netdev - Re: [PATCH 03/10 net-next] net/mlx5e: RX, Internal DMA mapping in page

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Date:   Fri, 18 Oct 2019 21:01:00 +0000
From:   Saeed Mahameed <saeedm@...lanox.com>
To:     "jonathan.lemon@...il.com" <jonathan.lemon@...il.com>,
        "ilias.apalodimas@...aro.org" <ilias.apalodimas@...aro.org>,
        Tariq Toukan <tariqt@...lanox.com>,
        "brouer@...hat.com" <brouer@...hat.com>
CC:     "kernel-team@...com" <kernel-team@...com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH 03/10 net-next] net/mlx5e: RX, Internal DMA mapping in
 page_pool

On Wed, 2019-10-16 at 15:50 -0700, Jonathan Lemon wrote:
> From: Tariq Toukan <tariqt@...lanox.com>
> 
> After RX page-cache is removed in previous patch, let the
> page_pool be responsible for the DMA mapping.
> 
> Issue: 1487631
> Signed-off-by: Tariq Toukan <tariqt@...lanox.com>
> 
> Signed-off-by: Jonathan Lemon <jonathan.lemon@...il.com>
> ---
>  drivers/net/ethernet/mellanox/mlx5/core/en.h     |  2 --
>  drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c |  3 +--
>  .../net/ethernet/mellanox/mlx5/core/en_main.c    |  2 +-
>  drivers/net/ethernet/mellanox/mlx5/core/en_rx.c  | 16 +-------------
> --
>  4 files changed, 3 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en.h
> b/drivers/net/ethernet/mellanox/mlx5/core/en.h
> index a1ab5c76177d..2e281c755b65 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en.h
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en.h
> @@ -926,10 +926,8 @@ bool
> mlx5e_check_fragmented_striding_rq_cap(struct mlx5_core_dev *mdev);
>  bool mlx5e_striding_rq_possible(struct mlx5_core_dev *mdev,
>  				struct mlx5e_params *params);
>  
> -void mlx5e_page_dma_unmap(struct mlx5e_rq *rq, struct mlx5e_dma_info
> *dma_info);
>  void mlx5e_page_release_dynamic(struct mlx5e_rq *rq,
>  				struct mlx5e_dma_info *dma_info);
> -void mlx5e_page_release(struct mlx5e_rq *rq, struct mlx5e_dma_info
> *dma_info);
>  void mlx5e_handle_rx_cqe(struct mlx5e_rq *rq, struct mlx5_cqe64
> *cqe);
>  void mlx5e_handle_rx_cqe_mpwrq(struct mlx5e_rq *rq, struct
> mlx5_cqe64 *cqe);
>  bool mlx5e_post_rx_wqes(struct mlx5e_rq *rq);
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
> b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
> index 1b26061cb959..8376b2789575 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
> @@ -161,8 +161,7 @@ bool mlx5e_xdp_handle(struct mlx5e_rq *rq, struct
> mlx5e_dma_info *di,
>  			goto xdp_abort;
>  		__set_bit(MLX5E_RQ_FLAG_XDP_XMIT, rq->flags);
>  		__set_bit(MLX5E_RQ_FLAG_XDP_REDIRECT, rq->flags);
> -		if (!xsk)
> -			mlx5e_page_dma_unmap(rq, di);
> +		/* xdp maps call xdp_release_frame() if needed */
>  		rq->stats->xdp_redirect++;
>  		return true;
>  	default:
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> index 168be1f800a3..2b828de1adf0 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> @@ -546,7 +546,7 @@ static int mlx5e_alloc_rq(struct mlx5e_channel
> *c,
>  	} else {
>  		/* Create a page_pool and register it with rxq */
>  		pp_params.order     = 0;
> -		pp_params.flags     = 0; /* No-internal DMA mapping in
> page_pool */
> +		pp_params.flags     = PP_FLAG_DMA_MAP;
>  		pp_params.pool_size = pool_size;
>  		pp_params.nid       = cpu_to_node(c->cpu);
>  		pp_params.dev       = c->pdev;
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
> b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
> index 033b8264a4e4..1b74d03fdf06 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
> @@ -190,14 +190,7 @@ static inline int mlx5e_page_alloc_pool(struct
> mlx5e_rq *rq,
>  	dma_info->page = page_pool_dev_alloc_pages(rq->page_pool);
>  	if (unlikely(!dma_info->page))
>  		return -ENOMEM;

Jakub is right, you need to dma_sync for device after allocating ..
pages recycled from cache can be synced for CPU .. you need to sync
them for device here.

> -
> -	dma_info->addr = dma_map_page(rq->pdev, dma_info->page, 0,
> -				      PAGE_SIZE, rq->buff.map_dir);
> -	if (unlikely(dma_mapping_error(rq->pdev, dma_info->addr))) {
> -		page_pool_recycle_direct(rq->page_pool, dma_info-
> >page);
> -		dma_info->page = NULL;
> -		return -ENOMEM;
> -	}
> +	dma_info->addr = page_pool_get_dma_addr(dma_info->page);
>  
>  	return 0;
>  }
> @@ -211,16 +204,9 @@ static inline int mlx5e_page_alloc(struct
> mlx5e_rq *rq,
>  		return mlx5e_page_alloc_pool(rq, dma_info);
>  }
>  
> -void mlx5e_page_dma_unmap(struct mlx5e_rq *rq, struct mlx5e_dma_info
> *dma_info)
> -{
> -	dma_unmap_page(rq->pdev, dma_info->addr, PAGE_SIZE, rq-
> >buff.map_dir);
> -}
> -
>  void mlx5e_page_release_dynamic(struct mlx5e_rq *rq,
>  				struct mlx5e_dma_info *dma_info)
>  {
> -	mlx5e_page_dma_unmap(rq, dma_info);
> -
>  	page_pool_recycle_direct(rq->page_pool, dma_info->page);
>  }
>