do I need a visa for cruise on celebrity millineum?

I am getting conflicting stories on whether I need a visa or not. I am flying into Shanghai and spending the night in motel. Then next day go to port in Shanghai and board cruise ship and have a day at sea and then visit South Korea. I then go to Tianjin, where I will be on excursions for Beijing . Do I need a visa or can I use the 144 hour visa free policy? I understand there is a problem with the fact I am visiting two Chinese ports.