From: Marcelo Tosatti <mtosatti@redhat.com>
To: Avi Kivity <avi@redhat.com>
Cc: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>,
LKML <linux-kernel@vger.kernel.org>, KVM <kvm@vger.kernel.org>
Subject: Re: [PATCH v3 05/11] KVM: MMU: do not mark accessed bit on pte write path
Date: Thu, 15 Sep 2011 10:11:13 -0300 [thread overview]
Message-ID: <20110915131113.GA6933@amt.cnet> (raw)
In-Reply-To: <4E7079FD.6050506@redhat.com>
On Wed, Sep 14, 2011 at 12:55:09PM +0300, Avi Kivity wrote:
> On 09/13/2011 09:29 PM, Xiao Guangrong wrote:
> >On 09/13/2011 06:53 PM, Avi Kivity wrote:
> >> On 08/30/2011 05:35 AM, Xiao Guangrong wrote:
> >>> In current code, the accessed bit is always set when page fault occurred,
> >>> do not need to set it on pte write path
> >>
> >> What about speculative sptes that are then only accessed via emulation?
> >>
> >
> >The gfn is read and written only via emulation? I think this case is very
> >very rare?
>
> Probably...
The access information will be transferred via the host pte, via
get_user_pages, to MM layer, in that case.
> Marcelo? Can you think of another case where spte.accessed is needed?
No, an spte updated via emulation will either be accessed directly, or
if via emulation, access to the gfn it points transferred via host pte.
next prev parent reply other threads:[~2011-09-15 13:11 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-30 2:34 [PATCH v3 01/11] KVM: MMU: avoid pte_list_desc running out in kvm_mmu_pte_write Xiao Guangrong
2011-08-30 2:34 ` [PATCH v3 02/11] KVM: x86: tag the instructions which are used to write page table Xiao Guangrong
2011-08-30 2:35 ` [PATCH v3 03/11] KVM: x86: retry non-page-table writing instruction Xiao Guangrong
2011-09-13 10:47 ` Avi Kivity
2011-09-13 18:24 ` Xiao Guangrong
2011-09-14 9:53 ` Avi Kivity
2011-09-14 10:19 ` Xiao Guangrong
2011-09-15 4:56 ` Xiao Guangrong
2011-08-30 2:35 ` [PATCH v3 04/11] KVM: x86: cleanup port-in/port-out emulated Xiao Guangrong
2011-08-30 2:35 ` [PATCH v3 05/11] KVM: MMU: do not mark accessed bit on pte write path Xiao Guangrong
2011-09-13 10:53 ` Avi Kivity
2011-09-13 18:29 ` Xiao Guangrong
2011-09-14 9:55 ` Avi Kivity
2011-09-15 13:11 ` Marcelo Tosatti [this message]
2011-08-30 2:36 ` [PATCH v3 06/11] KVM: MMU: cleanup FNAME(invlpg) Xiao Guangrong
2011-09-13 11:00 ` Avi Kivity
2011-09-13 18:31 ` Xiao Guangrong
2011-09-14 9:57 ` Avi Kivity
2011-08-30 2:36 ` [PATCH v3 07/11] KVM: MMU: fast prefetch spte on invlpg path Xiao Guangrong
2011-08-30 2:37 ` [PATCH v3 08/11] KVM: MMU: remove unnecessary kvm_mmu_free_some_pages Xiao Guangrong
2011-08-30 2:37 ` [PATCH v3 09/11] KVM: MMU: split kvm_mmu_pte_write function Xiao Guangrong
2011-08-30 2:37 ` [PATCH v3 10/11] KVM: MMU: fix detecting misaligned accessed Xiao Guangrong
2011-08-30 2:38 ` [PATCH v3 11/11] KVM: MMU: improve write flooding detected Xiao Guangrong
2011-09-13 11:07 ` Avi Kivity
2011-09-13 19:19 ` Xiao Guangrong
2011-09-14 9:59 ` Avi Kivity
2011-09-13 9:51 ` [PATCH v3 01/11] KVM: MMU: avoid pte_list_desc running out in kvm_mmu_pte_write Avi Kivity
2011-09-13 10:24 ` Xiao Guangrong
2011-09-13 10:50 ` Avi Kivity
2011-09-13 19:31 ` Xiao Guangrong
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