()
could correctly clean the TX queue base on the buffer type.

Also, some tests have been done on the i.MX93-EVK board with the xdpsock
tool, the following are the results.

Env: i.MX93 connects to a packet generator, the link speed is 1Gbps, and
flow-control is off. The RX packet size is 64 bytes including FCS. Only
one RX queue (CPU) is used to receive frames.

1. MAC swap L2 forwarding
1.1 Zero-copy mode
root@imx93evk:~# ./xdpsock -i eth0 -l -z
 sock0@eth0:0 l2fwd xdp-drv
                   pps            pkts           1.00
rx                 414715         415455
tx                 414715         415455

1.2 Copy mode
root@imx93evk:~# ./xdpsock -i eth0 -l -c
 sock0@eth0:0 l2fwd xdp-drv
                   pps            pkts           1.00
rx                 356396         356609
tx                 356396         356609

2. TX only
2.1 Zero-copy mode
root@imx93evk:~# ./xdpsock -i eth0 -t -s 64 -z
 sock0@eth0:0 txonly xdp-drv
                   pps            pkts           1.00
rx                 0              0
tx                 1119573        1126720

2.2 Copy mode
root@imx93evk:~# ./xdpsock -i eth0 -t -s 64 -c
sock0@eth0:0 txonly xdp-drv
                   pps            pkts           1.00
rx                 0              0
tx                 406864         407616

Signed-off-by: Wei Fang <wei.fang@nxp.com>
---
 drivers/net/ethernet/freescale/fec.h      |  13 +-
 drivers/net/ethernet/freescale/fec_main.c | 611 ++++++++++++++++++++--
 2 files changed, 582 insertions(+), 42 deletions(-)

diff --git a/drivers/net/ethernet/freescale/fec.h b/drivers/net/ethernet/freescale/fec.h
index ad7aba1a8536..7176803146f3 100644
--- a/drivers/net/ethernet/freescale/fec.h
+++ b/drivers/net/ethernet/freescale/fec.h

 		if (!bpf->prog)
 			xdp_features_clear_redirect_target(dev);

@@ -3994,7 +4497,8 @@ static int fec_enet_bpf(struct net_device *dev, struct netdev_bpf *bpf)
 		return 0;

 	case XDP_SETUP_XSK_POOL:
-		return -EOPNOTSUPP;
+		return fec_setup_xsk_pool(dev, bpf->xsk.pool,
+					  bpf->xsk.queue_id);

 	default:
 		return -EOPNOTSUPP;

@@ -4143,6 +4647,29 @@ static int fec_enet_xdp_xmit(struct net_device *dev,
 	return sent_frames;
 }

+static int fec_enet_xsk_wakeup(struct net_device *ndev, u32 queue, u32 flags)
+{
+	struct fec_enet_private *fep = netdev_priv(ndev);
+	struct fec_enet_priv_rx_q *rxq;
+
+	if (!netif_running(ndev) || !netif_carrier_ok(ndev))
+		return -ENETDOWN;
+
+	if (queue >= fep->num_rx_queues || queue >= fep->num_tx_queues)
+		return -ERANGE;
+
+	rxq = fep->rx_queue[queue];
+	if (!rxq->xsk_pool)
+		return -EINVAL;
+
+	if (!napi_if_scheduled_mark_missed(&fep->napi)) {
+		if (likely(napi_schedule_prep(&fep->napi)))
+			__napi_schedule(&fep->napi);
+	}
+
+	return 0;
+}
+
 static int fec_hwtstamp_get(struct net_device *ndev,
 			    struct kernel_hwtstamp_config *config)
 {

@@ -4205,6 +4732,7 @@ static const struct net_device_ops fec_netdev_ops = {
 	.ndo_set_features	= fec_set_features,
 	.ndo_bpf		= fec_enet_bpf,
 	.ndo_xdp_xmit		= fec_enet_xdp_xmit,
+	.ndo_xsk_wakeup		= fec_enet_xsk_wakeup,
 	.ndo_hwtstamp_get	= fec_hwtstamp_get,
 	.ndo_hwtstamp_set	= fec_hwtstamp_set,
 };

@@ -4332,7 +4860,8 @@ static int fec_enet_init(struct net_device *ndev)

 	if (!(fep->quirks & FEC_QUIRK_SWAP_FRAME))
 		ndev->xdp_features = NETDEV_XDP_ACT_BASIC |
-				     NETDEV_XDP_ACT_REDIRECT;
+				     NETDEV_XDP_ACT_REDIRECT |
+				     NETDEV_XDP_ACT_XSK_ZEROCOPY;

 	fec_restart(ndev);

--

2.34.1