"When Roy Keane says he wants you, it's a massive compliment," the Northern Ireland international told the Sunderland Echo.
"If he wanted to make this move permanent, it's something I would want to talk about.
"Playing in the Premier League in games that matter is what it's all about, and what I want to be doing for a few years to come.
"But nothing has been said at all by Sunderland or Manchester United about anything beyond this season.
"I am really enjoying playing a full part in Sunderland's season," he added.
"Sometimes it seems a bit unreal that I am back at Sunderland. It didn't look like it was going to happen when the gaffer (Keane) asked the question early in the season and United wanted me there.
"But it's great to be playing and testing myself in Premier League games, and it's something I want a lot more of.
"United is the club I support and to have the chance to make it there is still a great opportunity that no player surrenders easily.
"But if I was ever going to leave Manchester United, Sunderland would definitely be an option for me - if they want me."