igbvf: after mailbox write, wait for reply

Two of the VF mailbox commands were not waiting for a reply from the PF,
which can result in a VF mailbox timeout in the VM for the next command.
Signed-off-by: Greg Edwards <gedwards@ddn.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

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

@@ -230,6 +230,7 @@ static void e1000_update_mc_addr_list_vf(struct e1000_hw *hw,
 	u16 *hash_list = (u16 *)&msgbuf[1];
 	u32 hash_value;
 	u32 cnt, i;
+	s32 ret_val;
 
 	/* Each entry in the list uses 1 16 bit word.  We have 30
 	 * 16 bit words available in our HW msg buffer (minus 1 for the
@@ -250,7 +251,9 @@ static void e1000_update_mc_addr_list_vf(struct e1000_hw *hw,
 		mc_addr_list += ETH_ALEN;
 	}
 
-	mbx->ops.write_posted(hw, msgbuf, E1000_VFMAILBOX_SIZE);
+	ret_val = mbx->ops.write_posted(hw, msgbuf, E1000_VFMAILBOX_SIZE);
+	if (!ret_val)
+		mbx->ops.read_posted(hw, msgbuf, 1);
 }
 
 /**
@@ -293,11 +296,14 @@ void e1000_rlpml_set_vf(struct e1000_hw *hw, u16 max_size)
 {
 	struct e1000_mbx_info *mbx = &hw->mbx;
 	u32 msgbuf[2];
+	s32 ret_val;
 
 	msgbuf[0] = E1000_VF_SET_LPE;
 	msgbuf[1] = max_size;
 
-	mbx->ops.write_posted(hw, msgbuf, 2);
+	ret_val = mbx->ops.write_posted(hw, msgbuf, 2);
+	if (!ret_val)
+		mbx->ops.read_posted(hw, msgbuf, 1);
 }
 
 /**