Subject: [RFC V2 net-next v2 1/3] net: ena: implement XDP drop support

From: <[email-masked]>
Date: Thu, 31 Oct 2019 18:35:37 +0200

From: Sameeh Jubran <[email-masked]>

This commit implements the basic functionality of drop/pass logic in the
ena driver.

Signed-off-by: Sameeh Jubran <[email-masked]>
---
 drivers/net/ethernet/amazon/ena/ena_netdev.c | 132 +++++++++++++++++--
 drivers/net/ethernet/amazon/ena/ena_netdev.h |  29 ++++
 2 files changed, 152 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.c b/drivers/net/ethernet/amazon/ena/ena_netdev.c
index d46a91200..f3f042031 100644
--- a/drivers/net/ethernet/amazon/ena/ena_netdev.c
+++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c
@@ -33,10 +33,10 @@
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #ifdef CONFIG_RFS_ACCEL
+#include <linux/bpf_trace.h>
 #include <linux/cpu_rmap.h>
 #endif /* CONFIG_RFS_ACCEL */
 #include <linux/ethtool.h>
-#include <linux/if_vlan.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/numa.h>
@@ -105,6 +105,79 @@ static void update_rx_ring_mtu(struct ena_adapter *adapter, int mtu)
 		adapter->rx_ring[i].mtu = mtu;
 }
 
+static int ena_xdp_execute(struct ena_ring *rx_ring, struct xdp_buff *xdp)
+{
+	struct bpf_prog *xdp_prog = rx_ring->xdp_bpf_prog;
+	u32 verdict = XDP_PASS;
+
+	rcu_read_lock();
+
+	if (!xdp_prog)
+		goto out;
+
+	verdict = bpf_prog_run_xdp(xdp_prog, xdp);
+
+	if (unlikely(verdict == XDP_ABORTED))
+		trace_xdp_exception(rx_ring->netdev, xdp_prog, verdict);
+	else if (unlikely(verdict >= XDP_TX))
+		bpf_warn_invalid_xdp_action(verdict);
+out:
+	rcu_read_unlock();
+	return verdict;
+}
+
+static int ena_xdp_set(struct net_device *netdev, struct netdev_bpf *bpf)
+{
+	struct ena_adapter *adapter = netdev_priv(netdev);
+	struct bpf_prog *prog = bpf->prog;
+	struct bpf_prog *old_bpf_prog;
+	int i, prev_mtu;
+
+	if (ena_xdp_allowed(adapter)) {
+		old_bpf_prog = xchg(&adapter->xdp_bpf_prog, prog);
+
+		for (i = 0; i < adapter->num_io_queues; i++)
+			xchg(&adapter->rx_ring[i].xdp_bpf_prog, prog);
+
+		if (old_bpf_prog)
+			bpf_prog_put(old_bpf_prog);
+
+		prev_mtu = netdev->max_mtu;
+		netdev->max_mtu = prog ? ENA_XDP_MAX_MTU : adapter->max_mtu;
+		netif_info(adapter, drv, adapter->netdev, "xdp program set, changging the max_mtu from %d to %d",
+			   prev_mtu, netdev->max_mtu);
+
+	} else {
+		netif_err(adapter, drv, adapter->netdev, "Failed to set xdp program, the current MTU (%d) is larger than the maximal allowed MTU (%lu) while xdp is on",
+			  netdev->mtu, ENA_XDP_MAX_MTU);
+		NL_SET_ERR_MSG_MOD(bpf->extack, "Failed to set xdp program, the current MTU is larger than the maximal allowed MTU. Check the dmesg for more info");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/* This is the main xdp callback, it's used by the kernel to set/unset the xdp
+ * program as well as to query the current xdp program id.
+ */
+static int ena_xdp(struct net_device *netdev, struct netdev_bpf *bpf)
+{
+	struct ena_adapter *adapter = netdev_priv(netdev);
+
+	switch (bpf->command) {
+	case XDP_SETUP_PROG:
+		return ena_xdp_set(netdev, bpf);
+	case XDP_QUERY_PROG:
+		bpf->prog_id = adapter->xdp_bpf_prog ?
+			adapter->xdp_bpf_prog->aux->id : 0;
+		break;
+	default:
+		NL_SET_ERR_MSG_MOD(bpf->extack, "Unsupported XDP command");
+		return -EINVAL;
+	}
+	return 0;
+}
+
 static int ena_change_mtu(struct net_device *dev, int new_mtu)
 {
 	struct ena_adapter *adapter = netdev_priv(dev);
@@ -417,6 +490,9 @@ static void ena_free_rx_resources(struct ena_adapter *adapter,
 
