[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] [PATCH V2] arch: arm: vgic-v3: fix GICD_ISACTIVER range


  • To: Jürgen Groß <jgross@xxxxxxxx>, Julien Grall <julien@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>
  • From: Peng Fan <peng.fan@xxxxxxx>
  • Date: Wed, 27 Nov 2019 09:49:00 +0000
  • Accept-language: en-US
  • Arc-authentication-results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=nxp.com; dmarc=pass action=none header.from=nxp.com; dkim=pass header.d=nxp.com; arc=none
  • Arc-message-signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=FmVx3a5O792DRwHRoov2NQIWP/YqWv7yOGO3OFQjol0=; b=PPwWJdvq1wicjgojt629vhZ8YbTDSrChM9jDNch6DKbBqNo+btqM65uSLWXm/7bBMGMK6o/XJFSlUVuYHxKU0ton18DO4EOWWrxRHiKfu23Ow5GMIYJPMGXrtGF3iHZQUBf1GRxioAAUBQf+JYGQhZb08dNHO8tRdsO2J0hikyjbPBWkr9JemL651OUu4/UwA9awy6RQYSUDaVx3Df54fo5pkM00j77+jSVI6MWEimqw58QgePmRAvapVB5Z1FJFzHBH4vXLVtaov6CDY4rwWz1h9eXbXKz2DqrEmZxWDAMDS84rNSYkHVHBYPWf0ivhR4KJBTf6r08Opud8FJt6hw==
  • Arc-seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=lAFTbBw1euAaM1NYqfqn6Ol4Mmv+oFaIGWCOnGsEiDb9Lzof/6yJzESGe7IEDIDkYI08dGt1QzDOa4DyQs+cHM7mVMoptZwSEkxggPogDpkbsptdCnV4sqczSsi60EelCDsMJCkAqc1620edKYuQEvl4q7k3qNii2I0gvpeL6wUEZ9W3Wi5tE45WxVim2lgpAymHlhXhIPKOuAb+bxO6H2Itmu0m9/GjORrKVtp9jN41m836QGQkNJUAmfEhsoN8IiiQyiNzYY9IoAEtxh42+FH8bzb3khGv7p1itn8rtAAfbXi/SHl7vTeI54WY6YpW9tNbJSJoqUTmxtYFnVNMPQ==
  • Authentication-results: spf=none (sender IP is ) smtp.mailfrom=peng.fan@xxxxxxx;
  • Cc: "julien.grall@xxxxxxx" <julien.grall@xxxxxxx>, "xen-devel@xxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxx>, "Volodymyr_Babchuk@xxxxxxxx" <Volodymyr_Babchuk@xxxxxxxx>, Alice Guo <alice.guo@xxxxxxx>
  • Delivery-date: Wed, 27 Nov 2019 09:49:09 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
  • Thread-index: AQHVoQigeBpkjI1AYkOsm95VpW/YYaeXj4KAgAZiwICAAAEwAIAAKeCAgAAMKICAAF/UAIAAPyvQgAABqICAAANe8A==
  • Thread-topic: [Xen-devel] [PATCH V2] arch: arm: vgic-v3: fix GICD_ISACTIVER range

> Subject: Re: [Xen-devel] [PATCH V2] arch: arm: vgic-v3: fix GICD_ISACTIVER
> range
> 
> On 27.11.19 10:31, Peng Fan wrote:
> >> Subject: Re: [Xen-devel] [PATCH V2] arch: arm: vgic-v3: fix
> >> GICD_ISACTIVER range
> >>
> >> On 27.11.19 01:01, Julien Grall wrote:
> >>> Hi,
> >>>
> >>> On 26/11/2019 23:17, Stefano Stabellini wrote:
> >>>> On Tue, 26 Nov 2019, Julien Grall wrote:
> >>>>> Hi,
> >>>>>
> >>>>> On 26/11/2019 20:43, Stefano Stabellini wrote:
> >>>>>> + Juergen
> >>>>>>
> >>>>>> I missed that you weren't in CC to the original patch, sorry.
> >>>>>> I think this patch should go in, as otherwise Linux 5.4 could run
> >>>>>> into problems. It is also a pretty straightforward 4 lines patch.
> >>>>>
> >>>>> 5.5 (or 5.6) is not going to run on Xen for other reasons (still
> >>>>> in the vGIC)... So I would not view this as critical.
> >>>>
> >>>> 5.5 is not out yet, in fact, the dev window has just opened. Isn't
> >>>> your statement a bit premature?
> >>>
> >>> The GICv4.1 work [1] is going to prevent Linux booting on all
> >>> current versions of Xen. While I can't confirm this is going to be
> >>> merged in 5.5, I can tell you this will break.
> >>>
> >>>>
> >>>> In any case, even if potential future Linux releases could have
> >>>> other additional issues, I don't think it should change our current
> >>>> view on this specific issue which affects 5.4, just released.
> >>>
> >>> The patch is definitely not as straightforward as you may think.
> >>> Please refer to the discussion we had on the first version. I voiced
> >>> concern about this approach and gave point what could go wrong with
> >> happen.
> >>>
> >>> This patch may be better than the current state (i.e crashing), but
> >>> this wasn't tested enough to confirm this is the correct things to
> >>> do and no other bug will appear (I don't believe reading I*ACTIVER
> >>> was ever tested before).
> >>>
> >>> It is an annoying bug, but this is only affecting 5.4 which has just
> >>> been released. It feels to me this is a fairly risky choice to merge
> >>> it qutie late in the release without a good graps of the problem (see
> above).
> >>>
> >>> So I would definitly, prefer if this patch is getting through
> >>> backport once we get more testing.
> >>>
> >>> We can still document the bug in the release note and point people
> >>> to the patch.
> >>>
> >>> Anyway, this is Juergen choice here. But at least now he has the
> >>> full picture...
> >>>
> >>> Cheers,
> >>>
> >>> [1]
> >>>
> https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flwn.
> >>>
> >>
> net%2FArticles%2F800494%2F&amp;data=02%7C01%7Cpeng.fan%40nxp.co
> >> m%7Cdca
> >>>
> >>
> dfb39240749ee675e08d772fcd3ba%7C686ea1d3bc2b4c6fa92cd99c5c30163
> >> 5%7C0%7
> >>>
> >>
> C0%7C637104302519996592&amp;sdata=7Jv2IhI8HZgBTSuYzkEplFyhX1lzmv
> >> d73xb5
> >>> 2d6ERVQ%3D&amp;reserved=0
> >>>
> >>
> >> Thanks, Julien, for sharing your opinion.
> >>
> >> With that statement I'd like to defer this patch to 4.14.
> >
> > But without this patch, 5.4 kernel will crash. So you prefer we
> > develop the solution as Julien suggested for 4.13?
> 
> I certainly won't take a patch for 4.13 when a maintainer of the related code
> has reservations against it.
> 
> I think the best thing to do is to develop a proper patch the maintainers are
> happy with and don't try to force it into 4.13 now.
> Such a patch can still be backported to 4.13 later.

Ok.

Julien,

What's your suggestion to fix the issue? Do you have a rough idea?

Thanks,
Peng.

> 
> 
> Juergen
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel

 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.