From mboxrd@z Thu Jan  1 00:00:00 1970
From: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Subject: Re: [PATCH 3/6] KVM MMU: optimize/cleanup for marking parent unsync
Date: Wed, 14 Apr 2010 11:58:35 +0800
Message-ID: <4BC53D6B.6020501@cn.fujitsu.com>
References: <4BC2D2E2.1030604@cn.fujitsu.com> <4BC2D390.7050708@cn.fujitsu.com> <20100412171211.GC4976@amt.cnet> <4BC3CE83.8020705@cn.fujitsu.com> <20100413150137.GB24128@amt.cnet> <4BC5353A.30509@cn.fujitsu.com>
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Cc: Avi Kivity <avi@redhat.com>, KVM list <kvm@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>
To: Marcelo Tosatti <mtosatti@redhat.com>
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Xiao Guangrong wrote:
> 
> Actually, the origin code has a bug, the code segment in mmu_parent_walk():
> 
> |	if (!sp->multimapped && sp->parent_pte) {
> |		......
> |		return;
> |	}
> |	hlist_for_each_entry(pte_chain, node, &sp->parent_ptes, link)
> |		for (i = 0; i < NR_PTE_CHAIN_ENTRIES; ++i) {
> |			......
> |		}
> 
> So, if sp->parent_pte == NULL, it's unsafe...

Marcelo, please ignore this, it not a bug, just my mistake, sorry...