[Intel-wired-lan] [PATCH bpf v3 6/9] i40e: use xdp.frame_sz as XDP RxQ info frag_size

[Loktionov, Aleksandr]

> -----Original Message-----
> From: Zaremba, Larysa <larysa.zaremba at intel.com>
> Sent: Tuesday, February 17, 2026 2:25 PM
> To: bpf at vger.kernel.org
> Cc: Zaremba, Larysa <larysa.zaremba at intel.com>; Claudiu Manoil
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> Aleksandr <aleksandr.loktionov at intel.com>; Dragos Tatulea
> <dtatulea at nvidia.com>
> Subject: [PATCH bpf v3 6/9] i40e: use xdp.frame_sz as XDP RxQ info
> frag_size
> 
> The only user of frag_size field in XDP RxQ info is
> bpf_xdp_frags_increase_tail(). It clearly expects whole buffer size
> instead of DMA write size. Different assumptions in i40e driver
> configuration lead to negative tailroom.
> 
> Set frag_size to the same value as frame_sz in shared pages mode, use
> new helper to set frag_size when AF_XDP ZC is active.
> 
> Fixes: a045d2f2d03d ("i40e: set xdp_rxq_info::frag_size")
> Signed-off-by: Larysa Zaremba <larysa.zaremba at intel.com>
> ---
>  drivers/net/ethernet/intel/i40e/i40e_main.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c
> b/drivers/net/ethernet/intel/i40e/i40e_main.c
> index eaa5b65e6daf..e012a50a0448 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_main.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
> @@ -3561,6 +3561,7 @@ static int i40e_configure_rx_ring(struct
> i40e_ring *ring)
>  	struct i40e_vsi *vsi = ring->vsi;
>  	u32 chain_len = vsi->back->hw.func_caps.rx_buf_chain_len;
>  	u16 pf_q = vsi->base_queue + ring->queue_index;
> +	u32 xdp_frame_sz = i40e_rx_pg_size(ring) / 2;
>  	struct i40e_hw *hw = &vsi->back->hw;
>  	struct i40e_hmc_obj_rxq rx_ctx;
>  	int err = 0;
> @@ -3579,11 +3580,12 @@ static int i40e_configure_rx_ring(struct
> i40e_ring *ring)
> 
>  	ring->xsk_pool = i40e_xsk_pool(ring);
>  	if (ring->xsk_pool) {
> +		xdp_frame_sz = xsk_pool_get_rx_frag_step(ring-
> >xsk_pool);
>  		ring->rx_buf_len = xsk_pool_get_rx_frame_size(ring-
> >xsk_pool);
>  		err = __xdp_rxq_info_reg(&ring->xdp_rxq, ring->netdev,
>  					 ring->queue_index,
>  					 ring->q_vector->napi.napi_id,
> -					 ring->rx_buf_len);
> +					 xdp_frame_sz);
>  		if (err)
>  			return err;
>  		err = xdp_rxq_info_reg_mem_model(&ring->xdp_rxq,
> @@ -3599,7 +3601,7 @@ static int i40e_configure_rx_ring(struct
> i40e_ring *ring)
>  		err = __xdp_rxq_info_reg(&ring->xdp_rxq, ring->netdev,
>  					 ring->queue_index,
>  					 ring->q_vector->napi.napi_id,
> -					 ring->rx_buf_len);
> +					 xdp_frame_sz);
>  		if (err)
>  			return err;
>  		err = xdp_rxq_info_reg_mem_model(&ring->xdp_rxq,
> @@ -3610,7 +3612,7 @@ static int i40e_configure_rx_ring(struct
> i40e_ring *ring)
>  	}
> 
>  skip:
> -	xdp_init_buff(&ring->xdp, i40e_rx_pg_size(ring) / 2, &ring-
> >xdp_rxq);
> +	xdp_init_buff(&ring->xdp, xdp_frame_sz, &ring->xdp_rxq);
> 
>  	rx_ctx.dbuff = DIV_ROUND_UP(ring->rx_buf_len,
>  				    BIT_ULL(I40E_RXQ_CTX_DBUFF_SHIFT));
> --
> 2.52.0

Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov at intel.com>