RE01 maximum input voltage for IO pins

Hi, 

I have a RE01 controller in my design, where voltage supply to the VCC, IOVCC, IOVCC0 & IOVCC3 is 1.8V, and voltage at the MD pin and UART pins will be around 3.1V from the external hardware. Is it safe to provide 3.1V to these pins or I can provide maximum 2.1V?

From the RE01 - hardware design guide (section 6.1), I read the input voltage (guessing it’s for all IO pins) is "-0.3 to VCC+0.3 (max 4.6 V)". Does that mean I can provide maximum 2.1V(for my case)at I/O pins or it means I can provide up to 4.6V? 

Thank you.