spapr_pci: Fix extended config space accesses

The PAPR PHB acts as a legacy PCI bus but it allows PCIe extended
config space accesses anyway (for pseries-2.9 and newer machine
types).

Introduce a specific PCI bus subtype to inform the common PCI code
about that.

Fixes: c2077e2
Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <155414130834.574858.16502276132110219890.stgit@bahia.lan>
[dwg: Apply fix so we don't rename the default pci bus, breaking everything]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

hw/ppc/spapr_pci.c

@@ -1638,6 +1638,28 @@ static void spapr_phb_unrealize(DeviceState *dev, Error **errp)
     memory_region_del_subregion(get_system_memory(), &sphb->mem32window);
 }
 
+static bool spapr_phb_allows_extended_config_space(PCIBus *bus)
+{
+    SpaprPhbState *sphb = SPAPR_PCI_HOST_BRIDGE(BUS(bus)->parent);
+
+    return sphb->pcie_ecs;
+}
+
+static void spapr_phb_root_bus_class_init(ObjectClass *klass, void *data)
+{
+    PCIBusClass *pbc = PCI_BUS_CLASS(klass);
+
+    pbc->allows_extended_config_space = spapr_phb_allows_extended_config_space;
+}
+
+#define TYPE_SPAPR_PHB_ROOT_BUS "spapr-pci-host-bridge-root-bus"
+
+static const TypeInfo spapr_phb_root_bus_info = {
+    .name = TYPE_SPAPR_PHB_ROOT_BUS,
+    .parent = TYPE_PCI_BUS,
+    .class_init = spapr_phb_root_bus_class_init,
+};
+
 static void spapr_phb_realize(DeviceState *dev, Error **errp)
 {
     /* We don't use SPAPR_MACHINE() in order to exit gracefully if the user
@@ -1739,10 +1761,11 @@ static void spapr_phb_realize(DeviceState *dev, Error **errp)
     memory_region_add_subregion(get_system_memory(), sphb->io_win_addr,
                                 &sphb->iowindow);
 
-    bus = pci_register_root_bus(dev, NULL,
+    bus = pci_register_root_bus(dev, "pci.0",
                                 pci_spapr_set_irq, pci_spapr_map_irq, sphb,
                                 &sphb->memspace, &sphb->iospace,
-                                PCI_DEVFN(0, 0), PCI_NUM_PINS, TYPE_PCI_BUS);
+                                PCI_DEVFN(0, 0), PCI_NUM_PINS,
+                                TYPE_SPAPR_PHB_ROOT_BUS);
     phb->bus = bus;
     qbus_set_hotplug_handler(BUS(phb->bus), OBJECT(sphb), NULL);
 
@@ -2325,6 +2348,7 @@ void spapr_pci_rtas_init(void)
 static void spapr_pci_register_types(void)
 {
     type_register_static(&spapr_phb_info);
+    type_register_static(&spapr_phb_root_bus_info);
 }
 
 type_init(spapr_pci_register_types)