conf: restrict expander buses to connect only to a root bus

More misunderstanding/mistaken assumptions on my part - I had thought
that a pci-expander-bus could be plugged into any legacy PCI slot, and
that pcie-expander-bus could be plugged into any PCIe slot. This isn't
correct - they can both be plugged ontly into their respective root
buses. This patch adds that restriction.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1358712

src/conf/domain_addr.c

@@ -51,20 +51,17 @@ virDomainPCIControllerModelToConnectType(virDomainControllerModelPCI model)
         return 0;
 
     case VIR_DOMAIN_CONTROLLER_MODEL_PCI_BRIDGE:
-    case VIR_DOMAIN_CONTROLLER_MODEL_PCI_EXPANDER_BUS:
-        /* pci-bridge and pci-expander-bus are treated like a standard
-         * PCI endpoint device, because they can plug into any
-         * standard PCI slot.
+        /* pci-bridge is treated like a standard
+         * PCI endpoint device, because it can plug into any
+         * standard PCI slot (it just can't be hotplugged).
          */
         return VIR_PCI_CONNECT_TYPE_PCI_DEVICE;
 
+    case VIR_DOMAIN_CONTROLLER_MODEL_PCI_EXPANDER_BUS:
+        return VIR_PCI_CONNECT_TYPE_PCI_EXPANDER_BUS;
+
     case VIR_DOMAIN_CONTROLLER_MODEL_PCIE_EXPANDER_BUS:
-        /* pcie-expander-bus is treated like a standard PCIe endpoint
-         * device (the part of pcie-expander-bus that is plugged in
-         * isn't the expander bus itself, but a companion device used
-         * for setting it up).
-         */
-        return VIR_PCI_CONNECT_TYPE_PCIE_DEVICE;
+        return VIR_PCI_CONNECT_TYPE_PCIE_EXPANDER_BUS;
 
     case VIR_DOMAIN_CONTROLLER_MODEL_DMI_TO_PCI_BRIDGE:
         return VIR_PCI_CONNECT_TYPE_DMI_TO_PCI_BRIDGE;
@@ -137,6 +134,10 @@ virDomainPCIAddressFlagsCompatible(virPCIDeviceAddressPtr addr,
             connectStr = "pci-switch-downstream-port";
         } else if (devFlags & VIR_PCI_CONNECT_TYPE_DMI_TO_PCI_BRIDGE) {
             connectStr = "dmi-to-pci-bridge";
+        } else if (devFlags & VIR_PCI_CONNECT_TYPE_PCI_EXPANDER_BUS) {
+            connectStr = "pci-expander-bus";
+        } else if (devFlags & VIR_PCI_CONNECT_TYPE_PCIE_EXPANDER_BUS) {
+            connectStr = "pcie-expander-bus";
         } else {
             /* this should never happen. If it does, there is a
              * bug in the code that sets the flag bits for devices.
@@ -243,8 +244,14 @@ virDomainPCIAddressBusSetModel(virDomainPCIAddressBusPtr bus,
      * bus.
      */
     switch (model) {
-    case VIR_DOMAIN_CONTROLLER_MODEL_PCI_BRIDGE:
     case VIR_DOMAIN_CONTROLLER_MODEL_PCI_ROOT:
+        bus->flags = (VIR_PCI_CONNECT_HOTPLUGGABLE |
+                      VIR_PCI_CONNECT_TYPE_PCI_DEVICE |
+                      VIR_PCI_CONNECT_TYPE_PCI_EXPANDER_BUS);
+        bus->minSlot = 1;
+        bus->maxSlot = VIR_PCI_ADDRESS_SLOT_LAST;
+        break;
+    case VIR_DOMAIN_CONTROLLER_MODEL_PCI_BRIDGE:
         bus->flags = (VIR_PCI_CONNECT_HOTPLUGGABLE |
                       VIR_PCI_CONNECT_TYPE_PCI_DEVICE);
         bus->minSlot = 1;
@@ -265,7 +272,8 @@ virDomainPCIAddressBusSetModel(virDomainPCIAddressBusPtr bus,
          */
         bus->flags = (VIR_PCI_CONNECT_TYPE_PCIE_DEVICE |
                       VIR_PCI_CONNECT_TYPE_PCIE_ROOT_PORT |
-                      VIR_PCI_CONNECT_TYPE_DMI_TO_PCI_BRIDGE);
+                      VIR_PCI_CONNECT_TYPE_DMI_TO_PCI_BRIDGE |
+                      VIR_PCI_CONNECT_TYPE_PCIE_EXPANDER_BUS);
         bus->minSlot = 1;
         bus->maxSlot = VIR_PCI_ADDRESS_SLOT_LAST;
         break;

src/conf/domain_addr.h

@@ -41,6 +41,8 @@ typedef enum {
    VIR_PCI_CONNECT_TYPE_PCIE_SWITCH_UPSTREAM_PORT = 1 << 4,
    VIR_PCI_CONNECT_TYPE_PCIE_SWITCH_DOWNSTREAM_PORT = 1 << 5,
    VIR_PCI_CONNECT_TYPE_DMI_TO_PCI_BRIDGE = 1 << 6,
+   VIR_PCI_CONNECT_TYPE_PCI_EXPANDER_BUS = 1 << 7,
+   VIR_PCI_CONNECT_TYPE_PCIE_EXPANDER_BUS = 1 << 8,
 } virDomainPCIConnectFlags;
 
