[bpf-next V3 PATCH 01/15] mlx5: basic XDP_REDIRECT forward support

Jesper Dangaard Brouer
2018-03-09T20:55:10Z

This implements basic XDP redirect support in mlx5 driver.

Notice that the ndo_xdp_xmit() is NOT implemented, because that API
need some changes that this patchset is working towards.

The main purpose of this patch is have different drivers doing
XDP_REDIRECT to show how different memory models behave in a cross
driver world.

Update(pre-RFCv2 Tariq): Need to DMA unmap page before xdp_do_redirect,
as the return API does not exist yet to to keep this mapped.

Update(pre-RFCv3 Saeed): Don't mix XDP_TX and XDP_REDIRECT flushing,
introduce xdpsq.db.redirect_flush boolian.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
---
drivers/net/ethernet/mellanox/mlx5/core/en.h | 1 +
drivers/net/ethernet/mellanox/mlx5/core/en_rx.c | 27 ++++++++++++++++++++---
2 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en.h b/drivers/net/ethernet/mellanox/mlx5/core/en.h
index 4c9360b25532..28cc26debeda 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en.h
@@ -398,6 +398,7 @@ struct mlx5e_xdpsq {
struct {
struct mlx5e_dma_info *di;
bool doorbell;
+ bool redirect_flush;
} db;

/* read only */
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
index 8cce90dc461d..6dcc3e8fbd3e 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
@@ -236,14 +236,20 @@ static inline int mlx5e_page_alloc_mapped(struct mlx5e_rq *rq,
return 0;
}

+static inline void mlx5e_page_dma_unmap(struct mlx5e_rq *rq,
+ struct mlx5e_dma_info *dma_info)
+{
+ dma_unmap_page(rq->pdev, dma_info->addr, RQ_PAGE_SIZE(rq),
+ rq->buff.map_dir);
+}
+
void mlx5e_page_release(struct mlx5e_rq *rq, struct mlx5e_dma_info *dma_info,
bool recycle)
{
if (likely(recycle) && mlx5e_rx_cache_put(rq, dma_info))
return;

- dma_unmap_page(rq->pdev, dma_info->addr, RQ_PAGE_SIZE(rq),
- rq->buff.map_dir);
+ mlx5e_page_dma_unmap(rq, dma_info);
put_page(dma_info->page);
}

@@ -822,9 +828,10 @@ static inline int mlx5e_xdp_handle(struct mlx5e_rq *rq,
struct mlx5e_dma_info *di,
void *va, u16 *rx_headroom, u32 *len)
{
- const struct bpf_prog *prog = READ_ONCE(rq->xdp_prog);
+ struct bpf_prog *prog = READ_ONCE(rq->xdp_prog);
struct xdp_buff xdp;
u32 act;
+ int err;

if (!prog)
return false;
@@ -845,6 +852,15 @@ static inline int mlx5e_xdp_handle(struct mlx5e_rq *rq,
if (unlikely(!mlx5e_xmit_xdp_frame(rq, di, &xdp)))
trace_xdp_exception(rq->netdev, prog, act);
return true;
+ case XDP_REDIRECT:
+ /* When XDP enabled then page-refcnt==1 here */
+ err = xdp_do_redirect(rq->netdev, &xdp, prog);
+ if (!err) {
+ rq->wqe.xdp_xmit = true; /* XDP xmit owns page */
+ rq->xdpsq.db.redirect_flush = true;
+ mlx5e_page_dma_unmap(rq, di);
+ }
+ return true;
default:
bpf_warn_invalid_xdp_action(act);
case XDP_ABORTED:
@@ -1107,6 +1123,11 @@ int mlx5e_poll_rx_cq(struct mlx5e_cq *cq, int budget)
xdpsq->db.doorbell = false;
}

+ if (xdpsq->db.redirect_flush) {
+ xdp_do_flush_map();
+ xdpsq->db.redirect_flush = false;
+ }
+
mlx5_cqwq_update_db_record(&cq->wq);

/* ensure cq space is freed before enabling more cqes */