Re: [PATCH v2 net] i40e: When removing VF MAC filters, only check PF-set MAC

[Simon Horman <horms@kernel.org>]

On Wed, Jun 25, 2025 at 09:29:18AM +1000, Jamie Bainbridge wrote:
> When the PF is processing an Admin Queue message to delete a VF's MACs
> from the MAC filter, we currently check if the PF set the MAC and if
> the VF is trusted.
> 
> This results in undesirable behaviour, where if a trusted VF with a
> PF-set MAC sets itself down (which sends an AQ message to delete the
> VF's MAC filters) then the VF MAC is erased from the interface.
> 
> This results in the VF losing its PF-set MAC which should not happen.
> 
> There is no need to check for trust at all, because an untrusted VF
> cannot change its own MAC. The only check needed is whether the PF set
> the MAC. If the PF set the MAC, then don't erase the MAC on link-down.
> 
> Resolve this by changing the deletion check only for PF-set MAC.
> 
> (the out-of-tree driver has also intentionally removed the check for VF
> trust here with OOT driver version 2.26.8, this changes the Linux kernel
> driver behaviour and comment to match the OOT driver behaviour)
> 
> Fixes: ea2a1cfc3b201 ("i40e: Fix VF MAC filter removal")
> Signed-off-by: Jamie Bainbridge <jamie.bainbridge@gmail.com>
> ---
> v2: Reword commit message as suggested by Simon Horman.

Thanks for the update.

Reviewed-by: Simon Horman <horms@kernel.org>