 /* a combination of all bits that describe the type of connections
@@ -51,7 +53,9 @@ typedef enum {
     VIR_PCI_CONNECT_TYPE_PCIE_SWITCH_UPSTREAM_PORT | \
     VIR_PCI_CONNECT_TYPE_PCIE_SWITCH_DOWNSTREAM_PORT | \
     VIR_PCI_CONNECT_TYPE_PCIE_ROOT_PORT | \
-    VIR_PCI_CONNECT_TYPE_DMI_TO_PCI_BRIDGE)
+    VIR_PCI_CONNECT_TYPE_DMI_TO_PCI_BRIDGE | \
+    VIR_PCI_CONNECT_TYPE_PCI_EXPANDER_BUS | \
+    VIR_PCI_CONNECT_TYPE_PCIE_EXPANDER_BUS)
 
 /* combination of all bits that could be used to connect a normal
  * endpoint device (i.e. excluding the connection possible between an

tests/qemuxml2argvdata/qemuxml2argv-pci-expander-bus-bad-bus.xml

+<domain type='qemu'>
+  <name>expander-test</name>
+  <uuid>3ec6cbe1-b5a2-4515-b800-31a61855df41</uuid>
+  <memory unit='KiB'>219100</memory>
+  <currentMemory unit='KiB'>219100</currentMemory>
+  <vcpu placement='static'>16</vcpu>
+  <os>
+    <type arch='x86_64' machine='pc-i440fx-2.5'>hvm</type>
+  </os>
+  <devices>
+    <emulator>/usr/bin/qemu-system-x86_64</emulator>
+    <controller type='usb' index='0' model='none'/>
+    <controller type='ide' index='0'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
+    </controller>
+    <controller type='pci' index='0' model='pci-root'/>
+    <controller type='pci' index='1' model='pci-bridge'>
+    </controller>
+    <controller type='pci' index='2' model='pci-expander-bus'>
+      <address type='pci' bus='1' slot='1'/>
+    </controller>
+    <input type='mouse' bus='ps2'/>
+    <input type='keyboard' bus='ps2'/>
+    <memballoon model='none'/>
+  </devices>
+</domain>

tests/qemuxml2argvdata/qemuxml2argv-pcie-expander-bus-bad-bus.xml

+<domain type='qemu'>
+  <name>pcie-expander-bus-test</name>
+  <uuid>11dbdcdd-4c3b-482b-8903-9bdb8c0a2774</uuid>
+  <memory unit='KiB'>2097152</memory>
+  <currentMemory unit='KiB'>2097152</currentMemory>
+  <vcpu placement='static'>16</vcpu>
+  <os>
+    <type arch='x86_64' machine='q35'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <cpu>
+    <topology sockets='2' cores='4' threads='2'/>
+    <numa>
+      <cell cpus='0-7' memory='109550' unit='KiB'/>
+      <cell cpus='8-15' memory='109550' unit='KiB'/>
+    </numa>
+  </cpu>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/libexec/qemu-kvm</emulator>
+    <disk type='block' device='disk'>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='sda' bus='sata'/>
+      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
+    </disk>
+    <controller type='pci' index='0' model='pcie-root'/>
+    <controller type='pci' index='1' model='dmi-to-pci-bridge'>
+      <model name='i82801b11-bridge'/>
+    </controller>
+    <controller type='pci' index='2' model='pci-bridge'>
+      <model name='pci-bridge'/>
+      <target chassisNr='56'/>
+    </controller>
+    <controller type='pci' index='3' model='pcie-root-port'>
+      <target busNr='220'>
+        <node>1</node>
+      </target>
+      <address type='pci' bus='0x00'/>
+    </controller>
+    <controller type='pci' index='4' model='pcie-expander-bus'>
+      <address type='pci' bus='3'/>
+    </controller>
+    <memballoon model='none'/>
+  </devices>
+</domain>

tests/qemuxml2argvtest.c

@@ -1731,6 +1731,9 @@ mymain(void)
     DO_TEST_PARSE_ERROR("pci-expander-bus-bad-machine",
                         QEMU_CAPS_DEVICE_PCI_BRIDGE,
                         QEMU_CAPS_DEVICE_PXB);
+    DO_TEST_PARSE_ERROR("pci-expander-bus-bad-bus",
+                        QEMU_CAPS_DEVICE_PCI_BRIDGE,
+                        QEMU_CAPS_DEVICE_PXB);
 
     DO_TEST("pcie-expander-bus",
             QEMU_CAPS_DEVICE_PCI_BRIDGE,
@@ -1746,6 +1749,11 @@ mymain(void)
                         QEMU_CAPS_DEVICE_X3130_UPSTREAM,
                         QEMU_CAPS_DEVICE_XIO3130_DOWNSTREAM,
                         QEMU_CAPS_DEVICE_PXB_PCIE);
+    DO_TEST_PARSE_ERROR("pcie-expander-bus-bad-bus",
+                        QEMU_CAPS_DEVICE_PCI_BRIDGE,
+                        QEMU_CAPS_DEVICE_DMI_TO_PCI_BRIDGE,
+                        QEMU_CAPS_DEVICE_IOH3420,
+                        QEMU_CAPS_DEVICE_PXB_PCIE);
 
     DO_TEST("hostdev-scsi-lsi",
             QEMU_CAPS_VIRTIO_SCSI, QEMU_CAPS_SCSI_LSI,