ice: Implement ethtool hook for RSS switch

This patch implements ethtool hook for enabling/disabling
RSS. While disabling RSS, the LUT should be cleared. And
the LUT should be reconfigured while enabling RSS.

Signed-off-by: Md Fahad Iqbal Polash <md.fahad.iqbal.polash@intel.com>
Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

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

@@ -1222,6 +1222,38 @@ static void ice_vsi_map_rings_to_vectors(struct ice_vsi *vsi)
 	}
 }
 
+/**
+ * ice_vsi_manage_rss_lut - disable/enable RSS
+ * @vsi: the VSI being changed
+ * @ena: boolean value indicating if this is an enable or disable request
+ *
+ * In the event of disable request for RSS, this function will zero out RSS
+ * LUT, while in the event of enable request for RSS, it will reconfigure RSS
+ * LUT.
+ */
+int ice_vsi_manage_rss_lut(struct ice_vsi *vsi, bool ena)
+{
+	int err = 0;
+	u8 *lut;
+
+	lut = devm_kzalloc(&vsi->back->pdev->dev, vsi->rss_table_size,
+			   GFP_KERNEL);
+	if (!lut)
+		return -ENOMEM;
+
+	if (ena) {
+		if (vsi->rss_lut_user)
+			memcpy(lut, vsi->rss_lut_user, vsi->rss_table_size);
+		else
+			ice_fill_rss_lut(lut, vsi->rss_table_size,
+					 vsi->rss_size);
+	}
+
+	err = ice_set_rss(vsi, NULL, lut, vsi->rss_table_size);
+	devm_kfree(&vsi->back->pdev->dev, lut);
+	return err;
+}
+
 /**
  * ice_vsi_cfg_rss_lut_key - Configure RSS params for a VSI
  * @vsi: VSI to be configured

drivers/net/ethernet/intel/ice/ice_lib.h

@@ -70,5 +70,7 @@ void ice_vsi_free_tx_rings(struct ice_vsi *vsi);
 
 int ice_vsi_cfg_tc(struct ice_vsi *vsi, u8 ena_tc);
 
+int ice_vsi_manage_rss_lut(struct ice_vsi *vsi, bool ena);
+
 irqreturn_t ice_msix_clean_rings(int __always_unused irq, void *data);
 #endif /* !_ICE_LIB_H_ */

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

@@ -2412,6 +2412,12 @@ static int ice_set_features(struct net_device *netdev,
 	struct ice_vsi *vsi = np->vsi;
 	int ret = 0;
 
+	if (features & NETIF_F_RXHASH && !(netdev->features & NETIF_F_RXHASH))
+		ret = ice_vsi_manage_rss_lut(vsi, true);
+	else if (!(features & NETIF_F_RXHASH) &&
+		 netdev->features & NETIF_F_RXHASH)
+		ret = ice_vsi_manage_rss_lut(vsi, false);
+
 	if ((features & NETIF_F_HW_VLAN_CTAG_RX) &&
 	    !(netdev->features & NETIF_F_HW_VLAN_CTAG_RX))
 		ret = ice_vsi_manage_vlan_stripping(vsi, true);