From f01487119dda3d9f58c9729c7361ecc50a61c188 Mon Sep 17 00:00:00 2001 From: Andreas Herrmann Date: Tue, 27 Apr 2010 12:13:48 +0200 Subject: [PATCH] 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: # .32.x .33.x Signed-off-by: Andreas Herrmann LKML-Reference: <20100427101348.GC4489@alberich.amd.com> Signed-off-by: H. Peter Anvin --- arch/x86/kernel/process.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 28ad9f4..0415c3e 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; } -- 2.7.4