net/mlx5e: XDP TX forwarding support

Adding support for XDP_TX forwarding from xdp program.
Using XDP, now user can loop packets out of the same port.

We create a dedicated TX SQ for each channel that will serve
XDP programs that return XDP_TX action to loop packets back to
the wire directly from the channel RQ RX path.

For that RX pages will now need to be mapped bi-directionally,
and on XDP_TX action we will sync the page back to device then
queue it into SQ for transmission.  The XDP xmit frame function will
report back to the RX path if the page was consumed (transmitted), if so,
RX path will forget about that page as if it were released to the stack.
Later on, on XDP TX completion, the page will be released back to the
page cache.

For simplicity this patch will hit a doorbell on every XDP TX packet.

Next patch will introduce a xmit more like mechanism that will
queue up more than one packet into SQ w/o notifying the hardware,
once RX napi loop is done we will hit doorbell once for all XDP TX
packets form the previous loop.  This should drastically improve
XDP TX performance.

Signed-off-by: Saeed Mahameed <[email protected]>
Signed-off-by: Tariq Toukan <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

Author: Saeed Mahameed

drivers/net/ethernet/mellanox/mlx5/core/en.h

@@ -104,6 +104,15 @@
 #define MLX5E_ICOSQ_MAX_WQEBBS \
 	(DIV_ROUND_UP(sizeof(struct mlx5e_umr_wqe), MLX5_SEND_WQE_BB))
 
+#define MLX5E_XDP_MIN_INLINE (ETH_HLEN + VLAN_HLEN)
+#define MLX5E_XDP_IHS_DS_COUNT \
+	DIV_ROUND_UP(MLX5E_XDP_MIN_INLINE - 2, MLX5_SEND_WQE_DS)
+#define MLX5E_XDP_TX_DS_COUNT \
+	(MLX5E_XDP_IHS_DS_COUNT + \
+	 (sizeof(struct mlx5e_tx_wqe) / MLX5_SEND_WQE_DS) + 1 /* SG DS */)
+#define MLX5E_XDP_TX_WQEBBS \
+	DIV_ROUND_UP(MLX5E_XDP_TX_DS_COUNT, MLX5_SEND_WQEBB_NUM_DS)
+
 #define MLX5E_NUM_MAIN_GROUPS 9
 
 static inline u16 mlx5_min_rx_wqes(int wq_type, u32 wq_size)
@@ -319,6 +328,7 @@ struct mlx5e_rq {
 	struct {
 		u8             page_order;
 		u32            wqe_sz;    /* wqe data buffer size */
+		u8             map_dir;   /* dma map direction */
 	} buff;
 	__be32                 mkey_be;
 
@@ -384,14 +394,15 @@ enum {
 	MLX5E_SQ_STATE_BF_ENABLE,
 };
 
-struct mlx5e_ico_wqe_info {
+struct mlx5e_sq_wqe_info {
 	u8  opcode;
 	u8  num_wqebbs;
 };
 
 enum mlx5e_sq_type {
 	MLX5E_SQ_TXQ,
-	MLX5E_SQ_ICO
+	MLX5E_SQ_ICO,
+	MLX5E_SQ_XDP
 };
 
 struct mlx5e_sq {
@@ -418,7 +429,11 @@ struct mlx5e_sq {
 			struct mlx5e_sq_dma       *dma_fifo;
 			struct mlx5e_tx_wqe_info  *wqe_info;
 		} txq;
-		struct mlx5e_ico_wqe_info *ico_wqe;
+		struct mlx5e_sq_wqe_info *ico_wqe;
+		struct {
+			struct mlx5e_sq_wqe_info  *wqe_info;
+			struct mlx5e_dma_info     *di;
+		} xdp;
 	} db;
 
 	/* read only */
@@ -458,8 +473,10 @@ enum channel_flags {
 struct mlx5e_channel {
 	/* data path */
 	struct mlx5e_rq            rq;
+	struct mlx5e_sq            xdp_sq;
 	struct mlx5e_sq            sq[MLX5E_MAX_NUM_TC];
 	struct mlx5e_sq            icosq;   /* internal control operations */
+	bool                       xdp;
 	struct napi_struct         napi;
 	struct device             *pdev;
 	struct net_device         *netdev;
@@ -688,7 +705,7 @@ void mlx5e_cq_error_event(struct mlx5_core_cq *mcq, enum mlx5_event event);
 int mlx5e_napi_poll(struct napi_struct *napi, int budget);
 bool mlx5e_poll_tx_cq(struct mlx5e_cq *cq, int napi_budget);
 int mlx5e_poll_rx_cq(struct mlx5e_cq *cq, int budget);
-void mlx5e_free_tx_descs(struct mlx5e_sq *sq);
+void mlx5e_free_sq_descs(struct mlx5e_sq *sq);
 
 void mlx5e_page_release(struct mlx5e_rq *rq, struct mlx5e_dma_info *dma_info,
 			bool recycle);

