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authorIngo Molnar <mingo@elte.hu>2009-01-26 04:30:41 +0100
committerIngo Molnar <mingo@elte.hu>2009-01-26 12:36:24 +0100
commit99fb4d349db7e7dacb2099c5cc320a9e2d31c1ef (patch)
tree62d62cb8f17962e9318177240c6154a4ca708077
parentef5fa0ab24b87646c7bc98645acbb4b51fc2acd4 (diff)
x86: unmask CPUID levels on Intel CPUs, fix
Impact: fix boot hang on pre-model-15 Intel CPUs rdmsrl_safe() does not work in very early bootup code yet, because we dont have the pagefault handler installed yet so exception section does not get parsed. rdmsr_safe() will just crash and hang the bootup. So limit the MSR_IA32_MISC_ENABLE MSR read to those CPU types that support it. Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--arch/x86/kernel/cpu/intel.c19
1 files changed, 11 insertions, 8 deletions
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 43c1dcf0bec..549f2ada55f 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -29,14 +29,17 @@
static void __cpuinit early_init_intel(struct cpuinfo_x86 *c)
{
- u64 misc_enable;
-
- /* Unmask CPUID levels if masked */
- if (!rdmsrl_safe(MSR_IA32_MISC_ENABLE, &misc_enable) &&
- (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);
+ /* Unmask CPUID levels if masked: */
+ if (c->x86 == 6 && c->x86_model >= 15) {
+ 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) ||