From mboxrd@z Thu Jan  1 00:00:00 1970
From: Gleb Natapov <gleb@redhat.com>
Subject: Re: [PATCH v3 07/15] KVM: MMU: introduce nulls desc
Date: Mon, 25 Nov 2013 12:19:43 +0200
Message-ID: <20131125101943.GS2108@redhat.com>
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Cc: Marcelo Tosatti <mtosatti@redhat.com>, avi.kivity@gmail.com,
	"pbonzini@redhat.com Bonzini" <pbonzini@redhat.com>,
	linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	Eric Dumazet <dada1@cosmosbay.com>,
	Peter Zijlstra <peterz@infradead.org>
To: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
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On Mon, Nov 25, 2013 at 02:11:31PM +0800, Xiao Guangrong wrote:
> >=20
> > For example, nothing prevents lockless walker to move into some
> > parent_ptes chain, right?
>=20
> No.
>=20
> The nulls can help us to detect this case, for parent_ptes, the nulls=
 points
> to "shadow page" but for rmaps, the nulls points to slot.arch.rmap. T=
here
> is no chance that the =93rmap" is used as shadow page when slot-lock =
is held.
>=20
But meanwhile we will write protect non-last level sptes, no? Better to
create separate slab caches for rmap and parent_ptes lists.

--
			Gleb.