This is a note to let you know that I've just added the patch titled net/mlx5e: Fix hw mtu initializing at XDP SQ allocation to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: net-mlx5e-fix-hw-mtu-initializing-at-xdp-sq-allocati.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 58e76fdfc2426354183126d9dc8e4bb2981fa6d3 Author: Adham Faris <afaris@xxxxxxxxxx> Date: Wed Dec 14 16:02:57 2022 +0200 net/mlx5e: Fix hw mtu initializing at XDP SQ allocation [ Upstream commit 1e267ab88dc44c48f556218f7b7f14c76f7aa066 ] Current xdp xmit functions logic (mlx5e_xmit_xdp_frame_mpwqe or mlx5e_xmit_xdp_frame), validates xdp packet length by comparing it to hw mtu (configured at xdp sq allocation) before xmiting it. This check does not account for ethernet fcs length (calculated and filled by the nic). Hence, when we try sending packets with length > (hw-mtu - ethernet-fcs-size), the device port drops it and tx_errors_phy is incremented. Desired behavior is to catch these packets and drop them by the driver. Fix this behavior in XDP SQ allocation function (mlx5e_alloc_xdpsq) by subtracting ethernet FCS header size (4 Bytes) from current hw mtu value, since ethernet FCS is calculated and written to ethernet frames by the nic. Fixes: d8bec2b29a82 ("net/mlx5e: Support bpf_xdp_adjust_head()") Signed-off-by: Adham Faris <afaris@xxxxxxxxxx> Reviewed-by: Tariq Toukan <tariqt@xxxxxxxxxx> Signed-off-by: Saeed Mahameed <saeedm@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c index c1c4f380803a..be19f5cf9d15 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c @@ -977,7 +977,7 @@ static int mlx5e_alloc_xdpsq(struct mlx5e_channel *c, sq->channel = c; sq->uar_map = mdev->mlx5e_res.hw_objs.bfreg.map; sq->min_inline_mode = params->tx_min_inline_mode; - sq->hw_mtu = MLX5E_SW2HW_MTU(params, params->sw_mtu); + sq->hw_mtu = MLX5E_SW2HW_MTU(params, params->sw_mtu) - ETH_FCS_LEN; sq->xsk_pool = xsk_pool; sq->stats = sq->xsk_pool ?