RE: [PATCH bpf v3 7/9] libeth, idpf: use truesize as XDP RxQ info frag_size

[Loktionov, Aleksandr]

> -----Original Message-----
> From: Zaremba, Larysa <larysa.zaremba@xxxxxxxxx>
> Sent: Tuesday, February 17, 2026 2:25 PM
> To: bpf@xxxxxxxxxxxxxxx
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> Subject: [PATCH bpf v3 7/9] libeth, idpf: use truesize 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 idpf driver
> configuration lead to negative tailroom.
> 
> To make it worse, buffer sizes are not actually uniform in idpf when
> splitq is enabled, as there are several buffer queues, so rxq-
> >rx_buf_size is meaningless in this case.
> 
> Use truesize of the first bufq in AF_XDP ZC, as there is only one.
> Disable growinf tail for regular splitq.

"growing" -> " growing" ? 

Otherwise fine
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@xxxxxxxxx>

> 
> Fixes: ac8a861f632e ("idpf: prepare structures to support XDP")
> Signed-off-by: Larysa Zaremba <larysa.zaremba@xxxxxxxxx>
> ---
>  drivers/net/ethernet/intel/idpf/xdp.c   | 6 +++++-
>  drivers/net/ethernet/intel/idpf/xsk.c   | 1 +
>  drivers/net/ethernet/intel/libeth/xsk.c | 1 +
>  include/net/libeth/xsk.h                | 3 +++
>  4 files changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/intel/idpf/xdp.c
> b/drivers/net/ethernet/intel/idpf/xdp.c
> index 958d16f87424..7d91f21174de 100644
> --- a/drivers/net/ethernet/intel/idpf/xdp.c
> +++ b/drivers/net/ethernet/intel/idpf/xdp.c
> @@ -46,11 +46,15 @@ static int __idpf_xdp_rxq_info_init(struct
> idpf_rx_queue *rxq, void *arg)  {
>  	const struct idpf_vport *vport = rxq->q_vector->vport;
>  	bool split = idpf_is_queue_model_split(vport->rxq_model);
> +	u32 frag_size = 0;
>  	int err;
> 
> +	if (idpf_queue_has(XSK, rxq))
> +		frag_size = rxq->bufq_sets[0].bufq.truesize;
> +
>  	err = __xdp_rxq_info_reg(&rxq->xdp_rxq, vport->netdev, rxq-
> >idx,
>  				 rxq->q_vector->napi.napi_id,
> -				 rxq->rx_buf_size);
> +				 frag_size);
>  	if (err)
>  		return err;
> 
> diff --git a/drivers/net/ethernet/intel/idpf/xsk.c
> b/drivers/net/ethernet/intel/idpf/xsk.c
> index fd2cc43ab43c..95a665cb2f33 100644
> --- a/drivers/net/ethernet/intel/idpf/xsk.c
> +++ b/drivers/net/ethernet/intel/idpf/xsk.c
> @@ -401,6 +401,7 @@ int idpf_xskfq_init(struct idpf_buf_queue *bufq)
>  	bufq->pending = fq.pending;
>  	bufq->thresh = fq.thresh;
>  	bufq->rx_buf_size = fq.buf_len;
> +	bufq->truesize = fq.truesize;
> 
>  	if (!idpf_xskfq_refill(bufq))
>  		netdev_err(bufq->pool->netdev,
> diff --git a/drivers/net/ethernet/intel/libeth/xsk.c
> b/drivers/net/ethernet/intel/libeth/xsk.c
> index 846e902e31b6..4882951d5c9c 100644
> --- a/drivers/net/ethernet/intel/libeth/xsk.c
> +++ b/drivers/net/ethernet/intel/libeth/xsk.c
> @@ -167,6 +167,7 @@ int libeth_xskfq_create(struct libeth_xskfq *fq)
>  	fq->pending = fq->count;
>  	fq->thresh = libeth_xdp_queue_threshold(fq->count);
>  	fq->buf_len = xsk_pool_get_rx_frame_size(fq->pool);
> +	fq->truesize = xsk_pool_get_rx_frag_step(fq->pool);
> 
>  	return 0;
>  }
> diff --git a/include/net/libeth/xsk.h b/include/net/libeth/xsk.h index
> 481a7b28e6f2..82b5d21aae87 100644
> --- a/include/net/libeth/xsk.h
> +++ b/include/net/libeth/xsk.h
> @@ -597,6 +597,7 @@ __libeth_xsk_run_pass(struct libeth_xdp_buff *xdp,
>   * @pending: current number of XSkFQEs to refill
>   * @thresh: threshold below which the queue is refilled
>   * @buf_len: HW-writeable length per each buffer
> + * @truesize: step between consecutive buffers, 0 if none exists
>   * @nid: ID of the closest NUMA node with memory
>   */
>  struct libeth_xskfq {
> @@ -614,6 +615,8 @@ struct libeth_xskfq {
>  	u32			thresh;
> 
>  	u32			buf_len;
> +	u32			truesize;
> +
>  	int			nid;
>  };
> 
> --
> 2.52.0