Re: [Xen-devel] [PATCH v3 04/13] xen/arm: support for guest SGI

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2013-04-26 at 14:56 +0100, Sander Bogaert wrote:
> On 26-04-13 15:35, Julien Grall wrote:
> > On 04/26/2013 02:24 PM, Ian Campbell wrote:
> > 
> >> On Fri, 2013-04-26 at 13:12 +0100, Sander Bogaert wrote:
> >>> I've been running crashme ( executing random instructions ) on Xen on
> >>> Arm installed on an Arndale board. I'm using Julien's dom0 and Xen
> >>> branch. The Xen branch wasn't updated in a few days.
> >>>
> >>> I managed to crash Xen from dom0 userspace:
> >>> (XEN)
> >>> (XEN) ****************************************
> >>> (XEN) Panic on CPU 1:
> >>> (XEN) Unhandled SGI 2 on CPU1
> >>> (XEN) ****************************************
> >>> (XEN)
> >>> (XEN) Reboot in five seconds...
> >>>
> >>> Tracking this back to the source:
> >>> xen/arch/arm/gic.c:648 static void do_sgi
> >>> xen/arch/arm/gic.c:671 void gic_interrupt
> >>>
> >>> From what I understood from the source all sgi's except 0 & 1
> >>> would/will cause this panic since they are just not handled.
> >>
> >> Do you know how the SGI was triggered, because if guest/dom0 userspace
> >> can trigger an arbitrary SGI then we have big problems!
> >>
> >> Julien, does your tree have anything in it which might explain this?
> > 
> > 
> > This SGI should only be triggered to call a function on another CPU. But
> > it seems his xen tree doesn't have the patch applied. So nobody should
> > call this SGI.
> > 
> 
> I've been using 5ce4118f5768c6137d58888d57972bdfdf4c9aba in the branch
> 'arndale' on this repo:
> git://xenbits.xen.org/people/julieng/xen-unstable.git .
> 
> I will try to reproduce this, I did log my initial seed for crashme and
> the ones leading up to the crash. Is there something I can enable to get
> some more output? I thought Xen would print some data ( I've seen that
> before, the register content & such + a stacktrace ).

I think you can change the panic into a BUG_ON(1) which will get you
more info.

If you can repro then please can you share crashme + the seed with us?

> I should have started a new thread for this, I thought it was related to
> what this patch fixes.

No problem, please do start a new thread for any further updates.

Ian.


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