Allow omitting USB port

We were requiring a USB port path in the schema, but not enforcing it.
Omitting the USB port would lead to libvirt formatting it as (null).
Such domain cannot be started and will disappear after libvirtd restart
(since it cannot parse back the XML).

Only format the port if it has been specified and mark it as optional
in the XML schema.

docs/schemas/domaincommon.rng

@@ -4068,9 +4068,11 @@
     <attribute name="bus">
       <ref name="usbAddr"/>
     </attribute>
-    <attribute name="port">
-      <ref name="usbPort"/>
-    </attribute>
+    <optional>
+      <attribute name="port">
+        <ref name="usbPort"/>
+      </attribute>
+    </optional>
   </define>
   <define name="spaprvioaddress">
     <optional>

src/conf/domain_conf.c

@@ -4839,9 +4839,8 @@ virDomainDeviceInfoFormat(virBufferPtr buf,
         break;
 
     case VIR_DOMAIN_DEVICE_ADDRESS_TYPE_USB:
-        virBufferAsprintf(buf, " bus='%d' port='%s'",
-                          info->addr.usb.bus,
-                          info->addr.usb.port);
+        virBufferAsprintf(buf, " bus='%d'", info->addr.usb.bus);
+        virBufferEscapeString(buf, " port='%s'", info->addr.usb.port);
         break;
 
     case VIR_DOMAIN_DEVICE_ADDRESS_TYPE_SPAPRVIO:

src/qemu/qemu_command.c

@@ -375,7 +375,8 @@ qemuBuildDeviceAddressStr(virBufferPtr buf,
                                                        VIR_DOMAIN_CONTROLLER_TYPE_USB,
                                                        info->addr.usb.bus)))
             goto cleanup;
-        virBufferAsprintf(buf, ",bus=%s.0,port=%s", contAlias, info->addr.usb.port);
+        virBufferAsprintf(buf, ",bus=%s.0", contAlias);
+        virBufferEscapeString(buf, ",port=%s", info->addr.usb.port);
     } else if (info->type == VIR_DOMAIN_DEVICE_ADDRESS_TYPE_SPAPRVIO) {
         if (info->addr.spaprvio.has_reg)
             virBufferAsprintf(buf, ",reg=0x%llx", info->addr.spaprvio.reg);

tests/qemuxml2argvdata/qemuxml2argv-usb-port-missing.args

@@ -0,0 +1,26 @@
+LC_ALL=C \
+PATH=/bin \
+HOME=/home/test \
+USER=test \
+LOGNAME=test \
+QEMU_AUDIO_DRV=none \
+/usr/bin/qemu \
+-name QEMUGuest1 \
+-S \
+-M pc \
+-m 214 \
+-smp 1,sockets=1,cores=1,threads=1 \
+-uuid c7a5fdbd-edaf-9455-926a-d65c16db1809 \
+-nographic \
+-nodefconfig \
+-nodefaults \
+-chardev socket,id=charmonitor,path=/tmp/lib/domain--1-QEMUGuest1/monitor.sock,\
+server,nowait \
+-mon chardev=charmonitor,id=monitor,mode=readline \
+-no-acpi \
+-boot c \
+-usb \
+-device usb-hub,id=hub0,bus=usb.0 \
+-device usb-hub,id=hub1,bus=usb.0 \
+-device usb-mouse,id=input0,bus=usb.0 \
+-device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3

tests/qemuxml2argvdata/qemuxml2argv-usb-port-missing.xml

@@ -0,0 +1,25 @@
+<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>
+  <devices>
+    <emulator>/usr/bin/qemu</emulator>
+    <controller type='usb' index='0'/>
+    <memballoon model='virtio'/>
+    <input type='mouse' bus='usb'>
+      <address type='usb' bus='0'/>
+    </input>
+    <hub type='usb'>
+      <address type='usb' bus='0'/>
+    </hub>
+    <hub type='usb'>
+      <address type='usb' bus='0'/>
+    </hub>
+  </devices>
+</domain>

tests/qemuxml2argvtest.c

@@ -1163,6 +1163,9 @@ mymain(void)
     DO_TEST("usb-hub",
             QEMU_CAPS_CHARDEV, QEMU_CAPS_USB_HUB,
             QEMU_CAPS_NODEFCONFIG);
+    DO_TEST("usb-port-missing",
+            QEMU_CAPS_CHARDEV, QEMU_CAPS_USB_HUB,
+            QEMU_CAPS_NODEFCONFIG);
     DO_TEST("usb-ports",
             QEMU_CAPS_CHARDEV, QEMU_CAPS_USB_HUB,
             QEMU_CAPS_NODEFCONFIG);

tests/qemuxml2xmloutdata/qemuxml2xmlout-usb-port-missing.xml

@@ -0,0 +1,36 @@
+<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>
+    <controller type='usb' index='0'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>
+    </controller>
+    <controller type='pci' index='0' model='pci-root'/>
+    <input type='mouse' bus='usb'>
+      <address type='usb' bus='0'/>
+    </input>
+    <input type='mouse' bus='ps2'/>
+    <input type='keyboard' bus='ps2'/>
+    <hub type='usb'>
+      <address type='usb' bus='0'/>
+    </hub>
+    <hub type='usb'>
+      <address type='usb' bus='0'/>
+    </hub>
+    <memballoon model='virtio'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
+    </memballoon>
+  </devices>
+</domain>

tests/qemuxml2xmltest.c

@@ -591,6 +591,7 @@ mymain(void)
     DO_TEST("interface-server");
     DO_TEST("virtio-lun");
 
+    DO_TEST("usb-port-missing");
     DO_TEST("usb-redir");
     DO_TEST("usb-redir-filter");
     DO_TEST("usb-redir-filter-version");