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x86, amd: Check X86_FEATURE_OSVW bit before accessing OSVW MSRs

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If host CPU is exposed to a guest the OSVW MSRs are not guaranteed
to be present and a GP fault occurs. Thus checking the feature flag is
essential.

Cc: <stable@kernel.org> # .32.x .33.x
Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
LKML-Reference: <20100427101348.GC4489@alberich.amd.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
Andreas Herrmann 2010-04-27 12:13:48 +02:00 committed by H. Peter Anvin
parent b0c4d952a1
commit f01487119d
1 changed files with 7 additions and 5 deletions
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12
arch/x86/kernel/process.c
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@ -546,11 +546,13 @@ static int __cpuinit check_c1e_idle(const struct cpuinfo_x86 *c)
* check OSVW bit for CPUs that are not affected
* by erratum #400
*/
rdmsrl(MSR_AMD64_OSVW_ID_LENGTH, val);
if (val >= 2) {
rdmsrl(MSR_AMD64_OSVW_STATUS, val);
if (!(val & BIT(1)))
goto no_c1e_idle;
if (cpu_has(c, X86_FEATURE_OSVW)) {
rdmsrl(MSR_AMD64_OSVW_ID_LENGTH, val);
if (val >= 2) {
rdmsrl(MSR_AMD64_OSVW_STATUS, val);
if (!(val & BIT(1)))
goto no_c1e_idle;
}
}
return 1;
}