[dpdk-dev,3/3] examples/vhost: vhost example based on vhost library.
diff mbox

Message ID 1409648131-4301-4-git-send-email-huawei.xie@intel.com
State Superseded, archived
Headers show

Commit Message

Huawei Xie Sept. 2, 2014, 8:55 a.m. UTC
Signed-off-by: Huawei Xie <huawei.xie@intel.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
---
 examples/vhost/Makefile             |   52 +
 examples/vhost/libvirt/qemu-wrap.py |  366 ++++
 examples/vhost/main.c               | 3145 +++++++++++++++++++++++++++++++++++
 examples/vhost/main.h               |  109 ++
 4 files changed, 3672 insertions(+)
 create mode 100644 examples/vhost/Makefile
 create mode 100644 examples/vhost/libvirt/qemu-wrap.py
 create mode 100644 examples/vhost/main.c
 create mode 100644 examples/vhost/main.h

Patch
diff mbox

diff --git a/examples/vhost/Makefile b/examples/vhost/Makefile
new file mode 100644
index 0000000..a4d4fb0
--- /dev/null
+++ b/examples/vhost/Makefile
@@ -0,0 +1,52 @@ 
+#   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.
+
+ifeq ($(RTE_SDK),)
+$(error "Please define RTE_SDK environment variable")
+endif
+
+# Default target, can be overriden by command line or environment
+RTE_TARGET ?= x86_64-native-linuxapp-gcc
+
+include $(RTE_SDK)/mk/rte.vars.mk
+
+# binary name
+APP = vhost-switch
+
+# all source are stored in SRCS-y
+#SRCS-y := cusedrv.c loopback-userspace.c
+SRCS-y := main.c
+
+CFLAGS += -O2 -I/usr/local/include -D_FILE_OFFSET_BITS=64 -Wno-unused-parameter
+CFLAGS += $(WERROR_FLAGS)
+LDFLAGS += -lfuse
+
+include $(RTE_SDK)/mk/rte.extapp.mk
diff --git a/examples/vhost/libvirt/qemu-wrap.py b/examples/vhost/libvirt/qemu-wrap.py
new file mode 100644
index 0000000..8d820be
--- /dev/null
+++ b/examples/vhost/libvirt/qemu-wrap.py
@@ -0,0 +1,366 @@ 
+#!/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>",
+#            ]
+#
+#   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
+
+
+#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"
+              ]
+
+
+#############################################
+# 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+= " "
+
+    #Call QEMU
+    subprocess.call(emul_call, shell=True)
+
+
+    #Close usvhost files
+    for fd in fd_list:
+        os.close(fd)
+
+
+if __name__ == "__main__":
+    main()
diff --git a/examples/vhost/main.c b/examples/vhost/main.c
new file mode 100644
index 0000000..1fa3391
--- /dev/null
+++ b/examples/vhost/main.c
@@ -0,0 +1,3145 @@ 
+/*-
+ *   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.
+ */
+
+#include <arpa/inet.h>
+#include <getopt.h>
+#include <linux/if_ether.h>
+#include <linux/if_vlan.h>
+#include <linux/virtio_net.h>
+#include <linux/virtio_ring.h>
+#include <signal.h>
+#include <stdint.h>
+#include <sys/eventfd.h>
+#include <sys/param.h>
+#include <unistd.h>
+
+#include <rte_atomic.h>
+#include <rte_cycles.h>
+#include <rte_ethdev.h>
+#include <rte_log.h>
+#include <rte_string_fns.h>
+#include <rte_malloc.h>
+#include <rte_virtio_net.h>
+
+#include "main.h"
+
+#define MAX_QUEUES 128
+
+/* #define VHOST_DEBUG */
+
+/* Macros for printing using RTE_LOG */
+#define RTE_LOGTYPE_VHOST_CONFIG RTE_LOGTYPE_USER1
+#define RTE_LOGTYPE_VHOST_PORT   RTE_LOGTYPE_USER2
+#define RTE_LOGTYPE_VHOST_DATA   RTE_LOGTYPE_USER3
+
+
+#ifdef VHOST_DEBUG
+#define LOG_LEVEL RTE_LOG_DEBUG
+#define LOG_DEBUG(log_type, fmt, args...) RTE_LOG(DEBUG, log_type, fmt, ##args)
+#else
+#define LOG_LEVEL RTE_LOG_INFO
+#define LOG_DEBUG(log_type, fmt, args...) do {} while (0)
+#endif
+
+
+/* the maximum number of external ports supported */
+#define MAX_SUP_PORTS 1
+
+/*
+ * Calculate the number of buffers needed per port
+ */
+#define NUM_MBUFS_PER_PORT ((MAX_QUEUES*RTE_TEST_RX_DESC_DEFAULT) + \
+			(num_switching_cores * MAX_PKT_BURST) + \
+			(num_switching_cores * RTE_TEST_TX_DESC_DEFAULT) + \
+			(num_switching_cores * MBUF_CACHE_SIZE))
+
+#define MBUF_CACHE_SIZE 128
+#define MBUF_SIZE (2048 + sizeof(struct rte_mbuf) + RTE_PKTMBUF_HEADROOM)
+
+/*
+ * No frame data buffer allocated from host are required for zero copy
+ * implementation, guest will allocate the frame data buffer, and vhost
+ * directly use it.
+ */
+#define VIRTIO_DESCRIPTOR_LEN_ZCP 1518
+#define MBUF_SIZE_ZCP (VIRTIO_DESCRIPTOR_LEN_ZCP + sizeof(struct rte_mbuf) \
+	+ RTE_PKTMBUF_HEADROOM)
+#define MBUF_CACHE_SIZE_ZCP 0
+
+/*
+ * RX and TX Prefetch, Host, and Write-back threshold values should be
+ * carefully set for optimal performance. Consult the network
+ * controller's datasheet and supporting DPDK documentation for guidance
+ * on how these parameters should be set.
+ */
+#define RX_PTHRESH 8 /* Default values of RX prefetch threshold reg. */
+#define RX_HTHRESH 8 /* Default values of RX host threshold reg. */
+#define RX_WTHRESH 4 /* Default values of RX write-back threshold reg. */
+
+/*
+ * These default values are optimized for use with the Intel(R) 82599 10 GbE
+ * Controller and the DPDK ixgbe PMD. Consider using other values for other
+ * network controllers and/or network drivers.
+ */
+#define TX_PTHRESH 36 /* Default values of TX prefetch threshold reg. */
+#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_PKT_BURST 32 /* Max burst size for RX/TX */
+#define BURST_TX_DRAIN_US 100 /* TX drain every ~100us */
+
+#define BURST_RX_WAIT_US 15 /* Defines how long we wait between retries on RX */
+#define BURST_RX_RETRIES 4  /* Number of retries on RX. */
+
+/* State of virtio device. */
+#define DEVICE_MAC_LEARNING 0
+#define DEVICE_RX           1
+#define DEVICE_SAFE_REMOVE  2
+
+/* Config_core_flag status definitions. */
+#define REQUEST_DEV_REMOVAL 1
+#define ACK_DEV_REMOVAL 0
+
+/* Configurable number of RX/TX ring descriptors */
+#define RTE_TEST_RX_DESC_DEFAULT 1024
+#define RTE_TEST_TX_DESC_DEFAULT 512
+
+/*
+ * Need refine these 2 macros for legacy and DPDK based front end:
+ * Max vring avail descriptor/entries from guest - MAX_PKT_BURST
+ * And then adjust power 2.
