igbvf: Regard vf reset nack as success

vf reset nack actually represents the reset operation itself is
performed but no address is assigned. Therefore, e1000_reset_hw_vf
should fill the "perm_addr" with the zero address and return success on
such an occasion. This prevents its callers in netdev.c from saying PF
still resetting, and instead allows them to correctly report that no
address is assigned.

Fixes: 6ddbc4cf ("igb: Indicate failure on vf reset for empty mac address")
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Tested-by: Marek Szlosek <marek.szlosek@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/igbvf/vf.c

 // SPDX-License-Identifier: GPL-2.0
 /* Copyright(c) 2009 - 2018 Intel Corporation. */
 
+#include <linux/etherdevice.h>
+
 #include "vf.h"
 
 static s32 e1000_check_for_link_vf(struct e1000_hw *hw);
@@ -131,11 +133,16 @@ static s32 e1000_reset_hw_vf(struct e1000_hw *hw)
 		/* set our "perm_addr" based on info provided by PF */
 		ret_val = mbx->ops.read_posted(hw, msgbuf, 3);
 		if (!ret_val) {
-			if (msgbuf[0] == (E1000_VF_RESET |
-					  E1000_VT_MSGTYPE_ACK))
+			switch (msgbuf[0]) {
+			case E1000_VF_RESET | E1000_VT_MSGTYPE_ACK:
 				memcpy(hw->mac.perm_addr, addr, ETH_ALEN);
-			else
+				break;
+			case E1000_VF_RESET | E1000_VT_MSGTYPE_NACK:
+				eth_zero_addr(hw->mac.perm_addr);
+				break;
+			default:
 				ret_val = -E1000_ERR_MAC_INIT;
+			}
 		}
 	}