I ran into this last night, installing/using the latest version of Bootcamp - the time shown during Windows setup was incorrect. However after installing Windows and the Mac drivers, and setting the clock to use a timeserver (but NOT first adjusting it manually; this seemed to be important), it fixed itself.
I actually did the Windows install twice (hey I had my reasons...). The first time I manually fixed the incorrect time during setup, but that caused the time to screw up once I booted into OS X. The second time through I didn't fix the time, set the clock to use the timeserver again, etc. - and the time was then correct in both Windows and OS X.
I don't know much about EFI, but if this were BIOS-based I'd suspect that the computer internal clock's time zone was set to Shanghai time, and it's that offset that's causing the problem.