Re: [Xen-devel] [PATCHv10 0/9] Xen: extend kexec hypercall for use with pv-ops kernels

[Daniel Kiper <daniel.kiper@xxxxxxxxxx>]

On Thu, Nov 07, 2013 at 10:16:51PM +0100, Daniel Kiper wrote:
> On Wed, Nov 06, 2013 at 02:49:37PM +0000, David Vrabel wrote:
> > The series (for Xen 4.4) improves the kexec hypercall by making Xen
> > responsible for loading and relocating the image.  This allows kexec
> > to be usable by pv-ops kernels and should allow kexec to be usable
> > from a HVM or PVH privileged domain.
> >
> > I have now tested this with a Linux kernel image using the VGA console
> > which was what was causing problems in v9 (this turned out to be a
> > kexec-tools bug).
> >
> > The required patch series for kexec-tools will be posted shortly and
> > are available from the xen-v7 branch of:
>
> In general it works. However, quite often I am not able to execute panic
> kernel. Machine hangs with following message:
>
> (XEN) Domain 0 crashed: Executing crash image
>
> gdb shows:
>
> (gdb) bt
> #0  0xffff82d0801a0092 in do_nmi_crash (regs=<optimized out>) at crash.c:113
> #1  0xffff82d0802281d9 in nmi_crash () at entry.S:666
> #2  0x0000000000000000 in ?? ()
> (gdb)
>
> Especially second bt line scares me... ;-)))
>
> I have not been able to identify why NMI was activated because
> stack is completely cleared. I tried to record execution in gdb
> but it stops with following message:
>
> cpumask_clear_cpu (dstp=0xffff82d0802f7f78 <call_data+24>, cpu=0)
>     at /srv/dev/xen/xen_20130413_20131107.kexec/xen/include/xen/cpumask.h:108
> 108             clear_bit(cpumask_check(cpu), dstp->bits);
> Process record: failed to record execution log.
>
> Do you know how to find out why NMI was activated?
>
> I am able almost always reproduce this issue doing this:
>   - boot Xen,
>   - load panic kernel,
>   - echo c > /proc/sysrq-trigger,
>   - reboot from command line,
>   - boot Xen,
>   - load panic kernel,
>   - echo c > /proc/sysrq-trigger.

I am not able to reproduce this on real hardware. Sorry for confusion.

Hence, for whole Xen kexec/kdump series:

Reviewed-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
Tested-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>

Daniel

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