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Date: Thu, 12 Jan 2017 15:10:30 +0200
From: Saeed Mahameed <saeedm@....mellanox.co.il>
To: Martin KaFai Lau <kafai@...com>
Cc: Linux Netdev List <netdev@...r.kernel.org>,
Saeed Mahameed <saeedm@...lanox.com>,
Tariq Toukan <tariqt@...lanox.com>,
Kernel Team <kernel-team@...com>
Subject: Re: [PATCH net-next] net/mlx5e: Support bpf_xdp_adjust_head()
On Thu, Jan 12, 2017 at 4:09 AM, Martin KaFai Lau <kafai@...com> wrote:
> This patch adds bpf_xdp_adjust_head() support to mlx5e.
Hi Martin, Thanks for the patch !
you can find some comments below.
>
> 1. rx_headroom is added to struct mlx5e_rq. It uses
> an existing 4 byte hole in the struct.
> 2. The adjusted data length is checked against
> MLX5E_XDP_MIN_INLINE and MLX5E_SW2HW_MTU(rq->netdev->mtu).
> 3. The macro MLX5E_SW2HW_MTU is moved from en_main.c to en.h.
> MLX5E_HW2SW_MTU is also moved to en.h for symmetric reason
> but it is not a must.
>
> Signed-off-by: Martin KaFai Lau <kafai@...com>
> ---
> drivers/net/ethernet/mellanox/mlx5/core/en.h | 4 ++
> drivers/net/ethernet/mellanox/mlx5/core/en_main.c | 18 +++----
> drivers/net/ethernet/mellanox/mlx5/core/en_rx.c | 63 ++++++++++++++---------
> 3 files changed, 51 insertions(+), 34 deletions(-)
>
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en.h b/drivers/net/ethernet/mellanox/mlx5/core/en.h
> index a473cea10c16..0d9dd860a295 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en.h
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en.h
> @@ -51,6 +51,9 @@
>
> #define MLX5_SET_CFG(p, f, v) MLX5_SET(create_flow_group_in, p, f, v)
>
> +#define MLX5E_HW2SW_MTU(hwmtu) ((hwmtu) - (ETH_HLEN + VLAN_HLEN + ETH_FCS_LEN))
> +#define MLX5E_SW2HW_MTU(swmtu) ((swmtu) + (ETH_HLEN + VLAN_HLEN + ETH_FCS_LEN))
> +
> #define MLX5E_MAX_NUM_TC 8
>
> #define MLX5E_PARAMS_MINIMUM_LOG_SQ_SIZE 0x6
> @@ -369,6 +372,7 @@ struct mlx5e_rq {
>
> unsigned long state;
> int ix;
> + u16 rx_headroom;
>
> struct mlx5e_rx_am am; /* Adaptive Moderation */
> struct bpf_prog *xdp_prog;
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> index f74ba73c55c7..aba3691e0919 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> @@ -343,9 +343,6 @@ static void mlx5e_disable_async_events(struct mlx5e_priv *priv)
> synchronize_irq(mlx5_get_msix_vec(priv->mdev, MLX5_EQ_VEC_ASYNC));
> }
>
> -#define MLX5E_HW2SW_MTU(hwmtu) (hwmtu - (ETH_HLEN + VLAN_HLEN + ETH_FCS_LEN))
> -#define MLX5E_SW2HW_MTU(swmtu) (swmtu + (ETH_HLEN + VLAN_HLEN + ETH_FCS_LEN))
> -
> static inline int mlx5e_get_wqe_mtt_sz(void)
> {
> /* UMR copies MTTs in units of MLX5_UMR_MTT_ALIGNMENT bytes.