drivers/net/ethernet/mellanox/mlx5/core/en_main.c

@@ -64,6 +64,7 @@ struct mlx5e_cq_param {
 struct mlx5e_channel_param {
 	struct mlx5e_rq_param      rq;
 	struct mlx5e_sq_param      sq;
+	struct mlx5e_sq_param      xdp_sq;
 	struct mlx5e_sq_param      icosq;
 	struct mlx5e_cq_param      rx_cq;
 	struct mlx5e_cq_param      tx_cq;
@@ -180,6 +181,8 @@ static void mlx5e_update_sw_counters(struct mlx5e_priv *priv)
 		s->rx_csum_complete += rq_stats->csum_complete;
 		s->rx_csum_unnecessary_inner += rq_stats->csum_unnecessary_inner;
 		s->rx_xdp_drop += rq_stats->xdp_drop;
+		s->rx_xdp_tx += rq_stats->xdp_tx;
+		s->rx_xdp_tx_full += rq_stats->xdp_tx_full;
 		s->rx_wqe_err   += rq_stats->wqe_err;
 		s->rx_mpwqe_filler += rq_stats->mpwqe_filler;
 		s->rx_buff_alloc_err += rq_stats->buff_alloc_err;
@@ -478,6 +481,10 @@ static int mlx5e_create_rq(struct mlx5e_channel *c,
 	rq->priv    = c->priv;
 	rq->xdp_prog = priv->xdp_prog;
 
+	rq->buff.map_dir = DMA_FROM_DEVICE;
+	if (rq->xdp_prog)
+		rq->buff.map_dir = DMA_BIDIRECTIONAL;
+
 	switch (priv->params.rq_wq_type) {
 	case MLX5_WQ_TYPE_LINKED_LIST_STRIDING_RQ:
 		rq->handle_rx_cqe = mlx5e_handle_rx_cqe_mpwrq;
@@ -765,6 +772,28 @@ static void mlx5e_close_rq(struct mlx5e_rq *rq)
 	mlx5e_destroy_rq(rq);
 }
 
+static void mlx5e_free_sq_xdp_db(struct mlx5e_sq *sq)
+{
+	kfree(sq->db.xdp.di);
+	kfree(sq->db.xdp.wqe_info);
+}
+
+static int mlx5e_alloc_sq_xdp_db(struct mlx5e_sq *sq, int numa)
+{
+	int wq_sz = mlx5_wq_cyc_get_size(&sq->wq);
+
+	sq->db.xdp.di = kzalloc_node(sizeof(*sq->db.xdp.di) * wq_sz,
+				     GFP_KERNEL, numa);
+	sq->db.xdp.wqe_info = kzalloc_node(sizeof(*sq->db.xdp.wqe_info) * wq_sz,
+					   GFP_KERNEL, numa);
+	if (!sq->db.xdp.di || !sq->db.xdp.wqe_info) {
+		mlx5e_free_sq_xdp_db(sq);
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
 static void mlx5e_free_sq_ico_db(struct mlx5e_sq *sq)
 {
 	kfree(sq->db.ico_wqe);
@@ -819,6 +848,9 @@ static void mlx5e_free_sq_db(struct mlx5e_sq *sq)
 	case MLX5E_SQ_ICO:
 		mlx5e_free_sq_ico_db(sq);
 		break;
+	case MLX5E_SQ_XDP:
+		mlx5e_free_sq_xdp_db(sq);
+		break;
 	}
 }
 
@@ -829,11 +861,24 @@ static int mlx5e_alloc_sq_db(struct mlx5e_sq *sq, int numa)
 		return mlx5e_alloc_sq_txq_db(sq, numa);
 	case MLX5E_SQ_ICO:
 		return mlx5e_alloc_sq_ico_db(sq, numa);
+	case MLX5E_SQ_XDP:
+		return mlx5e_alloc_sq_xdp_db(sq, numa);
 	}
 
 	return 0;
 }
 
+static int mlx5e_sq_get_max_wqebbs(u8 sq_type)
+{
+	switch (sq_type) {
+	case MLX5E_SQ_ICO:
+		return MLX5E_ICOSQ_MAX_WQEBBS;
+	case MLX5E_SQ_XDP:
+		return MLX5E_XDP_TX_WQEBBS;
+	}
+	return MLX5_SEND_WQE_MAX_WQEBBS;
+}
+
 static int mlx5e_create_sq(struct mlx5e_channel *c,
 			   int tc,
 			   struct mlx5e_sq_param *param,
@@ -844,7 +889,6 @@ static int mlx5e_create_sq(struct mlx5e_channel *c,
 
 	void *sqc = param->sqc;
 	void *sqc_wq = MLX5_ADDR_OF(sqc, sqc, wq);
-	u16 sq_max_wqebbs;
 	int err;
 
 	sq->type      = param->type;
@@ -882,7 +926,6 @@ static int mlx5e_create_sq(struct mlx5e_channel *c,
 	if (err)
 		goto err_sq_wq_destroy;
 
