Re: [Qemu-devel] [PATCH 1/2] target-i386: fix cpuid leaf 0x0d

[Paolo Bonzini]

Il 02/12/2013 17:41, Liu, Jinsong ha scritto:
> From 57751d87392d7ee9df5698bc83b356de654453ef Mon Sep 17 00:00:00 2001
> From: Liu Jinsong <address@hidden>
> Date: Tue, 3 Dec 2013 04:17:50 +0800
> Subject: [PATCH 1/2] target-i386: fix cpuid leaf 0x0d
> 
> Fix cpuid leaf 0x0d which incorrectly parsed eax and ebx.
> However, before this patch the CPUID worked fine -- the
> sum of offset and size is same.

Not because of that.  It worked because the .offset field contained the
size _and_ was stored in the register that is supposed to hold the size
(eax), and likewise the .size field contained the offset _and_ was
stored in the register trhat is supposed to hold the offset (ebx).

Paolo

> Signed-off-by: Liu Jinsong <address@hidden>
> ---
>  target-i386/cpu.c |    6 +++---
>  1 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> index 864c80e..544b57f 100644
> --- a/target-i386/cpu.c
> +++ b/target-i386/cpu.c
> @@ -335,7 +335,7 @@ typedef struct ExtSaveArea {
>  
>  static const ExtSaveArea ext_save_areas[] = {
>      [2] = { .feature = FEAT_1_ECX, .bits = CPUID_EXT_AVX,
> -            .offset = 0x100, .size = 0x240 },
> +            .offset = 0x240, .size = 0x100 },
>  };
>  
>  const char *get_register_name_32(unsigned int reg)
> @@ -2225,8 +2225,8 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, 
> uint32_t count,
>              const ExtSaveArea *esa = &ext_save_areas[count];
>              if ((env->features[esa->feature] & esa->bits) == esa->bits &&
>                  (kvm_mask & (1 << count)) != 0) {
> -                *eax = esa->offset;
> -                *ebx = esa->size;
> +                *eax = esa->size;
> +                *ebx = esa->offset;
>              }
>          }
>          break;
>