macvlan: Add function to test for destination filtering support

This patch adds a function indicating if a given macvlan can fully supports
destination filtering, especially as it relates to unicast traffic. For
those macvlan interfaces that do not support destination filtering such
passthru or source mode filtering we should not be enabling offload
support.
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

include/linux/if_macvlan.h

@@ -88,4 +88,13 @@ static inline void *macvlan_accel_priv(struct net_device *dev)
 
 	return macvlan->accel_priv;
 }
+
+static inline bool macvlan_supports_dest_filter(struct net_device *dev)
+{
+	struct macvlan_dev *macvlan = netdev_priv(dev);
+
+	return macvlan->mode == MACVLAN_MODE_PRIVATE ||
+	       macvlan->mode == MACVLAN_MODE_VEPA ||
+	       macvlan->mode == MACVLAN_MODE_BRIDGE;
+}
 #endif /* _LINUX_IF_MACVLAN_H */