+ */
+/*
+ * For legacy front end, 128 descriptors,
+ * half for virtio header, another half for mbuf.
+ */
+#define RTE_TEST_RX_DESC_DEFAULT_ZCP 32   /* legacy: 32, DPDK virt FE: 128. */
+#define RTE_TEST_TX_DESC_DEFAULT_ZCP 64   /* legacy: 64, DPDK virt FE: 64.  */
+
+/* Get first 4 bytes in mbuf headroom. */
+#define MBUF_HEADROOM_UINT32(mbuf) (*(uint32_t *)((uint8_t *)(mbuf) \
+		+ sizeof(struct rte_mbuf)))
+
+/* true if x is a power of 2 */
+#define POWEROF2(x) ((((x)-1) & (x)) == 0)
+
+#define INVALID_PORT_ID 0xFF
+
+/* Max number of devices. Limited by vmdq. */
+#define MAX_DEVICES 64
+
+/* Size of buffers used for snprintfs. */
+#define MAX_PRINT_BUFF 6072
+
+/* Maximum character device basename size. */
+#define MAX_BASENAME_SZ 10
+
+/* Maximum long option length for option parsing. */
+#define MAX_LONG_OPT_SZ 64
+
+/* Used to compare MAC addresses. */
+#define MAC_ADDR_CMP 0xFFFFFFFFFFFFULL
+
+/* Number of descriptors per cacheline. */
+#define DESC_PER_CACHELINE (CACHE_LINE_SIZE / sizeof(struct vring_desc))
+
+/* mask of enabled ports */
+static uint32_t enabled_port_mask;
+
+/*Number of switching cores enabled*/
+static uint32_t num_switching_cores;
+
+/* number of devices/queues to support*/
+static uint32_t num_queues;
+static uint32_t num_devices;
+
+/*
+ * Enable zero copy, pkts buffer will directly dma to hw descriptor,
+ * disabled on default.
+ */
+static uint32_t zero_copy;
+static int mergeable;
+
+
+/* number of descriptors to apply*/
+static uint32_t num_rx_descriptor = RTE_TEST_RX_DESC_DEFAULT_ZCP;
+static uint32_t num_tx_descriptor = RTE_TEST_TX_DESC_DEFAULT_ZCP;
+
+/* max ring descriptor, ixgbe, i40e, e1000 all are 4096. */
+#define MAX_RING_DESC 4096
+
+struct vpool {
+	struct rte_mempool *pool;
+	struct rte_ring *ring;
+	uint32_t buf_size;
+} vpool_array[MAX_QUEUES + MAX_QUEUES];
+
+/*
+ * Enable VM2VM communications. If this is disabled then the MAC address
+ * compare is skipped.
+ */
+enum vm2vm_type {
+	VM2VM_DISABLED = 0,
+	VM2VM_SOFTWARE = 1,
+	VM2VM_HARDWARE = 2,
+	VM2VM_LAST
+};
+static enum vm2vm_type vm2vm_mode = VM2VM_SOFTWARE;
+
+/* The type of host physical address translated from guest physical address. */
+enum hpa_type {
+	PHYS_ADDR_CONTINUOUS = 0,
+	PHYS_ADDR_CROSS_SUBREG = 1,
+	PHYS_ADDR_INVALID = 2,
+	PHYS_ADDR_LAST
+};
+
+/* Enable stats. */
+static uint32_t enable_stats;
+/* Enable retries on RX. */
+static uint32_t enable_retry;
+/* Specify timeout (in useconds) between retries on RX. */
+static uint32_t burst_rx_delay_time = BURST_RX_WAIT_US;
+/* Specify the number of retries on RX. */
+static uint32_t burst_rx_retry_num = BURST_RX_RETRIES;
+
+/* Character device basename. Can be set by user. */
+static char dev_basename[MAX_BASENAME_SZ] = "vhost-net";
+
+/* Default configuration for rx and tx thresholds etc. */
+static struct rte_eth_rxconf rx_conf_default = {
+	.rx_thresh = {
+		.pthresh = RX_PTHRESH,
+		.hthresh = RX_HTHRESH,
+		.wthresh = RX_WTHRESH,
+	},
+	.rx_drop_en = 1,
+};
+
+/*
+ * These default values are optimized for use with the Intel(R) 82599 10 GbE
+ * Controller and the DPDK ixgbe/igb PMD. Consider using other values for other
+ * network controllers and/or network drivers.
+ */
+static struct rte_eth_txconf tx_conf_default = {
+	.tx_thresh = {
+		.pthresh = TX_PTHRESH,
+		.hthresh = TX_HTHRESH,
+		.wthresh = TX_WTHRESH,
+	},
+	.tx_free_thresh = 0, /* Use PMD default values */
+	.tx_rs_thresh = 0, /* Use PMD default values */
+};
+
+/* empty vmdq configuration structure. Filled in programatically */
+static struct rte_eth_conf vmdq_conf_default = {
+	.rxmode = {
+		.mq_mode        = ETH_MQ_RX_VMDQ_ONLY,
+		.split_hdr_size = 0,
+		.header_split   = 0, /**< Header Split disabled */
+		.hw_ip_checksum = 0, /**< IP checksum offload disabled */
+		.hw_vlan_filter = 0, /**< VLAN filtering disabled */
+		/*
+		 * It is necessary for 1G NIC such as I350,
+		 * this fixes bug of ipv4 forwarding in guest can't
+		 * forward pakets from one virtio dev to another virtio dev.
+		 */
+		.hw_vlan_strip  = 1, /**< VLAN strip enabled. */
+		.jumbo_frame    = 0, /**< Jumbo Frame Support disabled */
+		.hw_strip_crc   = 0, /**< CRC stripped by hardware */
+	},
+
+	.txmode = {
+		.mq_mode = ETH_MQ_TX_NONE,
+	},
+	.rx_adv_conf = {
+		/*
+		 * should be overridden separately in code with
+		 * appropriate values
+		 */
+		.vmdq_rx_conf = {
+			.nb_queue_pools = ETH_8_POOLS,
+			.enable_default_pool = 0,
+			.default_pool = 0,
+			.nb_pool_maps = 0,
+			.pool_map = {{0, 0},},
+		},
+	},
+};
+
+static unsigned lcore_ids[RTE_MAX_LCORE];
+static uint8_t ports[RTE_MAX_ETHPORTS];
+static unsigned num_ports; /**< The number of ports specified in command line */
+
+static const uint16_t external_pkt_default_vlan_tag = 2000;
+const uint16_t vlan_tags[] = {
+	1000, 1001, 1002, 1003, 1004, 1005, 1006, 1007,
+	1008, 1009, 1010, 1011,	1012, 1013, 1014, 1015,
+	1016, 1017, 1018, 1019, 1020, 1021, 1022, 1023,
+	1024, 1025, 1026, 1027, 1028, 1029, 1030, 1031,
+	1032, 1033, 1034, 1035, 1036, 1037, 1038, 1039,
+	1040, 1041, 1042, 1043, 1044, 1045, 1046, 1047,
+	1048, 1049, 1050, 1051, 1052, 1053, 1054, 1055,
+	1056, 1057, 1058, 1059, 1060, 1061, 1062, 1063,
+};
+
+/* ethernet addresses of ports */
+static struct ether_addr vmdq_ports_eth_addr[RTE_MAX_ETHPORTS];
+
+/* heads for the main used and free linked lists for the data path. */
+static struct virtio_net_data_ll *ll_root_used;
+static struct virtio_net_data_ll *ll_root_free;
+
+/*
+ * Array of data core structures containing information on individual core
+ * linked lists.
