Re: port-xen/53965: XEN DomU fails to poweroff in new HEAD kernels

[Greg Oster <oster%netbsd.org@localhost>]

On Sat, 9 Feb 2019 17:36:37 +0100
Manuel Bouyer <bouyer%antioche.eu.org@localhost> wrote:

> On Sat, Feb 09, 2019 at 02:20:00PM +0000, kre%munnari.OZ.AU@localhost wrote:
> > >Description:  
> > 	Sometime in the recent past, my XEN DomU kernels lost the
> > 	ability to power off the (virtual) machine (and cause the
> > 	XEN hypervisor to let go.)
> > 
> > 	It was working with 8.99.32 (of some vintage, the last
> > kernel update I did was probably a couple of weeks ago) and failed
> > 	with the first update to a 8.99.34 kernel I attempted
> > (though the first time I just assumed I left the "-p" off the
> > shutdown command by accident, and didn't think any more of it.)
> > 
> > 	Note I am running a very old (by current standards) Xen
> > kernel and Dom0 system, however they are (and have been) working
> > well, and as (ignoring my uses for testing up to date current
> > kernels, and particularly, shells) this is a production system I'm
> > in no great hurry to update it.
> > 
> > 	pkg_info on the Dom0 tells me:
> > 
> > 	onyx$ pkg_info | grep xen
> > 	xentools42-4.2.5nb15 Userland Tools for Xen 4.2.x
> > 	xenkernel42-4.2.2   Xen 4.2.x Kernel
> > 
> > 	(with some other noise that just happened to match.)  
> 
> I'm not seeing this with the Daily ATF runs:
> http://www-soc.lip6.fr/~bouyer/NetBSD-tests/xen/HEAD/
> but the server is running Xen 4.11
> 
> I wonder if it could be related to the recent Xen API version bump in
> our source tree

I'm seeing this with an 8.0_STABLE DOM0... I instrumented cpu_reset()
with printfs before/after the call to HYPERVISOR_reboot():

#ifdef XEN
        printf("calling HYPERVISOR_reboot()\n");
	HYPERVISOR_reboot();
        printf("done HYPERVISOR_reboot()\n");
#else

and both are printed:
[ 119.1643554] xbd1: detached
[ 119.3838479] rebooting...
[ 119.3838479] calling x86_disable_intr()
[ 119.3838479] calling HYPERVISOR_reboot()
[ 119.3838479] done HYPERVISOR_reboot()

I note that if I do a 'shutdown -h' I can enter 5 "+"'s to get to ddb,
but once it hits the "done HYPERVISOR_reboot()" I can no longer get to
ddb on the DOMU.

Is HYPERVISOR_reboot() expected to return?  The next line in
cpu_reset() is effectively: 

 for (;;);

so I'm thinking not...

Later...

Greg Oster