diff options
| author | H. Peter Anvin <hpa@linux.intel.com> | 2009-01-21 15:04:32 -0800 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-01-22 09:24:02 +0100 |
| commit | 066941bd4eeb159307a5d7d795100d0887c00442 (patch) | |
| tree | 2bd4dfc033f72cbe0b3532140f54df1869dd6180 /arch | |
| parent | bdf21a49bab28f0d9613e8d8724ef9c9168b61b9 (diff) | |
x86: unmask CPUID levels on Intel CPUs
Impact: Fixes crashes with misconfigured BIOSes on XSAVE hardware
Avuton Olrich reported early boot crashes with v2.6.28 and
bisected it down to dc1e35c6e95e8923cf1d3510438b63c600fee1e2
("x86, xsave: enable xsave/xrstor on cpus with xsave support").
If the CPUID limit bit in MSR_IA32_MISC_ENABLE is set, clear it to
make all CPUID information available. This is required for some
features to work, in particular XSAVE.
Reported-and-bisected-by: Avuton Olrich <avuton@gmail.com>
Tested-by: Avuton Olrich <avuton@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kernel/cpu/intel.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index 8ea6929e974..43c1dcf0bec 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -29,6 +29,16 @@ 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); + } + if ((c->x86 == 0xf && c->x86_model >= 0x03) || (c->x86 == 0x6 && c->x86_model >= 0x0e)) set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC); |