[ovs-dev] [PATCH RFC v6 1/1] netdev-dpdk: add dpdk vhost ports

Kevin Traynor kevin.traynor at intel.com
Thu Jan 8 23:05:02 UTC 2015


This patch adds support for a new port type to userspace datapath
called dpdkvhost. This allows KVM (QEMU) to offload the servicing
of virtio-net devices to its associated dpdkvhost port. Instructions
for use are in INSTALL.DPDK.

This has been tested on Intel multi-core platforms and with clients
that have virtio-net interfaces.

 ver 6:
   - rebased with master
   - modified to use DPDK v1.8.0 vhost library
   - reworked for review comments
 ver 5:
   - rebased against latest master
 ver 4:
   - added eventfd_link.h and eventfd_link.c to EXTRA_DIST in
 utilities/automake.mk
   - rebased with master to work with DPDK 1.7 ver 3:
   - rebased with master
 ver 2:
   - rebased with master

Signed-off-by: Ciara Loftus <ciara.loftus at intel.com>
Signed-off-by: Kevin Traynor <kevin.traynor at intel.com>
Signed-off-by: Maryam Tahhan <maryam.tahhan at intel.com>
---
 INSTALL.DPDK.md         |  236 +++++++++++++++++
 Makefile.am             |    4 +
 lib/automake.mk         |    1 +
 lib/netdev-dpdk.c       |  649 +++++++++++++++++++++++++++++++++++++++--------
 lib/netdev.c            |    3 +-
 utilities/automake.mk   |    3 +-
 utilities/qemu-wrap.py  |  389 ++++++++++++++++++++++++++++
 vswitchd/ovs-vswitchd.c |    4 +-
 8 files changed, 1177 insertions(+), 112 deletions(-)
 mode change 100644 => 100755 lib/netdev-dpdk.c
 create mode 100755 utilities/qemu-wrap.py

diff --git a/INSTALL.DPDK.md b/INSTALL.DPDK.md
index 2cc7636..da8116d 100644
--- a/INSTALL.DPDK.md
+++ b/INSTALL.DPDK.md
@@ -17,6 +17,7 @@ Building and Installing:
 ------------------------
 
 Required DPDK 1.7
+Optional `fuse`, `fuse-devel`
 
 1. Configure build & install DPDK:
   1. Set `$DPDK_DIR`
@@ -264,6 +265,241 @@ A general rule of thumb for better performance is that the client
 application should not be assigned the same dpdk core mask "-c" as
 the vswitchd.
 
+DPDK vHost:
+-----------
+
+Prerequisites:
+1.  DPDK 1.8 with vHost support enabled and recompile OVS as above.
+
+     Update `config/common_linuxapp` so that DPDK is built with vHost
+     libraries:
+
+     `CONFIG_RTE_LIBRTE_VHOST=y`
+
+2.  Insert the Fuse module:
+
+      `modprobe fuse`
+
+3.  Build and insert the `eventfd_link` module:
+
+     `cd $DPDK_DIR/lib/librte_vhost/eventfd_link/`
+     `make`
+     `insmod $DPDK_DIR/lib/librte_vhost/eventfd_link.ko`
+
+4.  Remove /dev/vhost-net character device:
+
+      `rm -rf /dev/vhost-net`
+
+Following the steps above to create a bridge, you can now add DPDK vHost
+as a port to the vswitch.
+
+`ovs-vsctl add-port br0 dpdkvhost0 -- set Interface dpdkvhost0 type=dpdkvhost`
+
+Unlike DPDK ring ports, DPDK vHost ports can have arbitrary names:
+
+`ovs-vsctl add-port br0 port123ABC -- set Interface port123ABC type=dpdkvhost`
+
+However, please note that when attaching userspace devices to QEMU, the
+name provided during the add-port operation must match the ifname parameter
+on the QEMU command line.
+
+DPDK vHost VM configuration:
+----------------------------
+
+1. Configure virtio-net adaptors:
+   The guest must be configured with virtio-net adapters and offloads
+   MUST BE DISABLED. This means the following parameters should be passed
+   to the QEMU binary:
+
+     ```
+     -netdev tap,id=<id>,script=no,downscript=no,ifname=<name>,vhost=on
+     -device virtio-net-pci,netdev=net1,mac=<mac>,csum=off,gso=off,
+     guest_tso4=off,guest_tso6=off,guest_ecn=off
+     ```
+
+     Repeat the above parameters for multiple devices.
+
+2. Configure huge pages:
+   QEMU must allocate the VM's memory on hugetlbfs. Vhost ports access a
+   virtio-net device's virtual rings and packet buffers mapping the VM's
+   physical memory on hugetlbfs. To enable vhost-ports to map the VM's
+   memory into their process address space, pass the following paramters
+   to QEMU:
+
+     `-mem-path /dev/hugepages -mem-prealloc`
+
+DPDK vHost with standard vHost:
+-------------------------------
+
+DPDK vHost ports use a Linux* character device to communicate with QEMU.
+By default it is set to `/dev/vhost-net`. This conflicts with the kernel
+vHost device, hence the need to remove `/dev/vhost-net` above. However,
+if you wish to use kernel vhost in parallel, you can specify an
+alternative basename on the vswitchd command line like so:
+
+     `./vswitchd/ovs-vswitchd --dpdk --basename my-vhost-net -c 0x1 ...`
+
+Note that the basename arguement and associated string must be the first
+arguements after `--dpdk` and come before the EAL arguements.
+
+DPDK vHost VM configuration with standard vHost:
+------------------------------------------------
+
+1. As with the "normal" (i.e. using `/dev/vhost-net`) DPDK vHost setup,
+the guest must be configured with virtio-net adapters and offloads
+MUST BE DISABLED. However, this time you must also pass in a `vhostfd`
+argument:
+
+     ```
+     -netdev tap,id=<id>,script=no,downscript=no,ifname=<name>,vhost=on,
+     vhostfd=<open_fd>
+     -device virtio-net-pci,netdev=net1,mac=<mac>,csum=off,gso=off,
+     guest_tso4=off,guest_tso6=off,guest_ecn=off
+     ```
+
+     The open file descriptor must be passed to QEMU running as a child
+     process.
+
+2. As above, QEMU must allocate the VM's memory on hugetlbfs:
+
+     `-mem-path /dev/hugepages -mem-prealloc`
+
+3. (Optional) If you are using libvirt, you must enable libvirt to access
+the userspace device file by adding it to controllers cgroup for libvirtd
+using the following steps:
+
+     1. In `/etc/libvirt/qemu.conf` add/edit the following lines:
+
+        ```
+        1) cgroup_controllers = [ ... "devices", ... ]
+        2) clear_emulator_capabilities = 0
+        3) user = "root"
+        4) group = "root"
+        5) cgroup_device_acl = [
+               "/dev/null", "/dev/full", "/dev/zero",
+               "/dev/random", "/dev/urandom",
+               "/dev/ptmx", "/dev/kvm", "/dev/kqemu",
+               "/dev/rtc", "/dev/hpet", "/dev/net/tun",
+               "/dev/<devbase-name>-<index>",
+               "/dev/hugepages"]
+        ```
+
+     2. Disable SELinux or set to permissive mode
+     3. Mount cgroup device controller:
+
+        ```
+        mkdir /dev/cgroup
+        mount -t cgroup none /dev/cgroup -o devices
+        ```
+
+     4. Restart the libvirtd process
+        For example, on Fedora:
+
+          `systemctl restart libvirtd.service`
+
+The easiest way to setup a Guest that isn't using `/dev/vhost-net` is to
+use the `qemu-wrap.py` script located in utilities. This Python script
+automates the requirements specified above and can be used in conjunction
+with libvirt.
+
+DPDK vHost VM configuration with QEMU wrapper:
+----------------------------------------------
+
+The QEMU wrapper script automatically detects and calls QEMU with the
+necessary parameters required to integrate with the vhost sample code.
+It performs the following actions:
+
+  * Automatically detects the location of the hugetlbfs and inserts this
+    into the command line parameters.
+  * Automatically open file descriptors for each virtio-net device and
+    inserts this into the command line parameters.
+  * Disables offloads on each virtio-net device.
+  * Calls QEMU passing both the command line parameters passed to the
+    script itself and those it has auto-detected.
+
+Before use, you **must** edit the configuration parameters section of the
+script to point to the correct emulator location and set any additional
+options. Of these settings, `emul_path` and `us_vhost_path` **must** be
+set. All other parameters are optional.
+
+To use directly from the command line simply pass the wrapper some of the
+QEMU parameters: it will configure the rest. For example:
+
+```
+qemu-wrap.py -cpu host -boot c -hda <disk image> -m 4096 -smp 4
+  --enable-kvm -nographic -vnc none -net none -netdev tap,id=net1,
+  script=no,downscript=no,ifname=if1,vhost=on -device virtio-net-pci,
+  netdev=net1,mac=00:00:00:00:00:01
+```
+
+To use with libvirt, follow these steps:
+
+1. Place `qemu-wrap.py` in libvirtd's binary search PATH ($PATH)
+   Ideally in the same directory that the QEMU binary is located.
+
+2. Ensure that the script has the same owner/group and file permissions as the
+   QEMU binary.
+
+3. Update the VM xml file using "virsh edit VM.xml"
+
+     1. Set the VM to use the launch script
+        Set the emulator path contained in the `<emulator><emulator/>` tags.
+        For example, replace:
+
+          `<emulator>/usr/bin/qemu-kvm<emulator/>`
+
+          with:
+
+          `<emulator>/usr/bin/qemu-wrap.py<emulator/>`
+
+     2. Set the VM's devices to use vhost-net offload
+        ```
+        <interface type='network'>
+          <mac address='xx:xx:xx:xx:xx:xx'/>
+          <source network='default'/>
+          <model type='virtio'/>
+          <driver name='vhost'/>
+          <address type=.../>
+        </interface>
+        ```
+
+     4. Enable libvirt to access our userpace device file by adding it
+     to controllers cgroup for libvirtd as specified above.
+
+     5. (Optional) Set `hugetlbfs_mount` variable
+        VMs using userspace vhost must use hugepage backed memory. This
+        can be enabled in the libvirt XML config by adding a memory
+        backing section to the XML config:
+
+          ```
+          <memoryBacking>
+          <hugepages/>
+          </memoryBacking>
+          ```
+
+          This memory backing section should be added after the `<memory>`
+          and `<currentMemory>` sections. This will add the `-mem-prealloc`
+          and `-mem-path <path>` flags to the QEMU command line. The
+          `hugetlbfs_mount` variable can be used to override the default
+          `<path>` passed through by libvirt.
+
+          If `-mem-prealloc` or `-mem-path <path>` are not passed through
+          and a vhost device is detected then these options will be
+          automatically added by this script. This script will detect the
+          system hugetlbfs mount point to be used for `<path>`. The default
+          `<path>` for this script can be overidden by the `hugetlbfs_dir`
+          variable in the configuration section of this script.
+
+4. Restart the libvirtd system process
+   For example on Fedora:
+
+     `systemctl restart libvirtd.service`
+
+5. Edit the Configuration Parameters section of the script to point to
+the correct emulator location and set any additional options.
+
+6. Use virt-manager to launch the VM
+
 Restrictions:
 -------------
 
