linux-kernel - Re: [PATCH v3 07/15] KVM: MMU: introduce nulls desc

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20131125181254.GB21858@amt.cnet>
Date:	Mon, 25 Nov 2013 16:12:54 -0200
From:	Marcelo Tosatti <mtosatti@...hat.com>
To:	Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>
Cc:	Gleb Natapov <gleb@...hat.com>, avi.kivity@...il.com,
	"pbonzini@...hat.com Bonzini" <pbonzini@...hat.com>,
	linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
	Eric Dumazet <dada1@...mosbay.com>,
	Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH v3 07/15] KVM: MMU: introduce nulls desc

On Mon, Nov 25, 2013 at 02:29:03PM +0800, Xiao Guangrong wrote:
> >> Also, there is no guarantee of termination (as long as sptes are
> >> deleted with the correct timing). BTW, can't see any guarantee of
> >> termination for rculist nulls either (a writer can race with a lockless
> >> reader indefinately, restarting the lockless walk every time).
> > 
> > Hmm, that can be avoided by checking dirty-bitmap before rewalk,
> > that means, if the dirty-bitmap has been set during lockless write-protection,
> > it�s unnecessary to write-protect its sptes. Your idea?
> This idea is based on the fact that the number of rmap is limited by
> RMAP_RECYCLE_THRESHOLD. So, in the case of adding new spte into rmap,
> we can break the rewalk at once, in the case of deleting, we can only
> rewalk RMAP_RECYCLE_THRESHOLD times.

Please explain in more detail.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/