dpdk: Deprecate vhost-user server ports.

Since vhost-user server mode ports are the preferred mechanism for
interconnecting Open vSwitch with VMs when using DPDK, and since there
are currently no known use cases for vhost-user server mode ports apart
from version incompatibilities with QEMU, announce that server mode ports
are considered deprecated and will be removed in a future release.

Cc: Ciara Loftus <ciara.loftus@intel.com>
Cc: Kevin Traynor <ktraynor@redhat.com>
Suggested-by: Darrell Ball <dball@vmware.com>
Signed-off-by: Aaron Conole <aconole@redhat.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>
Acked-by: Darrell Ball <dlu998@gmail.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>

Documentation/topics/dpdk/vhost-user.rst

@@ -32,13 +32,20 @@ documentation`_ on same.
 Quick Example
 -------------
 
-This example demonstrates how to add two ``dpdkvhostuser`` ports to an existing
-bridge called ``br0``::
+This example demonstrates how to add two ``dpdkvhostuserclient`` ports to an
+existing bridge called ``br0``::
 
-    $ ovs-vsctl add-port br0 dpdkvhostuser0 \
-        -- set Interface dpdkvhostuser0 type=dpdkvhostuser
-    $ ovs-vsctl add-port br0 dpdkvhostuser1 \
-        -- set Interface dpdkvhostuser1 type=dpdkvhostuser
+    $ ovs-vsctl add-port br0 dpdkvhostclient0 \
+        -- set Interface dpdkvhostclient0 type=dpdkvhostuserclient \
+           options:vhost-server-path=/tmp/dpdkvhostclient0
+    $ ovs-vsctl add-port br0 dpdkvhostclient1 \
+        -- set Interface dpdkvhostclient1 type=dpdkvhostuserclient \
+           options:vhost-server-path=/tmp/dpdkvhostclient1
+
+For the above examples to work, an appropriate server socket must be created
+at the paths specified (``/tmp/dpdkvhostclient0`` and
+``/tmp/dpdkvhostclient0``).  These sockets can be created with QEMU; see the
+:ref:`vhost-user client <dpdk-vhost-user-client>` section for details.
 
 vhost-user vs. vhost-user-client
 --------------------------------
@@ -59,7 +66,9 @@ means if OVS dies, all VMs **must** be restarted. On the other hand, for
 vhost-user-client ports, OVS acts as the client and QEMU the server. This means
 OVS can die and be restarted without issue, and it is also possible to restart
 an instance itself. For this reason, vhost-user-client ports are the preferred
-type for most use cases.
+type for all known use cases; the only limitation is that vhost-user client
+mode ports require QEMU version 2.7.  Ports of type vhost-user are currently
+deprecated and will be removed in a future release.
 
 .. _dpdk-vhost-user:
 
@@ -68,7 +77,8 @@ vhost-user
 
 .. important::
 
-   Use of vhost-user ports requires QEMU >= 2.2
+   Use of vhost-user ports requires QEMU >= 2.2;  vhost-user ports are
+   *deprecated*.
 
 To use vhost-user ports, you must first add said ports to the switch. DPDK
 vhost-user ports can have arbitrary names with the exception of forward and

NEWS

@@ -16,6 +16,8 @@ Post-v2.7.0
        Log level can be changed in a usual OVS way using
        'ovs-appctl vlog' commands for 'dpdk' module. Lower bound
        still can be configured via extra arguments for DPDK EAL.
+     * dpdkvhostuser ports are marked as deprecated.  They will be removed
+       in an upcoming release.
    - IPFIX now provides additional counters:
      * Total counters since metering process startup.
      * Per-flow TCP flag counters.

lib/netdev-dpdk.c

@@ -966,6 +966,8 @@ netdev_dpdk_vhost_construct(struct netdev *netdev)
     err = vhost_common_construct(netdev);
 
     ovs_mutex_unlock(&dpdk_mutex);
+    VLOG_WARN_ONCE("dpdkvhostuser ports are considered deprecated;  "
+                   "please migrate to dpdkvhostuserclient ports.");
     return err;
 }