From 2cb078603abb612e3bcd428fb8122c3d39e08832 Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Wed, 22 Jul 2009 09:59:35 -0700 Subject: x86, amd: Don't probe for extended APIC ID if APICs are disabled If we've logically disabled apics, don't probe the PCI space for the AMD extended APIC ID. [ Impact: prevent boot crash under Xen. ] Signed-off-by: Jeremy Fitzhardinge Reported-by: Bastian Blank Signed-off-by: H. Peter Anvin --- arch/x86/kernel/cpu/amd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86/kernel/cpu/amd.c') diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index 28e5f5956042..e2485b03f1cf 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -356,7 +356,7 @@ static void __cpuinit early_init_amd(struct cpuinfo_x86 *c) #endif #if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_PCI) /* check CPU config space for extended APIC ID */ - if (c->x86 >= 0xf) { + if (cpu_has_apic && c->x86 >= 0xf) { unsigned int val; val = read_pci_config(0, 24, 0, 0x68); if ((val & ((1 << 17) | (1 << 18))) == ((1 << 17) | (1 << 18))) -- cgit v1.2.3 From fbd8b1819e80ac5a176d085fdddc3a34d1499318 Mon Sep 17 00:00:00 2001 From: Kevin Winchester Date: Mon, 10 Aug 2009 19:56:45 -0300 Subject: x86: Clear incorrectly forced X86_FEATURE_LAHF_LM flag Due to an erratum with certain AMD Athlon 64 processors, the BIOS may need to force enable the LAHF_LM capability. Unfortunately, in at least one case, the BIOS does this even for processors that do not support the functionality. Add a specific check that will clear the feature bit for processors known not to support the LAHF/SAHF instructions. Signed-off-by: Kevin Winchester Acked-by: Borislav Petkov LKML-Reference: <4A80A5AD.2000209@gmail.com> Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/amd.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'arch/x86/kernel/cpu/amd.c') diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index e2485b03f1cf..63fddcd082cd 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -400,6 +400,13 @@ static void __cpuinit init_amd(struct cpuinfo_x86 *c) level = cpuid_eax(1); if((level >= 0x0f48 && level < 0x0f50) || level >= 0x0f58) set_cpu_cap(c, X86_FEATURE_REP_GOOD); + + /* + * Some BIOSes incorrectly force this feature, but only K8 + * revision D (model = 0x14) and later actually support it. + */ + if (c->x86_model < 0x14) + clear_cpu_cap(c, X86_FEATURE_LAHF_LM); } if (c->x86 == 0x10 || c->x86 == 0x11) set_cpu_cap(c, X86_FEATURE_REP_GOOD); -- cgit v1.2.3