net/mlx5e: XDP, Maintain a FIFO structure for xdp_info instances

This provides infrastructure to have multiple xdp_info instances
for the same consumer index.

Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

Author: Tariq Toukan

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

@@ -404,15 +404,24 @@ struct mlx5e_xdp_info {
 	struct mlx5e_dma_info di;
 };
 
+struct mlx5e_xdp_info_fifo {
+	struct mlx5e_xdp_info *xi;
+	u32 *cc;
+	u32 *pc;
+	u32 mask;
+};
+
 struct mlx5e_xdpsq {
 	/* data path */
 
 	/* dirtied @completion */
+	u32                        xdpi_fifo_cc;
 	u16                        cc;
 	bool                       redirect_flush;
 
 	/* dirtied @xmit */
-	u16                        pc ____cacheline_aligned_in_smp;
+	u32                        xdpi_fifo_pc ____cacheline_aligned_in_smp;
+	u16                        pc;
 	struct mlx5_wqe_ctrl_seg   *doorbell_cseg;
 
 	struct mlx5e_cq            cq;
@@ -421,7 +430,7 @@ struct mlx5e_xdpsq {
 	struct mlx5_wq_cyc         wq;
 	struct mlx5e_xdpsq_stats  *stats;
 	struct {
-		struct mlx5e_xdp_info     *xdpi;
+		struct mlx5e_xdp_info_fifo xdpi_fifo;
 	} db;
 	void __iomem              *uar_map;
 	u32                        sqn;

drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c

@@ -149,20 +149,18 @@ bool mlx5e_xmit_xdp_frame(struct mlx5e_xdpsq *sq, struct mlx5e_xdp_info *xdpi)
 
 	cseg->opmod_idx_opcode = cpu_to_be32((sq->pc << 8) | MLX5_OPCODE_SEND);
 
-	/* move page to reference to sq responsibility,
-	 * and mark so it's not put back in page-cache.
-	 */
-	sq->db.xdpi[pi] = *xdpi;
 	sq->pc++;
 
 	sq->doorbell_cseg = cseg;
 
+	mlx5e_xdpi_fifo_push(&sq->db.xdpi_fifo, xdpi);
 	stats->xmit++;
 	return true;
 }
 
 bool mlx5e_poll_xdpsq_cq(struct mlx5e_cq *cq, struct mlx5e_rq *rq)
 {
+	struct mlx5e_xdp_info_fifo *xdpi_fifo;
 	struct mlx5e_xdpsq *sq;
 	struct mlx5_cqe64 *cqe;
 	bool is_redirect;
@@ -179,6 +177,7 @@ bool mlx5e_poll_xdpsq_cq(struct mlx5e_cq *cq, struct mlx5e_rq *rq)
 		return false;
 
 	is_redirect = !rq;
+	xdpi_fifo = &sq->db.xdpi_fifo;
 
 	/* sq->cc must be updated only after mlx5_cqwq_update_db_record(),
 	 * otherwise a cq overrun may occur
@@ -200,19 +199,19 @@ bool mlx5e_poll_xdpsq_cq(struct mlx5e_cq *cq, struct mlx5e_rq *rq)
 					 get_cqe_opcode(cqe));
 
 		do {
-			u16 ci = mlx5_wq_cyc_ctr2ix(&sq->wq, sqcc);
-			struct mlx5e_xdp_info *xdpi = &sq->db.xdpi[ci];
+			struct mlx5e_xdp_info xdpi =
+				mlx5e_xdpi_fifo_pop(xdpi_fifo);
 
 			last_wqe = (sqcc == wqe_counter);
 			sqcc++;
 
 			if (is_redirect) {
-				xdp_return_frame(xdpi->xdpf);
-				dma_unmap_single(sq->pdev, xdpi->dma_addr,
-						 xdpi->xdpf->len, DMA_TO_DEVICE);
+				xdp_return_frame(xdpi.xdpf);
+				dma_unmap_single(sq->pdev, xdpi.dma_addr,
+						 xdpi.xdpf->len, DMA_TO_DEVICE);
 			} else {
 				/* Recycle RX page */
-				mlx5e_page_release(rq, &xdpi->di, true);
+				mlx5e_page_release(rq, &xdpi.di, true);
 			}
 		} while (!last_wqe);
 	} while ((++i < MLX5E_TX_CQ_POLL_BUDGET) && (cqe = mlx5_cqwq_get_cqe(&cq->wq)));
@@ -230,21 +229,22 @@ bool mlx5e_poll_xdpsq_cq(struct mlx5e_cq *cq, struct mlx5e_rq *rq)
 
