qemu: Adapt qemuBuildInterfaceCommandLine to to multiqueue net

In order to learn libvirt multiqueue several things must be done:

1) The '/dev/net/tun' device needs to be opened multiple times with
IFF_MULTI_QUEUE flag passed to ioctl(fd, TUNSETIFF, &ifr);

2) Similarly, '/dev/vhost-net' must be opened as many times as in 1)
in order to keep 1:1 ratio recommended by qemu and kernel folks.

3) The command line construction code needs to switch from 'fd=X' to
'fds=X:Y:...:Z' and from 'vhostfd=X' to 'vhostfds=X:Y:...:Z'.

4) The monitor handling code needs to learn to pass multiple FDs.

src/network/bridge_driver.c

@@ -2495,7 +2495,7 @@ networkStartNetworkVirtual(struct network_driver *driver,
         /* Keep tun fd open and interface up to allow for IPv6 DAD to happen */
         if (virNetDevTapCreateInBridgePort(network->def->bridge,
                                            &macTapIfName, &network->def->mac,
-                                           NULL, &tapfd, NULL, NULL,
+                                           NULL, &tapfd, 1, NULL, NULL,
                                            VIR_NETDEV_TAP_CREATE_USE_MAC_FOR_BRIDGE |
                                            VIR_NETDEV_TAP_CREATE_IFUP |
                                            VIR_NETDEV_TAP_CREATE_PERSIST) < 0) {

src/qemu/qemu_command.c

@@ -281,11 +281,12 @@ qemuNetworkIfaceConnect(virDomainDefPtr def,
                         virConnectPtr conn,
                         virQEMUDriverPtr driver,
                         virDomainNetDefPtr net,
-                        virQEMUCapsPtr qemuCaps)
+                        virQEMUCapsPtr qemuCaps,
+                        int *tapfd,
+                        int *tapfdSize)
 {
     char *brname = NULL;
-    int err;
+    int ret = -1;
-    int tapfd = -1;
     unsigned int tap_create_flags = VIR_NETDEV_TAP_CREATE_IFUP;
     bool template_ifname = false;
     int actualType = virDomainNetGetActualType(net);
@@ -297,7 +298,7 @@ qemuNetworkIfaceConnect(virDomainDefPtr def,
         virNetworkPtr network = virNetworkLookupByName(conn,
                                                        net->data.network.name);
         if (!network)
-            return -1;
+            return ret;
 
         active = virNetworkIsActive(network);
         if (active != 1) {
@@ -322,18 +323,18 @@ qemuNetworkIfaceConnect(virDomainDefPtr def,
         virFreeError(errobj);
 
         if (fail)
-            return -1;
+            return ret;
 
     } else if (actualType == VIR_DOMAIN_NET_TYPE_BRIDGE) {
         if (!(brname = strdup(virDomainNetGetActualBridgeName(net)))) {
             virReportOOMError();
-            return -1;
+            return ret;
         }
     } else {
         virReportError(VIR_ERR_INTERNAL_ERROR,
                        _("Network type %d is not supported"),
                        virDomainNetGetActualType(net));
-        return -1;
+        return ret;
     }
 
     if (!net->ifname ||
@@ -353,68 +354,97 @@ qemuNetworkIfaceConnect(virDomainDefPtr def,
         tap_create_flags |= VIR_NETDEV_TAP_CREATE_VNET_HDR;
     }
 
-    if (cfg->privileged)
+    if (cfg->privileged) {
-        err = virNetDevTapCreateInBridgePort(brname, &net->ifname, &net->mac,
+        if (virNetDevTapCreateInBridgePort(brname, &net->ifname, &net->mac,
-                                             def->uuid, &tapfd,
+                                           def->uuid, tapfd, *tapfdSize,
                                            virDomainNetGetActualVirtPortProfile(net),
                                            virDomainNetGetActualVlan(net),
-                                             tap_create_flags);
+                                           tap_create_flags) < 0) {
-    else
+            virDomainAuditNetDevice(def, net, "/dev/net/tun", false);
-        err = qemuCreateInBridgePortWithHelper(cfg, brname,
+            goto cleanup;
+        }
+    } else {
+        if (qemuCreateInBridgePortWithHelper(cfg, brname,
                                              &net->ifname,
-                                               &tapfd, tap_create_flags);
+                                             tapfd, tap_create_flags) < 0) {
-
+            virDomainAuditNetDevice(def, net, "/dev/net/tun", false);
-    virDomainAuditNetDevice(def, net, "/dev/net/tun", tapfd >= 0);
+            goto cleanup;
-    if (err < 0) {
+        }
-        if (template_ifname)
+        /* qemuCreateInBridgePortWithHelper can only create a single FD */
-            VIR_FREE(net->ifname);
+        if (*tapfdSize > 1) {
-        tapfd = -1;
+            VIR_WARN("Ignoring multiqueue network request");
+            *tapfdSize = 1;
+        }
     }
 
-    if (cfg->macFilter) {
+    virDomainAuditNetDevice(def, net, "/dev/net/tun", true);
-        if ((err = networkAllowMacOnPort(driver, net->ifname, &net->mac))) {
+
-            virReportSystemError(err,
+    if (cfg->macFilter &&
-                 _("failed to add ebtables rule to allow MAC address on '%s'"),
+        (ret = networkAllowMacOnPort(driver, net->ifname, &net->mac)) < 0) {
+        virReportSystemError(ret,
+                             _("failed to add ebtables rule "
+                               "to allow MAC address on '%s'"),
                              net->ifname);
     }
-    }
 
