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authorAndreas Herrmann <herrmann.der.user@googlemail.com>2010-04-27 12:13:48 +0200
committerH. Peter Anvin <hpa@linux.intel.com>2010-05-13 16:21:20 -0700
commitf01487119dda3d9f58c9729c7361ecc50a61c188 (patch)
treebbd1d01429950207716337fbbd9e9f356560258c /arch
parentb0c4d952a158a6a2547672cf4fc9d55e415410de (diff)
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>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/process.c12
1 files changed, 7 insertions, 5 deletions
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 28ad9f4d8b9..0415c3ef91b 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -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;
}