pci: Implement BusInfo.get_dev_path()

This works great for PCI since a <segment>:<bus>:<dev>.<fn> uniquely
describes a global address.  No need to traverse up the qdev tree.
PCI segment support is a placeholder for compatibility once we
support multiple segments.
Signed-off-by: NAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

hw/pci.c

@@ -58,11 +58,13 @@ struct PCIBus {
 };
 
 static void pcibus_dev_print(Monitor *mon, DeviceState *dev, int indent);
+static char *pcibus_get_dev_path(DeviceState *dev);
 
 static struct BusInfo pci_bus_info = {
     .name       = "PCI",
     .size       = sizeof(PCIBus),
     .print_dev  = pcibus_dev_print,
+    .get_dev_path = pcibus_get_dev_path,
     .props      = (Property[]) {
         DEFINE_PROP_PCI_DEVFN("addr", PCIDevice, devfn, -1),
         DEFINE_PROP_STRING("romfile", PCIDevice, romfile),
@@ -1853,6 +1855,18 @@ static void pcibus_dev_print(Monitor *mon, DeviceState *dev, int indent)
     }
 }
 
+static char *pcibus_get_dev_path(DeviceState *dev)
+{
+    PCIDevice *d = (PCIDevice *)dev;
+    char path[16];
+
+    snprintf(path, sizeof(path), "%04x:%02x:%02x.%x",
+             pci_find_domain(d->bus), d->config[PCI_SECONDARY_BUS],
+             PCI_SLOT(d->devfn), PCI_FUNC(d->devfn));
+
+    return strdup(path);
+}
+
 static PCIDeviceInfo bridge_info = {
     .qdev.name    = "pci-bridge",
     .qdev.size    = sizeof(PCIBridge),