-    if (tapfd >= 0 &&
+    if (virNetDevBandwidthSet(net->ifname,
-        virNetDevBandwidthSet(net->ifname,
                               virDomainNetGetActualBandwidth(net),
                               false) < 0) {
         virReportError(VIR_ERR_INTERNAL_ERROR,
                        _("cannot set bandwidth limits on %s"),
                        net->ifname);
-        VIR_FORCE_CLOSE(tapfd);
         goto cleanup;
     }
 
-    if (tapfd >= 0) {
+    if (net->filter && net->ifname &&
-        if ((net->filter) && (net->ifname)) {
+        virDomainConfNWFilterInstantiate(conn, def->uuid, net) < 0) {
-            if (virDomainConfNWFilterInstantiate(conn, def->uuid, net) < 0)
+        goto cleanup;
-                VIR_FORCE_CLOSE(tapfd);
-        }
     }
 
+    ret = 0;
+
 cleanup:
+    if (ret < 0) {
+        int i;
+        for (i = 0; i < *tapfdSize; i++)
+            VIR_FORCE_CLOSE(tapfd[i]);
+        if (template_ifname)
+            VIR_FREE(net->ifname);
+    }
     VIR_FREE(brname);
     virObjectUnref(cfg);
 
-    return tapfd;
+    return ret;
 }
 
 
+/**
+ * qemuOpenVhostNet:
+ * @def: domain definition
+ * @net: network definition
+ * @qemuCaps: qemu binary capabilities
+ * @vhostfd: array of opened vhost-net device
+ * @vhostfdSize: number of file descriptors in @vhostfd array
+ *
+ * Open vhost-net, multiple times - if requested.
+ * In case, no vhost-net is needed, @vhostfdSize is set to 0
+ * and 0 is returned.
+ *
+ * Returns: 0 on success
+ *         -1 on failure
+ */
 int
 qemuOpenVhostNet(virDomainDefPtr def,
                  virDomainNetDefPtr net,
                  virQEMUCapsPtr qemuCaps,
-                 int *vhostfd)
+                 int *vhostfd,
+                 int *vhostfdSize)
 {
-    *vhostfd = -1;   /* assume we won't use vhost */
+    int i;
 
     /* If the config says explicitly to not use vhost, return now */
     if (net->driver.virtio.name == VIR_DOMAIN_NET_BACKEND_TYPE_QEMU) {
+        *vhostfdSize = 0;
         return 0;
     }
 
@@ -430,6 +460,7 @@ qemuOpenVhostNet(virDomainDefPtr def,
                                    "this QEMU binary"));
             return -1;
         }
+        *vhostfdSize = 0;
         return 0;
     }
 
@@ -441,23 +472,34 @@ qemuOpenVhostNet(virDomainDefPtr def,
                                    "virtio network interfaces"));
             return -1;
         }
+        *vhostfdSize = 0;
         return 0;
     }
 
-    *vhostfd = open("/dev/vhost-net", O_RDWR);
+    for (i = 0; i < *vhostfdSize; i++) {
-    virDomainAuditNetDevice(def, net, "/dev/vhost-net", *vhostfd >= 0);
+        vhostfd[i] = open("/dev/vhost-net", O_RDWR);
 
         /* If the config says explicitly to use vhost and we couldn't open it,
          * report an error.
          */
-    if ((*vhostfd < 0) &&
+        if (vhostfd[i] < 0) {
-        (net->driver.virtio.name == VIR_DOMAIN_NET_BACKEND_TYPE_VHOST)) {
+            virDomainAuditNetDevice(def, net, "/dev/vhost-net", false);
+            if (net->driver.virtio.name == VIR_DOMAIN_NET_BACKEND_TYPE_VHOST) {
                 virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
                                "%s", _("vhost-net was requested for an interface, "
                                        "but is unavailable"));
-        return -1;
+                goto error;
             }
+        }
+    }
+    virDomainAuditNetDevice(def, net, "/dev/vhost-net", *vhostfdSize);
     return 0;
+
+error:
+    while (i--)
+        VIR_FORCE_CLOSE(vhostfd[i]);
+
+    return -1;
 }
 
 int
@@ -4109,13 +4151,16 @@ qemuBuildHostNetStr(virDomainNetDefPtr net,
                     virQEMUDriverPtr driver,
                     char type_sep,
                     int vlan,
-                    const char *tapfd,
+                    char **tapfd,
-                    const char *vhostfd)
+                    int tapfdSize,
+                    char **vhostfd,
+                    int vhostfdSize)
 {
     bool is_tap = false;
     virBuffer buf = VIR_BUFFER_INITIALIZER;
     enum virDomainNetType netType = virDomainNetGetActualType(net);
     virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
+    int i;
 
