Re: [PATCH v4 1/1] i40e: validate ring_len parameter against hardware-specific values

["Creeley, Brett" <bcreeley@amd.com>]

On 11/17/2025 12:33 AM, gregory.herrero@oracle.com wrote:
> Caution: This message originated from an External Source. Use proper caution when opening attachments, clicking links, or responding.
>
>
> From: Gregory Herrero <gregory.herrero@oracle.com>
>
> The maximum number of descriptors supported by the hardware is hardware
> dependent and can be retrieved using i40e_get_max_num_descriptors().
> Move this function to a shared header and use it when checking for valid
> ring_len parameter rather than using hardcoded value.
>
> By fixing an over-acceptance issue, behavior change could be seen where
> ring_len could now be rejected while configuring rx and tx queues if its
> size is larger than the hardware-specific maximum number of descriptors.
>
> Fixes: 55d225670def ("i40e: add validation for ring_len param")
> Signed-off-by: Gregory Herrero <gregory.herrero@oracle.com>
> ---
>   drivers/net/ethernet/intel/i40e/i40e.h         | 18 ++++++++++++++++++
>   drivers/net/ethernet/intel/i40e/i40e_ethtool.c | 12 ------------
>   .../net/ethernet/intel/i40e/i40e_virtchnl_pf.c |  4 ++--
>   3 files changed, 20 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/i40e/i40e.h b/drivers/net/ethernet/intel/i40e/i40e.h
> index 801a57a925da..5b367397ae43 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e.h
> +++ b/drivers/net/ethernet/intel/i40e/i40e.h
> @@ -1418,4 +1418,22 @@ static inline struct i40e_veb *i40e_pf_get_main_veb(struct i40e_pf *pf)
>          return (pf->lan_veb != I40E_NO_VEB) ? pf->veb[pf->lan_veb] : NULL;
>   }
>
> +/**
> + * i40e_get_max_num_descriptors - get maximum number of descriptors for this
> + * hardware.
> + * @pf: pointer to a PF
> + *
> + * Return: u32 value corresponding to the maximum number of descriptors.
> + **/

Nit, but the function name is descriptive enough without the documentation.

I think the purpose of the function would be even more obvious if the 
argument was a pointer to the hw structure instead of a pointer to the 
pf since the max is based on the hw not the pf.

Brett

> +static inline u32 i40e_get_max_num_descriptors(const struct i40e_pf *pf)
> +{
> +       const struct i40e_hw *hw = &pf->hw;
> +
> +       switch (hw->mac.type) {
> +       case I40E_MAC_XL710:
> +               return I40E_MAX_NUM_DESCRIPTORS_XL710;
> +       default:
> +               return I40E_MAX_NUM_DESCRIPTORS;
> +       }
> +}
>   #endif /* _I40E_H_ */
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_ethtool.c b/drivers/net/ethernet/intel/i40e/i40e_ethtool.c
> index 86c72596617a..61c39e881b00 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_ethtool.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_ethtool.c
> @@ -2013,18 +2013,6 @@ static void i40e_get_drvinfo(struct net_device *netdev,
>                  drvinfo->n_priv_flags += I40E_GL_PRIV_FLAGS_STR_LEN;
>   }
>
> -static u32 i40e_get_max_num_descriptors(struct i40e_pf *pf)
> -{
> -       struct i40e_hw *hw = &pf->hw;
> -
> -       switch (hw->mac.type) {
> -       case I40E_MAC_XL710:
> -               return I40E_MAX_NUM_DESCRIPTORS_XL710;
> -       default:
> -               return I40E_MAX_NUM_DESCRIPTORS;
> -       }
> -}
> -
>   static void i40e_get_ringparam(struct net_device *netdev,
>                                 struct ethtool_ringparam *ring,
>                                 struct kernel_ethtool_ringparam *kernel_ring,
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
> index 081a4526a2f0..cf831c649c9c 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
> @@ -656,7 +656,7 @@ static int i40e_config_vsi_tx_queue(struct i40e_vf *vf, u16 vsi_id,
>
>          /* ring_len has to be multiple of 8 */
>          if (!IS_ALIGNED(info->ring_len, 8) ||
> -           info->ring_len > I40E_MAX_NUM_DESCRIPTORS_XL710) {
> +           info->ring_len > i40e_get_max_num_descriptors(pf)) {
>                  ret = -EINVAL;
>                  goto error_context;
>          }
> @@ -726,7 +726,7 @@ static int i40e_config_vsi_rx_queue(struct i40e_vf *vf, u16 vsi_id,
>
>          /* ring_len has to be multiple of 32 */
>          if (!IS_ALIGNED(info->ring_len, 32) ||
> -           info->ring_len > I40E_MAX_NUM_DESCRIPTORS_XL710) {
> +           info->ring_len > i40e_get_max_num_descriptors(pf)) {
>                  ret = -EINVAL;
>                  goto error_param;
>          }
> --
> 2.51.0
>
>