qemu: Use PHBs to fill holes in PCI bus numbering

PCI bus has to be numbered sequentially, and no index can be
missing, so libvirt will fill in the blanks automatically for
the user.

Up until now, it has done so using either pci-bridge, for machine
types based on legacy PCI, or pcie-root-port, for machine types
based on PCI Express. Neither choice is good for pSeries guests,
where PHBs (pci-root) should be used instead.

Signed-off-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: Laine Stump <laine@laine.org>

src/qemu/qemu_domain_address.c

@@ -1097,10 +1097,14 @@ qemuDomainPCIAddressSetCreate(virDomainDefPtr def,
      * that don't yet have a corresponding controller in the domain
      * config.
      */
-    if (hasPCIeRoot)
+    if (qemuDomainIsPSeries(def)) {
+        /* pSeries guests should use PHBs (pci-root controllers) */
+        defaultModel = VIR_DOMAIN_CONTROLLER_MODEL_PCI_ROOT;
+    } else if (hasPCIeRoot) {
         defaultModel = VIR_DOMAIN_CONTROLLER_MODEL_PCIE_ROOT_PORT;
-    else
+    } else {
         defaultModel = VIR_DOMAIN_CONTROLLER_MODEL_PCI_BRIDGE;
+    }
 
     for (i = 1; i < addrs->nbuses; i++) {
 
@@ -2160,7 +2164,13 @@ qemuDomainAssignPCIAddresses(virDomainDefPtr def,
             dev.data.controller = def->controllers[contIndex];
             /* set connect flags so it will be properly addressed */
             qemuDomainFillDevicePCIConnectFlags(def, &dev, qemuCaps, driver);
-            if (qemuDomainPCIAddressReserveNextAddr(addrs,
+
+            /* Reserve an address for the controller. pci-root and pcie-root
+             * controllers don't plug into any other PCI controller, hence
+             * they should skip this step */
+            if (bus->model != VIR_DOMAIN_CONTROLLER_MODEL_PCI_ROOT &&
+                bus->model != VIR_DOMAIN_CONTROLLER_MODEL_PCIE_ROOT &&
+                qemuDomainPCIAddressReserveNextAddr(addrs,
                                                     &dev.data.controller->info) < 0) {
                 goto cleanup;
             }

tests/qemuxml2argvdata/qemuxml2argv-pseries-many-buses-2.args

@@ -19,4 +19,4 @@ server,nowait \
 -mon chardev=charmonitor,id=monitor,mode=readline \
 -boot c \
 -device spapr-pci-host-bridge,index=1,id=pci.2 \
--device pci-bridge,chassis_nr=1,id=pci.1,bus=pci.0,addr=0x1
+-device spapr-pci-host-bridge,index=2,id=pci.1

tests/qemuxml2argvtest.c

@@ -1767,7 +1767,6 @@ mymain(void)
     DO_TEST("pseries-many-buses-2",
             QEMU_CAPS_NODEFCONFIG,
             QEMU_CAPS_DEVICE_SPAPR_PCI_HOST_BRIDGE,
-            QEMU_CAPS_DEVICE_PCI_BRIDGE,
             QEMU_CAPS_VIRTIO_SCSI);
     DO_TEST("pseries-hostdevs-1",
             QEMU_CAPS_NODEFCONFIG,

tests/qemuxml2xmloutdata/qemuxml2xmlout-pseries-many-buses-2.xml

@@ -23,10 +23,9 @@
       <target index='1'/>
     </controller>
     <controller type='usb' index='0' model='none'/>
-    <controller type='pci' index='1' model='pci-bridge'>
-      <model name='pci-bridge'/>
-      <target chassisNr='1'/>
-      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'/>
+    <controller type='pci' index='1' model='pci-root'>
+      <model name='spapr-pci-host-bridge'/>
+      <target index='2'/>
     </controller>
     <memballoon model='none'/>
     <panic model='pseries'/>

tests/qemuxml2xmltest.c

@@ -686,7 +686,6 @@ mymain(void)
     DO_TEST("pseries-many-buses-2",
             QEMU_CAPS_NODEFCONFIG,
             QEMU_CAPS_DEVICE_SPAPR_PCI_HOST_BRIDGE,
-            QEMU_CAPS_DEVICE_PCI_BRIDGE,
             QEMU_CAPS_VIRTIO_SCSI);
     DO_TEST("pseries-hostdevs-1",
             QEMU_CAPS_NODEFCONFIG,