x86: unmask CPUID levels on Intel CPUs

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Impact: Fixes crashes with misconfigured BIOSes on XSAVE hardware

Avuton Olrich reported early boot crashes with v2.6.28 and
bisected it down to dc1e35c6e9
("x86, xsave: enable xsave/xrstor on cpus with xsave support").

If the CPUID limit bit in MSR_IA32_MISC_ENABLE is set, clear it to
make all CPUID information available.  This is required for some
features to work, in particular XSAVE.

Reported-and-bisected-by: Avuton Olrich <avuton@gmail.com>
Tested-by: Avuton Olrich <avuton@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

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This commit is contained in:

H. Peter Anvin 2009-01-21 15:04:32 -08:00 • committed by Ingo Molnar

parent bdf21a49ba

commit 066941bd4e

1 changed files with 10 additions and 0 deletions

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arch/x86/kernel/cpu/intel.c

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