Does my mortgage interest deduction need to be limited?

I have two loans, one for my main home that originated prior to Dec 2017 (~680K), I have another loan for a second home (not a rental)  (~500K) that originated after Dec 2017. So I should be able to claim all the interest on my first loan since it's below 1 million. My second loan is subject to the 750K limit, but I'm not clear if you look at each loan separately or if you need to look at the combined balance and prorate some of the interest ?