diff --git a/Makefile.am b/Makefile.am
index 6ad6fc2..c1fabdd 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -32,6 +32,10 @@ AM_CFLAGS = -Wstrict-prototypes
 AM_CFLAGS += $(WARNING_FLAGS)
 AM_CFLAGS += $(OVS_CFLAGS)
 
+if DPDK_NETDEV
+AM_CFLAGS += -D_FILE_OFFSET_BITS=64
+endif
+
 if NDEBUG
 AM_CPPFLAGS += -DNDEBUG
 AM_CFLAGS += -fomit-frame-pointer
diff --git a/lib/automake.mk b/lib/automake.mk
index 2a5844b..42c133e 100644
--- a/lib/automake.mk
+++ b/lib/automake.mk
@@ -336,6 +336,7 @@ lib_libopenvswitch_la_SOURCES += \
 endif
 
 if DPDK_NETDEV
+lib_libopenvswitch_la_LDFLAGS += -lfuse
 lib_libopenvswitch_la_SOURCES += \
        lib/netdev-dpdk.c \
        lib/netdev-dpdk.h
diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
old mode 100644
new mode 100755
index 6b77bc4..62a1a08
--- a/lib/netdev-dpdk.c
+++ b/lib/netdev-dpdk.c
@@ -30,6 +30,7 @@
 
 #include <rte_config.h>
 #include <rte_mbuf.h>
+#include <rte_virtio_net.h>
 
 #include "dpif-netdev.h"
 #include "list.h"
@@ -59,6 +60,7 @@ static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 20);
 #define OVS_CACHE_LINE_SIZE CACHE_LINE_SIZE
 #define OVS_VPORT_DPDK "ovs_dpdk"
 
+
 /*
  * need to reserve tons of extra space in the mbufs so we can align the
  * DMA addresses to 4KB.
@@ -85,6 +87,12 @@ static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 20);
 #define TX_HTHRESH 0  /* Default values of TX host threshold reg. */
 #define TX_WTHRESH 0  /* Default values of TX write-back threshold reg. */
 
+#define MAX_BASENAME_SZ NAME_MAX /* Maximum character device basename size. */
+#define MAX_PKT_BURST 32           /* Max burst size for RX/TX */
+
+/* Character device basename. */
+char *dev_basename = NULL;
+
 static const struct rte_eth_conf port_conf = {
     .rxmode = {
         .mq_mode = ETH_MQ_RX_RSS,
@@ -131,29 +139,30 @@ enum { MAX_TX_QUEUE_LEN = 384 };
 enum { DPDK_RING_SIZE = 256 };
 BUILD_ASSERT_DECL(IS_POW2(DPDK_RING_SIZE));
 enum { DRAIN_TSC = 200000ULL };
+enum { DPDK = 0, VHOST };
 
 static int rte_eal_init_ret = ENODEV;
 
-static struct ovs_mutex dpdk_mutex = OVS_MUTEX_INITIALIZER;
+static rte_spinlock_t dpdk_spinlock = RTE_SPINLOCK_INITIALIZER;
 
 /* Contains all 'struct dpdk_dev's. */
-static struct ovs_list dpdk_list OVS_GUARDED_BY(dpdk_mutex)
+static struct ovs_list dpdk_list OVS_GUARDED_BY(dpdk_spinlock)
     = OVS_LIST_INITIALIZER(&dpdk_list);
 
-static struct ovs_list dpdk_mp_list OVS_GUARDED_BY(dpdk_mutex)
+static struct ovs_list dpdk_mp_list OVS_GUARDED_BY(dpdk_spinlock)
     = OVS_LIST_INITIALIZER(&dpdk_mp_list);
 
-/* This mutex must be used by non pmd threads when allocating or freeing
+/* This spinlock must be used by non pmd threads when allocating or freeing
  * mbufs through mempools. Since dpdk_queue_pkts() and dpdk_queue_flush() may
- * use mempools, a non pmd thread should hold this mutex while calling them */
-struct ovs_mutex nonpmd_mempool_mutex = OVS_MUTEX_INITIALIZER;
+ * use mempools, a non pmd thread should hold this spinlock while calling them */
+rte_spinlock_t nonpmd_mempool_spinlock = RTE_SPINLOCK_INITIALIZER;
 
 struct dpdk_mp {
     struct rte_mempool *mp;
     int mtu;
     int socket_id;
     int refcount;
-    struct ovs_list list_node OVS_GUARDED_BY(dpdk_mutex);
+    struct ovs_list list_node OVS_GUARDED_BY(dpdk_spinlock);
 };
 
 /* There should be one 'struct dpdk_tx_queue' created for
@@ -170,7 +179,7 @@ struct dpdk_tx_queue {
    so we have to keep them around once they've been created
 */
 
-static struct ovs_list dpdk_ring_list OVS_GUARDED_BY(dpdk_mutex)
+static struct ovs_list dpdk_ring_list OVS_GUARDED_BY(dpdk_spinlock)
     = OVS_LIST_INITIALIZER(&dpdk_ring_list);
 
 struct dpdk_ring {
@@ -179,17 +188,18 @@ struct dpdk_ring {
     struct rte_ring *cring_rx;
     int user_port_id; /* User given port no, parsed from port name */
     int eth_port_id; /* ethernet device port id */
-    struct ovs_list list_node OVS_GUARDED_BY(dpdk_mutex);
+    struct ovs_list list_node OVS_GUARDED_BY(dpdk_spinlock);
 };
 
 struct netdev_dpdk {
     struct netdev up;
     int port_id;
     int max_packet_len;
+    int type; /* DPDK or VHOST */
 
     struct dpdk_tx_queue *tx_q;
 
-    struct ovs_mutex mutex OVS_ACQ_AFTER(dpdk_mutex);
+    rte_spinlock_t spinlock OVS_ACQ_AFTER(dpdk_spinlock);
 
     struct dpdk_mp *dpdk_mp;
     int mtu;
@@ -203,8 +213,11 @@ struct netdev_dpdk {
     struct rte_eth_link link;
     int link_reset_cnt;
 
+    /* virtio-net structure for vhost device */
+    OVSRCU_TYPE(struct virtio_net *) virtio_dev;
+
     /* In dpdk_list. */
-    struct ovs_list list_node OVS_GUARDED_BY(dpdk_mutex);
+    struct ovs_list list_node OVS_GUARDED_BY(dpdk_spinlock);
     rte_spinlock_t dpdkr_tx_lock;
 };
 
@@ -217,14 +230,18 @@ static bool thread_is_pmd(void);
 
 static int netdev_dpdk_construct(struct netdev *);
 
+void *start_cuse_session_loop(void *dummy);
+
+struct virtio_net * netdev_dpdk_get_virtio(const struct netdev_dpdk *dev);
+
 static bool
 is_dpdk_class(const struct netdev_class *class)
 {
     return class->construct == netdev_dpdk_construct;
 }
 
-/* XXX: use dpdk malloc for entire OVS. infact huge page shld be used
- * for all other sengments data, bss and text. */
+/* XXX: use dpdk malloc for entire OVS. in fact huge page should be used
+ * for all other segments data, bss and text. */
 
 static void *
 dpdk_rte_mzalloc(size_t sz)
@@ -239,7 +256,7 @@ dpdk_rte_mzalloc(size_t sz)
 }
 