     if (net->script && netType != VIR_DOMAIN_NET_TYPE_ETHERNET) {
         virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
@@ -4134,7 +4179,19 @@ qemuBuildHostNetStr(virDomainNetDefPtr net,
     case VIR_DOMAIN_NET_TYPE_BRIDGE:
     case VIR_DOMAIN_NET_TYPE_NETWORK:
     case VIR_DOMAIN_NET_TYPE_DIRECT:
-        virBufferAsprintf(&buf, "tap%cfd=%s", type_sep, tapfd);
+        virBufferAsprintf(&buf, "tap%c", type_sep);
+        /* for one tapfd 'fd=' shall be used,
+         * for more than one 'fds=' is the right choice */
+        if (tapfdSize == 1) {
+            virBufferAsprintf(&buf, "fd=%s", tapfd[0]);
+        } else {
+            virBufferAddLit(&buf, "fds=");
+            for (i = 0; i < tapfdSize; i++) {
+                if (i)
+                    virBufferAddChar(&buf, ':');
+                virBufferAdd(&buf, tapfd[i], -1);
+            }
+        }
         type_sep = ',';
         is_tap = true;
         break;
@@ -4194,8 +4251,19 @@ qemuBuildHostNetStr(virDomainNetDefPtr net,
     }
 
     if (is_tap) {
-        if (vhostfd && *vhostfd)
+        if (vhostfdSize) {
-            virBufferAsprintf(&buf, ",vhost=on,vhostfd=%s", vhostfd);
+            virBufferAddLit(&buf, ",vhost=on,");
+            if (vhostfdSize == 1) {
+                virBufferAsprintf(&buf, "vhostfd=%s", vhostfd[0]);
+            } else {
+                virBufferAddLit(&buf, "vhostfds=");
+                for (i = 0; i < vhostfdSize; i++) {
+                    if (i)
+                        virBufferAddChar(&buf, ':');
+                    virBufferAdd(&buf, vhostfd[i], -1);
+                }
+            }
+        }
         if (net->tune.sndbuf_specified)
             virBufferAsprintf(&buf, ",sndbuf=%lu", net->tune.sndbuf);
     }
@@ -6431,12 +6499,15 @@ qemuBuildInterfaceCommandLine(virCommandPtr cmd,
                               enum virNetDevVPortProfileOp vmop)
 {
     int ret = -1;
-    int tapfd = -1;
-    int vhostfd = -1;
     char *nic = NULL, *host = NULL;
-    char *tapfdName = NULL;
+    int *tapfd = NULL;
-    char *vhostfdName = NULL;
+    int tapfdSize = 0;
+    int *vhostfd = NULL;
+    int vhostfdSize = 0;
+    char **tapfdName = NULL;
+    char **vhostfdName = NULL;
     int actualType = virDomainNetGetActualType(net);
+    int i;
 
     if (actualType == VIR_DOMAIN_NET_TYPE_HOSTDEV) {
         /* NET_TYPE_HOSTDEV devices are really hostdev devices, so
@@ -6450,12 +6521,24 @@ qemuBuildInterfaceCommandLine(virCommandPtr cmd,
 
     if (actualType == VIR_DOMAIN_NET_TYPE_NETWORK ||
         actualType == VIR_DOMAIN_NET_TYPE_BRIDGE) {
-        tapfd = qemuNetworkIfaceConnect(def, conn, driver, net, qemuCaps);
+        if (VIR_ALLOC(tapfd) < 0 || VIR_ALLOC(tapfdName) < 0) {
-        if (tapfd < 0)
+            virReportOOMError();
+            goto cleanup;
+        }
+
+        tapfdSize = 1;
+        if (qemuNetworkIfaceConnect(def, conn, driver, net,
+                                    qemuCaps, tapfd, &tapfdSize) < 0)
             goto cleanup;
     } else if (actualType == VIR_DOMAIN_NET_TYPE_DIRECT) {
-        tapfd = qemuPhysIfaceConnect(def, driver, net, qemuCaps, vmop);
+        if (VIR_ALLOC(tapfd) < 0 || VIR_ALLOC(tapfdName) < 0) {
-        if (tapfd < 0)
+            virReportOOMError();
+            goto cleanup;
+        }
+        tapfdSize = 1;
+        tapfd[0] = qemuPhysIfaceConnect(def, driver, net,
+                                        qemuCaps, vmop);
+        if (tapfd[0] < 0)
             goto cleanup;
     }
 
@@ -6465,25 +6548,33 @@ qemuBuildInterfaceCommandLine(virCommandPtr cmd,
         actualType == VIR_DOMAIN_NET_TYPE_DIRECT) {
         /* Attempt to use vhost-net mode for these types of
            network device */
-        if (qemuOpenVhostNet(def, net, qemuCaps, &vhostfd) < 0)
+        if (VIR_ALLOC(vhostfd) < 0 || VIR_ALLOC(vhostfdName)) {
+            virReportOOMError();
+            goto cleanup;
+        }
+        vhostfdSize = 1;
+
+        if (qemuOpenVhostNet(def, net, qemuCaps, vhostfd, &vhostfdSize) < 0)
             goto cleanup;
     }
 
-    if (tapfd >= 0) {
+    for (i = 0; i < tapfdSize; i++) {
-        virCommandTransferFD(cmd, tapfd);
+        virCommandTransferFD(cmd, tapfd[i]);
-        if (virAsprintf(&tapfdName, "%d", tapfd) < 0) {
+        if (virAsprintf(&tapfdName[i], "%d", tapfd[i]) < 0) {
             virReportOOMError();
             goto cleanup;
         }
     }
 
-    if (vhostfd >= 0) {
+    for (i = 0; i < vhostfdSize; i++) {
-        virCommandTransferFD(cmd, vhostfd);
+        if (vhostfd[i] >= 0) {
-        if (virAsprintf(&vhostfdName, "%d", vhostfd) < 0) {
+            virCommandTransferFD(cmd, vhostfd[i]);
+            if (virAsprintf(&vhostfdName[i], "%d", vhostfd[i]) < 0) {
                 virReportOOMError();
                 goto cleanup;
             }
         }
+    }
 
