diff options
| author | Fenghua Yu <fenghua.yu@intel.com> | 2011-05-17 15:29:11 -0700 |
|---|---|---|
| committer | H. Peter Anvin <hpa@linux.intel.com> | 2011-05-17 15:40:23 -0700 |
| commit | 161ec53c702ce9df2f439804dfb9331807066daa (patch) | |
| tree | fbaaea8612b8f5482a2fa7f8e826eea8b5baf57f /arch/x86/kernel/cpu | |
| parent | 724a92ee45c04cb9d82884a856b03b1e594d9de1 (diff) | |
x86, mem, intel: Initialize Enhanced REP MOVSB/STOSB
If kernel intends to use enhanced REP MOVSB/STOSB, it must ensure
IA32_MISC_ENABLE.Fast_String_Enable (bit 0) is set and CPUID.(EAX=07H, ECX=0H):
EBX[bit 9] also reports 1.
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Link: http://lkml.kernel.org/r/1305671358-14478-3-git-send-email-fenghua.yu@intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/kernel/cpu')
| -rw-r--r-- | arch/x86/kernel/cpu/intel.c | 19 |
1 files changed, 15 insertions, 4 deletions
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index df86bc8c859..fc73a34ba8c 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -29,10 +29,10 @@ static void __cpuinit early_init_intel(struct cpuinfo_x86 *c) { + u64 misc_enable; + /* Unmask CPUID levels if masked: */ if (c->x86 > 6 || (c->x86 == 6 && c->x86_model >= 0xd)) { - u64 misc_enable; - rdmsrl(MSR_IA32_MISC_ENABLE, misc_enable); if (misc_enable & MSR_IA32_MISC_ENABLE_LIMIT_CPUID) { @@ -118,8 +118,6 @@ static void __cpuinit early_init_intel(struct cpuinfo_x86 *c) * (model 2) with the same problem. */ if (c->x86 == 15) { - u64 misc_enable; - rdmsrl(MSR_IA32_MISC_ENABLE, misc_enable); if (misc_enable & MSR_IA32_MISC_ENABLE_FAST_STRING) { @@ -130,6 +128,19 @@ static void __cpuinit early_init_intel(struct cpuinfo_x86 *c) } } #endif + + /* + * If fast string is not enabled in IA32_MISC_ENABLE for any reason, + * clear the fast string and enhanced fast string CPU capabilities. + */ + if (c->x86 > 6 || (c->x86 == 6 && c->x86_model >= 0xd)) { + rdmsrl(MSR_IA32_MISC_ENABLE, misc_enable); + if (!(misc_enable & MSR_IA32_MISC_ENABLE_FAST_STRING)) { + printk(KERN_INFO "Disabled fast string operations\n"); + setup_clear_cpu_cap(X86_FEATURE_REP_GOOD); + setup_clear_cpu_cap(X86_FEATURE_ERMS); + } + } } #ifdef CONFIG_X86_32 |