[Intel-wired-lan] [PATCH iwl-net] ice: fix accounting for filters shared by multiple VSIs

[Romanowski, Rafal]

> -----Original Message-----
> From: Intel-wired-lan <intel-wired-lan-bounces at osuosl.org> On Behalf Of Jacob
> Keller
> Sent: Wednesday, July 31, 2024 6:56 PM
> To: Intel Wired LAN <intel-wired-lan at lists.osuosl.org>; Nguyen, Anthony L
> <anthony.l.nguyen at intel.com>
> Cc: Keller, Jacob E <jacob.e.keller at intel.com>
> Subject: [Intel-wired-lan] [PATCH iwl-net] ice: fix accounting for filters shared by
> multiple VSIs
> 
> When adding a switch filter (such as a MAC or VLAN filter), it is expected that the
> driver will detect the case where the filter already exists, and return -EEXIST. This
> is used by calling code such as ice_vc_add_mac_addr, and ice_vsi_add_vlan to
> avoid incrementing the accounting fields such as
> vsi->num_vlan or vf->num_mac.
> 
> This logic works correctly for the case where only a single VSI has added a given
> switch filter.
> 
> When a second VSI adds the same switch filter, the driver converts the existing
> filter from an ICE_FWD_TO_VSI filter into an ICE_FWD_TO_VSI_LIST filter. This
> saves switch resources, by ensuring that multiple VSIs can re-use the same filter.
> 
> The ice_add_update_vsi_list() function is responsible for doing this conversion.
> When first converting a filter from the FWD_TO_VSI into FWD_TO_VSI_LIST, it
> checks if the VSI being added is the same as the existing rule's VSI. In such a case
> it returns -EEXIST.
> 
> However, when the switch rule has already been converted to a
> FWD_TO_VSI_LIST, the logic is different. Adding a new VSI in this case just
> requires extending the VSI list entry. The logic for checking if the rule already
> exists in this case returns 0 instead of -EEXIST.
> 
> This breaks the accounting logic mentioned above, so the counters for how many
> MAC and VLAN filters exist for a given VF or VSI no longer accurately reflect the
> actual count. This breaks other code which relies on these counts.
> 
> In typical usage this primarily affects such filters generally shared by multiple VSIs
> such as VLAN 0, or broadcast and multicast MAC addresses.
> 
> Fix this by correctly reporting -EEXIST in the case of adding the same VSI to a
> switch rule already converted to ICE_FWD_TO_VSI_LIST.
> 
> Fixes: 9daf8208dd4d ("ice: Add support for switch filter programming")
> Signed-off-by: Jacob Keller <jacob.e.keller at intel.com>
> ---
> ---
>  drivers/net/ethernet/intel/ice/ice_switch.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/intel/ice/ice_switch.c
> b/drivers/net/ethernet/intel/ice/ice_switch.c
> index fe8847184cb1..0160f0bae8d6 100644
> --- a/drivers/net/ethernet/intel/ice/ice_switch.c
> +++ b/drivers/net/ethernet/intel/ice/ice_switch.c
> @@ -3194,7 +3194,7 @@ ice_add_update_vsi_list(struct ice_hw *hw,


Tested-by: Rafal Romanowski <rafal.romanowski at intel.com>