addhardware: Move disk bus listing to virtinst

Drop the stable_default stuff as domcaps usage should make
it obsolete for any cases we care about

virtManager/addhardware.py

@@ -469,50 +469,12 @@ class vmmAddHardware(vmmGObjectUI):
 
     @staticmethod
     def populate_disk_bus_combo(vm, devtype, model):
-        # try to get supported disk bus types from domain capabilities
         domcaps = vm.get_domain_capabilities()
-        disk_bus_types = None
-        if "bus" in domcaps.devices.disk.enum_names():
-            disk_bus_types = domcaps.devices.disk.get_enum("bus").get_values()
-
-        # if there are no disk bus types in domain capabilities fallback to
-        # old code
-        if not disk_bus_types:
-            disk_bus_types = []
-            if vm.is_hvm():
-                if not vm.get_xmlobj().os.is_q35():
-                    disk_bus_types.append("ide")
-                disk_bus_types.append("sata")
-                disk_bus_types.append("fdc")
-
-                if not vm.xmlobj.stable_defaults():
-                    disk_bus_types.append("scsi")
-                    disk_bus_types.append("usb")
-
-            if vm.get_hv_type() in ["qemu", "kvm", "test"]:
-                disk_bus_types.append("sd")
-                disk_bus_types.append("virtio")
-                if "scsi" not in disk_bus_types:
-                    disk_bus_types.append("scsi")
-
-            if vm.conn.is_xen() or vm.conn.is_test():
-                disk_bus_types.append("xen")
-
-        rows = []
-        for bus in disk_bus_types:
-            rows.append([bus, DeviceDisk.pretty_disk_bus(bus)])
+        buses = DeviceDisk.get_recommended_buses(vm.xmlobj, domcaps, devtype)
 
         model.clear()
-
-        bus_map = {
-            "disk": ["ide", "sata", "scsi", "sd", "usb", "virtio", "xen"],
-            "floppy": ["fdc"],
-            "cdrom": ["ide", "sata", "scsi"],
-            "lun": ["scsi"],
-        }
-        for row in rows:
-            if row[0] in bus_map[devtype]:
-                model.append(row)
+        for bus in buses:
+            model.append([bus, DeviceDisk.pretty_disk_bus(bus)])
 
 
     @staticmethod

virtinst/devices/disk.py

@@ -142,6 +142,44 @@ class DeviceDisk(Device):
 
     error_policies = ["ignore", "stop", "enospace", "report"]
 
+    @staticmethod
+    def get_old_recommended_buses(guest):
+        ret = []
+        if guest.os.is_hvm() or guest.conn.is_test():
+            if not guest.os.is_q35():
+                ret.append("ide")
+            ret.append("sata")
+            ret.append("fdc")
+            ret.append("scsi")
+            ret.append("usb")
+
+            if guest.type in ["qemu", "kvm", "test"]:
+                ret.append("sd")
+                ret.append("virtio")
+                if "scsi" not in ret:
+                    ret.append("scsi")
+
+        if guest.conn.is_xen() or guest.conn.is_test():
+            ret.append("xen")
+
+        return ret
+
+    @staticmethod
+    def get_recommended_buses(guest, domcaps, devtype):
+        # try to get supported disk bus types from domain capabilities
+        if "bus" in domcaps.devices.disk.enum_names():
+            buses = domcaps.devices.disk.get_enum("bus").get_values()
+        else:
+            buses = DeviceDisk.get_old_recommended_buses(guest)
+
+        bus_map = {
+            "disk": ["ide", "sata", "scsi", "sd", "usb", "virtio", "xen"],
+            "floppy": ["fdc"],
+            "cdrom": ["ide", "sata", "scsi"],
+            "lun": ["scsi"],
+        }
+        return [bus for bus in buses if bus in bus_map.get(devtype, [])]
+
     @staticmethod
     def disk_type_to_xen_driver_name(disk_type):
         """