> @@ -534,9 +531,13 @@ static int mlx5e_create_rq(struct mlx5e_channel *c,
> goto err_rq_wq_destroy;
> }
>
> - rq->buff.map_dir = DMA_FROM_DEVICE;
> - if (rq->xdp_prog)
> + if (rq->xdp_prog) {
> rq->buff.map_dir = DMA_BIDIRECTIONAL;
> + rq->rx_headroom = XDP_PACKET_HEADROOM;
> + } else {
> + rq->buff.map_dir = DMA_FROM_DEVICE;
> + rq->rx_headroom = MLX5_RX_HEADROOM;
> + }
>
> switch (priv->params.rq_wq_type) {
> case MLX5_WQ_TYPE_LINKED_LIST_STRIDING_RQ:
> @@ -586,7 +587,7 @@ static int mlx5e_create_rq(struct mlx5e_channel *c,
> byte_count = rq->buff.wqe_sz;
>
> /* calc the required page order */
> - frag_sz = MLX5_RX_HEADROOM +
> + frag_sz = rq->rx_headroom +
> byte_count /* packet data */ +
> SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
> frag_sz = SKB_DATA_ALIGN(frag_sz);
> @@ -3153,11 +3154,6 @@ static int mlx5e_xdp_set(struct net_device *netdev, struct bpf_prog *prog)
> bool reset, was_opened;
> int i;
>
> - if (prog && prog->xdp_adjust_head) {
> - netdev_err(netdev, "Does not support bpf_xdp_adjust_head()\n");
> - return -EOPNOTSUPP;
> - }
> -
> mutex_lock(&priv->state_lock);
>
> if ((netdev->features & NETIF_F_LRO) && prog) {
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
> index 0e2fb3ed1790..914e00132e08 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
> @@ -264,7 +264,7 @@ int mlx5e_alloc_rx_wqe(struct mlx5e_rq *rq, struct mlx5e_rx_wqe *wqe, u16 ix)
> if (unlikely(mlx5e_page_alloc_mapped(rq, di)))
> return -ENOMEM;
>
> - wqe->data.addr = cpu_to_be64(di->addr + MLX5_RX_HEADROOM);
> + wqe->data.addr = cpu_to_be64(di->addr + rq->rx_headroom);
> return 0;
> }
>
> @@ -646,8 +646,7 @@ static inline void mlx5e_xmit_xdp_doorbell(struct mlx5e_sq *sq)
>
> static inline void mlx5e_xmit_xdp_frame(struct mlx5e_rq *rq,
> struct mlx5e_dma_info *di,
> - unsigned int data_offset,
> - int len)
> + const struct xdp_buff *xdp)
> {
> struct mlx5e_sq *sq = &rq->channel->xdp_sq;
> struct mlx5_wq_cyc *wq = &sq->wq;
> @@ -659,9 +658,17 @@ static inline void mlx5e_xmit_xdp_frame(struct mlx5e_rq *rq,
> struct mlx5_wqe_eth_seg *eseg = &wqe->eth;
> struct mlx5_wqe_data_seg *dseg;
>
> + ptrdiff_t data_offset = xdp->data - xdp->data_hard_start;
> dma_addr_t dma_addr = di->addr + data_offset + MLX5E_XDP_MIN_INLINE;
> - unsigned int dma_len = len - MLX5E_XDP_MIN_INLINE;
> - void *data = page_address(di->page) + data_offset;
> + unsigned int dma_len = xdp->data_end - xdp->data;
> +
> + if (unlikely(dma_len < MLX5E_XDP_MIN_INLINE ||
I don't think this can happen, MLX5E_XDP_MIN_INLINE is 18 bytes and
should not get bigger in the future,
Also i don't think it is possible for XDP prog to xmit packets smaller
than 18 bytes, let's remove this
> + MLX5E_SW2HW_MTU(rq->netdev->mtu) < dma_len)) {
> + rq->stats.xdp_drop++;
> + mlx5e_page_release(rq, di, true);
> + return;
> + }
> + dma_len -= MLX5E_XDP_MIN_INLINE;
Move this to after the below sanity check, it is better to separate
logic from pre-conditions
>
> if (unlikely(!mlx5e_sq_has_room_for(sq, MLX5E_XDP_TX_WQEBBS))) {
> if (sq->db.xdp.doorbell) {
> @@ -680,7 +687,7 @@ static inline void mlx5e_xmit_xdp_frame(struct mlx5e_rq *rq,
> memset(wqe, 0, sizeof(*wqe));
>
> /* copy the inline part */
> - memcpy(eseg->inline_hdr_start, data, MLX5E_XDP_MIN_INLINE);