 /* XXX this function should be called only by pmd threads (or by non pmd
- * threads holding the nonpmd_mempool_mutex) */
+ * threads holding the nonpmd_mempool_spinlock) */
 void
 free_dpdk_buf(struct dpif_packet *p)
 {
@@ -290,7 +307,7 @@ ovs_rte_pktmbuf_init(struct rte_mempool *mp,
 }
 
 static struct dpdk_mp *
-dpdk_mp_get(int socket_id, int mtu) OVS_REQUIRES(dpdk_mutex)
+dpdk_mp_get(int socket_id, int mtu) OVS_REQUIRES(dpdk_spinlock)
 {
     struct dpdk_mp *dmp = NULL;
     char mp_name[RTE_MEMPOOL_NAMESIZE];
@@ -378,13 +395,13 @@ dpdk_watchdog(void *dummy OVS_UNUSED)
     pthread_detach(pthread_self());
 
     for (;;) {
-        ovs_mutex_lock(&dpdk_mutex);
+        rte_spinlock_lock(&dpdk_spinlock);
         LIST_FOR_EACH (dev, list_node, &dpdk_list) {
-            ovs_mutex_lock(&dev->mutex);
+            rte_spinlock_lock(&dev->spinlock);
             check_link_status(dev);
-            ovs_mutex_unlock(&dev->mutex);
+            rte_spinlock_unlock(&dev->spinlock);
         }
-        ovs_mutex_unlock(&dpdk_mutex);
+        rte_spinlock_unlock(&dpdk_spinlock);
         xsleep(DPDK_PORT_WATCHDOG_INTERVAL);
     }
 
@@ -392,7 +409,7 @@ dpdk_watchdog(void *dummy OVS_UNUSED)
 }
 
 static int
-dpdk_eth_dev_init(struct netdev_dpdk *dev) OVS_REQUIRES(dpdk_mutex)
+dpdk_eth_dev_init(struct netdev_dpdk *dev) OVS_REQUIRES(dpdk_spinlock)
 {
     struct rte_pktmbuf_pool_private *mbp_priv;
     struct ether_addr eth_addr;
@@ -485,15 +502,15 @@ netdev_dpdk_alloc_txq(struct netdev_dpdk *netdev, unsigned int n_txqs)
 
 static int
 netdev_dpdk_init(struct netdev *netdev_, unsigned int port_no)
-    OVS_REQUIRES(dpdk_mutex)
+    OVS_REQUIRES(dpdk_spinlock)
 {
     struct netdev_dpdk *netdev = netdev_dpdk_cast(netdev_);
     int sid;
     int err = 0;
 
-    ovs_mutex_init(&netdev->mutex);
+    rte_spinlock_init(&netdev->spinlock);
 
-    ovs_mutex_lock(&netdev->mutex);
+    rte_spinlock_lock(&netdev->spinlock);
 
     /* If the 'sid' is negative, it means that the kernel fails
      * to obtain the pci numa info.  In that situation, always
@@ -502,6 +519,7 @@ netdev_dpdk_init(struct netdev *netdev_, unsigned int port_no)
     netdev->socket_id = sid < 0 ? SOCKET0 : sid;
     netdev_dpdk_alloc_txq(netdev, NR_QUEUE);
     netdev->port_id = port_no;
+    netdev->type = DPDK;
     netdev->flags = 0;
     netdev->mtu = ETHER_MTU;
     netdev->max_packet_len = MTU_TO_MAX_LEN(netdev->mtu);
@@ -526,7 +544,7 @@ unlock:
     if (err) {
         rte_free(netdev->tx_q);
     }
-    ovs_mutex_unlock(&netdev->mutex);
+    rte_spinlock_unlock(&netdev->spinlock);
     return err;
 }
 
@@ -546,6 +564,65 @@ dpdk_dev_parse_name(const char dev_name[], const char prefix[],
 }
 
 static int
+netdev_dpdk_vhost_construct(struct netdev *netdev_)
+{
+    struct netdev_dpdk *netdev = netdev_dpdk_cast(netdev_);
+    struct netdev_dpdk *tmp_netdev;
+    unsigned int port_no = 0;
+    int err = 0;
+    int sid = 0;
+
+    if (rte_eal_init_ret) {
+        return rte_eal_init_ret;
+    }
+    rte_spinlock_lock(&dpdk_spinlock);
+    rte_spinlock_init(&netdev->spinlock);
+    rte_spinlock_lock(&netdev->spinlock);
+
+    if (!list_is_empty(&dpdk_list)) {
+        LIST_FOR_EACH (tmp_netdev, list_node, &dpdk_list) {
+            if (tmp_netdev->type== VHOST) {
+                port_no++;
+            }
+        }
+    }
+
+    /* Retrieving socket id for master DPDK core */
+    sid = rte_lcore_to_socket_id(rte_get_master_lcore());
+    netdev->socket_id = sid < 0 ? SOCKET0 : sid;
+    netdev->port_id = port_no;
+    netdev->type = VHOST;
+
+    netdev->flags = 0;
+    netdev->mtu = ETHER_MTU;
+    netdev->max_packet_len = MTU_TO_MAX_LEN(netdev->mtu);
+
+    ovsrcu_set(&netdev->virtio_dev, NULL);
+    netdev->stats.rx_packets = 0;
+    netdev->stats.tx_packets = 0;
+
+    netdev->dpdk_mp = dpdk_mp_get(netdev->socket_id, netdev->mtu);
+    if (!netdev->dpdk_mp) {
+        err = ENOMEM;
+        goto unlock_dev;
+    }
+
+    netdev_->n_txq = NR_QUEUE;
+    netdev_->n_rxq = NR_QUEUE;
+
+    VLOG_INFO("%s  is associated with VHOST port #%d\n", netdev_->name,
+            netdev->port_id);
+
+    list_push_back(&dpdk_list, &netdev->list_node);
+
+unlock_dev:
+    rte_spinlock_unlock(&netdev->spinlock);
+    rte_spinlock_unlock(&dpdk_spinlock);
+
+    return err;
+}
+
+static int
 netdev_dpdk_construct(struct netdev *netdev)
 {
     unsigned int port_no;
@@ -561,9 +638,9 @@ netdev_dpdk_construct(struct netdev *netdev)
         return err;
     }
 
-    ovs_mutex_lock(&dpdk_mutex);
+    rte_spinlock_lock(&dpdk_spinlock);
     err = netdev_dpdk_init(netdev, port_no);
-    ovs_mutex_unlock(&dpdk_mutex);
+    rte_spinlock_unlock(&dpdk_spinlock);
     return err;
 }
 
@@ -572,17 +649,32 @@ netdev_dpdk_destruct(struct netdev *netdev_)
 {
     struct netdev_dpdk *dev = netdev_dpdk_cast(netdev_);
 
-    ovs_mutex_lock(&dev->mutex);
+    rte_spinlock_lock(&dev->spinlock);
     rte_eth_dev_stop(dev->port_id);
-    ovs_mutex_unlock(&dev->mutex);
+    rte_spinlock_unlock(&dev->spinlock);
 
-    ovs_mutex_lock(&dpdk_mutex);
+    rte_spinlock_lock(&dpdk_spinlock);
     rte_free(dev->tx_q);
     list_remove(&dev->list_node);
     dpdk_mp_put(dev->dpdk_mp);
-    ovs_mutex_unlock(&dpdk_mutex);
+    rte_spinlock_unlock(&dpdk_spinlock);
+}
+
+static void
+netdev_dpdk_vhost_destruct(struct netdev *netdev_)
+{
+    struct netdev_dpdk *dev = netdev_dpdk_cast(netdev_);
 
-    ovs_mutex_destroy(&dev->mutex);
+    /* Can't remove a port while a guest is attached to it. */
+    if (netdev_dpdk_get_virtio(dev) != NULL) {
+        VLOG_ERR("Can not remove port, vhost device still attached\n");
+                return;
+    }
+
+    rte_spinlock_lock(&dpdk_spinlock);
+    list_remove(&dev->list_node);
+    dpdk_mp_put(dev->dpdk_mp);
+    rte_spinlock_unlock(&dpdk_spinlock);
 }
 
 static void
@@ -598,11 +690,11 @@ netdev_dpdk_get_config(const struct netdev *netdev_, struct smap *args)
 {
     struct netdev_dpdk *dev = netdev_dpdk_cast(netdev_);
 
-    ovs_mutex_lock(&dev->mutex);
+    rte_spinlock_lock(&dev->spinlock);
 
     smap_add_format(args, "configured_rx_queues", "%d", netdev_->n_rxq);
     smap_add_format(args, "configured_tx_queues", "%d", netdev_->n_txq);
-    ovs_mutex_unlock(&dev->mutex);
+    rte_spinlock_unlock(&dev->spinlock);
 
     return 0;
 }
@@ -629,19 +721,42 @@ netdev_dpdk_set_multiq(struct netdev *netdev_, unsigned int n_txq,
         return err;
     }
 
-    ovs_mutex_lock(&dpdk_mutex);
-    ovs_mutex_lock(&netdev->mutex);
-
-    rte_eth_dev_stop(netdev->port_id);
+    rte_spinlock_lock(&dpdk_spinlock);
+    rte_spinlock_lock(&netdev->spinlock);
 
     netdev->up.n_txq = n_txq;
     netdev->up.n_rxq = n_rxq;
+
+    rte_eth_dev_stop(netdev->port_id);
     rte_free(netdev->tx_q);
     netdev_dpdk_alloc_txq(netdev, n_txq);
     err = dpdk_eth_dev_init(netdev);
 
