net/mlx5e: Add XDP multi buffer support to the non-linear legacy RQ

This commit adds XDP multi buffer support to the RX path in the
non-linear legacy RQ mode. mlx5e_xdp_handle is called from
mlx5e_skb_from_cqe_nonlinear.

XDP_TX action for fragmented XDP frames is not yet supported and
blocked.

Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

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

@@ -68,6 +68,11 @@ mlx5e_xmit_xdp_buff(struct mlx5e_xdpsq *sq, struct mlx5e_rq *rq,
 	if (unlikely(!xdpf))
 		return false;
 
+	if (unlikely(xdp_frame_has_frags(xdpf))) {
+		xdp_return_frame(xdpf);
+		return false;
+	}
+
 	xdptxd.data = xdpf->data;
 	xdptxd.len  = xdpf->len;
 

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

@@ -1572,6 +1572,7 @@ mlx5e_skb_from_cqe_nonlinear(struct mlx5e_rq *rq, struct mlx5_cqe64 *cqe,
 	struct mlx5e_dma_info *di = wi->di;
 	struct skb_shared_info *sinfo;
 	u32 frag_consumed_bytes;
+	struct bpf_prog *prog;
 	struct xdp_buff xdp;
 	struct sk_buff *skb;
 	u32 truesize;
@@ -1582,6 +1583,7 @@ mlx5e_skb_from_cqe_nonlinear(struct mlx5e_rq *rq, struct mlx5_cqe64 *cqe,
 
 	dma_sync_single_range_for_cpu(rq->pdev, di->addr, wi->offset,
 				      rq->buff.frame0_sz, DMA_FROM_DEVICE);
+	net_prefetchw(va); /* xdp_frame data area */
 	net_prefetch(va + rx_headroom);
 
 	mlx5e_fill_xdp_buff(rq, va, rx_headroom, frag_consumed_bytes, &xdp);
@@ -1629,6 +1631,17 @@ mlx5e_skb_from_cqe_nonlinear(struct mlx5e_rq *rq, struct mlx5_cqe64 *cqe,
 
 	di = head_wi->di;
 
+	prog = rcu_dereference(rq->xdp_prog);
+	if (prog && mlx5e_xdp_handle(rq, di, prog, &xdp)) {
+		if (test_bit(MLX5E_RQ_FLAG_XDP_XMIT, rq->flags)) {
+			int i;
+
+			for (i = wi - head_wi; i < rq->wqe.info.num_frags; i++)
+				mlx5e_put_rx_frag(rq, &head_wi[i], true);
+		}
+		return NULL; /* page/packet was consumed by XDP */
+	}
+
 	skb = mlx5e_build_linear_skb(rq, xdp.data_hard_start, rq->buff.frame0_sz,
 				     xdp.data - xdp.data_hard_start,
 				     xdp.data_end - xdp.data,