> + memcpy(eseg->inline_hdr_start, xdp->data, MLX5E_XDP_MIN_INLINE);
> eseg->inline_hdr_sz = cpu_to_be16(MLX5E_XDP_MIN_INLINE);
>
> dseg = (struct mlx5_wqe_data_seg *)cseg + (MLX5E_XDP_TX_DS_COUNT - 1);
> @@ -706,22 +713,16 @@ static inline void mlx5e_xmit_xdp_frame(struct mlx5e_rq *rq,
> static inline bool mlx5e_xdp_handle(struct mlx5e_rq *rq,
> const struct bpf_prog *prog,
> struct mlx5e_dma_info *di,
> - void *data, u16 len)
> + struct xdp_buff *xdp)
> {
> - struct xdp_buff xdp;
> u32 act;
>
> - if (!prog)
> - return false;
> -
> - xdp.data = data;
> - xdp.data_end = xdp.data + len;
> - act = bpf_prog_run_xdp(prog, &xdp);
> + act = bpf_prog_run_xdp(prog, xdp);
> switch (act) {
> case XDP_PASS:
> return false;
> case XDP_TX:
> - mlx5e_xmit_xdp_frame(rq, di, MLX5_RX_HEADROOM, len);
> + mlx5e_xmit_xdp_frame(rq, di, xdp);
> return true;
> default:
> bpf_warn_invalid_xdp_action(act);
> @@ -737,18 +738,19 @@ static inline
> struct sk_buff *skb_from_cqe(struct mlx5e_rq *rq, struct mlx5_cqe64 *cqe,
> u16 wqe_counter, u32 cqe_bcnt)
> {
> + const struct bpf_prog *xdp_prog;
> struct mlx5e_dma_info *di;
> struct sk_buff *skb;
> void *va, *data;
> - bool consumed;
> + u16 rx_headroom = rq->rx_headroom;
>
> di = &rq->dma_info[wqe_counter];
> va = page_address(di->page);
> - data = va + MLX5_RX_HEADROOM;
> + data = va + rx_headroom;
>
> dma_sync_single_range_for_cpu(rq->pdev,
> di->addr,
> - MLX5_RX_HEADROOM,
> + rx_headroom,
> rq->buff.wqe_sz,
> DMA_FROM_DEVICE);
> prefetch(data);
> @@ -760,11 +762,26 @@ struct sk_buff *skb_from_cqe(struct mlx5e_rq *rq, struct mlx5_cqe64 *cqe,
> }
>
> rcu_read_lock();
> - consumed = mlx5e_xdp_handle(rq, READ_ONCE(rq->xdp_prog), di, data,
> - cqe_bcnt);
> + xdp_prog = READ_ONCE(rq->xdp_prog);
> + if (xdp_prog) {
> + struct xdp_buff xdp;
> + bool consumed;
> +
> + xdp.data = data;
> + xdp.data_end = xdp.data + cqe_bcnt;
> + xdp.data_hard_start = va;
> +
> + consumed = mlx5e_xdp_handle(rq, xdp_prog, di, &xdp);
> +
> + if (consumed) {
> + rcu_read_unlock();
> + return NULL; /* page/packet was consumed by XDP */
> + }
> +
> + rx_headroom = xdp.data - xdp.data_hard_start;
> + cqe_bcnt = xdp.data_end - xdp.data;
> + }
This whole new logic belongs to mlx5e_xdp_handle, I would like to keep
xdp related code in one place.
move the xdp_buff initialization back to there and keep the xdp_prog
check in mlx5e_xdp_handle;
+ xdp_prog = READ_ONCE(rq->xdp_prog);
+ if (!xdp_prog)
+ return false
you can remove "const struct bpf_prog *prog" parameter from
mlx5e_xdp_handle and take it directly from rq.
if you need va for xdp_buff you can pass it as a paramter to
mlx5e_xdp_handle as well:
mlx5e_xdp_handle(rq, di, va, data, cqe_bcnt);
Make sense ?
> rcu_read_unlock();
> - if (consumed)
> - return NULL; /* page/packet was consumed by XDP */
>
> skb = build_skb(va, RQ_PAGE_SIZE(rq));
> if (unlikely(!skb)) {
> @@ -777,7 +794,7 @@ struct sk_buff *skb_from_cqe(struct mlx5e_rq *rq, struct mlx5_cqe64 *cqe,
> page_ref_inc(di->page);
> mlx5e_page_release(rq, di, true);
>
> - skb_reserve(skb, MLX5_RX_HEADROOM);
> + skb_reserve(skb, rx_headroom);
> skb_put(skb, cqe_bcnt);
>
> return skb;
> --
> 2.5.1
>
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