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xen-devel
[Xen-devel] Re: [PATCH] X86: cpuid faulting feature enable
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To: |
"Tian, Kevin" <kevin.tian@xxxxxxxxx>, "Liu, Jinsong" <jinsong.liu@xxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx> |
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Subject: |
[Xen-devel] Re: [PATCH] X86: cpuid faulting feature enable |
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From: |
Keir Fraser <keir.xen@xxxxxxxxx> |
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Date: |
Sat, 02 Jul 2011 08:49:57 +0100 |
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Cc: |
"Shan, Haitao" <haitao.shan@xxxxxxxxx>, "Li, Xin" <xin.li@xxxxxxxxx> |
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Sat, 02 Jul 2011 00:51:04 -0700 |
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[PATCH] X86: cpuid faulting feature enable |
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On 02/07/2011 04:15, "Tian, Kevin" <kevin.tian@xxxxxxxxx> wrote:
>> From: Keir Fraser [mailto:keir.xen@xxxxxxxxx] On Behalf Of Keir Fraser
>> Sent: Saturday, July 02, 2011 5:31 AM
>>
>> On 01/07/2011 15:32, "Liu, Jinsong" <jinsong.liu@xxxxxxxxx> wrote:
>>
>>> X86: cpuid faulting feature enable
>>>
>>> Latest Intel processor add cpuid faulting feature. This patch is used to
>>> support cpuid faulting in Xen.
>>> Like cpuid spoofing, cpuid faulting mainly used to support live migration.
>>> When cpl>0, cpuid instruction will produce GP, vmm then emulate execution
>> of
>>> the cpuid instruction. Hence will appear to guest software the value chosen
>> by
>>> the vmm.
>>
>> I fixed this up quite a bit and applied as c/s 23653. Please take a look and
>> give it a test. In particular note the changes I made in intel_init(), to
>> make sure that APs are at least as featureful as the BSP w.r.t. cpuid
>> faulting.
>>
>
> 2.42 + } else if (boot_cpu_has(X86_FEATURE_CPUID_FAULTING)) {
> 2.43 + BUG_ON(!probe_intel_cpuid_faulting());
> 2.44 + set_bit(X86_FEATURE_CPUID_FAULTING, c->x86_capability);
> 2.45 + }
> 2.46 +
> 2.47 + if (!cpu_has_cpuid_faulting)
> 2.48 + set_cpuidmask(c);
> 2.49 +
> 2.50 + BUG_ON(cpu_has(c, X86_FEATURE_CPUID_FAULTING) !=
> 2.51 + boot_cpu_has(X86_FEATURE_CPUID_FAULTING));
>
> the latter BUG_ON is useless since if AP is inconsistent with BSP we already
> get bug triggered in earlier BUG_ON.
Oops, I forgot to remove the redundant second BUG_ON. I'll do that now.
Thanks!
-- Keir
> Thanks
> Kevin
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