Smith is set to make $7.5 million in base salary this season and is entering the final year of his contract before he becomes an unrestricted free agent next season.
"I'd love to have it done," Smith said to the Kansas City Star. "I love Kansas City, I love the coaching staff, the players. ... But when you're talking about this many years and that type of deal, you want it done right. You want both sides happy, and you want it to be something that is going to last and you can play out. A lot of things go into it."
Smith completed 60.6 percent of his passes and set career-highs with 3,313 yards and 23 touchdowns in his first season in Kansas City.
He spent his first seven seasons with the San Francisco 49ers before he was traded in February 2013 for two draft picks.