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

[Gregory Herrero <gregory.herrero@oracle.com>]

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:
> > 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.
> 
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.

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
> > 
> >