i40evf: Fix turning TSO, GSO and GRO on after

This patch fixes the problem where each MTU change turns TSO,
GSO and GRO on from off state.

Now when TSO, GSO or GRO is turned off, MTU change does not
turn them on.
Signed-off-by: NPaweł Jabłoński <pawel.jablonski@intel.com>
Tested-by: NAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/i40evf/i40evf_main.c

@@ -3357,6 +3357,24 @@ int i40evf_process_config(struct i40evf_adapter *adapter)
 	if (vfres->vf_cap_flags & VIRTCHNL_VF_OFFLOAD_VLAN)
 		netdev->features |= NETIF_F_HW_VLAN_CTAG_FILTER;
 
+	/* Do not turn on offloads when they are requested to be turned off.
+	 * TSO needs minimum 576 bytes to work correctly.
+	 */
+	if (netdev->wanted_features) {
+		if (!(netdev->wanted_features & NETIF_F_TSO) ||
+		    netdev->mtu < 576)
+			netdev->features &= ~NETIF_F_TSO;
+		if (!(netdev->wanted_features & NETIF_F_TSO6) ||
+		    netdev->mtu < 576)
+			netdev->features &= ~NETIF_F_TSO6;
+		if (!(netdev->wanted_features & NETIF_F_TSO_ECN))
+			netdev->features &= ~NETIF_F_TSO_ECN;
+		if (!(netdev->wanted_features & NETIF_F_GRO))
+			netdev->features &= ~NETIF_F_GRO;
+		if (!(netdev->wanted_features & NETIF_F_GSO))
+			netdev->features &= ~NETIF_F_GSO;
+	}
+
 	adapter->vsi.id = adapter->vsi_res->vsi_id;
 
 	adapter->vsi.back = adapter;