remote/machine: add vfio-user property

Add vfio-user to x-remote machine. It is a boolean, which indicates if
the machine supports vfio-user protocol. The machine configures the bus
differently vfio-user and multiprocess protocols, so this property
informs it on how to configure the bus.

This property should be short lived. Once vfio-user fully replaces
multiprocess, this property could be removed.

Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
Signed-off-by: John G Johnson <john.g.johnson@oracle.com>
Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 5d51a152a419cbda35d070b8e49b772b60a7230a.1655151679.git.jag.raman@oracle.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

hw/remote/machine.c

@@ -58,6 +58,25 @@ static void remote_machine_init(MachineState *machine)
     qbus_set_hotplug_handler(BUS(pci_host->bus), OBJECT(s));
 }
 
+static bool remote_machine_get_vfio_user(Object *obj, Error **errp)
+{
+    RemoteMachineState *s = REMOTE_MACHINE(obj);
+
+    return s->vfio_user;
+}
+
+static void remote_machine_set_vfio_user(Object *obj, bool value, Error **errp)
+{
+    RemoteMachineState *s = REMOTE_MACHINE(obj);
+
+    if (phase_check(PHASE_MACHINE_CREATED)) {
+        error_setg(errp, "Error enabling vfio-user - machine already created");
+        return;
+    }
+
+    s->vfio_user = value;
+}
+
 static void remote_machine_class_init(ObjectClass *oc, void *data)
 {
     MachineClass *mc = MACHINE_CLASS(oc);
@@ -67,6 +86,10 @@ static void remote_machine_class_init(ObjectClass *oc, void *data)
     mc->desc = "Experimental remote machine";
 
     hc->unplug = qdev_simple_device_unplug_cb;
+
+    object_class_property_add_bool(oc, "vfio-user",
+                                   remote_machine_get_vfio_user,
+                                   remote_machine_set_vfio_user);
 }
 
 static const TypeInfo remote_machine = {

include/hw/remote/machine.h

@@ -22,6 +22,8 @@ struct RemoteMachineState {
 
     RemotePCIHost *host;
     RemoteIOHubState iohub;
+
+    bool vfio_user;
 };
 
 /* Used to pass to co-routine device and ioc. */