vhost-user: add support reconnect for vhost-user ports

For vhost-user ports, Open vSwitch acts as the server and QEMU the client.
When OVS crashed or restart, QEMU shoule be reconnect to OVS.

Signed-off-by: ZhiPeng Lu <lu.zhipeng@zte.com.cn>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>

docs/formatdomain.html.in

@@ -5673,7 +5673,7 @@ qemu-kvm -net nic,model=? /dev/null
   </interface>
   <interface type='vhostuser'>
     <mac address='52:54:00:3b:83:1b'/>
-    <source type='unix' path='/tmp/vhost2.sock' mode='client'/>
+    <source type='unix' path='/tmp/vhost2.sock' mode='client' reconnect='10'/>
     <model type='virtio'/>
     <driver queues='5'/>
   </interface>
@@ -5689,6 +5689,9 @@ qemu-kvm -net nic,model=? /dev/null
       are supported.
       vhost-user requires the virtio model type, thus the
       <code>&lt;model&gt;</code> element is mandatory.
+      <span class="since">Since 3.7.0</span> the element has an optional
+      attribute <code>reconnect</code> which configures reconnect timeout
+      (in seconds) if the connection is lost.
     </p>
 
     <h5><a id="elementNwfilter">Traffic filtering with NWFilter</a></h5>

docs/schemas/domaincommon.rng

@@ -2388,6 +2388,11 @@
                   <value>client</value>
                 </choice>
               </attribute>
+              <optional>
+                <attribute name="reconnect">
+                  <ref name='positiveInteger'/>
+                </attribute>
+              </optional>
               <empty/>
             </element>
             <ref name="interface-options"/>

src/conf/domain_conf.c

@@ -10240,6 +10240,7 @@ virDomainNetDefParseXML(virDomainXMLOptionPtr xmlopt,
     char *vhostuser_mode = NULL;
     char *vhostuser_path = NULL;
     char *vhostuser_type = NULL;
+    char *vhostuser_reconnect = NULL;
     char *trustGuestRxFilters = NULL;
     char *vhost_path = NULL;
     virNWFilterHashTablePtr filterparams = NULL;
@@ -10326,11 +10327,12 @@ virDomainNetDefParseXML(virDomainXMLOptionPtr xmlopt,
                     goto error;
                 }
             } else if (!vhostuser_path && !vhostuser_mode && !vhostuser_type
-                       && def->type == VIR_DOMAIN_NET_TYPE_VHOSTUSER &&
-                       virXMLNodeNameEqual(cur, "source")) {
+                       && !vhostuser_reconnect && def->type == VIR_DOMAIN_NET_TYPE_VHOSTUSER
+                       && virXMLNodeNameEqual(cur, "source")) {
                 vhostuser_type = virXMLPropString(cur, "type");
                 vhostuser_path = virXMLPropString(cur, "path");
                 vhostuser_mode = virXMLPropString(cur, "mode");
+                vhostuser_reconnect = virXMLPropString(cur, "reconnect");
             } else if (!def->virtPortProfile
                        && virXMLNodeNameEqual(cur, "virtualport")) {
                 if (def->type == VIR_DOMAIN_NET_TYPE_NETWORK) {
@@ -10552,8 +10554,24 @@ virDomainNetDefParseXML(virDomainXMLOptionPtr xmlopt,
 
         if (STREQ(vhostuser_mode, "server")) {
             def->data.vhostuser->data.nix.listen = true;
+            if (vhostuser_reconnect) {
+                virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                               _("'reconnect' attribute  unsupported "
+                                 "'server' mode for <interface type='vhostuser'>"));
+                goto error;
+            }
         } else if (STREQ(vhostuser_mode, "client")) {
             def->data.vhostuser->data.nix.listen = false;
+            if (vhostuser_reconnect) {
+                def->data.vhostuser->data.nix.reconnect.enabled = true;
+                if (virStrToLong_ui(vhostuser_reconnect, NULL, 10,
+                                    &def->data.vhostuser->data.nix.reconnect.timeout) < 0) {
+                    virReportError(VIR_ERR_INTERNAL_ERROR,
+                                   _("invalid vhostuser reconnect value %s"),
+                                   vhostuser_reconnect);
+                    goto error;
+                }
+            }
         } else {
             virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
                            _("Wrong <source> 'mode' attribute "
@@ -10998,6 +11016,7 @@ virDomainNetDefParseXML(virDomainXMLOptionPtr xmlopt,
     VIR_FREE(portgroup);
     VIR_FREE(address);
     VIR_FREE(port);
+    VIR_FREE(vhostuser_reconnect);
     VIR_FREE(vhostuser_type);
     VIR_FREE(vhostuser_path);
     VIR_FREE(vhostuser_mode);
@@ -22983,6 +23002,11 @@ virDomainNetDefFormat(virBufferPtr buf,
                 virBufferAsprintf(buf, " mode='%s'",
                                   def->data.vhostuser->data.nix.listen ?
                                   "server"  : "client");
+                if (def->data.vhostuser->data.nix.reconnect.enabled == true) {
+                    virBufferAsprintf(buf, " reconnect='%u'",
+                                      def->data.vhostuser->data.nix.reconnect.timeout);
+                }
+
                 sourceLines++;
             }
             break;

tests/qemuxml2argvdata/qemuxml2argv-net-vhostuser-multiq.args

@@ -32,7 +32,7 @@ addr=0x4 \
 -netdev socket,listen=:2015,id=hostnet2 \
 -device rtl8139,netdev=hostnet2,id=net2,mac=52:54:00:95:db:c0,bus=pci.0,\
 addr=0x5 \
--chardev socket,id=charnet3,path=/tmp/vhost2.sock \
+-chardev socket,id=charnet3,path=/tmp/vhost2.sock,reconnect=10 \
 -netdev vhost-user,chardev=charnet3,queues=4,id=hostnet3 \
 -device virtio-net-pci,mq=on,vectors=10,netdev=hostnet3,id=net3,\
 mac=52:54:00:ee:96:6d,bus=pci.0,addr=0x6

tests/qemuxml2argvdata/qemuxml2argv-net-vhostuser-multiq.xml

@@ -40,7 +40,7 @@
     </interface>
     <interface type='vhostuser'>
       <mac address='52:54:00:ee:96:6d'/>
-      <source type='unix' path='/tmp/vhost2.sock' mode='client'/>
+      <source type='unix' path='/tmp/vhost2.sock' mode='client' reconnect='10'/>
       <model type='virtio'/>
       <driver queues='4'/>
     </interface>