Re: [Qemu-devel] [PATCH] spapr: Explicitly check machine support before using EVENT_CLASS_HOT_PLUG

[Greg Kurz <groug@kaod.org>]

On Fri, 1 Mar 2019 16:24:48 +0100
Thomas Huth <thuth@redhat.com> wrote:

> On 01/03/2019 15.17, Greg Kurz wrote:
> > Recent commit b8165118f52c "spapr: support memory unplug for qtest" broke
> > CPU hotplug tests for old machine types:
> > 
> > $ QTEST_QEMU_BINARY=ppc64-softmmu/qemu-system-ppc64 ./tests/cpu-plug-test -m=slow
> > /ppc64/cpu-plug/pseries-3.1/device-add/2x3x1&maxcpus=6: OK
> > /ppc64/cpu-plug/pseries-2.12-sxxm/device-add/2x3x1&maxcpus=6: OK
> > /ppc64/cpu-plug/pseries-3.0/device-add/2x3x1&maxcpus=6: OK
> > /ppc64/cpu-plug/pseries-2.10/device-add/2x3x1&maxcpus=6: OK
> > /ppc64/cpu-plug/pseries-2.11/device-add/2x3x1&maxcpus=6: OK
> > /ppc64/cpu-plug/pseries-2.12/device-add/2x3x1&maxcpus=6: OK
> > /ppc64/cpu-plug/pseries-2.9/device-add/2x3x1&maxcpus=6: OK
> > /ppc64/cpu-plug/pseries-2.7/device-add/2x3x1&maxcpus=6: **
> > ERROR:/home/thuth/devel/qemu/hw/ppc/spapr_events.c:313:rtas_event_log_to_source: assertion failed: (source->enabled)
> > Broken pipe
> > /home/thuth/devel/qemu/tests/libqtest.c:143: kill_qemu() detected QEMU death from signal 6 (Aborted) (core dumped)
> > Aborted (core dumped)
> > 
> > The rtas_event_log_to_source() function is supposed to return the event
> > source to be used for a given event type. In the case of hotplug, it first
> > tries EVENT_CLASS_HOT_PLUG and, if the guest doesn't support it, it falls
> > back to EVENT_CLASS_EPOW.
> > 
> > This works well for machine types that enable EVENT_CLASS_HOT_PLUG. For
> > older machine types, this happened to work because they don't set the
> > OV5_HP_EVT bit in spapr->ov5. CAS hence logically keeps the bit cleared
> > in spapr->ov5_cas and we avoid the assert.
> > 
> > As shown by commit b8165118f52c, the logic is fragile and we need a
> > bigger hammer to ensure that rtas_event_log_to_source() doesn't go
> > down the EVENT_CLASS_HOT_PLUG path with older machine types.
> > 
> > Signed-off-by: Greg Kurz <groug@kaod.org>
> > ---
> >  hw/ppc/spapr_events.c |   12 +++++++-----
> >  1 file changed, 7 insertions(+), 5 deletions(-)  
> 
> Thanks, that fixes the problem for me!
> 
> Tested-by: Thomas Huth <thuth@redhat.com>

I realize I should have put this also:

Reported-by: Thomas Huth <thuth@redhat.com>

Cheers,

--
Greg