netdev - Re: [PATCH 2/2] PATCH: i40e Add module option to disable max VF limit

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Message-ID: <6133c0c5-8a1a-48c3-9083-8cd307293120@intel.com>
Date: Thu, 7 Aug 2025 09:17:30 -0700
From: Jacob Keller <jacob.e.keller@...el.com>
To: Simon Horman <horms@...nel.org>, David Hill <dhill@...hat.com>
CC: <netdev@...r.kernel.org>, <anthony.l.nguyen@...el.com>,
	<przemyslaw.kitszel@...el.com>, <andrew+netdev@...n.ch>,
	<davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
	<pabeni@...hat.com>
Subject: Re: [PATCH 2/2] PATCH: i40e Add module option to disable max VF limit



On 8/5/2025 12:52 PM, Simon Horman wrote:
> On Tue, Aug 05, 2025 at 09:40:42AM -0400, David Hill wrote:
>> When a VF reaches the limit introduced in this commit [1], the driver
>> refuses to add any more MACs to the filter which changes the behavior
>> from previous releases and might break some NFVs which sometimes add
>> more VFs than the hardcoded limit of 18 and variable limit depending
>> on the number of VFs created on a given PF.   Disabling limit_mac_per_vf
>> would revert to previous behavior.
>>
>> [1] commit cfb1d572c986 ("i40e: Add ensurance of MacVlan resources for every
>> trusted VF")
>>
>> Signed-off-by: David Hill <dhill@...hat.com>
> 
> Hi David,
> 
> Unfortunately adding new module parameters to Ethernet drivers is discouraged.
> I would suggest that devlink is an appropriate mechanism.
> 

At a glance, my initial suggestion would be modeling this with devlink
resources?

If each VF has a devlink port in the host, we could create a resource
that is the number of allowed filters for each VF, and the host could
control this through the resource...

I think this might even let us nest a resource so we have one for the
parent which is the total amount available and each VF port could have
its amount available.

A devlink parameter could work but is a bit less flexible and doesn't
show you the hierarchy with the total available filters within the PF vs
what each VF is consuming.


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