     /* Possible combinations:
      *
@@ -6496,8 +6587,9 @@ qemuBuildInterfaceCommandLine(virCommandPtr cmd,
     if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_NETDEV) &&
         virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE)) {
         if (!(host = qemuBuildHostNetStr(net, driver,
-                                         ',', vlan, tapfdName,
+                                         ',', vlan,
-                                         vhostfdName)))
+                                         tapfdName, tapfdSize,
+                                         vhostfdName, vhostfdSize)))
             goto cleanup;
         virCommandAddArgList(cmd, "-netdev", host, NULL);
     }
@@ -6513,8 +6605,9 @@ qemuBuildInterfaceCommandLine(virCommandPtr cmd,
     if (!(virQEMUCapsGet(qemuCaps, QEMU_CAPS_NETDEV) &&
           virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE))) {
         if (!(host = qemuBuildHostNetStr(net, driver,
-                                         ',', vlan, tapfdName,
+                                         ',', vlan,
-                                         vhostfdName)))
+                                         tapfdName, tapfdSize,
+                                         vhostfdName, vhostfdSize)))
             goto cleanup;
         virCommandAddArgList(cmd, "-net", host, NULL);
     }
@@ -6523,6 +6616,18 @@ qemuBuildInterfaceCommandLine(virCommandPtr cmd,
 cleanup:
     if (ret < 0)
         virDomainConfNWFilterTeardown(net);
+    for (i = 0; i < tapfdSize; i++) {
+        if (ret < 0)
+            VIR_FORCE_CLOSE(tapfd[i]);
+        VIR_FREE(tapfdName[i]);
+    }
+    for (i = 0; i < vhostfdSize; i++) {
+        if (ret < 0)
+            VIR_FORCE_CLOSE(vhostfd[i]);
+        VIR_FREE(vhostfdName[i]);
+    }
+    VIR_FREE(tapfd);
+    VIR_FREE(vhostfd);
     VIR_FREE(nic);
     VIR_FREE(host);
     VIR_FREE(tapfdName);

src/qemu/qemu_command.h

@@ -87,8 +87,10 @@ char * qemuBuildHostNetStr(virDomainNetDefPtr net,
                            virQEMUDriverPtr driver,
                            char type_sep,
                            int vlan,
-                           const char *tapfd,
+                           char **tapfd,
-                           const char *vhostfd);
+                           int tapfdSize,
+                           char **vhostfd,
+                           int vhostfdSize);
 
 /* Legacy, pre device support */
 char * qemuBuildNicStr(virDomainNetDefPtr net,
@@ -169,7 +171,9 @@ int qemuNetworkIfaceConnect(virDomainDefPtr def,
                             virConnectPtr conn,
                             virQEMUDriverPtr driver,
                             virDomainNetDefPtr net,
-                            virQEMUCapsPtr qemuCaps)
+                            virQEMUCapsPtr qemuCaps,
+                            int *tapfd,
+                            int *tapfdSize)
     ATTRIBUTE_NONNULL(2);
 
 int qemuPhysIfaceConnect(virDomainDefPtr def,
@@ -181,7 +185,8 @@ int qemuPhysIfaceConnect(virDomainDefPtr def,
 int qemuOpenVhostNet(virDomainDefPtr def,
                      virDomainNetDefPtr net,
                      virQEMUCapsPtr qemuCaps,
-                     int *vhostfd);
+                     int *vhostfd,
+                     int *vhostfdSize);
 
 int qemuNetworkPrepareDevices(virDomainDefPtr def);
 

src/qemu/qemu_hotplug.c

@@ -690,10 +690,12 @@ int qemuDomainAttachNetDevice(virConnectPtr conn,
                               virDomainNetDefPtr net)
 {
     qemuDomainObjPrivatePtr priv = vm->privateData;
-    char *tapfd_name = NULL;
+    char **tapfdName = NULL;
-    int tapfd = -1;
+    int *tapfd = NULL;
-    char *vhostfd_name = NULL;
+    int tapfdSize = 0;
-    int vhostfd = -1;
+    char **vhostfdName = NULL;
+    int *vhostfd = NULL;
+    int vhostfdSize = 0;
     char *nicstr = NULL;
     char *netstr = NULL;
     virNetDevVPortProfilePtr vport = NULL;
@@ -704,6 +706,7 @@ int qemuDomainAttachNetDevice(virConnectPtr conn,
     bool iface_connected = false;
     int actualType;
     virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
+    int i;
 
     /* preallocate new slot for device */
     if (VIR_REALLOC_N(vm->def->nets, vm->def->nnets+1) < 0) {
@@ -739,22 +742,37 @@ int qemuDomainAttachNetDevice(virConnectPtr conn,
 