 void mlx5e_free_xdpsq_descs(struct mlx5e_xdpsq *sq, struct mlx5e_rq *rq)
 {
+	struct mlx5e_xdp_info_fifo *xdpi_fifo = &sq->db.xdpi_fifo;
 	bool is_redirect = !rq;
 
 	while (sq->cc != sq->pc) {
-		u16 ci = mlx5_wq_cyc_ctr2ix(&sq->wq, sq->cc);
-		struct mlx5e_xdp_info *xdpi = &sq->db.xdpi[ci];
+		struct mlx5e_xdp_info xdpi =
+			mlx5e_xdpi_fifo_pop(xdpi_fifo);
 
 		sq->cc++;
 
 		if (is_redirect) {
-			xdp_return_frame(xdpi->xdpf);
-			dma_unmap_single(sq->pdev, xdpi->dma_addr,
-					 xdpi->xdpf->len, DMA_TO_DEVICE);
+			xdp_return_frame(xdpi.xdpf);
+			dma_unmap_single(sq->pdev, xdpi.dma_addr,
+					 xdpi.xdpf->len, DMA_TO_DEVICE);
 		} else {
 			/* Recycle RX page */
-			mlx5e_page_release(rq, &xdpi->di, false);
+			mlx5e_page_release(rq, &xdpi.di, false);
 		}
 	}
 }

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

@@ -57,4 +57,19 @@ static inline void mlx5e_xmit_xdp_doorbell(struct mlx5e_xdpsq *sq)
 	}
 }
 
+static inline void
+mlx5e_xdpi_fifo_push(struct mlx5e_xdp_info_fifo *fifo,
+		     struct mlx5e_xdp_info *xi)
+{
+	u32 i = (*fifo->pc)++ & fifo->mask;
+
+	fifo->xi[i] = *xi;
+}
+
+static inline struct mlx5e_xdp_info
+mlx5e_xdpi_fifo_pop(struct mlx5e_xdp_info_fifo *fifo)
+{
+	return fifo->xi[(*fifo->cc)++ & fifo->mask];
+}
+
 #endif

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

@@ -992,18 +992,35 @@ static void mlx5e_close_rq(struct mlx5e_rq *rq)
 
 static void mlx5e_free_xdpsq_db(struct mlx5e_xdpsq *sq)
 {
-	kvfree(sq->db.xdpi);
+	kvfree(sq->db.xdpi_fifo.xi);
+}
+
+static int mlx5e_alloc_xdpsq_fifo(struct mlx5e_xdpsq *sq, int numa)
+{
+	struct mlx5e_xdp_info_fifo *xdpi_fifo = &sq->db.xdpi_fifo;
+	int wq_sz        = mlx5_wq_cyc_get_size(&sq->wq);
+	int dsegs_per_wq = wq_sz * MLX5_SEND_WQEBB_NUM_DS;
+
+	xdpi_fifo->xi = kvzalloc_node(sizeof(*xdpi_fifo->xi) * dsegs_per_wq,
+				      GFP_KERNEL, numa);
+	if (!xdpi_fifo->xi)
+		return -ENOMEM;
+
+	xdpi_fifo->pc   = &sq->xdpi_fifo_pc;
+	xdpi_fifo->cc   = &sq->xdpi_fifo_cc;
+	xdpi_fifo->mask = dsegs_per_wq - 1;
+
+	return 0;
 }
 
 static int mlx5e_alloc_xdpsq_db(struct mlx5e_xdpsq *sq, int numa)
 {
-	int wq_sz = mlx5_wq_cyc_get_size(&sq->wq);
+	int err;
 
-	sq->db.xdpi = kvzalloc_node(array_size(wq_sz, sizeof(*sq->db.xdpi)),
-				    GFP_KERNEL, numa);
-	if (!sq->db.xdpi) {
+	err = mlx5e_alloc_xdpsq_fifo(sq, numa);
+	if (err) {
 		mlx5e_free_xdpsq_db(sq);
-		return -ENOMEM;
+		return err;
 	}
 
 	return 0;