pci: Create pci_bus_is_express helper

For testing the bus type.
Signed-off-by: NAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

hw/pci/pci.c

@@ -297,6 +297,11 @@ static void pci_bus_init(PCIBus *bus, DeviceState *parent,
     vmstate_register(NULL, -1, &vmstate_pcibus, bus);
 }
 
+bool pci_bus_is_express(PCIBus *bus)
+{
+    return object_dynamic_cast(OBJECT(bus), TYPE_PCIE_BUS);
+}
+
 void pci_bus_new_inplace(PCIBus *bus, DeviceState *parent,
                          const char *name,
                          MemoryRegion *address_space_mem,

hw/pci/pci.h

@@ -344,6 +344,7 @@ typedef int (*pci_hotplug_fn)(DeviceState *qdev, PCIDevice *pci_dev,
 #define PCI_BUS(obj) OBJECT_CHECK(PCIBus, (obj), TYPE_PCI_BUS)
 #define TYPE_PCIE_BUS "PCIE"
 
+bool pci_bus_is_express(PCIBus *bus);
 void pci_bus_new_inplace(PCIBus *bus, DeviceState *parent,
                          const char *name,
                          MemoryRegion *address_space_mem,