support for QEMU vhost-user

This patch adds support for the QEMU vhost-user feature to libvirt.
vhost-user enables the communication between a QEMU virtual machine
and other userspace process using the Virtio transport protocol.
It uses a char dev (e.g. Unix socket) for the control plane,
while the data plane based on shared memory.

The XML looks like:

<interface type='vhostuser'>
    <mac address='52:54:00:3b:83:1a'/>
    <source type='unix' path='/tmp/vhost.sock' mode='server'/>
    <model type='virtio'/>
</interface>

Signed-off-by: Michele Paolino <m.paolino@virtualopensystems.com>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>

docs/formatdomain.html.in

@@ -3944,6 +3944,37 @@ qemu-kvm -net nic,model=? /dev/null
       <span class="since">Since 0.9.5</span>
     </p>
 
+    <h5><a name="elementVhostuser">vhost-user interface</a></h5>
+
+    <p>
+    <span class="since">Since 1.2.7</span> the vhost-user enables the
+    communication between a QEMU virtual machine and other userspace process
+    using the Virtio transport protocol.  A char dev (e.g. Unix socket) is used
+    for the control plane, while the data plane is based on shared memory.
+    </p>
+
+<pre>
+  ...
+  &lt;devices&gt;
+    &lt;interface type='vhostuser'&gt;
+      &lt;mac address='52:54:00:3b:83:1a'/&gt;
+      &lt;source type='unix' path='/tmp/vhost.sock' mode='server'/&gt;
+      &lt;model type='virtio'/&gt;
+    &lt;/interface&gt;
+  &lt;/devices&gt;
+  ...</pre>
+
+    <p>
+      The <code>&lt;source&gt;</code> element has to be specified
+      along with the type of char device.
+      Currently, only type='unix' is supported, where the path (the
+      directory path of the socket) and mode attributes are required.
+      Both <code>mode='server'</code> and <code>mode='client'</code>
+      are supported.
+      vhost-user requires the virtio model type, thus the
+      <code>&lt;model&gt;</code> element is mandatory.
+    </p>
+
     <h4><a name="elementsInput">Input devices</a></h4>
 
     <p>

docs/schemas/domaincommon.rng

@@ -1976,6 +1976,31 @@
             <ref name="interface-options"/>
           </interleave>
         </group>
+        <group>
+          <attribute name="type">
+            <value>vhostuser</value>
+          </attribute>
+          <interleave>
+              <element name="source">
+                <attribute name="type">
+                  <choice>
+                    <value>unix</value>
+                  </choice>
+                </attribute>
+                <attribute name="path">
+                  <ref name="absFilePath"/>
+                </attribute>
+                <attribute name="mode">
+                  <choice>
+                    <value>server</value>
+                    <value>client</value>
+                  </choice>
+                </attribute>
+                <empty/>
+              </element>
+            <ref name="interface-options"/>
+          </interleave>
+        </group>
         <group>
           <attribute name="type">
             <value>network</value>

src/conf/domain_conf.c

@@ -348,6 +348,7 @@ VIR_ENUM_IMPL(virDomainFSWrpolicy, VIR_DOMAIN_FS_WRPOLICY_LAST,
 VIR_ENUM_IMPL(virDomainNet, VIR_DOMAIN_NET_TYPE_LAST,
               "user",
               "ethernet",
+              "vhostuser",
               "server",
               "client",
               "mcast",
@@ -1346,6 +1347,10 @@ void virDomainNetDefFree(virDomainNetDefPtr def)
         VIR_FREE(def->data.ethernet.ipaddr);
         break;
 
