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

hw/ppc/spapr.c

@@ -29,6 +29,7 @@
 #include "qapi/visitor.h"
 #include "sysemu/sysemu.h"
 #include "sysemu/numa.h"
+#include "sysemu/qtest.h"
 #include "hw/hw.h"
 #include "qemu/log.h"
 #include "hw/fw-path-provider.h"
@@ -1711,6 +1712,16 @@ static void spapr_machine_reset(void)
      */
     spapr_irq_reset(spapr, &error_fatal);
 
+    /*
+     * There is no CAS under qtest. Simulate one to please the code that
+     * depends on spapr->ov5_cas. This is especially needed to test device
+     * unplug, so we do that before resetting the DRCs.
+     */
+    if (qtest_enabled()) {
+        spapr_ovec_cleanup(spapr->ov5_cas);
+        spapr->ov5_cas = spapr_ovec_clone(spapr->ov5);
+    }
+
     /* DRC reset may cause a device to be unplugged. This will cause troubles
      * if this device is used by another device (eg, a running vhost backend
      * will crash QEMU if the DIMM holding the vring goes away). To avoid such