Merge branches 'x86/asm', 'x86/cleanups', 'x86/cpudetect', 'x86/debug', 'x86/doc...

[safe/jmp/linux-2.6] / arch / x86 / kernel / cpu / intel.c

diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 8ea6929..5deefae 100644 (file)
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -29,6 +29,19 @@
 
 static void __cpuinit early_init_intel(struct cpuinfo_x86 *c)
 {
+       /* 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) {
+                       misc_enable &= ~MSR_IA32_MISC_ENABLE_LIMIT_CPUID;
+                       wrmsrl(MSR_IA32_MISC_ENABLE, misc_enable);
+                       c->cpuid_level = cpuid_eax(0);
+               }
+       }
+
        if ((c->x86 == 0xf && c->x86_model >= 0x03) ||
                (c->x86 == 0x6 && c->x86_model >= 0x0e))
                set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC);
@@ -50,6 +63,18 @@ static void __cpuinit early_init_intel(struct cpuinfo_x86 *c)
                set_cpu_cap(c, X86_FEATURE_NONSTOP_TSC);
        }
 
+       /*
+        * There is a known erratum on Pentium III and Core Solo
+        * and Core Duo CPUs.
+        * " Page with PAT set to WC while associated MTRR is UC
+        *   may consolidate to UC "
+        * Because of this erratum, it is better to stick with
+        * setting WC in MTRR rather than using PAT on these CPUs.
+        *
+        * Enable PAT WC only on P4, Core 2 or later CPUs.
+        */
+       if (c->x86 == 6 && c->x86_model < 15)
+               clear_cpu_cap(c, X86_FEATURE_PAT);
 }
 
 #ifdef CONFIG_X86_32