Re: [Xen-devel] [PATCH] shut down domain when last vCPU goes down

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Fri, Feb 16, 2018 at 03:59:45PM +0000, Wei Liu wrote:
> On Fri, Feb 16, 2018 at 03:52:48PM +0000, Roger Pau Monné wrote:
> > On Fri, Feb 16, 2018 at 08:10:48AM -0700, Jan Beulich wrote:
> > > I've just had to deal with an early boot crash of Linux which occurred
> > > so early that even "earlyprintk=xen" did not produce any useful output.
> > > Hence the domain appeared to hang, while in fact it had brought down its
> > > only vCPU. By translating this to a shutdown, the situation will be
> > > better recognizable.
> > > 
> > > Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> > 
> > Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> > 
> > I'm wondering, is it common for a domain to shutdown by shutting down
> > all it's vCPUs?
> > 
> > In the scenario that you describe above it seems it would be more
> > helpful to issue a SHUTDOWN_crash instead maybe with a gdprintk
> > message in order to aid debugging.
> 
> There doesn't seem to be a reliable way to distinguish a crash vs a
> guest clean shutdown in you scheme though.

I agree, I guess the real problem is that the guest should use
SHUTDOWN_crash itself instead of shutting down the vCPU.

But I don't think a domain should try to perform a clean shutdown by
shutting down all of it's vCPUs, the proper way to do a clean shutdown
is to call SHUTDOWN_poweroff.

Roger.

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