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Re: [Qemu-devel] [PATCH] target-i386: set model=6 on qemu64 & qemu32 CPU
From: |
Igor Mammedov |
Subject: |
Re: [Qemu-devel] [PATCH] target-i386: set model=6 on qemu64 & qemu32 CPU models |
Date: |
Wed, 11 Sep 2013 10:22:23 +0200 |
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>