+    case VIR_DOMAIN_NET_TYPE_VHOSTUSER:
+        virDomainChrSourceDefFree(def->data.vhostuser);
+        break;
+
     case VIR_DOMAIN_NET_TYPE_SERVER:
     case VIR_DOMAIN_NET_TYPE_CLIENT:
     case VIR_DOMAIN_NET_TYPE_MCAST:
@@ -6618,6 +6623,9 @@ virDomainNetDefParseXML(virDomainXMLOptionPtr xmlopt,
     char *mode = NULL;
     char *linkstate = NULL;
     char *addrtype = NULL;
+    char *vhostuser_mode = NULL;
+    char *vhostuser_path = NULL;
+    char *vhostuser_type = NULL;
     virNWFilterHashTablePtr filterparams = NULL;
     virDomainActualNetDefPtr actual = NULL;
     xmlNodePtr oldnode = ctxt->node;
@@ -6663,6 +6671,12 @@ virDomainNetDefParseXML(virDomainXMLOptionPtr xmlopt,
                        xmlStrEqual(cur->name, BAD_CAST "source")) {
                 dev  = virXMLPropString(cur, "dev");
                 mode = virXMLPropString(cur, "mode");
+            } else if (!vhostuser_path && !vhostuser_mode && !vhostuser_type
+                       && def->type == VIR_DOMAIN_NET_TYPE_VHOSTUSER &&
+                       xmlStrEqual(cur->name, BAD_CAST "source")) {
+                vhostuser_type = virXMLPropString(cur, "type");
+                vhostuser_path = virXMLPropString(cur, "path");
+                vhostuser_mode = virXMLPropString(cur, "mode");
             } else if (!def->virtPortProfile
                        && xmlStrEqual(cur->name, BAD_CAST "virtualport")) {
                 if (def->type == VIR_DOMAIN_NET_TYPE_NETWORK) {
@@ -6820,6 +6834,65 @@ virDomainNetDefParseXML(virDomainXMLOptionPtr xmlopt,
         actual = NULL;
         break;
 
+    case VIR_DOMAIN_NET_TYPE_VHOSTUSER:
+        if (STRNEQ_NULLABLE(model, "virtio")) {
+            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                           _("Wrong or no <model> 'type' attribute "
+                             "specified with <interface type='vhostuser'/>. "
+                             "vhostuser requires the virtio-net* frontend"));
+            goto error;
+        }
+
+        if (STRNEQ_NULLABLE(vhostuser_type, "unix")) {
+            if (vhostuser_type)
+                virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                               _("Type='%s' unsupported for"
+                                 " <interface type='vhostuser'>"),
+                               vhostuser_type);
+            else
+                virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                               _("No <source> 'type' attribute "
+                                 "specified for <interface "
+                                 "type='vhostuser'>"));
+            goto error;
+        }
+
+        if (vhostuser_path == NULL) {
+            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                           _("No <source> 'path' attribute "
+                             "specified with <interface "
+                             "type='vhostuser'/>"));
+            goto error;
+        }
+
+        if (vhostuser_mode == NULL) {
+            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                           _("No <source> 'mode' attribute "
+                             "specified with <interface "
+                             "type='vhostuser'/>"));
+            goto error;
+        }
+
+        if (VIR_ALLOC(def->data.vhostuser) < 0)
+            goto error;
+
+        def->data.vhostuser->type = VIR_DOMAIN_CHR_TYPE_UNIX;
+        def->data.vhostuser->data.nix.path = vhostuser_path;
+        vhostuser_path = NULL;
+
+        if (STREQ(vhostuser_mode, "server"))
+            def->data.vhostuser->data.nix.listen = true;
+        else if (STREQ(vhostuser_mode, "client"))
+            def->data.vhostuser->data.nix.listen = false;
+        else {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("Wrong <source> 'mode' attribute "
+                             "specified with <interface "
+                             "type='vhostuser'/>"));
+            goto error;
+        }
+        break;
+
     case VIR_DOMAIN_NET_TYPE_ETHERNET:
         if (dev != NULL) {
             def->data.ethernet.dev = dev;
@@ -7065,6 +7138,9 @@ virDomainNetDefParseXML(virDomainXMLOptionPtr xmlopt,
     VIR_FREE(portgroup);
     VIR_FREE(address);
     VIR_FREE(port);
+    VIR_FREE(vhostuser_type);
+    VIR_FREE(vhostuser_path);
+    VIR_FREE(vhostuser_mode);
     VIR_FREE(ifname);
     VIR_FREE(dev);
     virDomainActualNetDefFree(actual);
@@ -15816,6 +15892,17 @@ virDomainNetDefFormat(virBufferPtr buf,
                                   def->data.ethernet.ipaddr);
             break;
 
+        case VIR_DOMAIN_NET_TYPE_VHOSTUSER:
+            if (def->data.vhostuser->type == VIR_DOMAIN_CHR_TYPE_UNIX) {
+                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'");
+                virBufferAddLit(buf, "/>\n");
+            }
+            break;
+
         case VIR_DOMAIN_NET_TYPE_BRIDGE:
             virBufferEscapeString(buf, "<source bridge='%s'/>\n",
                                   def->data.bridge.brname);

src/conf/domain_conf.h

@@ -130,6 +130,12 @@ typedef virDomainIdMapDef *virDomainIdMapDefPtr;
 typedef struct _virDomainPanicDef virDomainPanicDef;
 typedef virDomainPanicDef *virDomainPanicDefPtr;
 
