Re: [PATCH for-next v2] RDMA/efa: Validate SQ depth based on WQE size

[Leon Romanovsky <leon@kernel.org>]

On Sun, May 17, 2026 at 05:52:16PM +0000, Yonatan Nachum wrote:
> Change the SQ depth validation to take into account the SQ WQE size.
> This is needed since when using 128-byte WQE the max SQ depth is cut in
> half. On create QP command, userspace provides SQ ring size which is SQ
> depth X WQE size so we can calculate the requested WQE size in the
> kernel.
> 
> Fixes: 40909f664d27 ("RDMA/efa: Add EFA verbs implementation")
> Reviewed-by: Daniel Kranzdorf <dkkranzd@amazon.com>
> Reviewed-by: Michael Margolin <mrgolin@amazon.com>
> Signed-off-by: Yonatan Nachum <ynachum@amazon.com>
> ---
> Changelog:
> v2:
>  * Add fixes line.
> v1: https://lore.kernel.org/all/20260507112110.869212-1-ynachum@amazon.com/
> 
>  drivers/infiniband/hw/efa/efa_verbs.c | 39 ++++++++++++++++++---------
>  1 file changed, 27 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/infiniband/hw/efa/efa_verbs.c b/drivers/infiniband/hw/efa/efa_verbs.c
> index 395290ab0584..9a6cbb70581b 100644
> --- a/drivers/infiniband/hw/efa/efa_verbs.c
> +++ b/drivers/infiniband/hw/efa/efa_verbs.c
> @@ -597,14 +597,27 @@ static int qp_mmap_entries_setup(struct efa_qp *qp,
>  	return -ENOMEM;
>  }
>  
> +static int efa_calc_sq_wqe_size(u32 sq_ring_size, u32 max_send_wr)
> +{
> +	return max_send_wr == 0 ? 0 : sq_ring_size / max_send_wr;
> +}
> +
> +static u32 efa_calc_sq_max_depth(struct efa_dev *dev, u32 sq_wqe_size)
> +{
> +	return sq_wqe_size == 0 ? 0 :
> +		rounddown_pow_of_two(dev->dev_attr.max_llq_size / sq_wqe_size);
> +}

Please review sashiko's findings:
https://sashiko.dev/#/patchset/20260517175216.614494-1-ynachum@amazon.com

It appears that a valid input can trigger rounddown_pow_of_two(0).

Thanks