clarification about visa requirements

I am an American citizen living in Brazil. I will take a MSC Lirica cruise from Genova, Italy (leaving March 21) and arrive in Shanghai on April 26 at 19 h; we leave the next day at 16 h for Japan. The cruise then returns to Shanghai on May 1 at 5 am, and I will fly out of Shanghai on Turkish Airlines, hopefully the same day. What are my entry permit requirements? Thank you