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RE: [Xen-devel] [PATCH][UPDATE]Provide fast write emulation path

To: "Tim Deegan" <Tim.Deegan@xxxxxxxxxx>, "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx>
Subject: RE: [Xen-devel] [PATCH][UPDATE]Provide fast write emulation path
From: "Tian, Kevin" <kevin.tian@xxxxxxxxx>
Date: Fri, 15 Feb 2008 20:21:19 +0800
Cc: "Xu, Dongxiao" <dongxiao.xu@xxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx
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Thread-topic: [Xen-devel] [PATCH][UPDATE]Provide fast write emulation path
>From: Tim Deegan [mailto:Tim.Deegan@xxxxxxxxxx] 
>Sent: 2008年2月15日 19:36
>
>At 10:01 +0000 on 15 Feb (1203069706), Keir Fraser wrote:
>> I'd like a final ack from Tim on this one before applying.
>
>Ack.  
>
>I read through again and the only thing I can see is a risk that on SMP
>guests, a foreign vcpu might change the guest pagetable under our feet,
>leading to a risk of using inconsistent mappings for reads and writes.
>I think that's OK, though, because
> - we already have similar exposure from vTLB &c, and will do from OOS;
> - a guest with good TLB flush discipline should be entirely safe.
>

Yep. This is actually same as physical cpu behavior, as long as
inconsistent mappings are not stamped into shadow page table.

Thanks for comments,
Kevin

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