hw/pci: Add pci_bus_range() to get PCI bus number range

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>

1 files changed, 16 insertions, 0 deletions

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);