+ */
+static struct lcore_info lcore_info[RTE_MAX_LCORE];
+
+/* Used for queueing bursts of TX packets. */
+struct mbuf_table {
+	unsigned len;
+	unsigned txq_id;
+	struct rte_mbuf *m_table[MAX_PKT_BURST];
+};
+
+/* TX queue for each data core. */
+struct mbuf_table lcore_tx_queue[RTE_MAX_LCORE];
+
+/* TX queue fori each virtio device for zero copy. */
+struct mbuf_table tx_queue_zcp[MAX_QUEUES];
+
+/* Vlan header struct used to insert vlan tags on TX. */
+struct vlan_ethhdr {
+	unsigned char   h_dest[ETH_ALEN];
+	unsigned char   h_source[ETH_ALEN];
+	__be16          h_vlan_proto;
+	__be16          h_vlan_TCI;
+	__be16          h_vlan_encapsulated_proto;
+};
+
+/* IPv4 Header */
+struct ipv4_hdr {
+	uint8_t  version_ihl;		/**< version and header length */
+	uint8_t  type_of_service;	/**< type of service */
+	uint16_t total_length;		/**< length of packet */
+	uint16_t packet_id;		/**< packet ID */
+	uint16_t fragment_offset;	/**< fragmentation offset */
+	uint8_t  time_to_live;		/**< time to live */
+	uint8_t  next_proto_id;		/**< protocol ID */
+	uint16_t hdr_checksum;		/**< header checksum */
+	uint32_t src_addr;		/**< source address */
+	uint32_t dst_addr;		/**< destination address */
+} __attribute__((__packed__));
+
+/* Header lengths. */
+#define VLAN_HLEN       4
+#define VLAN_ETH_HLEN   18
+
+/* Per-device statistics struct */
+struct device_statistics {
+	uint64_t tx_total;
+	rte_atomic64_t rx_total_atomic;
+	uint64_t rx_total;
+	uint64_t tx;
+	rte_atomic64_t rx_atomic;
+	uint64_t rx;
+} __rte_cache_aligned;
+struct device_statistics dev_statistics[MAX_DEVICES];
+
+/*
+ * Builds up the correct configuration for VMDQ VLAN pool map
+ * according to the pool & queue limits.
+ */
+static inline int
+get_eth_conf(struct rte_eth_conf *eth_conf, uint32_t num_devices)
+{
+	struct rte_eth_vmdq_rx_conf conf;
+	unsigned i;
+
+	memset(&conf, 0, sizeof(conf));
+	conf.nb_queue_pools = (enum rte_eth_nb_pools)num_devices;
+	conf.nb_pool_maps = num_devices;
+	conf.enable_loop_back =
+		vmdq_conf_default.rx_adv_conf.vmdq_rx_conf.enable_loop_back;
+
+	for (i = 0; i < conf.nb_pool_maps; i++) {
+		conf.pool_map[i].vlan_id = vlan_tags[i];
+		conf.pool_map[i].pools = (1UL << i);
+	}
+
+	*eth_conf = vmdq_conf_default;
+	eth_conf->rx_adv_conf.vmdq_rx_conf = conf;
+	return 0;
+}
+
+/*
+ * Validate the device number according to the max pool number gotten form
+ * dev_info. If the device number is invalid, give the error message and
+ * return -1. Each device must have its own pool.
+ */
+static inline int
+validate_num_devices(uint32_t max_nb_devices)
+{
+	if (num_devices > max_nb_devices) {
+		RTE_LOG(ERR, VHOST_PORT, "invalid number of devices\n");
+		return -1;
+	}
+	return 0;
+}
+
+/*
+ * Initialises a given port using global settings and with the rx buffers
+ * coming from the mbuf_pool passed as parameter
+ */
+static inline int
+port_init(uint8_t port)
+{
+	struct rte_eth_dev_info dev_info;
+	struct rte_eth_conf port_conf;
+	uint16_t rx_rings, tx_rings;
+	uint16_t rx_ring_size, tx_ring_size;
+	int retval;
+	uint16_t q;
+
+	rte_eth_dev_info_get(port, &dev_info);
+
+	/*
+	 * Configure the number of supported virtio devices based on VMDQ
+	 * limits
+	 */
+	num_devices = dev_info.max_vmdq_pools;
+	num_queues = dev_info.max_rx_queues;
+
+	if (zero_copy) {
+		rx_ring_size = num_rx_descriptor;
+		tx_ring_size = num_tx_descriptor;
+		tx_rings = dev_info.max_tx_queues;
+	} else {
+		rx_ring_size = RTE_TEST_RX_DESC_DEFAULT;
+		tx_ring_size = RTE_TEST_TX_DESC_DEFAULT;
+		tx_rings = (uint16_t)rte_lcore_count();
+	}
+
+	retval = validate_num_devices(MAX_DEVICES);
+	if (retval < 0)
+		return retval;
+
+	/* Get port configuration. */
+	retval = get_eth_conf(&port_conf, num_devices);
+	if (retval < 0)
+		return retval;
+
+	if (port >= rte_eth_dev_count())
+		return -1;
+
+	rx_rings = (uint16_t)num_queues,
+	/* Configure ethernet device. */
+	retval = rte_eth_dev_configure(port, rx_rings, tx_rings, &port_conf);
+	if (retval != 0)
+		return retval;
+
+	/* Setup the queues. */
+	for (q = 0; q < rx_rings; q++) {
+		retval = rte_eth_rx_queue_setup(port, q, rx_ring_size,
+						rte_eth_dev_socket_id(port),
+						&rx_conf_default,
+						vpool_array[q].pool);
+		if (retval < 0)
+			return retval;
+	}
+	for (q = 0; q < tx_rings; q++) {
+		retval = rte_eth_tx_queue_setup(port, q, tx_ring_size,
+						rte_eth_dev_socket_id(port),
+						&tx_conf_default);
+		if (retval < 0)
+			return retval;
+	}
+
+	/* Start the device. */
+	retval  = rte_eth_dev_start(port);
+	if (retval < 0) {
+		RTE_LOG(ERR, VHOST_DATA, "Failed to start the device.\n");
+		return retval;
+	}
+
+	rte_eth_macaddr_get(port, &vmdq_ports_eth_addr[port]);
+	RTE_LOG(INFO, VHOST_PORT, "Max virtio devices supported: %u\n",
+		num_devices);
+	RTE_LOG(INFO, VHOST_PORT, "Port %u MAC: %02"PRIx8" %02"PRIx8" %02"PRIx8
+			" %02"PRIx8" %02"PRIx8" %02"PRIx8"\n",
+			(unsigned)port,
+			vmdq_ports_eth_addr[port].addr_bytes[0],
+			vmdq_ports_eth_addr[port].addr_bytes[1],
+			vmdq_ports_eth_addr[port].addr_bytes[2],
+			vmdq_ports_eth_addr[port].addr_bytes[3],
+			vmdq_ports_eth_addr[port].addr_bytes[4],
+			vmdq_ports_eth_addr[port].addr_bytes[5]);
+
+	return 0;
+}
+
+/*
+ * Set character device basename.
