From: Gleb Natapov <gleb@redhat.com>
To: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Cc: Avi Kivity <avi@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
LKML <linux-kernel@vger.kernel.org>, KVM <kvm@vger.kernel.org>
Subject: Re: [PATCH v3 2/3] KVM: MMU: fix accessed bit set on prefault path
Date: Tue, 30 Nov 2010 19:50:05 +0200 [thread overview]
Message-ID: <20101130175005.GA2924@redhat.com> (raw)
In-Reply-To: <4CF52BC6.9020401@cn.fujitsu.com>
On Wed, Dec 01, 2010 at 12:52:22AM +0800, Xiao Guangrong wrote:
> On 11/30/2010 09:29 PM, Gleb Natapov wrote:
>
> >> + if (!shadow_accessed_mask)
> >> + return;
> >> +
> > I don't get this. As far as I can see VMX inits shadow_accessed_mask to
> > be zero if ept is enabled. This line here means that we never prefault with ept
> > enabled. It is opposite from what it should be.
> >
>
> Since it's no accessed bit on EPT, it's no way to distinguish between actually
> accessed translations and prefault.
Why is this a problem? We do what this page to not be evicted again
since we expect it to be accessed.
--
Gleb.
next prev parent reply other threads:[~2010-11-30 17:50 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-30 9:34 [PATCH v3 1/3] KVM: MMU: rename 'no_apf' to 'prefault' Xiao Guangrong
2010-11-30 9:36 ` [PATCH v3 2/3] KVM: MMU: fix accessed bit set on prefault path Xiao Guangrong
2010-11-30 13:29 ` Gleb Natapov
2010-11-30 16:52 ` Xiao Guangrong
2010-11-30 17:50 ` Gleb Natapov [this message]
2010-11-30 18:15 ` Xiao Guangrong
2010-11-30 18:38 ` Gleb Natapov
2010-11-30 19:11 ` Xiao Guangrong
2010-11-30 19:20 ` Gleb Natapov
2010-12-01 2:20 ` Xiao Guangrong
2010-12-01 20:42 ` Marcelo Tosatti
2010-11-30 9:37 ` [PATCH v3 3/3] KVM: MMU: retry #PF for softmmu Xiao Guangrong
2010-12-02 1:19 ` Marcelo Tosatti
2010-12-02 3:44 ` Xiao Guangrong
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