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Re: [Xen-devel] [PATCH] Allow dom0 to write MSR IA32_ENERGY_PERF_BIAS

To: "Keir Fraser" <keir.fraser@xxxxxxxxxxxxx>, "Gang Wei" <gang.wei@xxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] Allow dom0 to write MSR IA32_ENERGY_PERF_BIAS
From: "Jan Beulich" <JBeulich@xxxxxxxxxx>
Date: Wed, 05 Jan 2011 08:17:15 +0000
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>>> On 05.01.11 at 09:13, Keir Fraser <keir.fraser@xxxxxxxxxxxxx> wrote:
> On 05/01/2011 07:59, "Jan Beulich" <JBeulich@xxxxxxxxxx> wrote:
> 
>>>> Why would you allow this only if Dom0 has its vcpus pinned?
>>> 
>>> It is meaningless if dom0 can't control all pcpus exactly. Only in case of
>>> dom0 vcpus pinned, it makes sense.
>> 
>> Disagree. The user mode tool could set its own affinity (virtual and
>> physical) and then issue the MSR write. Please don't enforce
>> restrictions where not really needed (I actually suppose that the
>> restriction should be removed for MSR_IA32_THERM_CONTROL too).
> 
> If so, it deserves a separate patch to strip out *all* the is_pinned checks
> at the same time.

You certainly don't mean *all*, but yes, I'm intending to submit such
a patch.

Jan


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