+ */
+static int
+us_vhost_parse_basename(const char *q_arg)
+{
+	/* parse number string */
+
+	if (strnlen(q_arg, MAX_BASENAME_SZ) > MAX_BASENAME_SZ)
+		return -1;
+	else
+		snprintf((char *)&dev_basename, MAX_BASENAME_SZ, "%s", q_arg);
+
+	return 0;
+}
+
+/*
+ * Parse the portmask provided at run time.
+ */
+static int
+parse_portmask(const char *portmask)
+{
+	char *end = NULL;
+	unsigned long pm;
+
+	errno = 0;
+
+	/* parse hexadecimal string */
+	pm = strtoul(portmask, &end, 16);
+	if ((portmask[0] == '\0') || (end == NULL) || (*end != '\0') ||
+		(errno != 0))
+		return -1;
+
+	if (pm == 0)
+		return -1;
+
+	return pm;
+
+}
+
+/*
+ * Parse num options at run time.
+ */
+static int
+parse_num_opt(const char *q_arg, uint32_t max_valid_value)
+{
+	char *end = NULL;
+	unsigned long num;
+
+	errno = 0;
+
+	/* parse unsigned int string */
+	num = strtoul(q_arg, &end, 10);
+	if ((q_arg[0] == '\0') || (end == NULL) || (*end != '\0') ||
+		(errno != 0))
+		return -1;
+
+	if (num > max_valid_value)
+		return -1;
+
+	return num;
+
+}
+
+/*
+ * Display usage
+ */
+static void
+us_vhost_usage(const char *prgname)
+{
+	RTE_LOG(INFO, VHOST_CONFIG, "%s [EAL options] -- -p PORTMASK\n"
+	"		--vm2vm [0|1|2]\n"
+	"		--rx_retry [0|1] --mergeable [0|1] --stats [0-N]\n"
+	"		--dev-basename <name> --dev-index [0-N]\n"
+	"		--nb-devices ND\n"
+	"		-p PORTMASK: Set mask for ports to be used by application\n"
+	"		--vm2vm [0|1|2]: disable/software(default)/hardware vm2vm comms\n"
+	"		--rx-retry [0|1]: disable/enable(default) retries on rx. Enable retry if destintation queue is full\n"
+	"		--rx-retry-delay [0-N]: timeout(in usecond) between retries on RX. This makes effect only if retries on rx enabled\n"
+	"		--rx-retry-num [0-N]: the number of retries on rx. This makes effect only if retries on rx enabled\n"
+	"		--mergeable [0|1]: disable(default)/enable RX mergeable buffers\n"
+	"		--stats [0-N]: 0: Disable stats, N: Time in seconds to print stats\n"
+	"		--dev-basename: The basename to be used for the character device.\n"
+	"		--dev-index [0-N]: Defaults to zero if not used. Index is appended to basename.\n"
+	"		--zero-copy [0|1]: disable(default)/enable rx/tx "
+			"zero copy\n"
+	"		--rx-desc-num [0-N]: the number of descriptors on rx, "
+			"used only when zero copy is enabled.\n"
+	"		--tx-desc-num [0-N]: the number of descriptors on tx, "
+			"used only when zero copy is enabled.\n",
+	       prgname);
+}
+
+/*
+ * Parse the arguments given in the command line of the application.
+ */
+static int
+us_vhost_parse_args(int argc, char **argv)
+{
+	int opt, ret;
+	int option_index;
+	unsigned i;
+	const char *prgname = argv[0];
+	static struct option long_option[] = {
+		{"vm2vm", required_argument, NULL, 0},
+		{"rx-retry", required_argument, NULL, 0},
+		{"rx-retry-delay", required_argument, NULL, 0},
+		{"rx-retry-num", required_argument, NULL, 0},
+		{"mergeable", required_argument, NULL, 0},
+		{"stats", required_argument, NULL, 0},
+		{"dev-basename", required_argument, NULL, 0},
+		{"dev-index", required_argument, NULL, 0},
+		{"zero-copy", required_argument, NULL, 0},
+		{"rx-desc-num", required_argument, NULL, 0},
+		{"tx-desc-num", required_argument, NULL, 0},
+		{NULL, 0, 0, 0},
+	};
+
+	/* Parse command line */
+	while ((opt = getopt_long(argc, argv, "p:", long_option, &option_index))
+		!= EOF) {
+		switch (opt) {
+		/* Portmask */
+		case 'p':
+			enabled_port_mask = parse_portmask(optarg);
+			if (enabled_port_mask == 0) {
+				RTE_LOG(INFO, VHOST_CONFIG,
+					"Invalid portmask\n");
+				us_vhost_usage(prgname);
+				return -1;
+			}
+			break;
+
+		case 0:
+			/* Enable/disable vm2vm comms. */
+			if (!strncmp(long_option[option_index].name, "vm2vm",
+				MAX_LONG_OPT_SZ)) {
+				ret = parse_num_opt(optarg, (VM2VM_LAST - 1));
+				if (ret == -1) {
+					RTE_LOG(INFO, VHOST_CONFIG,
+						"Invalid argument for "
+						"vm2vm [0|1|2]\n");
+					us_vhost_usage(prgname);
+					return -1;
+				} else {
+					vm2vm_mode = (enum vm2vm_type)ret;
+				}
+			}
+
+			/* Enable/disable retries on RX. */
+			if (!strncmp(long_option[option_index].name, "rx-retry",
+				MAX_LONG_OPT_SZ)) {
+				ret = parse_num_opt(optarg, 1);
+				if (ret == -1) {
+					RTE_LOG(INFO, VHOST_CONFIG,
+						"Invalid argument for "
+						"rx-retry [0|1]\n");
+					us_vhost_usage(prgname);
+					return -1;
+				} else {
+					enable_retry = ret;
+				}
+			}
+
+			/* Specify the retries delay time (in useconds) on RX */
+			if (!strncmp(long_option[option_index].name,
+				"rx-retry-delay", MAX_LONG_OPT_SZ)) {
+				ret = parse_num_opt(optarg, INT32_MAX);
+				if (ret == -1) {
+					RTE_LOG(INFO, VHOST_CONFIG, "Invalid "
+					"argument for rx-retry-delay [0-N]\n");
+					us_vhost_usage(prgname);
+					return -1;
+				} else {
+					burst_rx_delay_time = ret;
+				}
+			}
+
+			/* Specify the retries number on RX. */
+			if (!strncmp(long_option[option_index].name,
+				"rx-retry-num", MAX_LONG_OPT_SZ)) {
+				ret = parse_num_opt(optarg, INT32_MAX);
+				if (ret == -1) {
+					RTE_LOG(INFO, VHOST_CONFIG, "Invalid "
+					"argument for rx-retry-num [0-N]\n");
+					us_vhost_usage(prgname);
+					return -1;
+				} else {
+					burst_rx_retry_num = ret;
+				}
+			}
+
+			/* Enable/disable RX mergeable buffers. */
