Hi,
For the LX25 you have 4 I/O banks. Each bank has its own power supply, which is the VCCO pins. If you will connect the pins of bank 0 for example to 3.3 V devices then you should supply bank 0 VCCO_0 pins using a 3.3 V supply.
I think you should learn to check the datasheet of your device and if you can't find something there then ask the forums.
Are you willing to simply rely on a reply posted in a forum?
And what if it is not correct, would you jeopardize damaging your device?
Don't worry about my abality to read a datasheet.
I marked it solved because I received an other response from Xilinx itself. You can choose io bank power supply from 1.2, 1.8, 2.5 or 3.3V depending on your peripherals.