bnxt_en: Add basic XDP support.

Add basic ndo_xdp support to setup and query program, configure the NIC
to run in rx page mode, and support XDP_PASS, XDP_DROP, XDP_ABORTED
actions only.

v3: Pass modified offset and length to stack for XDP_PASS.
    Remove Kconfig option.

v2: Added trace_xdp_exception()
    Added dma_syncs.
    Added XDP headroom support.

Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Tested-by: Andy Gospodarek <gospo@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 157 insertions, 0 deletions

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c b/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c
new file mode 100644
index 000000000000..b822e461cbde
--- /dev/null
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c
@@ -0,0 +1,157 @@
+/* Broadcom NetXtreme-C/E network driver.
+ *
+ * Copyright (c) 2016-2017 Broadcom Limited
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation.
+ */
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/pci.h>
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/if_vlan.h>
+#include <linux/bpf.h>
+#include <linux/bpf_trace.h>
+#include <linux/filter.h>
+#include "bnxt_hsi.h"
+#include "bnxt.h"
+#include "bnxt_xdp.h"
+
+/* returns the following:
+ * true    - packet consumed by XDP and new buffer is allocated.
+ * false   - packet should be passed to the stack.
+ */
+bool bnxt_rx_xdp(struct bnxt *bp, struct bnxt_rx_ring_info *rxr, u16 cons,
+		 struct page *page, u8 **data_ptr, unsigned int *len, u8 *event)
+{
+	struct bpf_prog *xdp_prog = READ_ONCE(rxr->xdp_prog);
+	struct bnxt_sw_rx_bd *rx_buf;
+	struct pci_dev *pdev;
+	struct xdp_buff xdp;
+	dma_addr_t mapping;
+	void *orig_data;
+	u32 offset;
+	u32 act;
+
+	if (!xdp_prog)
+		return false;
+
+	pdev = bp->pdev;
+	rx_buf = &rxr->rx_buf_ring[cons];
+	offset = bp->rx_offset;
+
+	xdp.data_hard_start = *data_ptr - offset;
+	xdp.data = *data_ptr;
+	xdp.data_end = *data_ptr + *len;
+	orig_data = xdp.data;
+	mapping = rx_buf->mapping - bp->rx_dma_offset;
+
+	dma_sync_single_for_cpu(&pdev->dev, mapping + offset, *len, bp->rx_dir);
+
+	rcu_read_lock();
+	act = bpf_prog_run_xdp(xdp_prog, &xdp);
+	rcu_read_unlock();
+
+	if (orig_data != xdp.data) {
+		offset = xdp.data - xdp.data_hard_start;
+		*data_ptr = xdp.data_hard_start + offset;
+		*len = xdp.data_end - xdp.data;
+	}
+	switch (act) {
+	case XDP_PASS:
+		return false;
+
+	default:
+		bpf_warn_invalid_xdp_action(act);
+		/* Fall thru */
+	case XDP_ABORTED:
+		trace_xdp_exception(bp->dev, xdp_prog, act);
+		/* Fall thru */
+	case XDP_DROP:
+		bnxt_reuse_rx_data(rxr, cons, page);
+		break;
+	}
+	return true;
+}
+
+/* Under rtnl_lock */
+static int bnxt_xdp_set(struct bnxt *bp, struct bpf_prog *prog)
+{
+	struct net_device *dev = bp->dev;
+	int tx_xdp = 0, rc, tc;
+	struct bpf_prog *old;
+
+	if (prog && bp->dev->mtu > BNXT_MAX_PAGE_MODE_MTU) {
+		netdev_warn(dev, "MTU %d larger than largest XDP supported MTU %d.\n",
+			    bp->dev->mtu, BNXT_MAX_PAGE_MODE_MTU);
+		return -EOPNOTSUPP;
+	}
+	if (!(bp->flags & BNXT_FLAG_SHARED_RINGS)) {
+		netdev_warn(dev, "ethtool rx/tx channels must be combined to support XDP.\n");
+		return -EOPNOTSUPP;
+	}
+	if (prog)
+		tx_xdp = bp->rx_nr_rings;
+
+	tc = netdev_get_num_tc(dev);
+	if (!tc)
+		tc = 1;
+	rc = bnxt_reserve_rings(bp, bp->tx_nr_rings_per_tc, bp->rx_nr_rings,
+				tc, tx_xdp);
+	if (rc) {
+		netdev_warn(dev, "Unable to reserve enough TX rings to support XDP.\n");
+		return rc;
+	}
+	if (netif_running(dev))
+		bnxt_close_nic(bp, true, false);
+
+	old = xchg(&bp->xdp_prog, prog);
+	if (old)
+		bpf_prog_put(old);
+
+	if (prog) {
+		bnxt_set_rx_skb_mode(bp, true);
+	} else {
+		int rx, tx;
+
+		bnxt_set_rx_skb_mode(bp, false);
+		bnxt_get_max_rings(bp, &rx, &tx, true);
+		if (rx > 1) {
+			bp->flags &= ~BNXT_FLAG_NO_AGG_RINGS;
+			bp->dev->hw_features |= NETIF_F_LRO;
+		}
+	}
+	bp->tx_nr_rings_xdp = tx_xdp;
+	bp->tx_nr_rings = bp->tx_nr_rings_per_tc * tc + tx_xdp;
+	bp->cp_nr_rings = max_t(int, bp->tx_nr_rings, bp->rx_nr_rings);
+	bp->num_stat_ctxs = bp->cp_nr_rings;
+	bnxt_set_tpa_flags(bp);
+	bnxt_set_ring_params(bp);
+
+	if (netif_running(dev))
+		return bnxt_open_nic(bp, true, false);
+
+	return 0;
+}
+
+int bnxt_xdp(struct net_device *dev, struct netdev_xdp *xdp)
+{
+	struct bnxt *bp = netdev_priv(dev);
+	int rc;
+
+	switch (xdp->command) {
+	case XDP_SETUP_PROG:
+		rc = bnxt_xdp_set(bp, xdp->prog);
+		break;
+	case XDP_QUERY_PROG:
+		xdp->prog_attached = !!bp->xdp_prog;
+		rc = 0;
+		break;
+	default:
+		rc = -EINVAL;
+		break;
+	}
+	return rc;
+}