+			if (!strncmp(long_option[option_index].name, "mergeable",
+				MAX_LONG_OPT_SZ)) {
+				ret = parse_num_opt(optarg, 1);
+				if (ret == -1) {
+					RTE_LOG(INFO, VHOST_CONFIG, "Invalid "
+					"argument for mergeable [0|1]\n");
+					us_vhost_usage(prgname);
+					return -1;
+				} else
+					mergeable = !!ret;
+			}
+
+			/* Enable/disable stats. */
+			if (!strncmp(long_option[option_index].name, "stats",
+				MAX_LONG_OPT_SZ)) {
+				ret = parse_num_opt(optarg, INT32_MAX);
+				if (ret == -1) {
+					RTE_LOG(INFO, VHOST_CONFIG, "Invalid "
+					"argument for stats [0..N]\n");
+					us_vhost_usage(prgname);
+					return -1;
+				} else {
+					enable_stats = ret;
+				}
+			}
+
+			/* Set character device basename. */
+			if (!strncmp(long_option[option_index].name,
+				"dev-basename", MAX_LONG_OPT_SZ)) {
+				if (us_vhost_parse_basename(optarg) == -1) {
+					RTE_LOG(INFO, VHOST_CONFIG, "Invalid "
+					"argument for character device basename "
+					"(Max %d characters)\n",
+					MAX_BASENAME_SZ);
+					us_vhost_usage(prgname);
+					return -1;
+				}
+			}
+
+			/* Enable/disable rx/tx zero copy. */
+			if (!strncmp(long_option[option_index].name,
+				"zero-copy", MAX_LONG_OPT_SZ)) {
+				ret = parse_num_opt(optarg, 1);
+				if (ret == -1) {
+					RTE_LOG(INFO, VHOST_CONFIG,
+						"Invalid argument"
+						" for zero-copy [0|1]\n");
+					us_vhost_usage(prgname);
+					return -1;
+				} else
+					zero_copy = ret;
+
+				if (zero_copy) {
+#ifdef RTE_MBUF_SCATTER_GATHER
+					RTE_LOG(ERR, VHOST_CONFIG, "Before "
+					"running zero copy vhost APP, please "
+					"disable RTE_MBUF_SCATTER_GATHER "
+					"in config file and then rebuild DPDK "
+					"core lib!\n"
+					"Otherwise please disable zero copy "
+					"flag in command line!\n");
+					return -1;
+#endif
+				}
+			}
+
+			/* Specify the descriptor number on RX. */
+			if (!strncmp(long_option[option_index].name,
+				"rx-desc-num", MAX_LONG_OPT_SZ)) {
+				ret = parse_num_opt(optarg, MAX_RING_DESC);
+				if ((ret == -1) || (!POWEROF2(ret))) {
+					RTE_LOG(INFO, VHOST_CONFIG,
+					"Invalid argument for rx-desc-num[0-N],"
+					"power of 2 required.\n");
+					us_vhost_usage(prgname);
+					return -1;
+				} else {
+					num_rx_descriptor = ret;
+				}
+			}
+
+			/* Specify the descriptor number on TX. */
+			if (!strncmp(long_option[option_index].name,
+				"tx-desc-num", MAX_LONG_OPT_SZ)) {
+				ret = parse_num_opt(optarg, MAX_RING_DESC);
+				if ((ret == -1) || (!POWEROF2(ret))) {
+					RTE_LOG(INFO, VHOST_CONFIG,
+					"Invalid argument for tx-desc-num [0-N],"
+					"power of 2 required.\n");
+					us_vhost_usage(prgname);
+					return -1;
+				} else {
+					num_tx_descriptor = ret;
+				}
+			}
+
+			break;
+
+			/* Invalid option - print options. */
+		default:
+			us_vhost_usage(prgname);
+			return -1;
+		}
+	}
+
+	for (i = 0; i < RTE_MAX_ETHPORTS; i++) {
+		if (enabled_port_mask & (1 << i))
+			ports[num_ports++] = (uint8_t)i;
+	}
+
+	if ((num_ports ==  0) || (num_ports > MAX_SUP_PORTS)) {
+		RTE_LOG(INFO, VHOST_PORT, "Current enabled port number is %u,"
+			"but only %u port can be enabled\n", num_ports,
+			MAX_SUP_PORTS);
+		return -1;
+	}
+
+	if ((zero_copy == 1) && (vm2vm_mode == VM2VM_SOFTWARE)) {
+		RTE_LOG(INFO, VHOST_PORT,
+			"Vhost zero copy doesn't support software vm2vm, "
+			"please specify 'vm2vm 2' to use hardware vm2vm.\n");
+		return -1;
+	}
+
+	return 0;
+}
+
+/*
+ * Update the global var NUM_PORTS and array PORTS according to
+ * system ports number and return valid ports number.
+ */
+static unsigned check_ports_num(unsigned nb_ports)
+{
+	unsigned valid_num_ports = num_ports;
+	unsigned portid;
+
+	if (num_ports > nb_ports) {
+		RTE_LOG(INFO, VHOST_PORT, "\nSpecified port number(%u) exceeds "
+			"total system port number(%u)\n", num_ports, nb_ports);
+		num_ports = nb_ports;
+	}
+
+	for (portid = 0; portid < num_ports; portid++) {
+		if (ports[portid] >= nb_ports) {
+			RTE_LOG(INFO, VHOST_PORT, "\nSpecified port ID(%u) "
+				"exceeds max system port ID(%u)\n",
+				ports[portid], (nb_ports - 1));
+			ports[portid] = INVALID_PORT_ID;
+			valid_num_ports--;
+		}
+	}
+	return valid_num_ports;
+}
+
+/*
+ * Macro to print out packet contents. Wrapped in debug define so that the
+ * data path is not effected when debug is disabled.
+ */
+#ifdef VHOST_DEBUG
+#define PRINT_PACKET(device, addr, size, header) do { \
+	char *pkt_addr = (char *)(addr); \
+	unsigned int index; \
+	char packet[MAX_PRINT_BUFF]; \
+	if ((header)) \
+		snprintf(packet, MAX_PRINT_BUFF, "(%"PRIu64") Header size " \
+		"%d: ", (device->device_fh), (size)); \
+	else \
+		snprintf(packet, MAX_PRINT_BUFF, "(%"PRIu64") Packet size " \
+		"%d: ", (device->device_fh), (size)); \
+	for (index = 0; index < (size); index++) { \
+		snprintf(packet + strnlen(packet, MAX_PRINT_BUFF), \
+			MAX_PRINT_BUFF - strnlen(packet, MAX_PRINT_BUFF), \
+			"%02hhx ", pkt_addr[index]); \
+	} \
+	snprintf(packet + strnlen(packet, MAX_PRINT_BUFF), \
+		MAX_PRINT_BUFF - strnlen(packet, MAX_PRINT_BUFF), "\n"); \
+	LOG_DEBUG(VHOST_DATA, "%s", packet); \
+} while (0)
+#else
+#define PRINT_PACKET(device, addr, size, header) do {} while (0)
+#endif
+
+/*
+ * Function to convert guest physical addresses to vhost physical addresses.
