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 <maximmi@xxxxxxxxxxxx>
Reviewed-by: Tariq Toukan <tariqt@xxxxxxxxxxxx>
Acked-by: Saeed Mahameed <saeedm@xxxxxxxxxxxx>
---
.../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
