linux-kernel - Re: [PATCH v2 3/10] KVM: MMU: fix direct sp's access corruptted

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Message-ID: <4C287332.5080803@cn.fujitsu.com>
Date:	Mon, 28 Jun 2010 18:02:26 +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 v2 3/10] KVM: MMU: fix direct sp's access corruptted



Avi Kivity wrote:

> 
> Instead of adding a new bit, can you encode the protection in the direct
> sp's access bits?  So we'll have one sp for read-only or
> writeable-but-not-dirty small pages, and another sp for
> writeable-and-dirty small pages.
> 

It looks like it can't solve all problems, it fix the access corrupted,
but will cause D bit losed:

mapping A and mapping B both are writable-and-dirty, when mapping A write
#PF occurs, the mapping is writable, then we can't set B's D bit anymore.

Anyway, i think we should re-intall the mapping when the state is changed. :-(
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