releases/4.7.7/x86-boot-initialize-fpu-and-x86_feature_always-even-if-we-don-t-have-cpuid.patch

   1 From 05fb3c199bb09f5b85de56cc3ede194ac95c5e1f Mon Sep 17 00:00:00 2001
   2 From: Andy Lutomirski <luto@kernel.org>
   3 Date: Wed, 28 Sep 2016 16:06:33 -0700
   4 Subject: x86/boot: Initialize FPU and X86_FEATURE_ALWAYS even if we don't have CPUID
   5
   6 From: Andy Lutomirski <luto@kernel.org>
   7
   8 commit 05fb3c199bb09f5b85de56cc3ede194ac95c5e1f upstream.
   9
  10 Otherwise arch_task_struct_size == 0 and we die.  While we're at it,
  11 set X86_FEATURE_ALWAYS, too.
  12
  13 Reported-by: David Saggiorato <david@saggiorato.net>
  14 Tested-by: David Saggiorato <david@saggiorato.net>
  15 Signed-off-by: Andy Lutomirski <luto@kernel.org>
  16 Cc: Borislav Petkov <bp@alien8.de>
  17 Cc: Brian Gerst <brgerst@gmail.com>
  18 Cc: Dave Hansen <dave@sr71.net>
  19 Cc: Denys Vlasenko <dvlasenk@redhat.com>
  20 Cc: H. Peter Anvin <hpa@zytor.com>
  21 Cc: Josh Poimboeuf <jpoimboe@redhat.com>
  22 Cc: Linus Torvalds <torvalds@linux-foundation.org>
  23 Cc: Peter Zijlstra <peterz@infradead.org>
  24 Cc: Thomas Gleixner <tglx@linutronix.de>
  25 Fixes: aaeb5c01c5b ("x86/fpu, sched: Introduce CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT and use it on x86")
  26 Link: http://lkml.kernel.org/r/8de723afbf0811071185039f9088733188b606c9.1475103911.git.luto@kernel.org
  27 Signed-off-by: Ingo Molnar <mingo@kernel.org>
  28 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  29
  30 ---
  31  arch/x86/kernel/cpu/common.c |   29 ++++++++++++++---------------
  32  1 file changed, 14 insertions(+), 15 deletions(-)
  33
  34 --- a/arch/x86/kernel/cpu/common.c
  35 +++ b/arch/x86/kernel/cpu/common.c
  36 @@ -804,21 +804,20 @@ static void __init early_identify_cpu(st
  37                 identify_cpu_without_cpuid(c);
  38
  39         /* cyrix could have cpuid enabled via c_identify()*/
  40 -       if (!have_cpuid_p())
  41 -               return;
  42 -
  43 -       cpu_detect(c);
  44 -       get_cpu_vendor(c);
  45 -       get_cpu_cap(c);
  46 -
  47 -       if (this_cpu->c_early_init)
  48 -               this_cpu->c_early_init(c);
  49 -
  50 -       c->cpu_index = 0;
  51 -       filter_cpuid_features(c, false);
  52 -
  53 -       if (this_cpu->c_bsp_init)
  54 -               this_cpu->c_bsp_init(c);
  55 +       if (have_cpuid_p()) {
  56 +               cpu_detect(c);
  57 +               get_cpu_vendor(c);
  58 +               get_cpu_cap(c);
  59 +
  60 +               if (this_cpu->c_early_init)
  61 +                       this_cpu->c_early_init(c);
  62 +
  63 +               c->cpu_index = 0;
  64 +               filter_cpuid_features(c, false);
  65 +
  66 +               if (this_cpu->c_bsp_init)
  67 +                       this_cpu->c_bsp_init(c);
  68 +       }
  69
  70         setup_force_cpu_cap(X86_FEATURE_ALWAYS);
  71         fpu__init_system(c);