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From: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Avi Kivity <avi.kivity@gmail.com>, Gleb Natapov <gleb@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>, KVM <kvm@vger.kernel.org>
Subject: Re: [PATCH v2 03/12] KVM: MMU: simplify mmu_set_spte
Date: Tue, 29 Jan 2013 10:55:24 +0800	[thread overview]
Message-ID: <51073A1C.1050600@linux.vnet.ibm.com> (raw)
In-Reply-To: <20130129002151.GB10814@amt.cnet>

On 01/29/2013 08:21 AM, Marcelo Tosatti wrote:
> On Wed, Jan 23, 2013 at 06:05:29PM +0800, Xiao Guangrong wrote:
>> In order to detecting spte remapping, we can simply check whether the
>> spte has already been pointing to the pfn even if the spte is not the
>> last spte, for middle spte is pointing to the kernel pfn which can not
>> be mapped to userspace
> 
> This check is detecting spte overwrite, when a large spte is replaced by 
> pointer to spte table.
> 
> Can't see why check for different pfn is safe: only 'int level' can
> differ, and pfn be equivalent, for example.

The 'u64 *sptep' must on the "int level" we want to set, that means:
 page_header(__pa(sptep)).role.level == "int level".


We discussed this before :), the discussion can be found at:
http://marc.info/?l=kvm&m=135345057329427&w=2.


  reply	other threads:[~2013-01-29  2:55 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-01-23 10:04 [PATCH v2 01/12] KVM: MMU: lazily drop large spte Xiao Guangrong
2013-01-23 10:04 ` [PATCH v2 02/12] KVM: MMU: cleanup mapping-level Xiao Guangrong
2013-01-23 10:05 ` [PATCH v2 03/12] KVM: MMU: simplify mmu_set_spte Xiao Guangrong
2013-01-29  0:21   ` Marcelo Tosatti
2013-01-29  2:55     ` Xiao Guangrong [this message]
2013-01-29 21:53       ` Marcelo Tosatti
2013-01-30  3:22         ` Xiao Guangrong
2013-01-23 10:06 ` [PATCH v2 04/12] KVM: MMU: simplify set_spte Xiao Guangrong
2013-01-23 10:06 ` [PATCH v2 05/12] KVM: MMU: introduce vcpu_adjust_access Xiao Guangrong
2013-01-24 10:36   ` Gleb Natapov
2013-01-24 11:33     ` Xiao Guangrong
2013-01-23 10:07 ` [PATCH v2 06/12] KVM: MMU: introduce a static table to map guest access to spte access Xiao Guangrong
2013-01-25  0:15   ` Marcelo Tosatti
2013-01-25  2:46     ` Xiao Guangrong
2013-01-29  0:07       ` Marcelo Tosatti
2013-01-29  1:07         ` Marcelo Tosatti
2013-01-29 13:16           ` Gleb Natapov
2013-01-30  3:53           ` Xiao Guangrong
2013-01-23 10:07 ` [PATCH v2 07/12] KVM: MMU: remove pt_access in mmu_set_spte Xiao Guangrong
2013-01-23 10:08 ` [PATCH v2 08/12] KVM: MMU: cleanup __direct_map Xiao Guangrong
2013-01-23 10:09 ` [PATCH v2 09/12] KVM: MMU: introduce mmu_spte_establish Xiao Guangrong
2013-01-23 10:09 ` [PATCH v2 10/12] KVM: MMU: unify the code of walking pte list Xiao Guangrong
2013-01-27 13:28   ` Gleb Natapov
2013-01-29  3:01     ` Xiao Guangrong
2013-01-23 10:10 ` [PATCH v2 11/12] KVM: MMU: fix spte assertion Xiao Guangrong
2013-01-23 10:10 ` [PATCH v2 12/12] KVM: MMU: fast drop all spte on the pte_list Xiao Guangrong
2013-01-27 12:06 ` [PATCH v2 01/12] KVM: MMU: lazily drop large spte Gleb Natapov
2013-01-29  2:57   ` Xiao Guangrong

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