-    ovs_mutex_unlock(&netdev->mutex);
-    ovs_mutex_unlock(&dpdk_mutex);
+    rte_spinlock_unlock(&netdev->spinlock);
+    rte_spinlock_unlock(&dpdk_spinlock);
+
+    return err;
+}
+
+static int
+netdev_dpdk_vhost_set_multiq(struct netdev *netdev_, unsigned int n_txq,
+                       unsigned int n_rxq)
+{
+    struct netdev_dpdk *netdev = netdev_dpdk_cast(netdev_);
+    int err = 0;
+
+    if (netdev->up.n_txq == n_txq && netdev->up.n_rxq == n_rxq) {
+        return err;
+    }
+
+    rte_spinlock_lock(&dpdk_spinlock);
+    rte_spinlock_lock(&netdev->spinlock);
+
+    netdev->up.n_txq = n_txq;
+    netdev->up.n_rxq = n_rxq;
+
+    rte_spinlock_unlock(&netdev->spinlock);
+    rte_spinlock_unlock(&dpdk_spinlock);
 
     return err;
 }
@@ -666,9 +781,9 @@ netdev_dpdk_rxq_construct(struct netdev_rxq *rxq_)
     struct netdev_rxq_dpdk *rx = netdev_rxq_dpdk_cast(rxq_);
     struct netdev_dpdk *netdev = netdev_dpdk_cast(rx->up.netdev);
 
-    ovs_mutex_lock(&netdev->mutex);
+    rte_spinlock_lock(&netdev->spinlock);
     rx->port_id = netdev->port_id;
-    ovs_mutex_unlock(&netdev->mutex);
+    rte_spinlock_unlock(&netdev->spinlock);
 
     return 0;
 }
@@ -712,9 +827,9 @@ dpdk_queue_flush__(struct netdev_dpdk *dev, int qid)
         for (i = nb_tx; i < txq->count; i++) {
             rte_pktmbuf_free_seg(txq->burst_pkts[i]);
         }
-        ovs_mutex_lock(&dev->mutex);
+        rte_spinlock_lock(&dev->spinlock);
         dev->stats.tx_dropped += txq->count-nb_tx;
-        ovs_mutex_unlock(&dev->mutex);
+        rte_spinlock_unlock(&dev->spinlock);
     }
 
     txq->count = 0;
@@ -732,6 +847,36 @@ dpdk_queue_flush(struct netdev_dpdk *dev, int qid)
     dpdk_queue_flush__(dev, qid);
 }
 
+/*
+ * The receive path for the vhost port is the TX path out from guest.
+ */
+static int
+netdev_dpdk_vhost_rxq_recv(struct netdev_rxq *rxq_,
+                           struct dpif_packet **packets, int *c)
+{
+    struct netdev_rxq_dpdk *rx = netdev_rxq_dpdk_cast(rxq_);
+    struct netdev *netdev = rx->up.netdev;
+    struct netdev_dpdk *vhost_dev = netdev_dpdk_cast(netdev);
+    struct virtio_net *virtio_dev = netdev_dpdk_get_virtio(vhost_dev);
+    int qid = 1;
+    uint16_t nb_rx = 0;
+
+    if (virtio_dev != NULL && (virtio_dev->flags & VIRTIO_DEV_RUNNING)) {
+        nb_rx = rte_vhost_dequeue_burst(virtio_dev, qid,
+                vhost_dev->dpdk_mp->mp, (struct rte_mbuf **)packets,
+                MAX_PKT_BURST);
+        if (!nb_rx) {
+            return EAGAIN;
+        }
+
+        vhost_dev->stats.rx_packets += (uint64_t)nb_rx;
+    }
+
+    *c = (int) nb_rx;
+
+    return 0;
+ }
+
 static int
 netdev_dpdk_rxq_recv(struct netdev_rxq *rxq_, struct dpif_packet **packets,
                      int *c)
@@ -760,6 +905,44 @@ netdev_dpdk_rxq_recv(struct netdev_rxq *rxq_, struct dpif_packet **packets,
     return 0;
 }
 
+static int
+netdev_dpdk_vhost_send(struct netdev *netdev, int qid OVS_UNUSED, struct dpif_packet **pkts,
+                 int cnt, bool may_steal)
+{
+    int i;
+    int tx_pkts;
+
+    struct netdev_dpdk *vhost_dev = netdev_dpdk_cast(netdev);
+    struct virtio_net *virtio_dev = netdev_dpdk_get_virtio(vhost_dev);
+
+    if (virtio_dev == NULL || !(virtio_dev->flags & VIRTIO_DEV_RUNNING)) {
+        VLOG_WARN_RL(&rl, "virtio_dev not added yet");
+
+        rte_spinlock_lock(&vhost_dev->spinlock);
+        vhost_dev->stats.tx_dropped+= cnt;
+        rte_spinlock_unlock(&vhost_dev->spinlock);
+        goto out;
+    }
+
+    /* Hardcoded until mq support */
+    qid = VIRTIO_RXQ;
+
+    tx_pkts = rte_vhost_enqueue_burst(virtio_dev, qid,
+            (struct rte_mbuf **)pkts, cnt);
+
+    vhost_dev->stats.tx_packets += tx_pkts;
+    vhost_dev->stats.tx_dropped += (cnt - tx_pkts);
+
+out:
+    if (may_steal) {
+        for (i = 0; i < cnt; i++) {
+            dpif_packet_delete(pkts[i]);
+        }
+    }
+
+    return 0;
+}
+
 inline static void
 dpdk_queue_pkts(struct netdev_dpdk *dev, int qid,
                struct rte_mbuf **pkts, int cnt)
@@ -801,11 +984,11 @@ dpdk_do_tx_copy(struct netdev *netdev, int qid, struct dpif_packet ** pkts,
     int newcnt = 0;
     int i;
 
-    /* If we are on a non pmd thread we have to use the mempool mutex, because
+    /* If we are on a non pmd thread we have to use the mempool spinlock, because
      * every non pmd thread shares the same mempool cache */
 
     if (!thread_is_pmd()) {
-        ovs_mutex_lock(&nonpmd_mempool_mutex);
+        rte_spinlock_lock(&nonpmd_mempool_spinlock);
     }
 
     for (i = 0; i < cnt; i++) {
@@ -837,16 +1020,16 @@ dpdk_do_tx_copy(struct netdev *netdev, int qid, struct dpif_packet ** pkts,
     }
 
     if (OVS_UNLIKELY(dropped)) {
-        ovs_mutex_lock(&dev->mutex);
+        rte_spinlock_lock(&dev->spinlock);
         dev->stats.tx_dropped += dropped;
-        ovs_mutex_unlock(&dev->mutex);
+        rte_spinlock_unlock(&dev->spinlock);
     }
 
     dpdk_queue_pkts(dev, qid, mbufs, newcnt);
     dpdk_queue_flush(dev, qid);
 
     if (!thread_is_pmd()) {
-        ovs_mutex_unlock(&nonpmd_mempool_mutex);
+        rte_spinlock_unlock(&nonpmd_mempool_spinlock);
     }
 }
 
@@ -895,9 +1078,9 @@ netdev_dpdk_send__(struct netdev_dpdk *dev, int qid,
         }
 
         if (OVS_UNLIKELY(dropped)) {
-            ovs_mutex_lock(&dev->mutex);
+            rte_spinlock_lock(&dev->spinlock);
             dev->stats.tx_dropped += dropped;
-            ovs_mutex_unlock(&dev->mutex);
+            rte_spinlock_unlock(&dev->spinlock);
         }
     }
 }
@@ -918,12 +1101,12 @@ netdev_dpdk_set_etheraddr(struct netdev *netdev,
 {
     struct netdev_dpdk *dev = netdev_dpdk_cast(netdev);
 
-    ovs_mutex_lock(&dev->mutex);
+    rte_spinlock_lock(&dev->spinlock);
     if (!eth_addr_equals(dev->hwaddr, mac)) {
         memcpy(dev->hwaddr, mac, ETH_ADDR_LEN);
         netdev_change_seq_changed(netdev);
     }
-    ovs_mutex_unlock(&dev->mutex);
+    rte_spinlock_unlock(&dev->spinlock);
 
     return 0;
 }
@@ -934,9 +1117,9 @@ netdev_dpdk_get_etheraddr(const struct netdev *netdev,
 {
     struct netdev_dpdk *dev = netdev_dpdk_cast(netdev);
 
-    ovs_mutex_lock(&dev->mutex);
+    rte_spinlock_lock(&dev->spinlock);
     memcpy(mac, dev->hwaddr, ETH_ADDR_LEN);
-    ovs_mutex_unlock(&dev->mutex);
+    rte_spinlock_unlock(&dev->spinlock);
 
     return 0;
 }
@@ -946,9 +1129,9 @@ netdev_dpdk_get_mtu(const struct netdev *netdev, int *mtup)
 {
     struct netdev_dpdk *dev = netdev_dpdk_cast(netdev);
 
-    ovs_mutex_lock(&dev->mutex);
+    rte_spinlock_lock(&dev->spinlock);
     *mtup = dev->mtu;
-    ovs_mutex_unlock(&dev->mutex);
+    rte_spinlock_unlock(&dev->spinlock);
 
     return 0;
 }
@@ -961,8 +1144,8 @@ netdev_dpdk_set_mtu(const struct netdev *netdev, int mtu)
     struct dpdk_mp *old_mp;
     struct dpdk_mp *mp;
 