 	vfree(rx_ring->free_ids);
 	rx_ring->free_ids = NULL;
+
+	xdp_rxq_info_unreg_mem_model(&rx_ring->xdp_rxq);
+	xdp_rxq_info_unreg(&rx_ring->xdp_rxq);
 }
 
 /* ena_setup_all_rx_resources - allocate I/O Rx queues resources for all queues
@@ -1051,13 +1127,16 @@ static int ena_clean_rx_irq(struct ena_ring *rx_ring, struct napi_struct *napi,
 	u32 res_budget, work_done;
 
 	struct ena_com_rx_ctx ena_rx_ctx;
+	struct ena_rx_buffer *rx_info;
 	struct ena_adapter *adapter;
-	struct sk_buff *skb;
+	int xdp_verdict = XDP_PASS;
+	struct sk_buff *skb = NULL;
 	int refill_required;
 	int refill_threshold;
-	int rc = 0;
-	int total_len = 0;
+	struct xdp_buff xdp;
 	int rx_copybreak_pkt = 0;
+	int total_len = 0;
+	int rc = 0;
 	int i;
 
 	netif_dbg(rx_ring->adapter, rx_status, rx_ring->netdev,
@@ -1082,12 +1161,24 @@ static int ena_clean_rx_irq(struct ena_ring *rx_ring, struct napi_struct *napi,
 			  rx_ring->qid, ena_rx_ctx.descs, ena_rx_ctx.l3_proto,
 			  ena_rx_ctx.l4_proto, ena_rx_ctx.hash);
 
+		if (ena_xdp_present_ring(rx_ring)) {
+			rx_info = &rx_ring->rx_buffer_info[rx_ring->ena_bufs[0].req_id];
+			xdp.data = page_address(rx_info->page) +
+				rx_info->page_offset;
+			xdp.data_meta = xdp.data;
+			xdp.data_hard_start = xdp.data -
+				rx_info->page_offset;
+			xdp.data_end = xdp.data + rx_ring->ena_bufs[0].len;
+			xdp_verdict = ena_xdp_execute(rx_ring, &xdp);
+		}
+
 		/* allocate skb and fill it */
-		skb = ena_rx_skb(rx_ring, rx_ring->ena_bufs, ena_rx_ctx.descs,
-				 &next_to_clean);
+		if (xdp_verdict == XDP_PASS)
+			skb = ena_rx_skb(rx_ring, rx_ring->ena_bufs,
+					 ena_rx_ctx.descs, &next_to_clean);
 
 		/* exit if we failed to retrieve a buffer */
-		if (unlikely(!skb)) {
+		if (!skb) {
 			for (i = 0; i < ena_rx_ctx.descs; i++) {
 				rx_ring->free_ids[next_to_clean] =
 					rx_ring->ena_bufs[i].req_id;
@@ -1727,12 +1818,34 @@ static int ena_create_io_rx_queue(struct ena_adapter *adapter, int qid)
 		netif_err(adapter, ifup, adapter->netdev,
 			  "Failed to get RX queue handlers. RX queue num %d rc: %d\n",
 			  qid, rc);
-		ena_com_destroy_io_queue(ena_dev, ena_qid);
-		return rc;
+		goto err;
 	}
 
 	ena_com_update_numa_node(rx_ring->ena_com_io_cq, ctx.numa_node);
 