     if (actualType == VIR_DOMAIN_NET_TYPE_BRIDGE ||
         actualType == VIR_DOMAIN_NET_TYPE_NETWORK) {
-        if ((tapfd = qemuNetworkIfaceConnect(vm->def, conn, driver, net,
+        if (VIR_ALLOC(tapfd) < 0 || VIR_ALLOC(vhostfd) < 0) {
-                                             priv->qemuCaps)) < 0)
+            virReportOOMError();
+            goto cleanup;
+        }
+        tapfdSize = vhostfdSize = 1;
+        if (qemuNetworkIfaceConnect(vm->def, conn, driver, net,
+                                    priv->qemuCaps, tapfd, &tapfdSize) < 0)
             goto cleanup;
         iface_connected = true;
-        if (qemuOpenVhostNet(vm->def, net, priv->qemuCaps, &vhostfd) < 0)
+        if (qemuOpenVhostNet(vm->def, net, priv->qemuCaps, vhostfd, &vhostfdSize) < 0)
             goto cleanup;
     } else if (actualType == VIR_DOMAIN_NET_TYPE_DIRECT) {
-        if ((tapfd = qemuPhysIfaceConnect(vm->def, driver, net,
+        if (VIR_ALLOC(tapfd) < 0 || VIR_ALLOC(vhostfd) < 0) {
+            virReportOOMError();
+            goto cleanup;
+        }
+        tapfdSize = vhostfdSize = 1;
+        if ((tapfd[0] = qemuPhysIfaceConnect(vm->def, driver, net,
                                              priv->qemuCaps,
                                              VIR_NETDEV_VPORT_PROFILE_OP_CREATE)) < 0)
             goto cleanup;
         iface_connected = true;
-        if (qemuOpenVhostNet(vm->def, net, priv->qemuCaps, &vhostfd) < 0)
+        if (qemuOpenVhostNet(vm->def, net, priv->qemuCaps, vhostfd, &vhostfdSize) < 0)
             goto cleanup;
     } else if (actualType == VIR_DOMAIN_NET_TYPE_ETHERNET) {
-        if (qemuOpenVhostNet(vm->def, net, priv->qemuCaps, &vhostfd) < 0)
+        if (VIR_ALLOC(vhostfd) < 0) {
+            virReportOOMError();
+            goto cleanup;
+        }
+        vhostfdSize = 1;
+        if (qemuOpenVhostNet(vm->def, net, priv->qemuCaps, vhostfd, &vhostfdSize) < 0)
             goto cleanup;
     }
 
@@ -792,41 +810,51 @@ int qemuDomainAttachNetDevice(virConnectPtr conn,
         }
     }
 
-    if (tapfd != -1) {
+    if (VIR_ALLOC_N(tapfdName, tapfdSize) < 0 ||
-        if (virAsprintf(&tapfd_name, "fd-%s", net->info.alias) < 0)
+        VIR_ALLOC_N(vhostfdName, vhostfdSize) < 0) {
+        virReportOOMError();
+        goto cleanup;
+    }
+
+    for (i = 0; i < tapfdSize; i++) {
+        if (virAsprintf(&tapfdName[i], "fd-%s%d", net->info.alias, i) < 0)
             goto no_memory;
     }
 
-    if (vhostfd != -1) {
+    for (i = 0; i < vhostfdSize; i++) {
-        if (virAsprintf(&vhostfd_name, "vhostfd-%s", net->info.alias) < 0)
+        if (virAsprintf(&vhostfdName[i], "vhostfd-%s%d", net->info.alias, i) < 0)
             goto no_memory;
     }
 
     if (virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_NETDEV) &&
         virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_DEVICE)) {
         if (!(netstr = qemuBuildHostNetStr(net, driver,
-                                           ',', -1, tapfd_name,
+                                           ',', -1,
-                                           vhostfd_name)))
+                                           tapfdName, tapfdSize,
+                                           vhostfdName, vhostfdSize)))
             goto cleanup;
     } else {
         if (!(netstr = qemuBuildHostNetStr(net, driver,
-                                           ' ', vlan, tapfd_name,
+                                           ' ', vlan,
-                                           vhostfd_name)))
+                                           tapfdName, tapfdSize,
+                                           vhostfdName, vhostfdSize)))
             goto cleanup;
     }
 
     qemuDomainObjEnterMonitor(driver, vm);
     if (virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_NETDEV) &&
         virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_DEVICE)) {
-        if (qemuMonitorAddNetdev(priv->mon, netstr, tapfd, tapfd_name,
+        if (qemuMonitorAddNetdev(priv->mon, netstr,
-                                 vhostfd, vhostfd_name) < 0) {
+                                 tapfd, tapfdName, tapfdSize,
+                                 vhostfd, vhostfdName, vhostfdSize) < 0) {
             qemuDomainObjExitMonitor(driver, vm);
             virDomainAuditNet(vm, NULL, net, "attach", false);
             goto cleanup;
         }
     } else {
-        if (qemuMonitorAddHostNetwork(priv->mon, netstr, tapfd, tapfd_name,
+        if (qemuMonitorAddHostNetwork(priv->mon, netstr,
-                                      vhostfd, vhostfd_name) < 0) {
+                                      tapfd, tapfdName, tapfdSize,
+                                      vhostfd, vhostfdName, vhostfdSize) < 0) {
             qemuDomainObjExitMonitor(driver, vm);
             virDomainAuditNet(vm, NULL, net, "attach", false);
             goto cleanup;
@@ -834,8 +862,10 @@ int qemuDomainAttachNetDevice(virConnectPtr conn,
     }
     qemuDomainObjExitMonitor(driver, vm);
 
-    VIR_FORCE_CLOSE(tapfd);
+    for (i = 0; i < tapfdSize; i++)
-    VIR_FORCE_CLOSE(vhostfd);
+        VIR_FORCE_CLOSE(tapfd[i]);
+    for (i = 0; i < vhostfdSize; i++)
+        VIR_FORCE_CLOSE(vhostfd[i]);
 
     if (!virDomainObjIsActive(vm)) {
         virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
@@ -931,10 +961,18 @@ cleanup:
 
