From 74c3e3fcf350b2e7e3eaf9550528ee3f74e44b37 Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Fri, 19 Apr 2013 16:36:03 -0700 Subject: [PATCH] x86, microcode: Verify the family before dispatching microcode patching For each CPU vendor that implements CPU microcode patching, there will be a minimum family for which this is implemented. Verify this minimum level of support. This can be done in the dispatch function or early in the application functions. Doing the latter turned out to be somewhat awkward because of the ineviable split between the BSP and the AP paths, and rather than pushing deep into the application functions, do this in the dispatch function. Reported-by: "Bryan O'Donoghue" Suggested-by: Borislav Petkov Cc: Fenghua Yu Link: http://lkml.kernel.org/r/1366392183-4149-1-git-send-email-bryan.odonoghue.lkml@nexus-software.ie --- arch/x86/kernel/microcode_core_early.c | 38 +++++++++++++++++++++++++++------- 1 file changed, 31 insertions(+), 7 deletions(-) diff --git a/arch/x86/kernel/microcode_core_early.c b/arch/x86/kernel/microcode_core_early.c index 577db84..833d51d 100644 --- a/arch/x86/kernel/microcode_core_early.c +++ b/arch/x86/kernel/microcode_core_early.c @@ -45,9 +45,6 @@ static int __cpuinit x86_vendor(void) u32 eax = 0x00000000; u32 ebx, ecx = 0, edx; - if (!have_cpuid_p()) - return X86_VENDOR_UNKNOWN; - native_cpuid(&eax, &ebx, &ecx, &edx); if (CPUID_IS(CPUID_INTEL1, CPUID_INTEL2, CPUID_INTEL3, ebx, ecx, edx)) @@ -59,18 +56,45 @@ static int __cpuinit x86_vendor(void) return X86_VENDOR_UNKNOWN; } +static int __cpuinit x86_family(void) +{ + u32 eax = 0x00000001; + u32 ebx, ecx = 0, edx; + int x86; + + native_cpuid(&eax, &ebx, &ecx, &edx); + + x86 = (eax >> 8) & 0xf; + if (x86 == 15) + x86 += (eax >> 20) & 0xff; + + return x86; +} + void __init load_ucode_bsp(void) { - int vendor = x86_vendor(); + int vendor, x86; + + if (!have_cpuid_p()) + return; - if (vendor == X86_VENDOR_INTEL) + vendor = x86_vendor(); + x86 = x86_family(); + + if (vendor == X86_VENDOR_INTEL && x86 >= 6) load_ucode_intel_bsp(); } void __cpuinit load_ucode_ap(void) { - int vendor = x86_vendor(); + int vendor, x86; + + if (!have_cpuid_p()) + return; + + vendor = x86_vendor(); + x86 = x86_family(); - if (vendor == X86_VENDOR_INTEL) + if (vendor == X86_VENDOR_INTEL && x86 >= 6) load_ucode_intel_ap(); } -- 2.7.4