diff options
| -rw-r--r-- | arch/x86/kernel/cpu/common.c | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 0f8656361e04..21f086b4c1a8 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -213,6 +213,49 @@ static inline void squash_the_stupid_serial_number(struct cpuinfo_x86 *c) #endif /* + * Some CPU features depend on higher CPUID levels, which may not always + * be available due to CPUID level capping or broken virtualization + * software. Add those features to this table to auto-disable them. + */ +struct cpuid_dependent_feature { + u32 feature; + u32 level; +}; +static const struct cpuid_dependent_feature __cpuinitconst +cpuid_dependent_features[] = { + { X86_FEATURE_MWAIT, 0x00000005 }, + { X86_FEATURE_DCA, 0x00000009 }, + { X86_FEATURE_XSAVE, 0x0000000d }, + { 0, 0 } +}; + +static void __cpuinit filter_cpuid_features(struct cpuinfo_x86 *c, bool warn) +{ + const struct cpuid_dependent_feature *df; + for (df = cpuid_dependent_features; df->feature; df++) { + /* + * Note: cpuid_level is set to -1 if unavailable, but + * extended_extended_level is set to 0 if unavailable + * and the legitimate extended levels are all negative + * when signed; hence the weird messing around with + * signs here... + */ + if (cpu_has(c, df->feature) && + ((s32)df->feature < 0 ? + (u32)df->feature > (u32)c->extended_cpuid_level : + (s32)df->feature > (s32)c->cpuid_level)) { + clear_cpu_cap(c, df->feature); + if (warn) + printk(KERN_WARNING + "CPU: CPU feature %s disabled " + "due to lack of CPUID level 0x%x\n", + x86_cap_flags[df->feature], + df->level); + } + } +} + +/* * Naming convention should be: <Name> [(<Codename>)] * This table only is used unless init_<vendor>() below doesn't set it; * in particular, if CPUID levels 0x80000002..4 are supported, this isn't used @@ -573,6 +616,7 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c) #ifdef CONFIG_SMP c->cpu_index = boot_cpu_id; #endif + filter_cpuid_features(c, false); } void __init early_cpu_init(void) @@ -706,6 +750,9 @@ static void __cpuinit identify_cpu(struct cpuinfo_x86 *c) * we do "generic changes." */ + /* Filter out anything that depends on CPUID levels we don't have */ + filter_cpuid_features(c, true); + /* If the model name is still unset, do table lookup. */ if (!c->x86_model_id[0]) { char *p; |