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Re: [Qemu-devel] [PATCH] target-i386: set model=6 on qemu64 & qemu32 CPU
From: |
Andreas Färber |
Subject: |
Re: [Qemu-devel] [PATCH] target-i386: set model=6 on qemu64 & qemu32 CPU models |
Date: |
Wed, 11 Sep 2013 23:53:46 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130801 Thunderbird/17.0.8 |
Am 11.09.2013 10:37, schrieb Igor Mammedov:
> On Wed, 11 Sep 2013 10:25:58 +0200
> Andreas Färber <address@hidden> wrote:
>
>> Am 11.09.2013 10:22, schrieb 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 \
>>
>> Shouldn't this hunk be in PC_COMPAT_1_6 rather than alongside PMU, which
>> I believe was for 1_5?
> grr, you are right.
> my reviewed-by stands, provided compats are moved to PC_COMPAT_1_6.
Fixed now that Stefan's net-next pull has been merged. Thanks, applied
to qom-cpu:
https://github.com/afaerber/qemu-cpu/commits/qom-cpu
Andreas
>
>
>> Andreas
>>
>>>> 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>
>>>
>>
>>
>
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