[PULL v3 14/19] hw/pci: Add pci_bus_range() to get PCI bus number range

["Michael S. Tsirkin" <mst@redhat.com>]

From: Xingang Wang <wangxingang5@huawei.com>

This helps to get the min and max bus number of a PCI bus hierarchy.

Signed-off-by: Xingang Wang <wangxingang5@huawei.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Message-Id: <1625748919-52456-6-git-send-email-wangxingang5@huawei.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 include/hw/pci/pci.h |  1 +
 hw/pci/pci.c         | 16 ++++++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
index f4d51b672b..d0f4266e37 100644
--- a/include/hw/pci/pci.h
+++ b/include/hw/pci/pci.h
@@ -450,6 +450,7 @@ static inline PCIBus *pci_get_bus(const PCIDevice *dev)
     return PCI_BUS(qdev_get_parent_bus(DEVICE(dev)));
 }
 int pci_bus_num(PCIBus *s);
+void pci_bus_range(PCIBus *bus, int *min_bus, int *max_bus);
 static inline int pci_dev_bus_num(const PCIDevice *dev)
 {
     return pci_bus_num(pci_get_bus(dev));
diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index 27d588e268..23d2ae2ab2 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -537,6 +537,22 @@ int pci_bus_num(PCIBus *s)
     return PCI_BUS_GET_CLASS(s)->bus_num(s);
 }
 
+/* Returns the min and max bus numbers of a PCI bus hierarchy */
+void pci_bus_range(PCIBus *bus, int *min_bus, int *max_bus)
+{
+    int i;
+    *min_bus = *max_bus = pci_bus_num(bus);
+
+    for (i = 0; i < ARRAY_SIZE(bus->devices); ++i) {
+        PCIDevice *dev = bus->devices[i];
+
+        if (dev && PCI_DEVICE_GET_CLASS(dev)->is_bridge) {
+            *min_bus = MIN(*min_bus, dev->config[PCI_SECONDARY_BUS]);
+            *max_bus = MAX(*max_bus, dev->config[PCI_SUBORDINATE_BUS]);
+        }
+    }
+}
+
 int pci_bus_numa_node(PCIBus *bus)
 {
     return PCI_BUS_GET_CLASS(bus)->numa_node(bus);
-- 
MST