+	rc = xdp_rxq_info_reg(&rx_ring->xdp_rxq, adapter->netdev, qid);
+
+	if (rc) {
+		netif_err(adapter, ifup, adapter->netdev,
+			  "Failed to register xdp rx queue info. RX queue num %d rc: %d\n",
+			  qid, rc);
+		goto err;
+	}
+
+	rc = xdp_rxq_info_reg_mem_model(&rx_ring->xdp_rxq, MEM_TYPE_PAGE_SHARED,
+					NULL);
+
+	if (rc) {
+		netif_err(adapter, ifup, adapter->netdev,
+			  "Failed to register xdp rx queue info memory model. RX queue num %d rc: %d\n",
+			  qid, rc);
+		xdp_rxq_info_unreg(&rx_ring->xdp_rxq);
+		goto err;
+	}
+
+	return rc;
+err:
+	ena_com_destroy_io_queue(ena_dev, ena_qid);
 	return rc;
 }
 
@@ -2568,6 +2681,7 @@ static const struct net_device_ops ena_netdev_ops = {
 	.ndo_change_mtu		= ena_change_mtu,
 	.ndo_set_mac_address	= NULL,
 	.ndo_validate_addr	= eth_validate_addr,
+	.ndo_bpf		= ena_xdp,
 };
 
 static int ena_device_validate_params(struct ena_adapter *adapter,
diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.h b/drivers/net/ethernet/amazon/ena/ena_netdev.h
index bffd778f2..baaeeeeb0 100644
--- a/drivers/net/ethernet/amazon/ena/ena_netdev.h
+++ b/drivers/net/ethernet/amazon/ena/ena_netdev.h
@@ -36,6 +36,7 @@
 #include <linux/bitops.h>
 #include <linux/dim.h>
 #include <linux/etherdevice.h>
+#include <linux/if_vlan.h>
 #include <linux/inetdevice.h>
 #include <linux/interrupt.h>
 #include <linux/netdevice.h>
@@ -142,6 +143,14 @@
 
 #define ENA_MMIO_DISABLE_REG_READ	BIT(0)
 
+/* The max MTU size is configured to be the ethernet frame without the overhead
+ * of the ethernet header, which can have VLAN header, and the frame check
+ * sequence (FCS).
+ * The buffer sizes we share with the device are defined to be ENA_PAGE_SIZE
+ */
+#define ENA_XDP_MAX_MTU (ENA_PAGE_SIZE - ETH_HLEN - ETH_FCS_LEN - \
+				VLAN_HLEN - XDP_PACKET_HEADROOM)
+
 struct ena_irq {
 	irq_handler_t handler;
 	void *data;
@@ -291,6 +300,8 @@ struct ena_ring {
 
 	u8 *push_buf_intermediate_buf;
 	int empty_rx_queue;
+	struct bpf_prog *xdp_bpf_prog;
+	struct xdp_rxq_info xdp_rxq;
 } ____cacheline_aligned;
 
 struct ena_stats_dev {
@@ -379,6 +390,9 @@ struct ena_adapter {
 	u32 last_monitored_tx_qid;
 
 	enum ena_regs_reset_reason_types reset_reason;
+
+	/* XDP structures */
+	struct bpf_prog *xdp_bpf_prog;
 };
 
 void ena_set_ethtool_ops(struct net_device *netdev);
@@ -394,4 +408,19 @@ int ena_update_queue_count(struct ena_adapter *adapter, u32 new_channel_count);
 
 int ena_get_sset_count(struct net_device *netdev, int sset);
 
+static inline bool ena_xdp_present(struct ena_adapter *adapter)
+{
+	return !!adapter->xdp_bpf_prog;
+}
+
+static inline bool ena_xdp_present_ring(struct ena_ring *ring)
+{
+	return !!ring->xdp_bpf_prog;
+}
+
+static inline bool ena_xdp_allowed(struct ena_adapter *adapter)
+{
+	return adapter->netdev->mtu <= ENA_XDP_MAX_MTU;
+}
+
 #endif /* !(ENA_H) */
-- 
2.17.1