Merge pull request #1878 from vivianQizhu/extra_root_port

qemu_vm: Move extra root port to the end of make_create_command

shared/cfg/machines.cfg

@@ -17,7 +17,7 @@ variants:
         # port of pcie-switch, see RHBZ#1380285
         no WinXP Win2000 Win2003 RHEL.5 RHEL.6
         pci_bus = pci.0
-        pcie_extra_root_port = 3
+        pcie_extra_root_port = 1
     - @pseries:
         only ppc64, ppc64le
         machine_type = pseries

virttest/qemu_vm.py

@@ -35,6 +35,7 @@
 from virttest import error_context
 from virttest.compat_52lts import decode_to_text
 from virttest.qemu_devices import qdevices, qcontainer
+from virttest.qemu_devices.utils import DeviceError
 
 
 class QemuSegFaultError(virt_vm.VMError):
@@ -1413,10 +1414,6 @@ def sort_key(dev):
             for pcic in params.objects("pci_controllers"):
                 dev = devices.pcic_by_params(pcic, params.object_params(pcic))
                 pcics.append(dev)
-            pcie_extra_root_port = params.get('pcie_extra_root_port', 0)
-            for num in range(int(pcie_extra_root_port)):
-                pcics.append(devices.pcic_by_params("pcie_root_port_%s" % num,
-                                                    {"type": "pcie-root-port"}))
             if params.get("pci_controllers_autosort", "yes") == "yes":
                 pcics.sort(key=sort_key, reverse=False)
             devices.insert(pcics)
@@ -2342,6 +2339,21 @@ def sort_key(dev):
                 if ats:
                     add_virtio_option("ats", ats, devices, device, dev_type)
 
+        # Add extra root_port at the end of the command line only if there is
+        # free slot on pci.0, discarding them otherwise
+        pcie_extra_root_port = int(params.get('pcie_extra_root_port', 0))
+        for num in range(pcie_extra_root_port):
+            try:
+                dev = devices.pcic_by_params(
+                    "pcie_extra_root_port_%s"
+                    % num, {"type": "pcie-root-port"})
+                devices.insert(dev)
+            except DeviceError:
+                logging.warning("No sufficient free slot for extra"
+                                " root port, discarding %d of them"
+                                % (pcie_extra_root_port - num))
+                break
+
         return devices, spice_options
 
     def _nic_tap_add_helper(self, nic):