nb/via/vx900: Ensure framebuffer size is within limits

- Use log2() when rounding down size_mb to the closest power of 2.
  Do a sanity check beforehand that size_mb is nonzero, else log2()
  will return -1 and there will be an undefined integer shift.
- The framebuffer size needs to be between 8 and 512 MiB, so check
  after all the calculations are done to make sure this is the case.

Change-Id: I3962e5cdc094c8da22d8dbadf16637e02fa98689
Signed-off-by: Jacob Garber <jgarber1@ualberta.ca>
Found-by: Coverity CID 1391086
Reviewed-on: https://review.coreboot.org/c/coreboot/+/34355
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>

0 files changed, 0 insertions, 0 deletions