ice: Implement FCS/CRC and VLAN stripping co-existence policy

Make sure that only the valid combinations of FCS/CRC stripping and
VLAN stripping offloads are allowed.

You cannot have FCS/CRC stripping disabled while VLAN stripping is
enabled - this breaks the correctness of the FCS/CRC.

If administrator tries to enable VLAN stripping when FCS/CRC stripping is
disabled, the request should be rejected.

If administrator tries to disable FCS/CRC stripping when VLAN stripping
is enabled, the request should be rejected if VLANs are configured. If
there is no VLAN configured, then both FCS/CRC and VLAN stripping should
be disabled.

Testing Hints:
The default settings after driver load are:
- VLAN C-Tag offloads are enabled
- VLAN S-Tag offloads are disabled
- FCS/CRC stripping is enabled

Restore the default settings before each test with the command:
ethtool -K eth0 rx-fcs off rxvlan on txvlan on rx-vlan-stag-hw-parse off
tx-vlan-stag-hw-insert off

Test 1:
Disable FCS/CRC and VLAN stripping:
ethtool -K eth0 rx-fcs on rxvlan off
Try to enable VLAN stripping:
ethtool -K eth0 rxvlan on

Expected: VLAN stripping request is rejected

Test 2:
Try to disable FCS/CRC stripping:
ethtool -K eth0 rx-fcs on

Expected: VLAN stripping is also disabled, as there are no VLAN
configured

Test 3:
Add a VLAN:
ip link add link eth0 eth0.42 type vlan id 42
ip link set eth0 up
Try to disable FCS/CRC stripping:
ethtool -K eth0 rx-fcs on

Expected: FCS/CRC stripping request is rejected

Signed-off-by: Anatolii Gerasymenko <anatolii.gerasymenko@intel.com>
Tested-by: Gurucharan <gurucharanx.g@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/ice/ice_main.c

@@ -5722,6 +5722,9 @@ ice_fdb_del(struct ndmsg *ndm, __always_unused struct nlattr *tb[],
 					 NETIF_F_HW_VLAN_STAG_RX | \
 					 NETIF_F_HW_VLAN_STAG_TX)
 
+#define NETIF_VLAN_STRIPPING_FEATURES	(NETIF_F_HW_VLAN_CTAG_RX | \
+					 NETIF_F_HW_VLAN_STAG_RX)
+
 #define NETIF_VLAN_FILTERING_FEATURES	(NETIF_F_HW_VLAN_CTAG_FILTER | \
 					 NETIF_F_HW_VLAN_STAG_FILTER)
 
@@ -5808,6 +5811,14 @@ ice_fix_features(struct net_device *netdev, netdev_features_t features)
 			      NETIF_F_HW_VLAN_STAG_TX);
 	}
 
+	if (!(netdev->features & NETIF_F_RXFCS) &&
+	    (features & NETIF_F_RXFCS) &&
+	    (features & NETIF_VLAN_STRIPPING_FEATURES) &&
+	    !ice_vsi_has_non_zero_vlans(np->vsi)) {
+		netdev_warn(netdev, "Disabling VLAN stripping as FCS/CRC stripping is also disabled and there is no VLAN configured\n");
+		features &= ~NETIF_VLAN_STRIPPING_FEATURES;
+	}
+
 	return features;
 }
 
@@ -5901,6 +5912,13 @@ ice_set_vlan_features(struct net_device *netdev, netdev_features_t features)
 	current_vlan_features = netdev->features & NETIF_VLAN_OFFLOAD_FEATURES;
 	requested_vlan_features = features & NETIF_VLAN_OFFLOAD_FEATURES;
 	if (current_vlan_features ^ requested_vlan_features) {
+		if ((features & NETIF_F_RXFCS) &&
+		    (features & NETIF_VLAN_STRIPPING_FEATURES)) {
+			dev_err(ice_pf_to_dev(vsi->back),
+				"To enable VLAN stripping, you must first enable FCS/CRC stripping\n");
+			return -EIO;
+		}
+
 		err = ice_set_vlan_offload_features(vsi, features);
 		if (err)
 			return err;
@@ -5986,6 +6004,13 @@ ice_set_features(struct net_device *netdev, netdev_features_t features)
 	 * flag the packet data will have the 4 byte CRC appended
 	 */
 	if (changed & NETIF_F_RXFCS) {
+		if ((features & NETIF_F_RXFCS) &&
+		    (features & NETIF_VLAN_STRIPPING_FEATURES)) {
+			dev_err(ice_pf_to_dev(vsi->back),
+				"To disable FCS/CRC stripping, you must first disable VLAN stripping\n");
+			return -EIO;
+		}
+
 		ice_vsi_cfg_crc_strip(vsi, !!(features & NETIF_F_RXFCS));
 		ret = ice_down_up(vsi);
 		if (ret)