Re: [Intel-wired-lan] [PATCH iwl-next v4 6/6] ice: enable LLDP TX for VFs through tc

[Simon Horman <horms@kernel.org>]

On Fri, Feb 14, 2025 at 09:50:40AM +0100, Larysa Zaremba wrote:
> Only a single VSI can be in charge of sending LLDP frames, sometimes it is
> beneficial to assign this function to a VF, that is possible to do with tc
> capabilities in the switchdev mode. It requires first blocking the PF from
> sending the LLDP frames with a following command:
> 
> tc filter add dev <ifname> egress protocol lldp flower skip_sw action drop
> 
> Then it becomes possible to configure a forward rule from a VF port
> representor to uplink instead.
> 
> tc filter add dev <vf_ifname> ingress protocol lldp flower skip_sw
> action mirred egress redirect dev <ifname>
> 
> How LLDP exclusivity was done previously is LLDP traffic was blocked for a
> whole port by a single rule and PF was bypassing that. Now at least in the
> switchdev mode, every separate VSI has to have its own drop rule. Another
> complication is the fact that tc does not respect when the driver refuses
> to delete a rule, so returning an error results in a HW rule still present
> with no way to reference it through tc. This is addressed by allowing the
> PF rule to be deleted at any time, but making the VF forward rule "dormant"
> in such case, this means it is deleted from HW but stays in tc and driver's
> bookkeeping to be restored when drop rule is added back to the PF.
> 
> Implement tc configuration handling which enables the user to transmit LLDP
> packets from VF instead of PF.
> 
> Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
> Signed-off-by: Larysa Zaremba <larysa.zaremba@intel.com>

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