+ * This is used to convert virtio buffer addresses.
+ */
+static inline uint64_t __attribute__((always_inline))
+gpa_to_hpa(struct vhost_dev  *vdev, uint64_t guest_pa,
+	uint32_t buf_len, enum hpa_type *addr_type)
+{
+	struct virtio_memory_regions_hpa *region;
+	uint32_t regionidx;
+	uint64_t vhost_pa = 0;
+
+	*addr_type = PHYS_ADDR_INVALID;
+
+	for (regionidx = 0; regionidx < vdev->nregions_hpa; regionidx++) {
+		region = &vdev->regions_hpa[regionidx];
+		if ((guest_pa >= region->guest_phys_address) &&
+			(guest_pa <= region->guest_phys_address_end)) {
+			vhost_pa = region->host_phys_addr_offset + guest_pa;
+			if (likely((guest_pa + buf_len - 1)
+				<= region->guest_phys_address_end))
+				*addr_type = PHYS_ADDR_CONTINUOUS;
+			else
+				*addr_type = PHYS_ADDR_CROSS_SUBREG;
+			break;
+		}
+	}
+
+	LOG_DEBUG(VHOST_DATA, "(%"PRIu64") GPA %p| HPA %p\n",
+		dev->device_fh, (void *)(uintptr_t)guest_pa,
+		(void *)(uintptr_t)vhost_pa);
+
+	return vhost_pa;
+}
+
+/*
+ * Compares a packet destination MAC address to a device MAC address.
+ */
+static inline int __attribute__((always_inline))
+ether_addr_cmp(struct ether_addr *ea, struct ether_addr *eb)
+{
+	return (((*(uint64_t *)ea ^ *(uint64_t *)eb) & MAC_ADDR_CMP) == 0);
+}
+
+/*
+ * This function learns the MAC address of the device and registers this along
+ * with a vlan tag to a VMDQ.
+ */
+static int
+link_vmdq(struct vhost_dev *vdev, struct rte_mbuf *m)
+{
+	struct ether_hdr *pkt_hdr;
+	struct virtio_net_data_ll *dev_ll;
+	struct virtio_net *dev = vdev->dev;
+	int i, ret;
+
+	/* Learn MAC address of guest device from packet */
+	pkt_hdr = (struct ether_hdr *)m->pkt.data;
+
+	dev_ll = ll_root_used;
+
+	while (dev_ll != NULL) {
+		if (ether_addr_cmp(&(pkt_hdr->s_addr),
+			&dev_ll->vdev->mac_address)) {
+			RTE_LOG(INFO, VHOST_DATA, "(%"PRIu64") WARNING: This "
+			"device is using an existing MAC address and has not "
+			"been registered.\n", dev->device_fh);
+			return -1;
+		}
+		dev_ll = dev_ll->next;
+	}
+
+	for (i = 0; i < ETHER_ADDR_LEN; i++)
+		vdev->mac_address.addr_bytes[i] = pkt_hdr->s_addr.addr_bytes[i];
+
+	/* vlan_tag currently uses the device_id. */
+	vdev->vlan_tag = vlan_tags[dev->device_fh];
+
+	/* Print out VMDQ registration info. */
+	RTE_LOG(INFO, VHOST_DATA, "(%"PRIu64") MAC_ADDRESS %02x:%02x:%02x:%02x:"
+		"%02x:%02x and VLAN_TAG %d registered\n",
+		dev->device_fh,
+		vdev->mac_address.addr_bytes[0],
+		vdev->mac_address.addr_bytes[1],
+		vdev->mac_address.addr_bytes[2],
+		vdev->mac_address.addr_bytes[3],
+		vdev->mac_address.addr_bytes[4],
+		vdev->mac_address.addr_bytes[5],
+		vdev->vlan_tag);
+
+	/* Register the MAC address on the pool specified by device_fh. */
+	ret = rte_eth_dev_mac_addr_add(ports[0], &vdev->mac_address,
+		(uint32_t)dev->device_fh);
+	if (ret)
+		RTE_LOG(ERR, VHOST_DATA, "(%"PRIu64") Failed to add device "
+			"MAC address to VMDQ\n", dev->device_fh);
+
+	/* Enable stripping of the vlan tag as we handle routing. */
+	rte_eth_dev_set_vlan_strip_on_queue(ports[0],
+		(uint16_t)vdev->vmdq_rx_q, 1);
+
+	/* Set device as ready for RX. */
+	vdev->ready = DEVICE_RX;
+
+	return 0;
+}
+
+/*
+ * Removes MAC address and vlan tag from VMDQ. Ensures that nothing is adding
+ * buffers to the RX queue before disabling RX on the device.
+ */
+static inline void
+unlink_vmdq(struct vhost_dev *vdev)
+{
+	unsigned i = 0;
+	unsigned rx_count;
+	struct rte_mbuf *pkts_burst[MAX_PKT_BURST];
+
+	if (vdev->ready == DEVICE_RX) {
+		/*clear MAC and VLAN settings*/
+		rte_eth_dev_mac_addr_remove(ports[0], &vdev->mac_address);
+		for (i = 0; i < 6; i++)
+			vdev->mac_address.addr_bytes[i] = 0;
+
+		vdev->vlan_tag = 0;
+
+		/*Clear out the receive buffers*/
+		rx_count = rte_eth_rx_burst(ports[0], (uint16_t)vdev->vmdq_rx_q,
+				pkts_burst, MAX_PKT_BURST);
+		while (rx_count) {
+			for (i = 0; i < rx_count; i++)
+				rte_pktmbuf_free(pkts_burst[i]);
+
+			rx_count = rte_eth_rx_burst(ports[0],
+					(uint16_t)vdev->vmdq_rx_q, pkts_burst,
+					MAX_PKT_BURST);
+		}
+
+		vdev->ready = DEVICE_MAC_LEARNING;
+	}
+}
+
+/*
+ * Check if the packet destination MAC address is for a local device. If so
+ * put the packet on that devices RX queue. If not then return.
