qemuBuildInterfaceCommandLine: Move hostdev handling a bit further

The idea is to have function that does some checking of the
arguments at its beginning and then have one big switch for all
the interface types it supports. Each one of them generating the
corresponding part of the command line.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>

src/qemu/qemu_command.c

@@ -7881,13 +7881,6 @@ qemuBuildInterfaceCommandLine(virCommandPtr cmd,
     if (actualType == VIR_DOMAIN_NET_TYPE_VHOSTUSER)
         return qemuBuildVhostuserCommandLine(cmd, def, net, qemuCaps, bootindex);
 
-    if (actualType == VIR_DOMAIN_NET_TYPE_HOSTDEV) {
-        /* NET_TYPE_HOSTDEV devices are really hostdev devices, so
-         * their commandlines are constructed with other hostdevs.
-         */
-        return 0;
-    }
-
     /* Currently nothing besides TAP devices supports multiqueue. */
     if (net->driver.virtio.queues > 0 &&
         !(actualType == VIR_DOMAIN_NET_TYPE_NETWORK ||
@@ -7967,6 +7960,12 @@ qemuBuildInterfaceCommandLine(virCommandPtr cmd,
         if (qemuInterfaceEthernetConnect(def, driver, net,
                                        tapfd, tapfdSize) < 0)
             goto cleanup;
+    } else if (actualType == VIR_DOMAIN_NET_TYPE_HOSTDEV) {
+        /* NET_TYPE_HOSTDEV devices are really hostdev devices, so
+         * their commandlines are constructed with other hostdevs.
+         */
+        ret = 0;
+        goto cleanup;
     }
 
     /* For types whose implementations use a netdev on the host, add

tests/qemuxml2argvdata/qemuxml2argv-net-hostdev-fail.xml

+<domain type='qemu'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory unit='KiB'>219136</memory>
+  <currentMemory unit='KiB'>219136</currentMemory>
+  <vcpu placement='static'>1</vcpu>
+  <os>
+    <type arch='i686' machine='pc'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu</emulator>
+    <disk type='block' device='disk'>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='hda' bus='ide'/>
+      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
+    </disk>
+    <controller type='usb' index='0'/>
+    <controller type='ide' index='0'/>
+    <controller type='pci' index='0' model='pci-root'/>
+    <interface type='hostdev' managed='yes'>
+      <mac address='00:11:22:33:44:55'/>
+      <source>
+        <address type='pci' domain='0x0000' bus='0x03' slot='0x07' function='0x1'/>
+      </source>
+      <model type='virtio'/>
+      <filterref filter='myfilter'/>
+      <backend tap='/dev/mytap'/>
+      <driver queues='4'/>
+    </interface>
+    <input type='mouse' bus='ps2'/>
+    <input type='keyboard' bus='ps2'/>
+    <memballoon model='virtio'/>
+  </devices>
+</domain>

tests/qemuxml2argvtest.c

@@ -1109,6 +1109,10 @@ mymain(void)
             QEMU_CAPS_DEVICE_VFIO_PCI, QEMU_CAPS_HOST_PCI_MULTIDOMAIN);
     DO_TEST_FAILURE("net-hostdev-vfio-multidomain",
                     QEMU_CAPS_NODEFCONFIG, QEMU_CAPS_DEVICE_VFIO_PCI);
+    DO_TEST_FAILURE("net-hostdev-fail",
+                    QEMU_CAPS_NODEFCONFIG,
+                    QEMU_CAPS_DEVICE_VFIO_PCI);
+
 
     DO_TEST("serial-vc", NONE);
     DO_TEST("serial-pty", NONE);