Commit f0148711 authored Apr 27, 2010 by Andreas Herrmann Committed by H. Peter Anvin May 13, 2010

x86, amd: Check X86_FEATURE_OSVW bit before accessing OSVW MSRs



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>

parent b0c4d952

arch/x86/kernel/process.c

+7 −5

Original line number	Diff line number	Diff line
		@@ -546,12 +546,14 @@ static int __cpuinit check_c1e_idle(const struct cpuinfo_x86 *c)
		* check OSVW bit for CPUs that are not affected
		* by erratum #400
		*/
		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;
		}