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authorFenghua Yu <fenghua.yu@intel.com>2011-05-17 15:29:11 -0700
committerH. Peter Anvin <hpa@linux.intel.com>2011-05-17 15:40:23 -0700
commit161ec53c702ce9df2f439804dfb9331807066daa (patch)
treefbaaea8612b8f5482a2fa7f8e826eea8b5baf57f /arch
parent724a92ee45c04cb9d82884a856b03b1e594d9de1 (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')
-rw-r--r--arch/x86/kernel/cpu/intel.c19
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