[Intel-wired-lan] [PATCH bpf-next v3 06/11] mlx5e: modify driver for handling offsets
Laatz, Kevin
kevin.laatz at intel.com
Thu Jul 25 17:00:42 UTC 2019
On 25/07/2019 11:15, Maxim Mikityanskiy wrote:
> 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 at intel.com>
>>
>> ---
>> 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.
Will look into it and make the changes for the v4
>> 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.
Nice suggestion! I will move it to the xdp_umem_get_* functions in the
v4. Thanks
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