+/* forward declarations virDomainChrSourceDef, required by
+ * virDomainNetDef
+ */
+typedef struct _virDomainChrSourceDef virDomainChrSourceDef;
+typedef virDomainChrSourceDef *virDomainChrSourceDefPtr;
+
 /* Flags for the 'type' field in virDomainDeviceDef */
 typedef enum {
     VIR_DOMAIN_DEVICE_NONE = 0,
@@ -790,6 +796,7 @@ struct _virDomainFSDef {
 typedef enum {
     VIR_DOMAIN_NET_TYPE_USER,
     VIR_DOMAIN_NET_TYPE_ETHERNET,
+    VIR_DOMAIN_NET_TYPE_VHOSTUSER,
     VIR_DOMAIN_NET_TYPE_SERVER,
     VIR_DOMAIN_NET_TYPE_CLIENT,
     VIR_DOMAIN_NET_TYPE_MCAST,
@@ -875,6 +882,7 @@ struct _virDomainNetDef {
             char *dev;
             char *ipaddr;
         } ethernet;
+        virDomainChrSourceDefPtr vhostuser;
         struct {
             char *address;
             int port;
@@ -1001,8 +1009,6 @@ typedef enum {
 } virDomainChrSpicevmcName;
 
 /* The host side information for a character device.  */
-typedef struct _virDomainChrSourceDef virDomainChrSourceDef;
-typedef virDomainChrSourceDef *virDomainChrSourceDefPtr;
 struct _virDomainChrSourceDef {
     int type; /* virDomainChrType */
     union {

src/libxl/libxl_conf.c

@@ -986,6 +986,7 @@ libxlMakeNic(virDomainDefPtr def,
                 return -1;
             break;
         }
+        case VIR_DOMAIN_NET_TYPE_VHOSTUSER:
         case VIR_DOMAIN_NET_TYPE_USER:
         case VIR_DOMAIN_NET_TYPE_SERVER:
         case VIR_DOMAIN_NET_TYPE_CLIENT:

src/lxc/lxc_process.c

@@ -437,6 +437,7 @@ static int virLXCProcessSetupInterfaces(virConnectPtr conn,
 
         case VIR_DOMAIN_NET_TYPE_USER:
         case VIR_DOMAIN_NET_TYPE_ETHERNET:
+        case VIR_DOMAIN_NET_TYPE_VHOSTUSER:
         case VIR_DOMAIN_NET_TYPE_SERVER:
         case VIR_DOMAIN_NET_TYPE_CLIENT:
         case VIR_DOMAIN_NET_TYPE_MCAST:

src/qemu/qemu_command.c

@@ -6848,6 +6848,76 @@ qemuBuildGraphicsCommandLine(virQEMUDriverConfigPtr cfg,
     return 0;
 }
 
+static int
+qemuBuildVhostuserCommandLine(virCommandPtr cmd,
+                              virDomainDefPtr def,
+                              virDomainNetDefPtr net,
+                              virQEMUCapsPtr qemuCaps)
+{
+    virBuffer chardev_buf = VIR_BUFFER_INITIALIZER;
+    virBuffer netdev_buf = VIR_BUFFER_INITIALIZER;
+    char *nic = NULL;
+
+    if (!qemuDomainSupportsNetdev(def, qemuCaps, net)) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       "%s", _("Netdev support unavailable"));
+        goto error;
+    }
+
+    switch ((virDomainChrType) net->data.vhostuser->type) {
+    case VIR_DOMAIN_CHR_TYPE_UNIX:
+        virBufferAsprintf(&chardev_buf, "socket,id=char%s,path=%s%s",
+                          net->info.alias, net->data.vhostuser->data.nix.path,
+                          net->data.vhostuser->data.nix.listen ? ",server" : "");
+        break;
+
+    case VIR_DOMAIN_CHR_TYPE_NULL:
+    case VIR_DOMAIN_CHR_TYPE_VC:
+    case VIR_DOMAIN_CHR_TYPE_PTY:
+    case VIR_DOMAIN_CHR_TYPE_DEV:
+    case VIR_DOMAIN_CHR_TYPE_FILE:
+    case VIR_DOMAIN_CHR_TYPE_PIPE:
+    case VIR_DOMAIN_CHR_TYPE_STDIO:
+    case VIR_DOMAIN_CHR_TYPE_UDP:
+    case VIR_DOMAIN_CHR_TYPE_TCP:
+    case VIR_DOMAIN_CHR_TYPE_SPICEVMC:
+    case VIR_DOMAIN_CHR_TYPE_SPICEPORT:
+    case VIR_DOMAIN_CHR_TYPE_NMDM:
+    case VIR_DOMAIN_CHR_TYPE_LAST:
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("vhost-user type '%s' not supported"),
+                        virDomainChrTypeToString(net->data.vhostuser->type));
+        goto error;
+    }
+
+    virBufferAsprintf(&netdev_buf, "type=vhost-user,id=host%s,chardev=char%s",
+                      net->info.alias, net->info.alias);
+
+    virCommandAddArg(cmd, "-chardev");
+    virCommandAddArgBuffer(cmd, &chardev_buf);
+
+    virCommandAddArg(cmd, "-netdev");
+    virCommandAddArgBuffer(cmd, &netdev_buf);
+
+    if (!(nic = qemuBuildNicDevStr(def, net, -1, 0, 0, qemuCaps))) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       "%s", _("Error generating NIC -device string"));
+        goto error;
+    }
+
+    virCommandAddArgList(cmd, "-device", nic, NULL);
+    VIR_FREE(nic);
+
+    return 0;
+
+ error:
+    virBufferFreeAndReset(&chardev_buf);
+    virBufferFreeAndReset(&netdev_buf);
+    VIR_FREE(nic);
+
+    return -1;
+}
+
 static int
 qemuBuildInterfaceCommandLine(virCommandPtr cmd,
                               virQEMUDriverPtr driver,
@@ -6871,6 +6941,9 @@ qemuBuildInterfaceCommandLine(virCommandPtr cmd,
     int actualType = virDomainNetGetActualType(net);
     size_t i;
 