     VIR_FREE(nicstr);
     VIR_FREE(netstr);
-    VIR_FREE(tapfd_name);
+    for (i = 0; i < tapfdSize; i++) {
-    VIR_FORCE_CLOSE(tapfd);
+        VIR_FORCE_CLOSE(tapfd[i]);
-    VIR_FREE(vhostfd_name);
+        VIR_FREE(tapfdName[i]);
-    VIR_FORCE_CLOSE(vhostfd);
+    }
+    VIR_FREE(tapfd);
+    VIR_FREE(tapfdName);
+    for (i = 0; i < vhostfdSize; i++) {
+        VIR_FORCE_CLOSE(vhostfd[i]);
+        VIR_FREE(vhostfdName[i]);
+    }
+    VIR_FREE(vhostfd);
+    VIR_FREE(vhostfdName);
     virObjectUnref(cfg);
 
     return ret;

src/qemu/qemu_monitor.c

@@ -2477,14 +2477,16 @@ cleanup:
 
 int qemuMonitorAddHostNetwork(qemuMonitorPtr mon,
                               const char *netstr,
-                              int tapfd, const char *tapfd_name,
+                              int *tapfd, char **tapfdName, int tapfdSize,
-                              int vhostfd, const char *vhostfd_name)
+                              int *vhostfd, char **vhostfdName, int vhostfdSize)
 {
     int ret = -1;
-    VIR_DEBUG("mon=%p netstr=%s tapfd=%d tapfd_name=%s "
+    int i = 0, j = 0;
-              "vhostfd=%d vhostfd_name=%s",
+
-              mon, netstr, tapfd, NULLSTR(tapfd_name),
+    VIR_DEBUG("mon=%p netstr=%s tapfd=%p tapfdName=%p tapfdSize=%d "
-              vhostfd, NULLSTR(vhostfd_name));
+              "vhostfd=%p vhostfdName=%p vhostfdSize=%d",
+              mon, netstr, tapfd, tapfdName, tapfdSize,
+              vhostfd, vhostfdName, vhostfdSize);
 
     if (!mon) {
         virReportError(VIR_ERR_INVALID_ARG, "%s",
@@ -2492,11 +2494,12 @@ int qemuMonitorAddHostNetwork(qemuMonitorPtr mon,
         return -1;
     }
 
-    if (tapfd >= 0 && qemuMonitorSendFileHandle(mon, tapfd_name, tapfd) < 0)
+    for (i = 0; i < tapfdSize; i++) {
-        return -1;
+        if (qemuMonitorSendFileHandle(mon, tapfdName[i], tapfd[i]) < 0)
-    if (vhostfd >= 0 &&
+            goto cleanup;
-        qemuMonitorSendFileHandle(mon, vhostfd_name, vhostfd) < 0) {
+    }
-        vhostfd = -1;
+    for (j = 0; j < vhostfdSize; j++) {
+        if (qemuMonitorSendFileHandle(mon, vhostfdName[j], vhostfd[j]) < 0)
             goto cleanup;
     }
 
@@ -2508,10 +2511,14 @@ int qemuMonitorAddHostNetwork(qemuMonitorPtr mon,
 
 cleanup:
     if (ret < 0) {
-        if (tapfd >= 0 && qemuMonitorCloseFileHandle(mon, tapfd_name) < 0)
+        while (i--) {
-            VIR_WARN("failed to close device handle '%s'", tapfd_name);
+            if (qemuMonitorCloseFileHandle(mon, tapfdName[i]) < 0)
-        if (vhostfd >= 0 && qemuMonitorCloseFileHandle(mon, vhostfd_name) < 0)
+                VIR_WARN("failed to close device handle '%s'", tapfdName[i]);
-            VIR_WARN("failed to close device handle '%s'", vhostfd_name);
+        }
+        while (j--) {
+            if (qemuMonitorCloseFileHandle(mon, vhostfdName[j]) < 0)
+                VIR_WARN("failed to close device handle '%s'", vhostfdName[j]);
+        }
     }
 
     return ret;
@@ -2543,14 +2550,16 @@ int qemuMonitorRemoveHostNetwork(qemuMonitorPtr mon,
 
 int qemuMonitorAddNetdev(qemuMonitorPtr mon,
                          const char *netdevstr,
-                         int tapfd, const char *tapfd_name,
+                         int *tapfd, char **tapfdName, int tapfdSize,
-                         int vhostfd, const char *vhostfd_name)
+                         int *vhostfd, char **vhostfdName, int vhostfdSize)
 {
     int ret = -1;
-    VIR_DEBUG("mon=%p netdevstr=%s tapfd=%d tapfd_name=%s "
+    int i = 0, j = 0;
-              "vhostfd=%d vhostfd_name=%s",
+
-              mon, netdevstr, tapfd, NULLSTR(tapfd_name),
+    VIR_DEBUG("mon=%p netdevstr=%s tapfd=%p tapfdName=%p tapfdSize=%d"
-              vhostfd, NULLSTR(vhostfd_name));
+              "vhostfd=%p vhostfdName=%p vhostfdSize=%d",
+              mon, netdevstr, tapfd, tapfdName, tapfdSize,
+              vhostfd, vhostfdName, tapfdSize);
 
     if (!mon) {
         virReportError(VIR_ERR_INVALID_ARG, "%s",
@@ -2558,11 +2567,12 @@ int qemuMonitorAddNetdev(qemuMonitorPtr mon,
         return -1;
     }
 
