Charlie Sheen -- Makeout Sesh with Hardcore Porn Star ... Signs Point to Dating

Seems Charlie Sheen has a brand new girlfriend ... 'cause the Warlock was open-mouth kissing a hardcore porn star over Thanksgiving weekend ... and it looks like it was more than just a hookup.

The porn star on the receiving end is 24-year-old Brett Rossi -- star of such flicks as "She Loves My Big Breasts 2" and "Bondage Tongue Bath."

The two were spotted swapping spit in Cabo a few days ago. We're told they met in L.A. last month and Charlie took her to Mexico to celebrate Thanksgiving with a few other friends.

Rossi's the classy kind of porn star too -- as far as we can tell, she doesn't really do hardcore male-female sex scenes ... mostly just solo and girl-girl stuff with the likes of Twistys and Penthouse.

As for the other women in Charlie's life -- you know, the three "Angels" he's dating -- we're told Charlie's still with them, too.

The more, the merrier.