From mboxrd@z Thu Jan  1 00:00:00 1970
From: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Subject: Re: [PATCH v2 8/10] KVM: MMU: prefetch ptes when intercepted guest
 #PF
Date: Wed, 30 Jun 2010 08:58:22 +0800
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References: <4C2498EC.2010006@cn.fujitsu.com> <4C249BEA.1030908@cn.fujitsu.com> <20100628130431.GA6209@amt.cnet> <4C29A9CC.2080508@cn.fujitsu.com> <20100629114446.GB26369@amt.cnet>
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Cc: Avi Kivity <avi@redhat.com>, LKML <linux-kernel@vger.kernel.org>,
	KVM list <kvm@vger.kernel.org>
To: Marcelo Tosatti <mtosatti@redhat.com>
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Marcelo Tosatti wrote:

>>> Also prefetch should be disabled for EPT, due to lack of accessed bit.
>>>
>> But we call mmu_set_spte() with speculative == false, it not touch the accessed bit.
> 
> There is no accessed bit on EPT. So the aging code (kvm_age_rmapp)
> considers any present translation as accessed. There is no way to
> distinguish between actually accessed translations and prefetched (but
> unused) ones.
> 

You are right, i'll disable the prefetch for EPT in the next version, thanks for
you point it out.