conf: tests: fix virDomainNetDefFormat for vhost-user in client mode

The mode attribute is required for the source element of vhost-user.
Thus virDomainNetDefFormat should always generate a xml with it and not
only when the mode is server.

The commit fixes the issue. And it adds a vhostuser interface in
'client' mode to qemuxml2argv-net-vhostuser.(args|xml) to test this
usecase.
Signed-off-by: NMaxime Leroy <maxime.leroy@6wind.com>
(cherry picked from commit 30272074)

src/conf/domain_conf.c

@@ -16829,8 +16829,9 @@ virDomainNetDefFormat(virBufferPtr buf,
                 virBufferAddLit(buf, "<source type='unix'");
                 virBufferEscapeString(buf, " path='%s'",
                                       def->data.vhostuser->data.nix.path);
-                if (def->data.vhostuser->data.nix.listen)
-                    virBufferAddLit(buf, " mode='server'");
+                virBufferAsprintf(buf, " mode='%s'",
+                                  def->data.vhostuser->data.nix.listen ?
+                                  "server"  : "client");
                 virBufferAddLit(buf, "/>\n");
             }
             break;

tests/qemuxml2argvdata/qemuxml2argv-net-vhostuser.args

@@ -2,6 +2,9 @@ LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test QEMU_AUDIO_DRV=none \
 /usr/bin/qemu -S -M \
 pc -m 214 -smp 1 -nographic -nodefaults -monitor unix:/tmp/test-monitor,server,nowait \
 -no-acpi -boot c -usb -hda /dev/HostVG/QEMUGuest1 \
--chardev socket,id=charnet0,path=/tmp/vhost.sock,server \
+-chardev socket,id=charnet0,path=/tmp/vhost0.sock,server \
 -netdev type=vhost-user,id=hostnet0,chardev=charnet0 \
--device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:ee:96:6b,bus=pci.0,addr=0x3
+-device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:ee:96:6b,bus=pci.0,addr=0x3 \
+-chardev socket,id=charnet1,path=/tmp/vhost1.sock \
+-netdev type=vhost-user,id=hostnet1,chardev=charnet1 \
+-device virtio-net-pci,netdev=hostnet1,id=net1,mac=52:54:00:ee:96:6c,bus=pci.0,addr=0x4

tests/qemuxml2argvdata/qemuxml2argv-net-vhostuser.xml

@@ -25,7 +25,12 @@
     <controller type='pci' index='0' model='pci-root'/>
     <interface type='vhostuser'>
       <mac address='52:54:00:ee:96:6b'/>
-      <source type='unix' path='/tmp/vhost.sock' mode='server'/>
+      <source type='unix' path='/tmp/vhost0.sock' mode='server'/>
+      <model type='virtio'/>
+    </interface>
+    <interface type='vhostuser'>
+      <mac address='52:54:00:ee:96:6c'/>
+      <source type='unix' path='/tmp/vhost1.sock' mode='client'/>
       <model type='virtio'/>
     </interface>
     <memballoon model='none'/>