pci: Use helper to find device's root bus in pci_find_domain()

Currently pci_find_domain() performs two functions - it locates the PCI
root bus above the given bus, then looks up that root bus's domain number.
This patch adds a helper function to perform the first task, finding the
root bus for a given PCI device.  This is then used in pci_find_domain().
This changes pci_find_domain()'s signature slightly, taking a PCIDevice
instead of a PCIBus - since all callers passed something of the form
dev->bus, this simplifies things slightly.
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

hw/pci/pci-hotplug-old.c

@@ -276,7 +276,7 @@ void pci_device_hot_add(Monitor *mon, const QDict *qdict)
 
     if (dev) {
         monitor_printf(mon, "OK domain %d, bus %d, slot %d, function %d\n",
-                       pci_find_domain(dev->bus),
+                       pci_find_domain(dev),
                        pci_bus_num(dev->bus), PCI_SLOT(dev->devfn),
                        PCI_FUNC(dev->devfn));
     } else

hw/pci/pci.c

@@ -259,18 +259,24 @@ PCIBus *pci_find_primary_bus(void)
     return NULL;
 }
 
-int pci_find_domain(const PCIBus *bus)
+PCIBus *pci_device_root_bus(const PCIDevice *d)
 {
-    PCIDevice *d;
-    struct PCIHostBus *host;
+    PCIBus *bus = d->bus;
 
-    /* obtain root bus */
     while ((d = bus->parent_dev) != NULL) {
         bus = d->bus;
     }
 
+    return bus;
+}
+
+int pci_find_domain(const PCIDevice *dev)
+{
+    const PCIBus *rootbus = pci_device_root_bus(dev);
+    struct PCIHostBus *host;
+
     QLIST_FOREACH(host, &host_buses, next) {
-        if (host->bus == bus) {
+        if (host->bus == rootbus) {
             return host->domain;
         }
     }
@@ -1997,7 +2003,7 @@ int pci_add_capability(PCIDevice *pdev, uint8_t cap_id,
                 fprintf(stderr, "ERROR: %04x:%02x:%02x.%x "
                         "Attempt to add PCI capability %x at offset "
                         "%x overlaps existing capability %x at offset %x\n",
-                        pci_find_domain(pdev->bus), pci_bus_num(pdev->bus),
+                        pci_find_domain(pdev), pci_bus_num(pdev->bus),
                         PCI_SLOT(pdev->devfn), PCI_FUNC(pdev->devfn),
                         cap_id, offset, overlapping_cap, i);
                 return -EINVAL;
@@ -2152,7 +2158,7 @@ static char *pcibus_get_dev_path(DeviceState *dev)
     path[path_len] = '\0';
 
     /* First field is the domain. */
-    s = snprintf(domain, sizeof domain, "%04x:00", pci_find_domain(d->bus));
+    s = snprintf(domain, sizeof domain, "%04x:00", pci_find_domain(d));
     assert(s == domain_len);
     memcpy(path, domain, domain_len);
 

hw/pci/pcie_aer.c

@@ -1022,8 +1022,7 @@ int do_pcie_aer_inject_error(Monitor *mon,
     *ret_data = qobject_from_jsonf("{'id': %s, "
                                    "'domain': %d, 'bus': %d, 'devfn': %d, "
                                    "'ret': %d}",
-                                   id,
-                                   pci_find_domain(dev->bus),
+                                   id, pci_find_domain(dev),
                                    pci_bus_num(dev->bus), dev->devfn,
                                    ret);
     assert(*ret_data);

include/hw/pci/pci.h

@@ -390,7 +390,8 @@ void pci_for_each_device(PCIBus *bus, int bus_num,
                          void (*fn)(PCIBus *bus, PCIDevice *d, void *opaque),
                          void *opaque);
 PCIBus *pci_find_primary_bus(void);
-int pci_find_domain(const PCIBus *bus);
+PCIBus *pci_device_root_bus(const PCIDevice *d);
+int pci_find_domain(const PCIDevice *dev);
 PCIDevice *pci_find_device(PCIBus *bus, int bus_num, uint8_t devfn);
 int pci_qdev_find_device(const char *id, PCIDevice **pdev);
 PCIBus *pci_get_bus_devfn(int *devfnp, const char *devaddr);