-    ovs_mutex_lock(&dpdk_mutex);
-    ovs_mutex_lock(&dev->mutex);
+    rte_spinlock_lock(&dpdk_spinlock);
+    rte_spinlock_lock(&dev->spinlock);
     if (dev->mtu == mtu) {
         err = 0;
         goto out;
@@ -995,8 +1178,8 @@ netdev_dpdk_set_mtu(const struct netdev *netdev, int mtu)
     dpdk_mp_put(old_mp);
     netdev_change_seq_changed(netdev);
 out:
-    ovs_mutex_unlock(&dev->mutex);
-    ovs_mutex_unlock(&dpdk_mutex);
+    rte_spinlock_unlock(&dev->spinlock);
+    rte_spinlock_unlock(&dpdk_spinlock);
     return err;
 }
 
@@ -1004,6 +1187,44 @@ static int
 netdev_dpdk_get_carrier(const struct netdev *netdev_, bool *carrier);
 
 static int
+netdev_dpdk_vhost_get_stats(const struct netdev *netdev,
+                            struct netdev_stats *stats)
+{
+    struct netdev_dpdk *dev = netdev_dpdk_cast(netdev);
+
+    rte_spinlock_lock(&dev->spinlock);
+    memset(stats, 0, sizeof(*stats));
+    /* Unsupported Stats */
+    stats->rx_errors = UINT64_MAX;
+    stats->tx_errors = UINT64_MAX;
+    stats->multicast = UINT64_MAX;
+    stats->collisions = UINT64_MAX;
+    stats->rx_crc_errors = UINT64_MAX;
+    stats->rx_fifo_errors = UINT64_MAX;
+    stats->rx_frame_errors = UINT64_MAX;
+    stats->rx_length_errors = UINT64_MAX;
+    stats->rx_missed_errors= UINT64_MAX;
+    stats->rx_over_errors= UINT64_MAX;
+    stats->tx_aborted_errors= UINT64_MAX;
+    stats->tx_carrier_errors= UINT64_MAX;
+    stats->tx_errors= UINT64_MAX;
+    stats->tx_fifo_errors= UINT64_MAX;
+    stats->tx_heartbeat_errors= UINT64_MAX;
+    stats->tx_window_errors= UINT64_MAX;
+    stats->rx_bytes += UINT64_MAX;
+    stats->rx_dropped += UINT64_MAX;
+    stats->tx_bytes += UINT64_MAX;
+
+    /* Supported Stats */
+    stats->rx_packets += dev->stats.rx_packets;
+    stats->tx_packets += dev->stats.tx_packets;
+    stats->tx_dropped += dev->stats.tx_dropped;
+    rte_spinlock_unlock(&dev->spinlock);
+
+    return 0;
+}
+
+static int
 netdev_dpdk_get_stats(const struct netdev *netdev, struct netdev_stats *stats)
 {
     struct netdev_dpdk *dev = netdev_dpdk_cast(netdev);
@@ -1011,7 +1232,7 @@ netdev_dpdk_get_stats(const struct netdev *netdev, struct netdev_stats *stats)
     bool gg;
 
     netdev_dpdk_get_carrier(netdev, &gg);
-    ovs_mutex_lock(&dev->mutex);
+    rte_spinlock_lock(&dev->spinlock);
     rte_eth_stats_get(dev->port_id, &rte_stats);
 
     memset(stats, 0, sizeof(*stats));
@@ -1025,7 +1246,7 @@ netdev_dpdk_get_stats(const struct netdev *netdev, struct netdev_stats *stats)
     stats->multicast = rte_stats.imcasts;
 
     stats->tx_dropped = dev->stats.tx_dropped;
-    ovs_mutex_unlock(&dev->mutex);
+    rte_spinlock_unlock(&dev->spinlock);
 
     return 0;
 }
@@ -1040,9 +1261,9 @@ netdev_dpdk_get_features(const struct netdev *netdev_,
     struct netdev_dpdk *dev = netdev_dpdk_cast(netdev_);
     struct rte_eth_link link;
 
-    ovs_mutex_lock(&dev->mutex);
+    rte_spinlock_lock(&dev->spinlock);
     link = dev->link;
-    ovs_mutex_unlock(&dev->mutex);
+    rte_spinlock_unlock(&dev->spinlock);
 
     if (link.link_duplex == ETH_LINK_AUTONEG_DUPLEX) {
         if (link.link_speed == ETH_LINK_SPEED_AUTONEG) {
@@ -1082,9 +1303,9 @@ netdev_dpdk_get_ifindex(const struct netdev *netdev)
     struct netdev_dpdk *dev = netdev_dpdk_cast(netdev);
     int ifindex;
 
-    ovs_mutex_lock(&dev->mutex);
+    rte_spinlock_lock(&dev->spinlock);
     ifindex = dev->port_id;
-    ovs_mutex_unlock(&dev->mutex);
+    rte_spinlock_unlock(&dev->spinlock);
 
     return ifindex;
 }
@@ -1094,10 +1315,31 @@ netdev_dpdk_get_carrier(const struct netdev *netdev_, bool *carrier)
 {
     struct netdev_dpdk *dev = netdev_dpdk_cast(netdev_);
 
-    ovs_mutex_lock(&dev->mutex);
+    rte_spinlock_lock(&dev->spinlock);
+
     check_link_status(dev);
     *carrier = dev->link.link_status;
-    ovs_mutex_unlock(&dev->mutex);
+
+    rte_spinlock_unlock(&dev->spinlock);
+
+    return 0;
+}
+
+static int
+netdev_dpdk_vhost_get_carrier(const struct netdev *netdev_, bool *carrier)
+{
+    struct netdev_dpdk *dev = netdev_dpdk_cast(netdev_);
+    struct virtio_net *virtio_dev = netdev_dpdk_get_virtio(dev);
+
+    rte_spinlock_lock(&dev->spinlock);
+
+    if (virtio_dev != NULL && (virtio_dev->flags & VIRTIO_DEV_RUNNING)) {
+        *carrier =1;
+    } else {
+        *carrier = 0 ;
+    }
+
+    rte_spinlock_unlock(&dev->spinlock);
 
     return 0;
 }
@@ -1108,9 +1350,9 @@ netdev_dpdk_get_carrier_resets(const struct netdev *netdev_)
     struct netdev_dpdk *dev = netdev_dpdk_cast(netdev_);
     long long int carrier_resets;
 
-    ovs_mutex_lock(&dev->mutex);
+    rte_spinlock_lock(&dev->spinlock);
     carrier_resets = dev->link_reset_cnt;
-    ovs_mutex_unlock(&dev->mutex);
+    rte_spinlock_unlock(&dev->spinlock);
 
     return carrier_resets;
 }
@@ -1125,7 +1367,7 @@ netdev_dpdk_set_miimon(struct netdev *netdev_ OVS_UNUSED,
 static int
 netdev_dpdk_update_flags__(struct netdev_dpdk *dev,
                            enum netdev_flags off, enum netdev_flags on,
-                           enum netdev_flags *old_flagsp) OVS_REQUIRES(dev->mutex)
+                           enum netdev_flags *old_flagsp) OVS_REQUIRES(dev->spinlock)
 {
     int err;
 
@@ -1141,18 +1383,20 @@ netdev_dpdk_update_flags__(struct netdev_dpdk *dev,
         return 0;
     }
 
-    if (dev->flags & NETDEV_UP) {
-        err = rte_eth_dev_start(dev->port_id);
-        if (err)
-            return -err;
-    }
+    if (dev->type == DPDK) {
+        if (dev->flags & NETDEV_UP) {
+            err = rte_eth_dev_start(dev->port_id);
+            if (err)
+                return -err;
+        }
 
-    if (dev->flags & NETDEV_PROMISC) {
-        rte_eth_promiscuous_enable(dev->port_id);
-    }
+        if (dev->flags & NETDEV_PROMISC) {
+            rte_eth_promiscuous_enable(dev->port_id);
+        }
 
-    if (!(dev->flags & NETDEV_UP)) {
-        rte_eth_dev_stop(dev->port_id);
+        if (!(dev->flags & NETDEV_UP)) {
+            rte_eth_dev_stop(dev->port_id);
+        }
     }
 
     return 0;
@@ -1166,9 +1410,9 @@ netdev_dpdk_update_flags(struct netdev *netdev_,
     struct netdev_dpdk *netdev = netdev_dpdk_cast(netdev_);
     int error;
 
-    ovs_mutex_lock(&netdev->mutex);
+    rte_spinlock_lock(&netdev->spinlock);
     error = netdev_dpdk_update_flags__(netdev, off, on, old_flagsp);
-    ovs_mutex_unlock(&netdev->mutex);
+    rte_spinlock_unlock(&netdev->spinlock);
 
     return error;
 }
@@ -1182,9 +1426,9 @@ netdev_dpdk_get_status(const struct netdev *netdev_, struct smap *args)
     if (dev->port_id < 0)
         return ENODEV;
 
-    ovs_mutex_lock(&dev->mutex);
+    rte_spinlock_lock(&dev->spinlock);
     rte_eth_dev_info_get(dev->port_id, &dev_info);
-    ovs_mutex_unlock(&dev->mutex);
+    rte_spinlock_unlock(&dev->spinlock);
 
     smap_add_format(args, "driver_name", "%s", dev_info.driver_name);
 
