Re: [Qemu-devel] [PATCH] target-i386: set model=6 on qemu64 & qemu32 CPU models

[Igor Mammedov]

On Tue, 10 Sep 2013 17:48:59 -0300
Eduardo Habkost <address@hidden> wrote:

> There's no Intel CPU with family=6,model=2, and Linux and Windows guests
> disable SEP when seeing that combination due to Pentium Pro erratum #82.
> 
> In addition to just having SEP ignored by guests, Skype (and maybe other
> applications) runs sysenter directly without passing through ntdll on
> Windows, and crashes because Windows ignored the SEP CPUID bit.
> 
> So, having model > 2 is a better default on qemu64 and qemu32 for two
> reasons: making SEP really available for guests, and avoiding crashing
> applications that work on bare metal.
> 
> model=3 would fix the problem, but it causes CPU enumeration problems
> for Windows guests[1]. So this patch sets model=6, that matches "Athlon
> (PM core)" on AMD and "P2 with on-die L2 cache" on Intel and it allows
> Windows to use all CPUs as well as fixing sysenter.
> 
> [1] https://bugzilla.redhat.com/show_bug.cgi?id=508623
> 
> Cc: Andrea Arcangeli <address@hidden>
> Signed-off-by: Eduardo Habkost <address@hidden>
> ---
>  include/hw/i386/pc.h | 8 ++++++++
>  target-i386/cpu.c    | 4 ++--
>  2 files changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> index 7fb04d8..195e962 100644
> --- a/include/hw/i386/pc.h
> +++ b/include/hw/i386/pc.h
> @@ -258,6 +258,14 @@ int e820_add_entry(uint64_t, uint64_t, uint32_t);
>              .driver = TYPE_X86_CPU,\
>              .property = "pmu",\
>              .value = "on",\
> +        },{\
> +            .driver   = "qemu64-" TYPE_X86_CPU,\
> +            .property = "model",\
> +            .value    = stringify(2),\
> +        },{\
> +            .driver   = "qemu32-" TYPE_X86_CPU,\
> +            .property = "model",\
> +            .value    = stringify(3),\
>          }
>  
>  #define PC_COMPAT_1_4 \
> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> index c36345e..36cfbce 100644
> --- a/target-i386/cpu.c
> +++ b/target-i386/cpu.c
> @@ -544,7 +544,7 @@ static x86_def_t builtin_x86_defs[] = {
>          .level = 4,
>          .vendor = CPUID_VENDOR_AMD,
>          .family = 6,
> -        .model = 2,
> +        .model = 6,
>          .stepping = 3,
>          .features[FEAT_1_EDX] =
>              PPRO_FEATURES |
> @@ -647,7 +647,7 @@ static x86_def_t builtin_x86_defs[] = {
>          .level = 4,
>          .vendor = CPUID_VENDOR_INTEL,
>          .family = 6,
> -        .model = 3,
> +        .model = 6,
>          .stepping = 3,
>          .features[FEAT_1_EDX] =
>              PPRO_FEATURES,

Reviewed-By: Igor Mammedov <address@hidden>