+ */
+static inline int __attribute__((always_inline))
+virtio_tx_local(struct vhost_dev *vdev, struct rte_mbuf *m)
+{
+	struct virtio_net_data_ll *dev_ll;
+	struct ether_hdr *pkt_hdr = (struct ether_hdr *)m->pkt.data;
+	uint64_t ret = 0;
+	struct virtio_net *dev = vdev->dev;
+	struct virtio_net *tdev; /* destination virito device */
+
+	/* Get the used devices list*/
+	dev_ll = ll_root_used;
+
+	while (dev_ll != NULL) {
+		if ((dev_ll->vdev->ready == DEVICE_RX) &&
+			ether_addr_cmp(&(pkt_hdr->d_addr),
+				&dev_ll->vdev->mac_address)) {
+
+			if (dev_ll->vdev->dev->device_fh == dev->device_fh) {
+				LOG_DEBUG(VHOST_DATA, "(%"PRIu64") TX: Source "
+				"and destination MAC addresses are the same. "
+				"Dropping packet.\n", dev->device_fh);
+				return 0;
+			}
+			tdev = dev_ll->vdev->dev;
+
+			LOG_DEBUG(VHOST_DATA, "(%"PRIu64") TX: MAC address is "
+				"local\n", tdev->device_fh);
+
+			if (unlikely(dev_ll->vdev->remove)) {
+				LOG_DEBUG(VHOST_DATA, "(%"PRIu64") Device is "
+				"marked for removal\n", tdev->device_fh);
+			} else {
+				/* Send the packet to the local virtio device*/
+				ret = rte_vhost_enqueue_burst(tdev, VIRTIO_RXQ,
+					&m, 1);
+				if (enable_stats) {
+					rte_atomic64_add(
+					&dev_statistics[tdev->device_fh].rx_total_atomic,
+					1);
+					rte_atomic64_add(
+					&dev_statistics[tdev->device_fh].rx_atomic,
+					ret);
+					dev_statistics[tdev->device_fh].tx_total++;
+					dev_statistics[tdev->device_fh].tx += ret;
+				}
+			}
+
+			return 0;
+		}
+		dev_ll = dev_ll->next;
+	}
+
+	return -1;
+}
+
+/*
+ * This function routes the TX packet to the correct interface. This may be a
+ * local device or the physical port.
+ */
+static inline void __attribute__((always_inline))
+virtio_tx_route(struct vhost_dev *vdev, struct rte_mbuf *m,
+		struct rte_mempool *mbuf_pool, uint16_t vlan_tag) {
+	struct mbuf_table *tx_q;
+	struct rte_mbuf **m_table;
+	unsigned len, ret, offset = 0;
+	const uint16_t lcore_id = rte_lcore_id();
+	struct virtio_net_data_ll *dev_ll = ll_root_used;
+	struct ether_hdr *pkt_hdr = (struct ether_hdr *)m->pkt.data;
+	struct virtio_net *dev = vdev->dev;
+
+	/* Check if destination is local VM*/
+	if (vm2vm_mode == VM2VM_SOFTWARE && (virtio_tx_local(vdev, m) == 0)) {
+		rte_pktmbuf_free(m);
+		return;
+	}
+
+	if (vm2vm_mode == VM2VM_HARDWARE) {
+		while (dev_ll != NULL) {
+			if ((dev_ll->vdev->ready == DEVICE_RX)
+				&& ether_addr_cmp(&(pkt_hdr->d_addr),
+				&dev_ll->vdev->mac_address)) {
+				/*
+				 * Drop the packet if the TX packet is
+				 * destined for the TX device.
+				 */
+				if (dev_ll->vdev->dev->device_fh ==
+					dev->device_fh) {
+					LOG_DEBUG(VHOST_DATA,
+					"(%"PRIu64") TX: Source and destination "
+					"MAC addresses are the same. Dropping "
+					"packet.\n",
+					dev_ll->vdev->device_fh);
+					rte_pktmbuf_free(m);
+					return;
+				}
+				offset = 4;
+				vlan_tag =
+				(uint16_t)
+				vlan_tags[(uint16_t)dev_ll->vdev->dev->device_fh];
+
+				LOG_DEBUG(VHOST_DATA,
+				"(%"PRIu64") TX: pkt to local VM device id:"
+				"(%"PRIu64") vlan tag: %d.\n",
+				dev->device_fh, dev_ll->vdev->dev->device_fh,
+				vlan_tag);
+
+				break;
+			}
+			dev_ll = dev_ll->next;
+		}
+	}
+
+	LOG_DEBUG(VHOST_DATA, "(%"PRIu64") TX: MAC address is external\n",
+		dev->device_fh);
+
+	/*Add packet to the port tx queue*/
+	tx_q = &lcore_tx_queue[lcore_id];
+	len = tx_q->len;
+
+	m->ol_flags = PKT_TX_VLAN_PKT;
+	m->pkt.data_len += offset;
+	m->pkt.pkt_len = m->pkt.data_len;
+	m->pkt.vlan_macip.f.vlan_tci = vlan_tag;
+
+	tx_q->m_table[len] = m;
+	len++;
+	if (enable_stats) {
+		dev_statistics[dev->device_fh].tx_total++;
+		dev_statistics[dev->device_fh].tx++;
+	}
+
+	if (unlikely(len == MAX_PKT_BURST)) {
+		m_table = (struct rte_mbuf **)tx_q->m_table;
+		ret = rte_eth_tx_burst(ports[0], (uint16_t)tx_q->txq_id,
+				m_table, (uint16_t) len);
+		/*
+		 * Free any buffers not handled by TX and update the port
+		 * stats.
+		 */
+		if (unlikely(ret < len)) {
+			do {
+				rte_pktmbuf_free(m_table[ret]);
+			} while (++ret < len);
+		}
+
+		len = 0;
+	}
+
+	tx_q->len = len;
+	return;
+}
+/*
+ * This function is called by each data core. It handles all RX/TX registered
+ * with the core. For TX the specific lcore linked list is used. For RX, MAC
+ * addresses are compared with all devices in the main linked list.
+ */
+static int
+switch_worker(__attribute__((unused)) void *arg)
+{
+	struct rte_mempool *mbuf_pool = arg;
+	struct virtio_net *dev = NULL;
+	struct vhost_dev *vdev = NULL;
+	struct rte_mbuf *pkts_burst[MAX_PKT_BURST];
+	struct virtio_net_data_ll *dev_ll;
+	struct mbuf_table *tx_q;
+	volatile struct lcore_ll_info *lcore_ll;
+	const uint64_t drain_tsc = (rte_get_tsc_hz() + US_PER_S - 1) /
+					US_PER_S * BURST_TX_DRAIN_US;
+	uint64_t prev_tsc, diff_tsc, cur_tsc, ret_count = 0;
+	unsigned ret, i;
+	const uint16_t lcore_id = rte_lcore_id();
+	const uint16_t num_cores = (uint16_t)rte_lcore_count();
+	uint16_t rx_count = 0;
+	uint16_t tx_count;
+	uint32_t retry = 0;
+
+	RTE_LOG(INFO, VHOST_DATA, "Procesing on Core %u started\n", lcore_id);
+	lcore_ll = lcore_info[lcore_id].lcore_ll;
+	prev_tsc = 0;
+
+	tx_q = &lcore_tx_queue[lcore_id];
+	for (i = 0; i < num_cores; i++) {
+		if (lcore_ids[i] == lcore_id) {
+			tx_q->txq_id = i;
+			break;
+		}
+	}
+
+	while (1) {
+		cur_tsc = rte_rdtsc();
+		/*
+		 * TX burst queue drain
+		 */
+		diff_tsc = cur_tsc - prev_tsc;
+		if (unlikely(diff_tsc > drain_tsc)) {
+
+			if (tx_q->len) {
+				LOG_DEBUG(VHOST_DATA, "TX queue drained after "
+					"timeout with burst size %u\n", tx_q->len);
+
+				/*Tx any packets in the queue*/
+				ret = rte_eth_tx_burst(ports[0],
+					(uint16_t)tx_q->txq_id,
+					(struct rte_mbuf **)tx_q->m_table,
+					(uint16_t)tx_q->len);
+				if (unlikely(ret < tx_q->len)) {
+					do {
+						rte_pktmbuf_free(tx_q->m_table[ret]);
+					} while (++ret < tx_q->len);
+				}
+
+				tx_q->len = 0;
+			}
+
+			prev_tsc = cur_tsc;
+
+		}
+
+		rte_prefetch0(lcore_ll->ll_root_used);
+		/*
+		 * Inform the configuration core that we have exited the linked
+		 * list and that no devices are in use if requested.