@@ -1208,7 +1452,7 @@ netdev_dpdk_get_status(const struct netdev *netdev_, struct smap *args)
 
 static void
 netdev_dpdk_set_admin_state__(struct netdev_dpdk *dev, bool admin_state)
-    OVS_REQUIRES(dev->mutex)
+    OVS_REQUIRES(dev->spinlock)
 {
     enum netdev_flags old_flags;
 
@@ -1239,9 +1483,9 @@ netdev_dpdk_set_admin_state(struct unixctl_conn *conn, int argc,
         if (netdev && is_dpdk_class(netdev->netdev_class)) {
             struct netdev_dpdk *dpdk_dev = netdev_dpdk_cast(netdev);
 
-            ovs_mutex_lock(&dpdk_dev->mutex);
+            rte_spinlock_lock(&dpdk_dev->spinlock);
             netdev_dpdk_set_admin_state__(dpdk_dev, up);
-            ovs_mutex_unlock(&dpdk_dev->mutex);
+            rte_spinlock_unlock(&dpdk_dev->spinlock);
 
             netdev_close(netdev);
         } else {
@@ -1252,17 +1496,149 @@ netdev_dpdk_set_admin_state(struct unixctl_conn *conn, int argc,
     } else {
         struct netdev_dpdk *netdev;
 
-        ovs_mutex_lock(&dpdk_mutex);
+        rte_spinlock_lock(&dpdk_spinlock);
         LIST_FOR_EACH (netdev, list_node, &dpdk_list) {
-            ovs_mutex_lock(&netdev->mutex);
+            rte_spinlock_lock(&netdev->spinlock);
             netdev_dpdk_set_admin_state__(netdev, up);
-            ovs_mutex_unlock(&netdev->mutex);
+            rte_spinlock_unlock(&netdev->spinlock);
         }
-        ovs_mutex_unlock(&dpdk_mutex);
+        rte_spinlock_unlock(&dpdk_spinlock);
     }
     unixctl_command_reply(conn, "OK");
 }
 
+/*
+ * Set virtqueue flags so that we do not receive interrupts.
+ */
+static void
+set_irq_status(struct virtio_net *dev)
+{
+    dev->virtqueue[VIRTIO_RXQ]->used->flags = VRING_USED_F_NO_NOTIFY;
+    dev->virtqueue[VIRTIO_TXQ]->used->flags = VRING_USED_F_NO_NOTIFY;
+}
+
+/*
+ * A new virtio-net device is added to a vhost port.
+ */
+static int
+new_device(struct virtio_net *dev)
+{
+    struct netdev_dpdk *netdev;
+    bool exists = false;
+
+    /* Disable notifications. */
+    set_irq_status(dev);
+    dev->flags |= VIRTIO_DEV_RUNNING;
+
+    rte_spinlock_lock(&dpdk_spinlock);
+    /* Add device to the vhost port with the same name as that passed down. */
+    LIST_FOR_EACH(netdev, list_node, &dpdk_list) {
+        if (strncmp(dev->ifname, netdev->up.name, IFNAMSIZ) == 0) {
+            rte_spinlock_lock(&netdev->spinlock);
+            ovsrcu_set(&netdev->virtio_dev, dev);
+            rte_spinlock_unlock(&netdev->spinlock);
+            exists = true;
+            break;
+        }
+    }
+    rte_spinlock_unlock(&dpdk_spinlock);
+
+    if (!exists) {
+        VLOG_ERR("(%ld)  VHOST Device can't be added - name not found \n",
+            dev->device_fh);
+        return -1;
+    }
+
+    VLOG_INFO("(%ld)  VHOST Device has been added \n", dev->device_fh);
+
+    return 0;
+}
+
+/*
+ * Remove a virtio-net device from the specific vhost port.  Use dev->remove
+ * flag to stop any more packets from being sent or received to/from a VM and
+ * ensure all currently queued packets have been sent/received before removing
+ *  the device.
+ */
+static void
+destroy_device(volatile struct virtio_net *dev)
+{
+    struct netdev_dpdk *vhost_dev;
+    dev->flags &= ~VIRTIO_DEV_RUNNING;
+
+    rte_spinlock_lock(&dpdk_spinlock);
+    LIST_FOR_EACH (vhost_dev, list_node, &dpdk_list) {
+        if (netdev_dpdk_get_virtio(vhost_dev) == dev) {
+
+            /*
+             * Wait for other threads to quiesce before
+             * setting the virtio_dev to NULL.
+             */
+            ovsrcu_synchronize();
+
+            rte_spinlock_lock(&vhost_dev->spinlock);
+            ovsrcu_set(&vhost_dev->virtio_dev, NULL);
+            rte_spinlock_unlock(&vhost_dev->spinlock);
+
+            ovsrcu_quiesce_start();
+        }
+    }
+    rte_spinlock_unlock(&dpdk_spinlock);
+
+    VLOG_INFO("%ld Vhost Device has been removed\n", dev->device_fh);
+}
+
+struct virtio_net *
+netdev_dpdk_get_virtio(const struct netdev_dpdk *dev)
+{
+    return ovsrcu_get(struct virtio_net *, &dev->virtio_dev);
+}
+
+
+/*
+ * These callbacks allow virtio-net devices to be added to vhost ports when
+ * configuration has been fully complete.
+ */
+const struct virtio_net_device_ops virtio_net_device_ops =
+{
+    .new_device =  new_device,
+    .destroy_device = destroy_device,
+};
+
+static int
+dpdk_vhost_class_init(void)
+{
+    int err = -1;
+
+    rte_vhost_driver_callback_register(&virtio_net_device_ops);
+
+    /* Register CUSE device to handle IOCTLs.
+     * Unless otherwise specified on the vswitchd command line, dev_basename
+     * is set to vhost-net.
+     */
+    err = rte_vhost_driver_register(dev_basename);
+
+    if (err != 0) {
+        VLOG_ERR("CUSE device setup failure.\n");
+        return -1;
+    }
+
+    ovs_thread_create("cuse_thread", start_cuse_session_loop, NULL);
+
+    return 0;
+}
+
+void *
+start_cuse_session_loop(void *dummy OVS_UNUSED)
+{
+     pthread_detach(pthread_self());
+
+     ovsrcu_quiesce_start();
+     rte_vhost_driver_session_start();
+
+     return NULL;
+}
+
 static void
 dpdk_common_init(void)
 {
@@ -1332,7 +1708,7 @@ dpdk_ring_create(const char dev_name[], unsigned int port_no,
 }
 
 static int
-dpdk_ring_open(const char dev_name[], unsigned int *eth_port_id) OVS_REQUIRES(dpdk_mutex)
+dpdk_ring_open(const char dev_name[], unsigned int *eth_port_id) OVS_REQUIRES(dpdk_spinlock)
 {
     struct dpdk_ring *ivshmem;
     unsigned int port_no;
@@ -1379,7 +1755,7 @@ netdev_dpdk_ring_construct(struct netdev *netdev)
         return rte_eal_init_ret;
     }
 
-    ovs_mutex_lock(&dpdk_mutex);
+    rte_spinlock_lock(&dpdk_spinlock);
 
     err = dpdk_ring_open(netdev->name, &port_no);
     if (err) {
@@ -1389,11 +1765,12 @@ netdev_dpdk_ring_construct(struct netdev *netdev)
     err = netdev_dpdk_init(netdev, port_no);
 
 unlock_dpdk:
-    ovs_mutex_unlock(&dpdk_mutex);
+    rte_spinlock_unlock(&dpdk_spinlock);
     return err;
 }
 
-#define NETDEV_DPDK_CLASS(NAME, INIT, CONSTRUCT, MULTIQ, SEND)      \
+#define NETDEV_DPDK_CLASS(NAME, INIT, CONSTRUCT, DESTRUCT, MULTIQ, SEND, \
+    GET_CARRIER, GET_STATS, GET_FEATURES, GET_STATUS, RXQ_RECV)          \
 {                                                             \
     NAME,                                                     \
     INIT,                       /* init */                    \
@@ -1402,14 +1779,14 @@ unlock_dpdk:
                                                               \
     netdev_dpdk_alloc,                                        \
     CONSTRUCT,                                                \
-    netdev_dpdk_destruct,                                     \
+    DESTRUCT,                                                 \
     netdev_dpdk_dealloc,                                      \
     netdev_dpdk_get_config,                                   \
     NULL,                       /* netdev_dpdk_set_config */  \
     NULL,                       /* get_tunnel_config */       \
-    NULL, /* build header */                                  \
-    NULL, /* push header */                                   \
-    NULL, /* pop header */                                    \
+    NULL,                       /* build header */            \
+    NULL,                       /* push header */             \
+    NULL,                       /* pop header */              \
     netdev_dpdk_get_numa_id,    /* get_numa_id */             \
     MULTIQ,                     /* set_multiq */              \
                                                               \
@@ -1421,11 +1798,11 @@ unlock_dpdk:
     netdev_dpdk_get_mtu,                                      \
     netdev_dpdk_set_mtu,                                      \
     netdev_dpdk_get_ifindex,                                  \
-    netdev_dpdk_get_carrier,                                  \
+    GET_CARRIER,                                              \
     netdev_dpdk_get_carrier_resets,                           \
     netdev_dpdk_set_miimon,                                   \
-    netdev_dpdk_get_stats,                                    \
-    netdev_dpdk_get_features,                                 \
+    GET_STATS,                                                \
+    GET_FEATURES,                                             \
     NULL,                       /* set_advertisements */      \
                                                               \
     NULL,                       /* set_policing */            \
@@ -1447,7 +1824,7 @@ unlock_dpdk:
     NULL,                       /* get_in6 */                 \
     NULL,                       /* add_router */              \
     NULL,                       /* get_next_hop */            \
-    netdev_dpdk_get_status,                                   \
+    GET_STATUS,                                               \
     NULL,                       /* arp_lookup */              \
                                                               \
     netdev_dpdk_update_flags,                                 \
@@ -1456,7 +1833,7 @@ unlock_dpdk:
     netdev_dpdk_rxq_construct,                                \
     netdev_dpdk_rxq_destruct,                                 \
     netdev_dpdk_rxq_dealloc,                                  \
-    netdev_dpdk_rxq_recv,                                     \
+    RXQ_RECV,                                                 \
     NULL,                       /* rx_wait */                 \
     NULL,                       /* rxq_drain */               \
 }
@@ -1465,16 +1842,43 @@ int
 dpdk_init(int argc, char **argv)
 {
     int result;
+    int base = 0;
 
     if (argc < 2 || strcmp(argv[1], "--dpdk"))
         return 0;
 
