On 2019-07-24 08:10, Kevin Laatz wrote:
> With the addition of the unaligned chunks option, we need to make sure we
> handle the offsets accordingly based on the mode we are currently running
> in. This patch modifies the driver to appropriately mask the address for
> each case.
>
> Signed-off-by: Kevin Laatz <kevin.laatz@xxxxxxxxx>
>
> ---
> v3:
> - Use new helper function to handle offset
> ---
> drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c | 8 ++++++--
> drivers/net/ethernet/mellanox/mlx5/core/en/xsk/tx.c | 9 +++++++--
> 2 files changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
> index b0b982cf69bb..d5245893d2c8 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
> @@ -122,6 +122,7 @@ bool mlx5e_xdp_handle(struct mlx5e_rq *rq, struct mlx5e_dma_info *di,
> void *va, u16 *rx_headroom, u32 *len, bool xsk)
> {
> struct bpf_prog *prog = READ_ONCE(rq->xdp_prog);
> + struct xdp_umem *umem = rq->umem;
> struct xdp_buff xdp;
> u32 act;
> int err;
> @@ -138,8 +139,11 @@ bool mlx5e_xdp_handle(struct mlx5e_rq *rq, struct mlx5e_dma_info *di,
> xdp.rxq = &rq->xdp_rxq;
>
> act = bpf_prog_run_xdp(prog, &xdp);
> - if (xsk)
> - xdp.handle += xdp.data - xdp.data_hard_start;
> + if (xsk) {
> + u64 off = xdp.data - xdp.data_hard_start;
> +
> + xdp.handle = xsk_umem_handle_offset(umem, xdp.handle, off);
> + }
What's missed is that umem_headroom is added to handle directly in
mlx5e_xsk_page_alloc_umem. In my understanding umem_headroom should go
to the offset part (high 16 bits) of the handle, to
xsk_umem_handle_offset has to support increasing the offset.
> switch (act) {
> case XDP_PASS:
> *rx_headroom = xdp.data - xdp.data_hard_start;
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/tx.c b/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/tx.c
> index 35e188cf4ea4..f596e63cba00 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/tx.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/tx.c
> @@ -61,6 +61,7 @@ bool mlx5e_xsk_tx(struct mlx5e_xdpsq *sq, unsigned int budget)
> struct mlx5e_xdp_xmit_data xdptxd;
> bool work_done = true;
> bool flush = false;
> + u64 addr, offset;
>
> xdpi.mode = MLX5E_XDP_XMIT_MODE_XSK;
>
> @@ -82,8 +83,12 @@ bool mlx5e_xsk_tx(struct mlx5e_xdpsq *sq, unsigned int budget)
> break;
> }
>
> - xdptxd.dma_addr = xdp_umem_get_dma(umem, desc.addr);
> - xdptxd.data = xdp_umem_get_data(umem, desc.addr);
> + /* for unaligned chunks need to take offset from upper bits */
> + offset = (desc.addr >> XSK_UNALIGNED_BUF_OFFSET_SHIFT);
> + addr = (desc.addr & XSK_UNALIGNED_BUF_ADDR_MASK);
> +
> + xdptxd.dma_addr = xdp_umem_get_dma(umem, addr + offset);
> + xdptxd.data = xdp_umem_get_data(umem, addr + offset);
Why can't these calculations be encapsulated into
xdp_umem_get_{dma,data}? I think they are common for all drivers, aren't
they?
Even if there is some reason not to put this bitshifting stuff into
xdp_umem_get_* functions, I suggest to encapsulate it into a function
anyway, because it's a good idea to keep those calculations in a single
place.
> xdptxd.len = desc.len;
>
> dma_sync_single_for_device(sq->pdev, xdptxd.dma_addr,
>
