Re: [Xen-devel] [Patch] cpu synchronization while doing MTRR register update

[Tim Deegan <Tim.Deegan@xxxxxxxxxx>]

Hi, 

At 19:26 +0100 on 04 Aug (1249413981), Nitin A Kamble wrote:
> Processors starting with westmere are caching VMCS data for better VMX
> performance. These processors also has Hyper-threading support. With
> hyper-threading, when one thread's cache is disabled, it also disables
> cache for the sibling threads. And MTRR register updating procedure
> involves cache disabling. So if cpus are not synchronized, updating MTRR
> registers on a thread, results in the VMCS data from sibling threads
> becoming inaccessible, and it causes system failure.

What's the observed failure here?  Hang/crash on resume from S3?  Or
something more common?

Cheers,

Tim.

-- 
Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, Citrix Systems (R&D) Ltd.
[Company #02300071, SL9 0DZ, UK.]

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