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

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

On 12/12/2025 12:22 PM, Gregory Herrero wrote:
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>
>
> On Fri, Dec 12, 2025 at 09:37:20AM -0800, Creeley, Brett wrote:
>> On 11/17/2025 12:33 AM, gregory.herrero@oracle.com wrote:
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>>>
>>>
>>> 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.
>>
> I agree, it's just that it will require changing the 5 callers of this
> function and invalidate the testing from Rafal Romanowski.
> Please let me know what you think, I can wait before sending v5.

I'm fine with the PF being the parameter. However, the documentation 
should really be removed IMO.

Thanks,

Brett
>
> Thanks,
> Gregory
>>> +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
>>>
>>>