-    /* Make sure program name passed to rte_eal_init() is vswitchd. */
+    /* Ignore the --dpdk argument, but keep the program name argument as this
+     * is needed later for a call to rte_eal_init()
+     */
     argv[1] = argv[0];
 
     argc--;
     argv++;
 
+    /* If the basename parameter has been provided, set 'dev_basename' to
+     * this string if it meets the correct criteria. Otherwise, set it to the
+     * default (vhost-net).
+     */
+
+    if (strcmp(argv[1], "--basename")==0 &&
+            (sizeof(argv[2]) <= MAX_BASENAME_SZ)) {
+        dev_basename = argv[2];
+
+        /* Remove the basename configuration parameters from the argument
+         * list, so that the correct elements are passed to the DPDK
+         * initialization function (including the program name as the first).
+         */
+        argv[2] = argv[0];
+        argc -= 2;
+        argv += 2;    /* Increment by two to bypass the basename arguments */
+        base = 2;
+
+        VLOG_INFO("User-provided basename in use: /dev/%s\n", dev_basename);
+    } else {
+        dev_basename = "vhost-net";
+        VLOG_INFO("No basename provided - defaulting to /dev/vhost-net\n");
+    }
+
     /* Make sure things are initialized ... */
     result = rte_eal_init(argc, argv);
     if (result < 0) {
@@ -1491,7 +1895,7 @@ dpdk_init(int argc, char **argv)
     /* We are called from the main thread here */
     thread_set_nonpmd();
 
-    return result + 1;
+    return result + 1 + base;
 }
 
 const struct netdev_class dpdk_class =
@@ -1499,16 +1903,42 @@ const struct netdev_class dpdk_class =
         "dpdk",
         NULL,
         netdev_dpdk_construct,
+        netdev_dpdk_destruct,
         netdev_dpdk_set_multiq,
-        netdev_dpdk_eth_send);
+        netdev_dpdk_eth_send,
+        netdev_dpdk_get_carrier,
+        netdev_dpdk_get_stats,
+        netdev_dpdk_get_features,
+        netdev_dpdk_get_status,
+        netdev_dpdk_rxq_recv);
 
 const struct netdev_class dpdk_ring_class =
     NETDEV_DPDK_CLASS(
         "dpdkr",
         NULL,
         netdev_dpdk_ring_construct,
+        netdev_dpdk_destruct,
+        NULL,
+        netdev_dpdk_ring_send,
+        netdev_dpdk_get_carrier,
+        netdev_dpdk_get_stats,
+        netdev_dpdk_get_features,
+        netdev_dpdk_get_status,
+        netdev_dpdk_rxq_recv);
+
+const struct netdev_class dpdk_vhost_class =
+    NETDEV_DPDK_CLASS(
+        "dpdkvhost",
+        dpdk_vhost_class_init,
+        netdev_dpdk_vhost_construct,
+        netdev_dpdk_vhost_destruct,
+        netdev_dpdk_vhost_set_multiq,
+        netdev_dpdk_vhost_send,
+        netdev_dpdk_vhost_get_carrier,
+        netdev_dpdk_vhost_get_stats,
+        NULL,
         NULL,
-        netdev_dpdk_ring_send);
+        netdev_dpdk_vhost_rxq_recv);
 
 void
 netdev_dpdk_register(void)
@@ -1523,6 +1953,7 @@ netdev_dpdk_register(void)
         dpdk_common_init();
         netdev_register_provider(&dpdk_class);
         netdev_register_provider(&dpdk_ring_class);
+        netdev_register_provider(&dpdk_vhost_class);
         ovsthread_once_done(&once);
     }
 }
diff --git a/lib/netdev.c b/lib/netdev.c
index 2bda77f..48d77bd 100644
--- a/lib/netdev.c
+++ b/lib/netdev.c
@@ -108,7 +108,8 @@ bool
 netdev_is_pmd(const struct netdev *netdev)
 {
     return (!strcmp(netdev->netdev_class->type, "dpdk") ||
-            !strcmp(netdev->netdev_class->type, "dpdkr"));
+            !strcmp(netdev->netdev_class->type, "dpdkr") ||
+            !strcmp(netdev->netdev_class->type, "dpdkvhost"));
 }
 