-    if (tapfd >= 0 && qemuMonitorSendFileHandle(mon, tapfd_name, tapfd) < 0)
+    for (i = 0; i < tapfdSize; i++) {
-        return -1;
+        if (qemuMonitorSendFileHandle(mon, tapfdName[i], tapfd[i]) < 0)
-    if (vhostfd >= 0 &&
+            goto cleanup;
-        qemuMonitorSendFileHandle(mon, vhostfd_name, vhostfd) < 0) {
+    }
-        vhostfd = -1;
+    for (j = 0; j < vhostfdSize; j++) {
+        if (qemuMonitorSendFileHandle(mon, vhostfdName[j], vhostfd[j]) < 0)
             goto cleanup;
     }
 
@@ -2573,10 +2583,14 @@ int qemuMonitorAddNetdev(qemuMonitorPtr mon,
 
 cleanup:
     if (ret < 0) {
-        if (tapfd >= 0 && qemuMonitorCloseFileHandle(mon, tapfd_name) < 0)
+        while (i--) {
-            VIR_WARN("failed to close device handle '%s'", tapfd_name);
+            if (qemuMonitorCloseFileHandle(mon, tapfdName[i]) < 0)
-        if (vhostfd >= 0 && qemuMonitorCloseFileHandle(mon, vhostfd_name) < 0)
+                VIR_WARN("failed to close device handle '%s'", tapfdName[i]);
-            VIR_WARN("failed to close device handle '%s'", vhostfd_name);
+        }
+        while (j--) {
+            if (qemuMonitorCloseFileHandle(mon, vhostfdName[j]) < 0)
+                VIR_WARN("failed to close device handle '%s'", vhostfdName[j]);
+        }
     }
 
     return ret;

src/qemu/qemu_monitor.h

@@ -501,8 +501,8 @@ int qemuMonitorRemoveFd(qemuMonitorPtr mon, int fdset, int fd);
  */
 int qemuMonitorAddHostNetwork(qemuMonitorPtr mon,
                               const char *netstr,
-                              int tapfd, const char *tapfd_name,
+                              int *tapfd, char **tapfdName, int tapfdSize,
-                              int vhostfd, const char *vhostfd_name);
+                              int *vhostfd, char **vhostfdName, int vhostfdSize);
 
 int qemuMonitorRemoveHostNetwork(qemuMonitorPtr mon,
                                  int vlan,
@@ -510,8 +510,8 @@ int qemuMonitorRemoveHostNetwork(qemuMonitorPtr mon,
 
 int qemuMonitorAddNetdev(qemuMonitorPtr mon,
                          const char *netdevstr,
-                         int tapfd, const char *tapfd_name,
+                         int *tapfd, char **tapfdName, int tapfdSize,
-                         int vhostfd, const char *vhostfd_name);
+                         int *vhostfd, char **vhostfdName, int vhostfdSize);
 
 int qemuMonitorRemoveNetdev(qemuMonitorPtr mon,
                             const char *alias);

src/uml/uml_conf.c

@@ -109,6 +109,7 @@ umlConnectTapDevice(virConnectPtr conn,
                     const char *bridge)
 {
     bool template_ifname = false;
+    int tapfd;
 
     if (!net->ifname ||
         STRPREFIX(net->ifname, VIR_NET_GENERATED_PREFIX) ||
@@ -121,7 +122,7 @@ umlConnectTapDevice(virConnectPtr conn,
     }
 
     if (virNetDevTapCreateInBridgePort(bridge, &net->ifname, &net->mac,
-                                       vm->uuid, NULL,
+                                       vm->uuid, &tapfd, 1,
                                        virDomainNetGetActualVirtPortProfile(net),
                                        virDomainNetGetActualVlan(net),
                                        VIR_NETDEV_TAP_CREATE_IFUP |
@@ -139,9 +140,11 @@ umlConnectTapDevice(virConnectPtr conn,
         }
     }
 
+    VIR_FORCE_CLOSE(tapfd);
     return 0;
 
 error:
+    VIR_FORCE_CLOSE(tapfd);
     return -1;
 }
 

src/util/virnetdevtap.c

@@ -140,7 +140,8 @@ virNetDevProbeVnetHdr(int tapfd)
 /**
  * virNetDevTapCreate:
  * @ifname: the interface name
- * @tapfd: file descriptor return value for the new tap device
+ * @tapfds: array of file descriptors return value for the new tap device
+ * @tapfdSize: number of file descriptors in @tapfd
  * @flags: OR of virNetDevTapCreateFlags. Only one flag is recognized:
  *
  *   VIR_NETDEV_TAP_CREATE_VNET_HDR
@@ -148,31 +149,37 @@ virNetDevProbeVnetHdr(int tapfd)
  *   VIR_NETDEV_TAP_CREATE_PERSIST
  *     - The device will persist after the file descriptor is closed
  *
- * Creates a tap interface.
+ * Creates a tap interface. The caller must use virNetDevTapDelete to
- * If the @tapfd parameter is supplied, the open tap device file descriptor
+ * remove a persistent TAP device when it is no longer needed. In case
- * will be returned, otherwise the TAP device will be closed. The caller must
+ * @tapfdSize is greater than one, multiqueue extension is requested
- * use virNetDevTapDelete to remove a persistent TAP device when it is no
+ * from kernel.
- * longer needed.
  *
  * Returns 0 in case of success or -1 on failure.
  */
 int virNetDevTapCreate(char **ifname,
                        int *tapfd,
+                       int tapfdSize,
                        unsigned int flags)
 {
-    int fd;
+    int i;
     struct ifreq ifr;
     int ret = -1;
+    int fd;
 
