RE: [Intel-wired-lan] [PATCH v2 net] i40e: When removing VF MAC filters, only check PF-set MAC

[Romanowski, Rafal]

> -----Original Message-----
> From: Intel-wired-lan <intel-wired-lan-bounces@xxxxxxxxxx> On Behalf Of Simon
> Horman
> Sent: Wednesday, June 25, 2025 11:08 AM
> To: Jamie Bainbridge <jamie.bainbridge@xxxxxxxxx>
> Cc: Vecera, Ivan <ivecera@xxxxxxxxxx>; Brett Creeley
> <brett.creeley@xxxxxxx>; Kitszel, Przemyslaw <przemyslaw.kitszel@xxxxxxxxx>;
> linux-kernel@xxxxxxxxxxxxxxx; Andrew Lunn <andrew+netdev@xxxxxxx>; Eric
> Dumazet <edumazet@xxxxxxxxxx>; netdev@xxxxxxxxxxxxxxx; Nguyen, Anthony L
> <anthony.l.nguyen@xxxxxxxxx>; intel-wired-lan@xxxxxxxxxxxxxxxx; Jakub Kicinski
> <kuba@xxxxxxxxxx>; Paolo Abeni <pabeni@xxxxxxxxxx>; David S. Miller
> <davem@xxxxxxxxxxxxx>
> Subject: Re: [Intel-wired-lan] [PATCH v2 net] i40e: When removing VF MAC
> filters, only check PF-set MAC
> 
> 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@xxxxxxxxx>
> > ---
> > v2: Reword commit message as suggested by Simon Horman.
> 
> Thanks for the update.
> 
> Reviewed-by: Simon Horman <horms@xxxxxxxxxx>


Tested-by: Rafal Romanowski <rafal.romanowski@xxxxxxxxx>