virnetdevopenvswitch: Get names for dpdkvhostuserclient too

There are two types of vhostuser ports:

  dpdkvhostuser - OVS creates the socket and QEMU connects to it
  dpdkvhostuserclient - QEMU creates the socket and OVS connects to it

But of course ovs-vsctl syntax for fetching ifname is different.
So far, we've implemented the former. The lack of implementation
for the latter means that we are not detecting the interface name
and thus not reporting it in domain XML, or failing to get
interface statistics.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1767013

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>

src/qemu/qemu_command.c

@@ -8004,6 +8004,7 @@ qemuBuildInterfaceCommandLine(virQEMUDriverPtr driver,
             goto cleanup;
 
         if (virNetDevOpenvswitchGetVhostuserIfname(net->data.vhostuser->data.nix.path,
+                                                   net->data.vhostuser->data.nix.listen,
                                                    &net->ifname) < 0)
             goto cleanup;
 

src/qemu/qemu_hotplug.c

@@ -1305,6 +1305,7 @@ qemuDomainAttachNetDevice(virQEMUDriverPtr driver,
             goto cleanup;
 
         if (virNetDevOpenvswitchGetVhostuserIfname(net->data.vhostuser->data.nix.path,
+                                                   net->data.vhostuser->data.nix.listen,
                                                    &net->ifname) < 0)
             goto cleanup;
 

src/util/virnetdevopenvswitch.c

@@ -469,11 +469,22 @@ virNetDevOpenvswitchInterfaceGetMaster(const char *ifname, char **master)
 
 
 /**
- * virNetDevOpenvswitchVhostuserGetIfname:
+ * virNetDevOpenvswitchGetVhostuserIfname:
  * @path: the path of the unix socket
+ * @server: true if OVS creates the @path
  * @ifname: the retrieved name of the interface
  *
- * Retrieves the ovs ifname from vhostuser unix socket path.
+ * Retrieves the OVS ifname from vhostuser UNIX socket path.
+ * There are two types of vhostuser ports which differ in client/server
+ * role:
+ *
+ * dpdkvhostuser - OVS creates the socket and QEMU connects to it
+ *                 (@server = true)
+ * dpdkvhostuserclient - QEMU creates the socket and OVS connects to it
+ *                       (@server = false)
+ *
+ * Since the way of retrieving ifname is different in these two cases,
+ * caller must set @server according to the interface definition.
  *
  * Returns: 1 if interface is an openvswitch interface,
  *          0 if it is not, but no other error occurred,
@@ -481,33 +492,46 @@ virNetDevOpenvswitchInterfaceGetMaster(const char *ifname, char **master)
  */
 int
 virNetDevOpenvswitchGetVhostuserIfname(const char *path,
+                                       bool server,
                                        char **ifname)
 {
-    const char *tmpIfname = NULL;
-    int status;
     g_autoptr(virCommand) cmd = NULL;
+    int status;
 
-    /* Openvswitch vhostuser path are hardcoded to
+    cmd = virCommandNew(OVS_VSCTL);
+    virNetDevOpenvswitchAddTimeout(cmd);
+
+    if (server) {
+        virCommandAddArgList(cmd, "--no-headings", "--columns=name", "find",
+                             "Interface", NULL);
+        virCommandAddArgPair(cmd, "options:vhost-server-path", "path");
+    } else {
+        const char *tmpIfname = NULL;
+
+        /* Openvswitch vhostuser path is hardcoded to
          * /<runstatedir>/openvswitch/<ifname>
          * for example: /var/run/openvswitch/dpdkvhostuser0
          *
-     * so we pick the filename and check it's a openvswitch interface
+         * so we pick the filename and check it's an openvswitch interface
          */
         if (!path ||
-        !(tmpIfname = strrchr(path, '/')))
+            !(tmpIfname = strrchr(path, '/'))) {
             return 0;
+        }
 
         tmpIfname++;
-    cmd = virCommandNew(OVS_VSCTL);
-    virNetDevOpenvswitchAddTimeout(cmd);
         virCommandAddArgList(cmd, "get", "Interface", tmpIfname, "name", NULL);
-    if (virCommandRun(cmd, &status) < 0 ||
+    }
-        status) {
+
+    virCommandSetOutputBuffer(cmd, ifname);
+    if (virCommandRun(cmd, &status) < 0)
+        return -1;
+
+    if (status != 0) {
         /* it's not a openvswitch vhostuser interface. */
         return 0;
     }
 
-    *ifname = g_strdup(tmpIfname);
     return 1;
 }
 

src/util/virnetdevopenvswitch.h

@@ -61,6 +61,7 @@ int virNetDevOpenvswitchInterfaceGetMaster(const char *ifname, char **master)
     ATTRIBUTE_NONNULL(1) G_GNUC_WARN_UNUSED_RESULT;
 
 int virNetDevOpenvswitchGetVhostuserIfname(const char *path,
+                                           bool server,
                                            char **ifname)
     ATTRIBUTE_NONNULL(2) G_GNUC_WARN_UNUSED_RESULT G_GNUC_NO_INLINE;
 

tests/qemuxml2argvmock.c

@@ -217,6 +217,7 @@ virCommandPassFD(virCommandPtr cmd,
 
 int
 virNetDevOpenvswitchGetVhostuserIfname(const char *path G_GNUC_UNUSED,
+                                       bool server G_GNUC_UNUSED,
                                        char **ifname)
 {
     *ifname = g_strdup("vhost-user0");