q35: allow dynamic sysbus

Allow adding sysbus devices with -device on Q35.

At first Q35 will support only intel-iommu to be added this way,
however the command line will support all sysbus devices.

Mark with 'cannot_instantiate_with_device_add_yet' the ones
causing immediate problems (e.g. crashes).

Signed-off-by: Marcel Apfelbaum <marcel@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/i386/pc_q35.c

@@ -290,6 +290,7 @@ static void pc_q35_machine_options(MachineClass *m)
     m->default_machine_opts = "firmware=bios-256k.bin";
     m->default_display = "std";
     m->no_floppy = 1;
+    m->has_dynamic_sysbus = true;
 }
 
 static void pc_q35_2_7_machine_options(MachineClass *m)

hw/pci-bridge/pci_expander_bridge.c

@@ -149,6 +149,8 @@ static void pxb_host_class_init(ObjectClass *class, void *data)
     PCIHostBridgeClass *hc = PCI_HOST_BRIDGE_CLASS(class);
 
     dc->fw_name = "pci";
+    /* Reason: Internal part of the pxb/pxb-pcie device, not usable by itself */
+    dc->cannot_instantiate_with_device_add_yet = true;
     sbc->explicit_ofw_unit_address = pxb_host_ofw_unit_address;
     hc->root_bus_path = pxb_host_root_bus_path;
 }

hw/pci-host/piix.c

@@ -865,6 +865,8 @@ static void i440fx_pcihost_class_init(ObjectClass *klass, void *data)
     dc->realize = i440fx_pcihost_realize;
     dc->fw_name = "pci";
     dc->props = i440fx_props;
+    /* Reason: needs to be wired up by pc_init1 */
+    dc->cannot_instantiate_with_device_add_yet = true;
 }
 
 static const TypeInfo i440fx_pcihost_info = {

hw/pci-host/q35.c

@@ -142,6 +142,8 @@ static void q35_host_class_init(ObjectClass *klass, void *data)
     hc->root_bus_path = q35_host_root_bus_path;
     dc->realize = q35_host_realize;
     dc->props = mch_props;
+    /* Reason: needs to be wired up by pc_q35_init */
+    dc->cannot_instantiate_with_device_add_yet = true;
     set_bit(DEVICE_CATEGORY_BRIDGE, dc->categories);
     dc->fw_name = "pci";
 }