From: Xiao Guangrong <xiaoguangrong.eric@gmail.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>,
Avi Kivity <avi@redhat.com>, LKML <linux-kernel@vger.kernel.org>,
KVM <kvm@vger.kernel.org>
Subject: Re: [PATCH v3 5/9] KVM: MMU: introduce SPTE_WRITE_PROTECT bit
Date: Sat, 21 Apr 2012 12:29:44 +0800 [thread overview]
Message-ID: <4F9237B8.9090503@gmail.com> (raw)
In-Reply-To: <20120421005555.GA16526@amt.cnet>
On 04/21/2012 08:55 AM, Marcelo Tosatti wrote:
>> So this is an example of implicit assumptions which break if you update
>> spte without mmu_lock. Certainly there are more cases. :(
>
> OK, i now see you mentioned a similar case in the document, for
> rmap_write_protect.
>
> More importantly than the particular flush TLB case, the point is
> every piece of code that reads and writes sptes must now be aware that
> mmu_lock alone does not guarantee stability. Everything must be audited.
>
Yes, that is true, but it is not hard to audit the code since we only
change the spte from read-only to writable, also all information that
fast page fault depends on is from spte.
next prev parent reply other threads:[~2012-04-21 4:29 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-20 8:16 [PATCH v3 0/9] KVM: MMU: fast page fault Xiao Guangrong
2012-04-20 8:17 ` [PATCH v3 1/9] KVM: MMU: return bool in __rmap_write_protect Xiao Guangrong
2012-04-20 8:17 ` [PATCH v3 2/9] KVM: MMU: abstract spte write-protect Xiao Guangrong
2012-04-20 21:33 ` Marcelo Tosatti
2012-04-21 1:10 ` Takuya Yoshikawa
2012-04-21 4:34 ` Xiao Guangrong
2012-04-21 3:24 ` Xiao Guangrong
2012-04-21 4:18 ` Marcelo Tosatti
2012-04-21 6:52 ` Xiao Guangrong
2012-04-20 8:18 ` [PATCH v3 3/9] KVM: VMX: export PFEC.P bit on ept Xiao Guangrong
2012-04-20 8:18 ` [PATCH v3 4/9] KVM: MMU: introduce SPTE_ALLOW_WRITE bit Xiao Guangrong
2012-04-20 21:39 ` Marcelo Tosatti
2012-04-21 3:30 ` Xiao Guangrong
2012-04-21 4:22 ` Marcelo Tosatti
2012-04-21 6:55 ` Xiao Guangrong
2012-04-22 15:12 ` Avi Kivity
2012-04-23 7:24 ` Xiao Guangrong
2012-04-20 8:19 ` [PATCH v3 5/9] KVM: MMU: introduce SPTE_WRITE_PROTECT bit Xiao Guangrong
2012-04-20 21:52 ` Marcelo Tosatti
2012-04-21 0:40 ` Marcelo Tosatti
2012-04-21 0:55 ` Marcelo Tosatti
2012-04-21 1:38 ` Takuya Yoshikawa
2012-04-21 4:29 ` Xiao Guangrong [this message]
2012-04-21 4:00 ` Xiao Guangrong
2012-04-24 0:45 ` Marcelo Tosatti
2012-04-24 3:34 ` Xiao Guangrong
2012-04-21 3:47 ` Xiao Guangrong
2012-04-21 4:38 ` Marcelo Tosatti
2012-04-21 7:25 ` Xiao Guangrong
2012-04-24 0:24 ` Marcelo Tosatti
2012-04-20 8:19 ` [PATCH v3 6/9] KVM: MMU: fast path of handling guest page fault Xiao Guangrong
2012-04-20 8:20 ` [PATCH v3 7/9] KVM: MMU: trace fast " Xiao Guangrong
2012-04-20 8:20 ` [PATCH v3 8/9] KVM: MMU: fix kvm_mmu_pagetable_walk tracepoint Xiao Guangrong
2012-04-20 8:21 ` [PATCH v3 9/9] KVM: MMU: document mmu-lock and fast page fault Xiao Guangrong
2012-04-21 0:59 ` [PATCH v3 0/9] KVM: MMU: " Marcelo Tosatti
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