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RE: [Xen-devel] Re: [PATCH] Fix cpu hotplug bug of mtrr update inconsist

To: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] Re: [PATCH] Fix cpu hotplug bug of mtrr update inconsistency
From: "Liu, Jinsong" <jinsong.liu@xxxxxxxxx>
Date: Wed, 2 Jun 2010 13:30:12 +0800
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Thread-topic: [Xen-devel] Re: [PATCH] Fix cpu hotplug bug of mtrr update inconsistency
Keir Fraser wrote:
> On 01/06/2010 10:18, "Keir Fraser" <keir.fraser@xxxxxxxxxxxxx> wrote:
> 
>> I suggest we leave the call where it is, and fix set_mtrr() to not
>> race CPUs coming online. It is called elsewhere other than
>> mtrr_ap_init() after all. Also if you call mtrr_ap_init() before
>> being in cpu_online_map, you then race further MTRR changes: 
>>  - CPU X calls mtrr_ap_init()
>>  - CPU Y calls set_mtrr() to actually change an MTRR.
>>  - CPU X adds itself to cpu_online_map
>>  - Aiee, CPU X is missing Y's update
>> 
>> I'll make a patch.
> 
> xen-unstable:21499.
> 
>  -- Keir

Yeah, good method :)
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