+    if (actualType == VIR_DOMAIN_NET_TYPE_VHOSTUSER)
+        return qemuBuildVhostuserCommandLine(cmd, def, net, qemuCaps);
+
     if (actualType == VIR_DOMAIN_NET_TYPE_HOSTDEV) {
         /* NET_TYPE_HOSTDEV devices are really hostdev devices, so
          * their commandlines are constructed with other hostdevs.

src/uml/uml_conf.c

@@ -182,6 +182,11 @@ umlBuildCommandLineNet(virConnectPtr conn,
         }
         break;
 
+    case VIR_DOMAIN_NET_TYPE_VHOSTUSER:
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("vhostuser networking type not supported"));
+        goto error;
+
     case VIR_DOMAIN_NET_TYPE_SERVER:
         virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
                        _("TCP server networking type not supported"));

src/xenxs/xen_sxpr.c

@@ -1931,6 +1931,7 @@ xenFormatSxprNet(virConnectPtr conn,
             virBufferEscapeSexpr(buf, "(ip '%s')", def->data.ethernet.ipaddr);
         break;
 
+    case VIR_DOMAIN_NET_TYPE_VHOSTUSER:
     case VIR_DOMAIN_NET_TYPE_USER:
     case VIR_DOMAIN_NET_TYPE_SERVER:
     case VIR_DOMAIN_NET_TYPE_CLIENT:

tests/qemuxml2argvdata/qemuxml2argv-net-vhostuser.args

@@ -0,0 +1,7 @@
+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 \
+-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

tests/qemuxml2argvdata/qemuxml2argv-net-vhostuser.xml

@@ -0,0 +1,33 @@
+<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>
+    <disk type='block' device='disk'>
+      <driver name='qemu' type='raw'/>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='hda' bus='ide'/>
+      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
+    </disk>
+    <controller type='usb' index='0'/>
+    <controller type='ide' index='0'/>
+    <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'/>
+      <model type='virtio'/>
+    </interface>
+    <memballoon model='none'/>
+  </devices>
+</domain>

tests/qemuxml2argvtest.c

@@ -933,6 +933,7 @@ mymain(void)
     DO_TEST_FAILURE("misc-enable-s4", NONE);
     DO_TEST("misc-no-reboot", NONE);
     DO_TEST("misc-uuid", QEMU_CAPS_NAME, QEMU_CAPS_UUID);
+    DO_TEST("net-vhostuser", QEMU_CAPS_DEVICE, QEMU_CAPS_NETDEV);
     DO_TEST("net-user", NONE);
     DO_TEST("net-virtio", NONE);
     DO_TEST("net-virtio-device",

tests/qemuxml2xmltest.c

@@ -247,6 +247,7 @@ mymain(void)
     DO_TEST("misc-disable-suspends");
     DO_TEST("misc-enable-s4");
     DO_TEST("misc-no-reboot");
+    DO_TEST("net-vhostuser");
     DO_TEST("net-user");
     DO_TEST("net-virtio");
     DO_TEST("net-virtio-device");