tree 849514b44863461c542872173221c3f365a0e6a7
parent 75a048119e76540d73132cfc8e0fa0c0a8bb6c83
author H. Peter Anvin <hpa@linux.intel.com> 1232760050 -0800
committer H. Peter Anvin <hpa@linux.intel.com> 1232762885 -0800

x86: filter CPU features dependent on unavailable CPUID levels

Impact: Fixes potential crashes on misconfigured systems.

Some CPU features require specific CPUID levels to be available in
order to function, as they contain information about the operation of
a specific feature.  However, some BIOSes and virtualization software
provide the ability to mask CPUID levels in order to support legacy
operating systems.  We try to enable such CPUID levels when we know
how to do it, but for the remaining cases, filter out such CPU
features when there is no way for us to support them.

Do this in one place, in the CPUID code, with a table-driven approach.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>