From mboxrd@z Thu Jan 1 00:00:00 1970 From: Julien Grall Subject: Re: unhandled word causes Xen crash with recent Linux kernels, was: Re: [PATCH v2 05/11] xen/arm: vgic: Properly emulate the full register Date: Mon, 30 Nov 2015 12:22:06 +0000 Message-ID: <565C3F6E.1090005@citrix.com> References: <1447867686-19371-1-git-send-email-julien.grall@citrix.com> <1447867686-19371-6-git-send-email-julien.grall@citrix.com> <56557EE0.6010507@huawei.com> <1448454385.17688.96.camel@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta14.messagelabs.com ([193.109.254.103]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1a3NUS-000870-Ua for xen-devel@lists.xenproject.org; Mon, 30 Nov 2015 12:23:33 +0000 In-Reply-To: <1448454385.17688.96.camel@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Ian Campbell , Stefano Stabellini , Shannon Zhao Cc: xen-devel@lists.xenproject.org List-Id: xen-devel@lists.xenproject.org Hi Ian, On 25/11/15 12:26, Ian Campbell wrote: > On Wed, 2015-11-25 at 12:15 +0000, Stefano Stabellini wrote: >> On Wed, 25 Nov 2015, Shannon Zhao wrote: >>> Upstream Linux kernel applies below patch which will write >>> GICD_ICACTIVER. But since Xen doesn't support it, so it will cause Dom0 >>> initializes GIC failed. >>> >>> 0eece2b22849c90b730815c893425a36b9d10fd5 (irqchip/gic: Make sure all >>> interrupts are deactivated at boot) >>> >>> (XEN) d0v0: vGICD: unhandled word write 0xffffffff to ICACTIVER4 >>> (XEN) traps.c:2447:d0v0 HSR=0x93860046 pc=0xffffffc0008d63f0 >>> gva=0xffffff8000004384 gpa=0x0000002f000384 >>> (XEN) DOM0: Unhandled fault: ttbr address size fault (0x96000000) at >>> 0xffffff8000004384 >>> (XEN) DOM0: Internal error: : 96000000 [#1] PREEMPT SMP >>> (XEN) DOM0: Modules linked in: >>> (XEN) DOM0: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.4.0-rc2+ #364 >>> (XEN) DOM0: Hardware name: (null) (DT) >>> (XEN) DOM0: task: ffffffc000969970 ti: ffffffc00095c000 task.ti: >>> ffffffc00095c000 >>> (XEN) DOM0: PC is at gic_dist_config+0x78/0xa0 >>> (XEN) DOM0: LR is at __gic_init_bases+0x240/0x2bc >>> >>> Do we have a plan to fix this? >> >> Thanks for the reporting the issue, I can reproduce the problem. Given >> that this is a very serious regression and that we cannot really "fix" >> the Linux side because Linux is not doing anything wrong, I think we >> have to go with a very simple change, something we can easily backport >> to all past Xen releases. >> >> I suggest we turn the "unhandled word write" into a write_ignore, see >> below: > > As discussed IRL this might be tolerable as a patch intended for > backporting purposes, but I would want to see it in a series along with one > or more not-for-backport patches which actually makes the register work as > it should. I have the feeling that fixing properly GICD_I*ACTIVER will take sometimes as we also need to take into consideration hardware interrupt routed to a guest. As this is preventing Linux upstream to run on the latest, can we get a simple fix for now? Regards, -- Julien Grall