spapr: Simulate CAS for qtest

spapr: Simulate CAS for qtest

The RTAS event hotplug code for machine types 2.8 and newer depends on
the CAS negotiated ov5 in order to work properly. However, there's no
CAS when running under qtest. There has been a tentative to trick the
code by faking the OV5_HP_EVT bit, but it turned out to break other
assumptions in the code and the change got reverted.

Go for a more general approach and simulate a CAS when running under
qtest. For simplicity, this pseudo CAS simple simulates the case where
the guest supports the same features as the machine. It is done at
reset time, just before we reset the DRCs, which could potentially
exercise the unplug code.

This allows to test unplug on spapr with both older and newer machine
types.

Suggested-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <155146875704.147873.10563808578795890265.stgit@bahia.lan>
Tested-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>