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>

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;
         }