[PATCH bpf-next v3 12/16] net/mlx5e: XDP_TX from UMEM support
From: Maxim Mikityanskiy <hidden>
Date: 2019-05-24 09:35:42
Also in:
bpf
Subsystem:
mellanox mlx5 core vpi driver, networking drivers, the rest, xdp (express data path) · Maintainers:
Saeed Mahameed, Leon Romanovsky, Tariq Toukan, Mark Bloch, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds, Alexei Starovoitov, Daniel Borkmann, David S. Miller, Jesper Dangaard Brouer, John Fastabend
When an XDP program returns XDP_TX, and the RQ is XSK-enabled, it requires careful handling, because convert_to_xdp_frame creates a new page and copies the data there, while our driver expects the xdp_frame to point to the same memory as the xdp_buff. Handle this case separately: map the page, and in the end unmap it and call xdp_return_frame. Signed-off-by: Maxim Mikityanskiy <redacted> Reviewed-by: Tariq Toukan <redacted> Acked-by: Saeed Mahameed <redacted> --- .../net/ethernet/mellanox/mlx5/core/en/xdp.c | 50 ++++++++++++++++--- 1 file changed, 42 insertions(+), 8 deletions(-)
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
index b3e118fc4521..1364bdff702c 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c@@ -69,14 +69,48 @@ mlx5e_xmit_xdp_buff(struct mlx5e_xdpsq *sq, struct mlx5e_rq *rq, xdptxd.data = xdpf->data; xdptxd.len = xdpf->len; - xdpi.mode = MLX5E_XDP_XMIT_MODE_PAGE; + if (xdp->rxq->mem.type == MEM_TYPE_ZERO_COPY) { + /* The xdp_buff was in the UMEM and was copied into a newly + * allocated page. The UMEM page was returned via the ZCA, and + * this new page has to be mapped at this point and has to be + * unmapped and returned via xdp_return_frame on completion. + */ + + /* Prevent double recycling of the UMEM page. Even in case this + * function returns false, the xdp_buff shouldn't be recycled, + * as it was already done in xdp_convert_zc_to_xdp_frame. + */ + __set_bit(MLX5E_RQ_FLAG_XDP_XMIT, rq->flags); /* non-atomic */ + + xdpi.mode = MLX5E_XDP_XMIT_MODE_FRAME; - dma_addr = di->addr + (xdpf->data - (void *)xdpf); - dma_sync_single_for_device(sq->pdev, dma_addr, xdptxd.len, DMA_TO_DEVICE); + dma_addr = dma_map_single(sq->pdev, xdptxd.data, xdptxd.len, + DMA_TO_DEVICE); + if (dma_mapping_error(sq->pdev, dma_addr)) { + xdp_return_frame(xdpf); + return false; + } - xdptxd.dma_addr = dma_addr; - xdpi.page.rq = rq; - xdpi.page.di = *di; + xdptxd.dma_addr = dma_addr; + xdpi.frame.xdpf = xdpf; + xdpi.frame.dma_addr = dma_addr; + } else { + /* Driver assumes that convert_to_xdp_frame returns an xdp_frame + * that points to the same memory region as the original + * xdp_buff. It allows to map the memory only once and to use + * the DMA_BIDIRECTIONAL mode. + */ + + xdpi.mode = MLX5E_XDP_XMIT_MODE_PAGE; + + dma_addr = di->addr + (xdpf->data - (void *)xdpf); + dma_sync_single_for_device(sq->pdev, dma_addr, xdptxd.len, + DMA_TO_DEVICE); + + xdptxd.dma_addr = dma_addr; + xdpi.page.rq = rq; + xdpi.page.di = *di; + } return sq->xmit_xdp_frame(sq, &xdptxd, &xdpi); }
@@ -298,13 +332,13 @@ static void mlx5e_free_xdpsq_desc(struct mlx5e_xdpsq *sq, switch (xdpi.mode) { case MLX5E_XDP_XMIT_MODE_FRAME: - /* XDP_REDIRECT */ + /* XDP_TX from the XSK RQ and XDP_REDIRECT */ dma_unmap_single(sq->pdev, xdpi.frame.dma_addr, xdpi.frame.xdpf->len, DMA_TO_DEVICE); xdp_return_frame(xdpi.frame.xdpf); break; case MLX5E_XDP_XMIT_MODE_PAGE: - /* XDP_TX */ + /* XDP_TX from the regular RQ */ mlx5e_page_release(xdpi.page.rq, &xdpi.page.di, recycle); break; default:
--
2.19.1