 static void
diff --git a/utilities/automake.mk b/utilities/automake.mk
index 834be58..2d4e0cc 100644
--- a/utilities/automake.mk
+++ b/utilities/automake.mk
@@ -41,7 +41,8 @@ EXTRA_DIST += \
 	utilities/ovs-save \
 	utilities/ovs-tcpundump.in \
 	utilities/ovs-test.in \
-	utilities/ovs-vlan-test.in
+	utilities/ovs-vlan-test.in \
+	utilities/qemu-wrap.py
 MAN_ROOTS += \
 	utilities/ovs-appctl.8.in \
 	utilities/ovs-benchmark.1.in \
diff --git a/utilities/qemu-wrap.py b/utilities/qemu-wrap.py
new file mode 100755
index 0000000..5cee849
--- /dev/null
+++ b/utilities/qemu-wrap.py
@@ -0,0 +1,389 @@
+#!/usr/bin/python
+#
+#   BSD LICENSE
+#
+#   Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
+#   All rights reserved.
+#
+#   Redistribution and use in source and binary forms, with or without
+#   modification, are permitted provided that the following conditions
+#   are met:
+#
+#     * Redistributions of source code must retain the above copyright
+#       notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above copyright
+#       notice, this list of conditions and the following disclaimer in
+#       the documentation and/or other materials provided with the
+#       distribution.
+#     * Neither the name of Intel Corporation nor the names of its
+#       contributors may be used to endorse or promote products derived
+#       from this software without specific prior written permission.
+#
+#   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+#   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+#   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+#   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+#   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+#   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+#   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+#   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+#   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+#   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+#   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+
+#####################################################################
+# This script is designed to modify the call to the QEMU emulator
+# to support userspace vhost when starting a guest machine through
+# libvirt with vhost enabled. The steps to enable this are as follows
+# and should be run as root:
+#
+# 1. Place this script in a libvirtd's binary search PATH ($PATH)
+#    A good location would be in the same directory that the QEMU
+#    binary is located
+#
+# 2. Ensure that the script has the same owner/group and file
+#    permissions as the QEMU binary
+#
+# 3. Update the VM xml file using "virsh edit VM.xml"
+#
+#    3.a) Set the VM to use the launch script
+#
+#        Set the emulator path contained in the
+#        <emulator><emulator/> tags
+#
+#        e.g replace <emulator>/usr/bin/qemu-kvm<emulator/>
+#        with    <emulator>/usr/bin/qemu-wrap.py<emulator/>
+#
+#     3.b) Set the VM's device's to use vhost-net offload
+#
+#        <interface type="network">
+#           <model type="virtio"/>
+#           <driver name="vhost"/>
+#        <interface/>
+#
+# 4. Enable libvirt to access our userpace device file by adding it to
+#    controllers cgroup for libvirtd using the following steps
+#
+#   4.a) In /etc/libvirt/qemu.conf add/edit the following lines:
+#         1) cgroup_controllers = [ ... "devices", ... ]
+#         2) clear_emulator_capabilities = 0
+#         3) user = "root"
+#         4) group = "root"
+#         5) cgroup_device_acl = [
+#                "/dev/null", "/dev/full", "/dev/zero",
+#                "/dev/random", "/dev/urandom",
+#                "/dev/ptmx", "/dev/kvm", "/dev/kqemu",
+#                "/dev/rtc", "/dev/hpet", "/dev/net/tun",
+#                "/dev/<devbase-name>-<index>",
+#                "/dev/hugepages"
+#            ]
+#
+#   4.b) Disable SELinux or set to permissive mode
+#
+#   4.c) Mount cgroup device controller
+#        "mkdir /dev/cgroup"
+#        "mount -t cgroup none /dev/cgroup -o devices"
+#
+#   4.d) Set hugetlbfs_mount variable - ( Optional )
+#        VMs using userspace vhost must use hugepage backed
+#        memory. This can be enabled in the libvirt XML
+#        config by adding a memory backing section to the
+#        XML config e.g.
+#             <memoryBacking>
+#             <hugepages/>
+#             </memoryBacking>
+#        This memory backing section should be added after the
+#        <memory> and <currentMemory> sections. This will add
+#        flags "-mem-prealloc -mem-path <path>" to the QEMU
+#        command line. The hugetlbfs_mount variable can be used
+#        to override the default <path> passed through by libvirt.
+#
+#        if "-mem-prealloc" or "-mem-path <path>" are not passed
+#        through and a vhost device is detected then these options will
+#        be automatically added by this script. This script will detect
+#        the system hugetlbfs mount point to be used for <path>. The
+#        default <path> for this script can be overidden by the
+#        hugetlbfs_dir variable in the configuration section of this script.
+#
+#
+#   4.e) Restart the libvirtd system process
+#        e.g. on Fedora "systemctl restart libvirtd.service"
+#
+#
+#   4.f) Edit the Configuration Parameters section of this script
+#        to point to the correct emulator location and set any
+#        addition options
+#
+# The script modifies the libvirtd Qemu call by modifying/adding
+# options based on the configuration parameters below.
+# NOTE:
+#     emul_path and us_vhost_path must be set
+#     All other parameters are optional
+#####################################################################
+
+
+#############################################
+# Configuration Parameters
+#############################################
+#Path to QEMU binary
+emul_path = "/usr/local/bin/qemu-system-x86_64"
+
+#Path to userspace vhost device file
+# This filename should match the --dev-basename --dev-index parameters of
+# the command used to launch the userspace vhost sample application e.g.
+# if the sample app lauch command is:
+#    ./build/vhost-switch ..... --dev-basename usvhost --dev-index 1
+# then this variable should be set to:
+#   us_vhost_path = "/dev/usvhost-1"
+us_vhost_path = "/dev/usvhost-1"
+
+#List of additional user defined emulation options. These options will
+#be added to all Qemu calls
+emul_opts_user = []
+
+#List of additional user defined emulation options for vhost only.
+#These options will only be added to vhost enabled guests
+emul_opts_user_vhost = []
+
+#For all VHOST enabled VMs, the VM memory is preallocated from hugetlbfs
+# Set this variable to one to enable this option for all VMs
+use_huge_all = 0
+
+#Instead of autodetecting, override the hugetlbfs directory by setting
+#this variable
+hugetlbfs_dir = ""
+
+#############################################
+
+
+#############################################
+# ****** Do Not Modify Below this Line ******
+#############################################
+
+import sys, os, subprocess
+import time
+import signal
+
+
+#List of open userspace vhost file descriptors
+fd_list = []
+
+#additional virtio device flags when using userspace vhost
+vhost_flags = [ "csum=off",
+                "gso=off",
+                "guest_tso4=off",
+                "guest_tso6=off",
+                "guest_ecn=off"
+              ]
+
+#String of the path to the Qemu process pid
+qemu_pid = "/tmp/%d-qemu.pid" % os.getpid()
+
+#############################################
+# Signal haldler to kill Qemu subprocess
+#############################################
+def kill_qemu_process(signum, stack):
+    pidfile = open(qemu_pid, 'r')
+    pid = int(pidfile.read())
+    os.killpg(pid, signal.SIGTERM)
+    pidfile.close()
+
+
+#############################################
+# Find the system hugefile mount point.
+# Note:
+# if multiple hugetlbfs mount points exist
+# then the first one found will be used
+#############################################
+def find_huge_mount():
+
+    if (len(hugetlbfs_dir)):
+        return hugetlbfs_dir
+
+    huge_mount = ""
+
+    if (os.access("/proc/mounts", os.F_OK)):
+        f = open("/proc/mounts", "r")
+        line = f.readline()
+        while line:
+            line_split = line.split(" ")
+            if line_split[2] == 'hugetlbfs':
+                huge_mount = line_split[1]
+                break
+            line = f.readline()
+    else:
+        print "/proc/mounts not found"
+        exit (1)
+
+    f.close
+    if len(huge_mount) == 0:
+        print "Failed to find hugetlbfs mount point"
+        exit (1)
+
+    return huge_mount
+
+
+#############################################
+# Get a userspace Vhost file descriptor
+#############################################
+def get_vhost_fd():
+
+    if (os.access(us_vhost_path, os.F_OK)):
+        fd = os.open( us_vhost_path, os.O_RDWR)
+    else:
+        print ("US-Vhost file %s not found" %us_vhost_path)
+        exit (1)
+
+    return fd
+
+
+#############################################
+# Check for vhostfd. if found then replace
+# with our own vhost fd and append any vhost
+# flags onto the end
+#############################################
+def modify_netdev_arg(arg):
+
+    global fd_list
+    vhost_in_use = 0
+    s = ''
+    new_opts = []
+    netdev_opts = arg.split(",")
+
+    for opt in netdev_opts:
+        #check if vhost is used
+        if "vhost" == opt[:5]:
+            vhost_in_use = 1
+        else:
+            new_opts.append(opt)
+
+    #if using vhost append vhost options
+    if vhost_in_use == 1:
+        #append vhost on option
+        new_opts.append('vhost=on')
+        #append vhostfd ption
+        new_fd = get_vhost_fd()
+        new_opts.append('vhostfd=' + str(new_fd))
+        fd_list.append(new_fd)
+
+    #concatenate all options
+    for opt in new_opts:
+        if len(s) > 0:
+            s+=','
+
+        s+=opt
+
+    return s
+
+
+#############################################
+# Main
+#############################################
+def main():
+
+    global fd_list
+    global vhost_in_use
+    new_args = []
+    num_cmd_args = len(sys.argv)
+    emul_call = ''
+    mem_prealloc_set = 0
+    mem_path_set = 0
+    num = 0;
+
+    #parse the parameters
+    while (num < num_cmd_args):
+        arg = sys.argv[num]
+
+        #Check netdev +1 parameter for vhostfd
+        if arg == '-netdev':
+            num_vhost_devs = len(fd_list)
+            new_args.append(arg)
+
+            num+=1
+            arg = sys.argv[num]
+            mod_arg = modify_netdev_arg(arg)
+            new_args.append(mod_arg)
+
+            #append vhost flags if this is a vhost device
+            # and -device is the next arg
+            # i.e -device -opt1,-opt2,...,-opt3,%vhost
+            if (num_vhost_devs < len(fd_list)):
+                num+=1
+                arg = sys.argv[num]
+                if arg == '-device':
+                    new_args.append(arg)
+                    num+=1
+                    new_arg = sys.argv[num]
+                    for flag in vhost_flags:
+                        new_arg = ''.join([new_arg,',',flag])
+                    new_args.append(new_arg)
+                else:
+                    new_args.append(arg)
+        elif arg == '-mem-prealloc':
+            mem_prealloc_set = 1
+            new_args.append(arg)
+        elif arg == '-mem-path':
+            mem_path_set = 1
+            new_args.append(arg)
+
+        else:
+            new_args.append(arg)
+
+        num+=1
+
+    #Set Qemu binary location
+    emul_call+=emul_path
+    emul_call+=" "
+
+    #Add prealloc mem options if using vhost and not already added
+    if ((len(fd_list) > 0) and (mem_prealloc_set == 0)):
+        emul_call += "-mem-prealloc "
+
+    #Add mempath mem options if using vhost and not already added
+    if ((len(fd_list) > 0) and (mem_path_set == 0)):
+        #Detect and add hugetlbfs mount point
+        mp = find_huge_mount()
+        mp = "".join(["-mem-path ", mp])
+        emul_call += mp
+        emul_call += " "
+
+    #add user options
+    for opt in emul_opts_user:
+        emul_call += opt
+        emul_call += " "
+
+    #Add add user vhost only options
+    if len(fd_list) > 0:
+        for opt in emul_opts_user_vhost:
+            emul_call += opt
+            emul_call += " "
+
+    #Add updated libvirt options
+    iter_args = iter(new_args)
+    #skip 1st arg i.e. call to this script
+    next(iter_args)
+    for arg in iter_args:
+        emul_call+=str(arg)
+        emul_call+= " "
+
+    emul_call += "-pidfile %s " % qemu_pid
+    #Call QEMU
+    process = subprocess.Popen(emul_call, shell=True, preexec_fn=os.setsid)
+
+    for sig in [signal.SIGTERM, signal.SIGINT, signal.SIGHUP, signal.SIGQUIT]:
+        signal.signal(sig, kill_qemu_process)
+
+    process.wait()
+
+    #Close usvhost files
+    for fd in fd_list:
+        os.close(fd)
+    #Cleanup temporary files
+    if os.access(qemu_pid, os.F_OK):
+        os.remove(qemu_pid)
+
+
+
+if __name__ == "__main__":
+    main()
diff --git a/vswitchd/ovs-vswitchd.c b/vswitchd/ovs-vswitchd.c
index 812c00b..822d53e 100644
--- a/vswitchd/ovs-vswitchd.c
+++ b/vswitchd/ovs-vswitchd.c
@@ -252,7 +252,9 @@ usage(void)
     daemon_usage();
     vlog_usage();
     printf("\nDPDK options:\n"
-           "  --dpdk options          Initialize DPDK datapath.\n");
+           "  --dpdk options          Initialize DPDK datapath.\n"
+           "  --basename BASENAME     override default character device name\n"
+           "                          for use with userspace vHost.\n");
     printf("\nOther options:\n"
            "  --unixctl=SOCKET        override default control socket name\n"
            "  -h, --help              display this help message\n"
-- 
1.7.4.1




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