I have a flight booked from Nanjing to Beijing and then fly to Amsterdam.

The flight from Nanjing is operated by China Eastern Airlines and the flight to Amsterdam is a KLM Royal Dutch Airline flight (but it is operated by China Southern Airlines).

Do I have to leave the "security checked area" of Terminla 2 to check in at KLM for the connection flight to Amsterdam?
Where is the KLM checkin at Terminal 2?

Thank you very much