From: Avi Kivity <avi@redhat.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>,
LKML <linux-kernel@vger.kernel.org>,
KVM list <kvm@vger.kernel.org>
Subject: Re: [PATCH v4 5/6] KVM: MMU: combine guest pte read between walk and pte prefetch
Date: Sat, 03 Jul 2010 14:48:35 +0300 [thread overview]
Message-ID: <4C2F2393.9050301@redhat.com> (raw)
In-Reply-To: <20100702170303.GC25969@amt.cnet>
On 07/02/2010 08:03 PM, Marcelo Tosatti wrote:
> On Thu, Jul 01, 2010 at 09:55:56PM +0800, Xiao Guangrong wrote:
>
>> Combine guest pte read between guest pte walk and pte prefetch
>>
>> Signed-off-by: Xiao Guangrong<xiaoguangrong@cn.fujitsu.com>
>> ---
>> arch/x86/kvm/paging_tmpl.h | 48 ++++++++++++++++++++++++++++++-------------
>> 1 files changed, 33 insertions(+), 15 deletions(-)
>>
> Can't do this, it can miss invlpg:
>
> vcpu0 vcpu1
> read guest ptes
> modify guest pte
> invlpg
> instantiate stale
> guest pte
>
> See how the pte is reread inside fetch with mmu_lock held.
>
Note, this is fine if the pte is unsync, since vcpu0 will soon invlpg
it. It's only broken for sync ptes.
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
next prev parent reply other threads:[~2010-07-03 11:48 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-01 13:53 [PATCH v4 1/6] KVM: MMU: introduce gfn_to_pfn_atomic() function Xiao Guangrong
2010-07-01 13:53 ` [PATCH v4 2/6] KVM: MMU: introduce gfn_to_page_many_atomic() function Xiao Guangrong
2010-07-01 13:54 ` [PATCH v4 3/6] KVM: MMU: introduce pte_prefetch_topup_memory_cache() Xiao Guangrong
2010-07-01 13:55 ` [PATCH v4 4/6] KVM: MMU: prefetch ptes when intercepted guest #PF Xiao Guangrong
2010-07-02 16:54 ` Marcelo Tosatti
2010-07-03 8:08 ` Xiao Guangrong
2010-07-05 12:01 ` Marcelo Tosatti
2010-07-06 0:50 ` Xiao Guangrong
2010-07-01 13:55 ` [PATCH v4 5/6] KVM: MMU: combine guest pte read between walk and pte prefetch Xiao Guangrong
2010-07-02 17:03 ` Marcelo Tosatti
2010-07-03 10:31 ` Xiao Guangrong
2010-07-03 12:08 ` Avi Kivity
2010-07-03 12:16 ` Xiao Guangrong
2010-07-03 12:26 ` Avi Kivity
2010-07-03 12:31 ` Xiao Guangrong
2010-07-03 12:44 ` Avi Kivity
2010-07-03 12:49 ` Avi Kivity
2010-07-03 13:03 ` Xiao Guangrong
2010-07-04 14:30 ` Avi Kivity
2010-07-05 2:52 ` Xiao Guangrong
2010-07-05 8:23 ` Avi Kivity
2010-07-05 8:45 ` Xiao Guangrong
2010-07-05 9:05 ` Avi Kivity
2010-07-05 9:09 ` Xiao Guangrong
2010-07-05 9:20 ` Avi Kivity
2010-07-05 9:31 ` Xiao Guangrong
2010-07-03 12:57 ` Xiao Guangrong
2010-07-04 14:32 ` Avi Kivity
2010-07-03 11:48 ` Avi Kivity [this message]
2010-07-01 13:56 ` [PATCH v4 6/6] KVM: MMU: trace " Xiao Guangrong
2010-07-02 16:47 ` [PATCH v4 1/6] KVM: MMU: introduce gfn_to_pfn_atomic() function Marcelo Tosatti
2010-07-03 3:13 ` Nick Piggin
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