From: Ian Campbell <ian.campbell@citrix.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: Wei.Liu2@citrix.com, Tim Deegan <tim@xen.org>,
Ian Jackson <ian.jackson@eu.citrix.com>,
Julien Grall <julien.grall@citrix.com>,
stefano.stabellini@citrix.com, xen-devel@lists.xenproject.org,
Keir Fraser <keir@xen.org>
Subject: Re: [PATCH for-4.6] xen/mm: populate_physmap: validate correctly the gfn for direct mapped domain
Date: Thu, 13 Aug 2015 11:41:43 +0100 [thread overview]
Message-ID: <1439462503.23981.81.camel@citrix.com> (raw)
In-Reply-To: <55CC8DC5020000780009A9D6@prv-mh.provo.novell.com>
On Thu, 2015-08-13 at 04:29 -0600, Jan Beulich wrote:
> >
> > > > On 13.08.15 at 12:14, <ian.campbell@citrix.com> wrote:
> > There isn't a race here is there? What if the reference were dropped
> > after
> > this check but before the guest_physmap_add_page (which takes new
> > references)? We are implicitly relying on a guarantee made elsewhere
> > that a
> > direct mapped guest never drops the final ref until it is destroyed
> > (which
> > can't be happening in this window I think), but it would be obviously
> > safer
> > against such bugs if we just held the ref until after the p2m was
> > updated.
>
> Yeah, we depend on this, and what you suggest would indeed be
> an improvment.
>
> > Another thing for a future/4.7 cleanup I guess.
>
> Right.
>
> But as bottom line I take it that your objections to the patch going in
> soon have been eliminated?
Correct.
Acked-by: Ian Campbell <ian.campbell@citrix.com>
prev parent reply other threads:[~2015-08-13 10:41 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-11 17:41 [PATCH for-4.6] xen/mm: populate_physmap: validate correctly the gfn for direct mapped domain Julien Grall
2015-08-12 9:16 ` Jan Beulich
2015-08-12 9:25 ` Julien Grall
2015-08-12 9:19 ` Wei Liu
2015-08-12 9:28 ` Wei Liu
2015-08-13 9:33 ` Ian Campbell
2015-08-13 9:54 ` Jan Beulich
2015-08-13 10:14 ` Ian Campbell
2015-08-13 10:29 ` Jan Beulich
2015-08-13 10:41 ` Ian Campbell [this message]
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