+    memset(&ifr, 0, sizeof(ifr));
+    for (i = 0; i < tapfdSize; i++) {
         if ((fd = open("/dev/net/tun", O_RDWR)) < 0) {
             virReportSystemError(errno, "%s",
                                  _("Unable to open /dev/net/tun, is tun module loaded?"));
-        return -1;
+            goto cleanup;
         }
 
         memset(&ifr, 0, sizeof(ifr));
 
-    ifr.ifr_flags = IFF_TAP|IFF_NO_PI;
+        ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
+        /* If tapfdSize is greater than one, request multiqueue */
+        if (tapfdSize > 1)
+            ifr.ifr_flags |= IFF_MULTI_QUEUE;
 
 # ifdef IFF_VNET_HDR
         if ((flags &  VIR_NETDEV_TAP_CREATE_VNET_HDR) &&
@@ -195,6 +202,14 @@ int virNetDevTapCreate(char **ifname,
             goto cleanup;
         }
 
+        if (i == 0) {
+            /* In case we are looping more than once, set other
+             * TAPs to have the same name */
+            VIR_FREE(*ifname);
+            if (ifr.ifr_name && VIR_STRDUP(*ifname, ifr.ifr_name) < 0)
+                goto cleanup;
+        }
+
         if ((flags & VIR_NETDEV_TAP_CREATE_PERSIST) &&
             (errno = ioctl(fd, TUNSETPERSIST, 1))) {
             virReportSystemError(errno,
@@ -202,22 +217,17 @@ int virNetDevTapCreate(char **ifname,
                                  NULLSTR(*ifname));
             goto cleanup;
         }
-
+        tapfd[i] = fd;
-    VIR_FREE(*ifname);
-    if (!(*ifname = strdup(ifr.ifr_name))) {
-        virReportOOMError();
-        goto cleanup;
     }
-    if (tapfd)
-        *tapfd = fd;
-    else
-        VIR_FORCE_CLOSE(fd);
 
     ret = 0;
 
 cleanup:
-    if (ret < 0)
+    if (ret < 0) {
         VIR_FORCE_CLOSE(fd);
+        while (i--)
+            VIR_FORCE_CLOSE(tapfd[i]);
+    }
 
     return ret;
 }
@@ -266,6 +276,7 @@ cleanup:
 #else /* ! TUNSETIFF */
 int virNetDevTapCreate(char **ifname ATTRIBUTE_UNUSED,
                        int *tapfd ATTRIBUTE_UNUSED,
+                       int tapfdSize ATTRIBUTE_UNUSED,
                        unsigned int flags ATTRIBUTE_UNUSED)
 {
     virReportSystemError(ENOSYS, "%s",
@@ -286,7 +297,8 @@ int virNetDevTapDelete(const char *ifname ATTRIBUTE_UNUSED)
  * @brname: the bridge name
  * @ifname: the interface name (or name template)
  * @macaddr: desired MAC address
- * @tapfd: file descriptor return value for the new tap device
+ * @tapfd: array of file descriptor return value for the new tap device
+ * @tapfdSize: number of file descriptors in @tapfd
  * @virtPortProfile: bridge/port specific configuration
  * @flags: OR of virNetDevTapCreateFlags:
 
@@ -314,6 +326,7 @@ int virNetDevTapCreateInBridgePort(const char *brname,
                                    const virMacAddrPtr macaddr,
                                    const unsigned char *vmuuid,
                                    int *tapfd,
+                                   int tapfdSize,
                                    virNetDevVPortProfilePtr virtPortProfile,
                                    virNetDevVlanPtr virtVlan,
                                    unsigned int flags)
@@ -321,7 +334,7 @@ int virNetDevTapCreateInBridgePort(const char *brname,
     virMacAddr tapmac;
     char macaddrstr[VIR_MAC_STRING_BUFLEN];
 
-    if (virNetDevTapCreate(ifname, tapfd, flags) < 0)
+    if (virNetDevTapCreate(ifname, tapfd, tapfdSize, flags) < 0)
         return -1;
 
     /* We need to set the interface MAC before adding it
@@ -372,9 +385,9 @@ int virNetDevTapCreateInBridgePort(const char *brname,
 
     return 0;
 
- error:
+error:
-    if (tapfd)
+    while (tapfdSize)
-        VIR_FORCE_CLOSE(*tapfd);
+        VIR_FORCE_CLOSE(tapfd[--tapfdSize]);
 
     return -1;
 }

src/util/virnetdevtap.h

@@ -29,6 +29,7 @@
 
 int virNetDevTapCreate(char **ifname,
                        int *tapfd,
+                       int tapfdSize,
                        unsigned int flags)
     ATTRIBUTE_NONNULL(1) ATTRIBUTE_RETURN_CHECK;
 
@@ -55,6 +56,7 @@ int virNetDevTapCreateInBridgePort(const char *brname,
                                    const virMacAddrPtr macaddr,
                                    const unsigned char *vmuuid,
                                    int *tapfd,
+                                   int tapfdSize,
                                    virNetDevVPortProfilePtr virtPortProfile,
                                    virNetDevVlanPtr virtVlan,
                                    unsigned int flags)