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| author |   Ingo Molnar <mingo@elte.hu> | 2009-01-26 04:30:41 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-01-26 12:36:24 +0100 |
| commit | 99fb4d349db7e7dacb2099c5cc320a9e2d31c1ef (patch) | |
| tree | 62d62cb8f17962e9318177240c6154a4ca708077 /arch/x86/kernel/cpu/intel.c | |
| parent | x86: work around PAGE_KERNEL_WC not getting WC in iomap_atomic_prot_pfn. (diff) | |
| download | linux-dev-99fb4d349db7e7dacb2099c5cc320a9e2d31c1ef.tar.xz linux-dev-99fb4d349db7e7dacb2099c5cc320a9e2d31c1ef.zip | |
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>
Diffstat (limited to '')
| -rw-r--r-- | arch/x86/kernel/cpu/intel.c | 19 |
1 files changed, 11 insertions, 8 deletions
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index 43c1dcf0bec7..549f2ada55f5 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) || |