From 066941bd4eeb159307a5d7d795100d0887c00442 Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Wed, 21 Jan 2009 15:04:32 -0800 Subject: 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 Tested-by: Avuton Olrich Signed-off-by: H. Peter Anvin --- arch/x86/kernel/cpu/intel.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'arch/x86/kernel/cpu/intel.c') diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index 8ea6929e974c..43c1dcf0bec7 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); -- cgit From 99fb4d349db7e7dacb2099c5cc320a9e2d31c1ef Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Mon, 26 Jan 2009 04:30:41 +0100 Subject: 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 --- arch/x86/kernel/cpu/intel.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) (limited to 'arch/x86/kernel/cpu/intel.c') 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) || -- cgit From 30a0fb947a68ad3ab8a7184e3b3d79dce10e3688 Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Mon, 26 Jan 2009 09:40:58 -0800 Subject: x86: correct the CPUID pattern for MSR_IA32_MISC_ENABLE availability Impact: re-enable CPUID unmasking on affected processors As far as I am capable of discerning from the documentation, MSR_IA32_MISC_ENABLE should be available for all family 0xf CPUs, as well as family 6 for model >= 0xd (newer Pentium M). The documentation on this isn't ideal, so we need to be on the lookout for errors, still. Signed-off-by: H. Peter Anvin --- arch/x86/kernel/cpu/intel.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86/kernel/cpu/intel.c') diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index 549f2ada55f5..430e5c38a544 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -30,7 +30,7 @@ static void __cpuinit early_init_intel(struct cpuinfo_x86 *c) { /* Unmask CPUID levels if masked: */ - if (c->x86 == 6 && c->x86_model >= 15) { + if (c->x86 > 6 || (c->x86 == 6 && c->x86_model >= 0xd)) { u64 misc_enable; rdmsrl(MSR_IA32_MISC_ENABLE, misc_enable); -- cgit