Hello,
Only Symantec Endpoint Protection 12.1 RU2 supports both Windows 8 and Windows 2012.
Check this Article:
About Windows 8 and Symantec Endpoint Protection 12.1
http://www.symantec.com/docs/TECH174348
In case if you are thinking of Migration to Symantec Endpoint Protection 12.1 RU2, here is the Article:
Best practices for upgrading to Symantec Endpoint Protection 12.1.2
http://www.symantec.com/docs/TECH163700
Hope that helps!!