linux-kernel - Re: [PATCH v4 5/6] KVM: MMU: combine guest pte read between walk and pte prefetch

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Date:	Mon, 05 Jul 2010 17:31:48 +0800
From:	Xiao Guangrong <xiaoguangrong@...fujitsu.com>
To:	Avi Kivity <avi@...hat.com>
CC:	Marcelo Tosatti <mtosatti@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	KVM list <kvm@...r.kernel.org>
Subject: Re: [PATCH v4 5/6] KVM: MMU: combine guest pte read between walk
 and pte prefetch



Avi Kivity wrote:

> 
> Note: I think we have to check _after_ kvm_mmu_get_page(), otherwise we
> might be checking a page that is not write-protected and can change again.
> 
> So the logic needs to be something like
> 
> for_each_shadow_entry:
>     if (!last_level && !present(*spte))
>         kvm_mmu_get_page
>     verify gpte
>     if (last_level)
>         mmu_set_spte()
> 

Agree! Will do it.
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