-	sq_max_wqebbs = MLX5_SEND_WQE_MAX_WQEBBS;
 	if (sq->type == MLX5E_SQ_TXQ) {
 		int txq_ix;
 
@@ -891,10 +934,7 @@ static int mlx5e_create_sq(struct mlx5e_channel *c,
 		priv->txq_to_sq_map[txq_ix] = sq;
 	}
 
-	if (sq->type == MLX5E_SQ_ICO)
-		sq_max_wqebbs = MLX5E_ICOSQ_MAX_WQEBBS;
-
-	sq->edge      = (sq->wq.sz_m1 + 1) - sq_max_wqebbs;
+	sq->edge = (sq->wq.sz_m1 + 1) - mlx5e_sq_get_max_wqebbs(sq->type);
 	sq->bf_budget = MLX5E_SQ_BF_BUDGET;
 
 	return 0;
@@ -1068,7 +1108,7 @@ static void mlx5e_close_sq(struct mlx5e_sq *sq)
 	}
 
 	mlx5e_disable_sq(sq);
-	mlx5e_free_tx_descs(sq);
+	mlx5e_free_sq_descs(sq);
 	mlx5e_destroy_sq(sq);
 }
 
@@ -1429,14 +1469,31 @@ static int mlx5e_open_channel(struct mlx5e_priv *priv, int ix,
 		}
 	}
 
+	if (priv->xdp_prog) {
+		/* XDP SQ CQ params are same as normal TXQ sq CQ params */
+		err = mlx5e_open_cq(c, &cparam->tx_cq, &c->xdp_sq.cq,
+				    priv->params.tx_cq_moderation);
+		if (err)
+			goto err_close_sqs;
+
+		err = mlx5e_open_sq(c, 0, &cparam->xdp_sq, &c->xdp_sq);
+		if (err) {
+			mlx5e_close_cq(&c->xdp_sq.cq);
+			goto err_close_sqs;
+		}
+	}
+
+	c->xdp = !!priv->xdp_prog;
 	err = mlx5e_open_rq(c, &cparam->rq, &c->rq);
 	if (err)
-		goto err_close_sqs;
+		goto err_close_xdp_sq;
 
 	netif_set_xps_queue(netdev, get_cpu_mask(c->cpu), ix);
 	*cp = c;
 
 	return 0;
+err_close_xdp_sq:
+	mlx5e_close_sq(&c->xdp_sq);
 
 err_close_sqs:
 	mlx5e_close_sqs(c);
@@ -1465,9 +1522,13 @@ static int mlx5e_open_channel(struct mlx5e_priv *priv, int ix,
 static void mlx5e_close_channel(struct mlx5e_channel *c)
 {
 	mlx5e_close_rq(&c->rq);
+	if (c->xdp)
+		mlx5e_close_sq(&c->xdp_sq);
 	mlx5e_close_sqs(c);
 	mlx5e_close_sq(&c->icosq);
 	napi_disable(&c->napi);
+	if (c->xdp)
+		mlx5e_close_cq(&c->xdp_sq.cq);
 	mlx5e_close_cq(&c->rq.cq);
 	mlx5e_close_tx_cqs(c);
 	mlx5e_close_cq(&c->icosq.cq);
@@ -1618,12 +1679,28 @@ static void mlx5e_build_icosq_param(struct mlx5e_priv *priv,
 	param->type = MLX5E_SQ_ICO;
 }
 
+static void mlx5e_build_xdpsq_param(struct mlx5e_priv *priv,
+				    struct mlx5e_sq_param *param)
+{
+	void *sqc = param->sqc;
+	void *wq = MLX5_ADDR_OF(sqc, sqc, wq);
+
+	mlx5e_build_sq_param_common(priv, param);
+	MLX5_SET(wq, wq, log_wq_sz,     priv->params.log_sq_size);
+
+	param->max_inline = priv->params.tx_max_inline;
+	/* FOR XDP SQs will support only L2 inline mode */
+	param->min_inline_mode = MLX5_INLINE_MODE_NONE;
+	param->type = MLX5E_SQ_XDP;
+}
+
 static void mlx5e_build_channel_param(struct mlx5e_priv *priv, struct mlx5e_channel_param *cparam)
 {
 	u8 icosq_log_wq_sz = MLX5E_PARAMS_MINIMUM_LOG_SQ_SIZE;
 
 	mlx5e_build_rq_param(priv, &cparam->rq);
 	mlx5e_build_sq_param(priv, &cparam->sq);
+	mlx5e_build_xdpsq_param(priv, &cparam->xdp_sq);
 	mlx5e_build_icosq_param(priv, &cparam->icosq, icosq_log_wq_sz);
 	mlx5e_build_rx_cq_param(priv, &cparam->rx_cq);
 	mlx5e_build_tx_cq_param(priv, &cparam->tx_cq);