[PATCH v5 5/5] net/mlx4: add loopback Tx from VF

[Adrien Mazarguil <adrien.mazarguil@6wind.com>]

From: Moti Haimovsky <motih@mellanox.com>

This patch adds loopback functionality used when the chip is a VF in order
to enable packet transmission between VFs and PF.

Signed-off-by: Moti Haimovsky <motih@mellanox.com>
Acked-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>
---
 drivers/net/mlx4/mlx4_rxtx.c | 33 +++++++++++++++++++++------------
 drivers/net/mlx4/mlx4_rxtx.h |  1 +
 drivers/net/mlx4/mlx4_txq.c  |  2 ++
 3 files changed, 24 insertions(+), 12 deletions(-)

diff --git a/drivers/net/mlx4/mlx4_rxtx.c b/drivers/net/mlx4/mlx4_rxtx.c
index 87c5261..36173ad 100644
--- a/drivers/net/mlx4/mlx4_rxtx.c
+++ b/drivers/net/mlx4/mlx4_rxtx.c
@@ -311,10 +311,13 @@ mlx4_post_send(struct txq *txq, struct rte_mbuf *pkt)
 	struct mlx4_wqe_data_seg *dseg;
 	struct mlx4_sq *sq = &txq->msq;
 	struct rte_mbuf *buf;
+	union {
+		uint32_t flags;
+		uint16_t flags16[2];
+	} srcrb;
 	uint32_t head_idx = sq->head & sq->txbb_cnt_mask;
 	uint32_t lkey;
 	uintptr_t addr;
-	uint32_t srcrb_flags;
 	uint32_t owner_opcode = MLX4_OPCODE_SEND;
 	uint32_t byte_count;
 	int wqe_real_size;
@@ -414,22 +417,16 @@ mlx4_post_send(struct txq *txq, struct rte_mbuf *pkt)
 	/* Fill the control parameters for this packet. */
 	ctrl->fence_size = (wqe_real_size >> 4) & 0x3f;
 	/*
-	 * The caller should prepare "imm" in advance in order to support
-	 * VF to VF communication (when the device is a virtual-function
-	 * device (VF)).
-	 */
-	ctrl->imm = 0;
-	/*
 	 * For raw Ethernet, the SOLICIT flag is used to indicate that no ICRC
 	 * should be calculated.
 	 */
 	txq->elts_comp_cd -= nr_txbbs;
 	if (unlikely(txq->elts_comp_cd <= 0)) {
 		txq->elts_comp_cd = txq->elts_comp_cd_init;
-		srcrb_flags = RTE_BE32(MLX4_WQE_CTRL_SOLICIT |
+		srcrb.flags = RTE_BE32(MLX4_WQE_CTRL_SOLICIT |
 				       MLX4_WQE_CTRL_CQ_UPDATE);
 	} else {
-		srcrb_flags = RTE_BE32(MLX4_WQE_CTRL_SOLICIT);
+		srcrb.flags = RTE_BE32(MLX4_WQE_CTRL_SOLICIT);
 	}
 	/* Enable HW checksum offload if requested */
 	if (txq->csum &&
@@ -443,14 +440,26 @@ mlx4_post_send(struct txq *txq, struct rte_mbuf *pkt)
 			owner_opcode |= MLX4_WQE_CTRL_IIP_HDR_CSUM |
 					MLX4_WQE_CTRL_IL4_HDR_CSUM;
 			if (pkt->ol_flags & PKT_TX_OUTER_IP_CKSUM)
-				srcrb_flags |=
+				srcrb.flags |=
 					RTE_BE32(MLX4_WQE_CTRL_IP_HDR_CSUM);
 		} else {
-			srcrb_flags |= RTE_BE32(MLX4_WQE_CTRL_IP_HDR_CSUM |
+			srcrb.flags |= RTE_BE32(MLX4_WQE_CTRL_IP_HDR_CSUM |
 						MLX4_WQE_CTRL_TCP_UDP_CSUM);
 		}
 	}
-	ctrl->srcrb_flags = srcrb_flags;
+	if (txq->lb) {
+		/*
+		 * Copy destination MAC address to the WQE, this allows
+		 * loopback in eSwitch, so that VFs and PF can communicate
+		 * with each other.
+		 */
+		srcrb.flags16[0] = *(rte_pktmbuf_mtod(pkt, uint16_t *));
+		ctrl->imm = *(rte_pktmbuf_mtod_offset(pkt, uint32_t *,
+						      sizeof(uint16_t)));
+	} else {
+		ctrl->imm = 0;
+	}
+	ctrl->srcrb_flags = srcrb.flags;
 	/*
 	 * Make sure descriptor is fully written before
 	 * setting ownership bit (because HW can start
diff --git a/drivers/net/mlx4/mlx4_rxtx.h b/drivers/net/mlx4/mlx4_rxtx.h
index 51af69c..e10bbca 100644
--- a/drivers/net/mlx4/mlx4_rxtx.h
+++ b/drivers/net/mlx4/mlx4_rxtx.h
@@ -128,6 +128,7 @@ struct txq {
 	uint32_t max_inline; /**< Max inline send size. */
 	uint32_t csum:1; /**< Enable checksum offloading. */
 	uint32_t csum_l2tun:1; /**< Same for L2 tunnels. */
+	uint32_t lb:1; /**< Whether packets should be looped back by eSwitch. */
 	uint8_t *bounce_buf;
 	/**< Memory used for storing the first DWORD of data TXBBs. */
 	struct {
diff --git a/drivers/net/mlx4/mlx4_txq.c b/drivers/net/mlx4/mlx4_txq.c
index 41cdc4d..df4feb5 100644
--- a/drivers/net/mlx4/mlx4_txq.c
+++ b/drivers/net/mlx4/mlx4_txq.c
@@ -278,6 +278,8 @@ mlx4_tx_queue_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
 			RTE_MIN(MLX4_PMD_TX_PER_COMP_REQ, desc / 4),
 		.csum = priv->hw_csum,
 		.csum_l2tun = priv->hw_csum_l2tun,
+		/* Enable Tx loopback for VF devices. */
+		.lb = !!priv->vf,
 		.bounce_buf = bounce_buf,
 	};
 	txq->cq = ibv_create_cq(priv->ctx, desc, NULL, NULL, 0);
-- 
2.1.4