PCI: fix multiple bridge problems

When several PCI bridges were in use, monitor command "info pci" would
enter into infinite loop. Buses behind the bridge were not discoverable
because secondary and subordinate bus numbers were not used properly.
Other buses were not found because bus search terminated on first miss.
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

hw/pci.c

@@ -1299,7 +1299,7 @@ static QObject *pci_get_dev_dict(PCIDevice *dev, PCIBus *bus, int bus_num)
         "'io_range': { 'base': %" PRId64 ", 'limit': %" PRId64 "}, "
         "'memory_range': { 'base': %" PRId64 ", 'limit': %" PRId64 "}, "
         "'prefetchable_range': { 'base': %" PRId64 ", 'limit': %" PRId64 "} }",
-        dev->config[0x19], dev->config[PCI_SECONDARY_BUS],
+        dev->config[PCI_PRIMARY_BUS], dev->config[PCI_SECONDARY_BUS],
         dev->config[PCI_SUBORDINATE_BUS],
         pci_bridge_get_base(dev, PCI_BASE_ADDRESS_SPACE_IO),
         pci_bridge_get_limit(dev, PCI_BASE_ADDRESS_SPACE_IO),
@@ -1310,12 +1310,16 @@ static QObject *pci_get_dev_dict(PCIDevice *dev, PCIBus *bus, int bus_num)
         pci_bridge_get_limit(dev, PCI_BASE_ADDRESS_SPACE_MEMORY |
                                 PCI_BASE_ADDRESS_MEM_PREFETCH));
 
-        if (dev->config[0x19] != 0) {
-            qdict = qobject_to_qdict(pci_bridge);
-            qdict_put_obj(qdict, "devices",
-                          pci_get_devices_list(bus, dev->config[0x19]));
-        }
+        if (dev->config[PCI_SECONDARY_BUS] != 0) {
+            PCIBus *child_bus = pci_find_bus(bus, dev->config[PCI_SECONDARY_BUS]);
 
+            if (child_bus) {
+                qdict = qobject_to_qdict(pci_bridge);
+                qdict_put_obj(qdict, "devices",
+                              pci_get_devices_list(child_bus,
+                                                   dev->config[PCI_SECONDARY_BUS]));
+            }
+        }
         qdict = qobject_to_qdict(obj);
         qdict_put_obj(qdict, "pci_bridge", pci_bridge);
     }
@@ -1542,7 +1546,7 @@ static void pci_bridge_write_config(PCIDevice *d,
 
 PCIBus *pci_find_bus(PCIBus *bus, int bus_num)
 {
-    PCIBus *sec;
+    PCIBus *sec, *ret;
 
     if (!bus)
         return NULL;
@@ -1553,11 +1557,13 @@ PCIBus *pci_find_bus(PCIBus *bus, int bus_num)
 
     /* try child bus */
     QLIST_FOREACH(sec, &bus->child, sibling) {
-
         if (!bus->parent_dev /* pci host bridge */
-            || (pci_bus_num(sec) <= bus_num &&
-                bus->parent_dev->config[PCI_SUBORDINATE_BUS])) {
-            return pci_find_bus(sec, bus_num);
+            || (pci_bus_num(sec) >= bus_num &&
+                bus_num <= bus->parent_dev->config[PCI_SUBORDINATE_BUS]) ) {
+            ret = pci_find_bus(sec, bus_num);
+            if (ret) {
+                return ret;
+            }
         }
     }