+		 */
+		if (lcore_ll->dev_removal_flag == REQUEST_DEV_REMOVAL)
+			lcore_ll->dev_removal_flag =  ACK_DEV_REMOVAL;
+
+		/* Process devices */
+		dev_ll = lcore_ll->ll_root_used;
+
+		while (likely(dev_ll != NULL)) {
+			vdev = dev_ll->vdev;
+			dev = vdev->dev;
+
+			if (unlikely(vdev->remove)) {
+				dev_ll = dev_ll->next;
+				unlink_vmdq(vdev);
+				vdev->ready = DEVICE_SAFE_REMOVE;
+				continue;
+			}
+			if (likely(vdev->ready == DEVICE_RX)) {
+				/* Handle guest RX */
+				rx_count = rte_eth_rx_burst(ports[0],
+						vdev->vmdq_rx_q, pkts_burst,
+						MAX_PKT_BURST);
+
+				if (rx_count) {
+					/*
+					 * Retry is enabled and the queue is
+					 * full then we wait and retry to avoid
+					 * packet loss. Here MAX_PKT_BURST must
+					 * be less than virtio queue size.
+					 */
+					if (enable_retry && unlikely(rx_count >
+						rte_vring_available_entries(dev, VIRTIO_RXQ))) {
+						for (retry = 0;
+							retry < burst_rx_retry_num;
+							retry++) {
+							rte_delay_us(burst_rx_delay_time);
+							if (rx_count <= rte_vring_available_entries(dev, VIRTIO_RXQ))
+								break;
+						}
+					}
+					ret_count = rte_vhost_enqueue_burst(dev,
+					VIRTIO_RXQ, pkts_burst, rx_count);
+					if (enable_stats) {
+						rte_atomic64_add(
+						&dev_statistics[dev_ll->vdev->dev->device_fh].rx_total_atomic,
+						rx_count);
+						rte_atomic64_add(
+						&dev_statistics[dev_ll->vdev->dev->device_fh].rx_atomic, ret_count);
+					}
+					while (likely(rx_count)) {
+						rx_count--;
+						rte_pktmbuf_free_seg(pkts_burst[rx_count]);
+					}
+
+				}
+			}
+
+			if (!vdev->remove) {
+				/* Handle guest TX*/
+				tx_count = rte_vhost_dequeue_burst(dev,
+						VIRTIO_TXQ, mbuf_pool,
+						pkts_burst, MAX_PKT_BURST);
+				/*
+				 * If this is the first received packet we need
+				 * to learn the MAC and setup VMDQ.
+				 */
+				if (unlikely(vdev->ready == DEVICE_MAC_LEARNING)
+					&& tx_count) {
+					if (vdev->remove || (link_vmdq(vdev,
+						pkts_burst[0]) == -1)) {
+						while (tx_count--)
+							rte_pktmbuf_free(pkts_burst[tx_count]);
+					}
+				}
+				while (tx_count)
+					virtio_tx_route(vdev,
+						pkts_burst[--tx_count],
+						mbuf_pool,
+						(uint16_t)dev->device_fh);
+			}
+
+			/*move to the next device in the list*/
+			dev_ll = dev_ll->next;
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * This function gets available ring number for zero copy rx.
+ * Only one thread will call this funciton for a paticular virtio device,
+ * so, it is designed as non-thread-safe function.
+ */
+static inline uint32_t __attribute__((always_inline))
+get_available_ring_num_zcp(struct virtio_net *dev)
+{
+	struct vhost_virtqueue *vq = dev->virtqueue[VIRTIO_RXQ];
+	uint16_t avail_idx;
+
+	avail_idx = *((volatile uint16_t *)&vq->avail->idx);
+	return (uint32_t)(avail_idx - vq->last_used_idx_res);
+}
+
+/*
+ * This function gets available ring index for zero copy rx,
+ * it will retry 'burst_rx_retry_num' times till it get enough ring index.
+ * Only one thread will call this funciton for a paticular virtio device,
+ * so, it is designed as non-thread-safe function.
+ */
+static inline uint32_t __attribute__((always_inline))
+get_available_ring_index_zcp(struct virtio_net *dev,
+	uint16_t *res_base_idx, uint32_t count)
+{
+	struct vhost_virtqueue *vq = dev->virtqueue[VIRTIO_RXQ];
+	uint16_t avail_idx;
+	uint32_t retry = 0;
+	uint16_t free_entries;
+
+	*res_base_idx = vq->last_used_idx_res;
+	avail_idx = *((volatile uint16_t *)&vq->avail->idx);
+	free_entries = (avail_idx - *res_base_idx);
+
+	LOG_DEBUG(VHOST_DATA, "(%"PRIu64") in get_available_ring_index_zcp: "
+			"avail idx: %d, "
+			"res base idx:%d, free entries:%d\n",
+			dev->device_fh, avail_idx, *res_base_idx,
+			free_entries);
+
+	/*
+	 * If retry is enabled and the queue is full then we wait
+	 * and retry to avoid packet loss.
+	 */
+	if (enable_retry && unlikely(count > free_entries)) {
+		for (retry = 0; retry < burst_rx_retry_num; retry++) {
+			rte_delay_us(burst_rx_delay_time);
+			avail_idx = *((volatile uint16_t *)&vq->avail->idx);
+			free_entries = (avail_idx - *res_base_idx);
+			if (count <= free_entries)
+				break;
+		}
+	}
+
+	/*check that we have enough buffers*/
+	if (unlikely(count > free_entries))
+		count = free_entries;
+
+	if (unlikely(count == 0)) {
+		LOG_DEBUG(VHOST_DATA,
+			"(%"PRIu64") Fail in get_available_ring_index_zcp: "
+			"avail idx: %d, res base idx:%d, free entries:%d\n",
+			dev->device_fh, avail_idx,
+			*res_base_idx, free_entries);
+		return 0;
+	}
+
+	vq->last_used_idx_res = *res_base_idx + count;
+
+	return count;
+}
+
+/*
+ * This function put descriptor back to used list.
+ */
+static inline void __attribute__((always_inline))
+put_desc_to_used_list_zcp(struct vhost_virtqueue *vq, uint16_t desc_idx)
+{
+	uint16_t res_cur_idx = vq->last_used_idx;
+	vq->used->ring[res_cur_idx & (vq->size - 1)].id = (uint32_t)desc_idx;
+	vq->used->ring[res_cur_idx & (vq->size - 1)].len = 0;
+	rte_compiler_barrier();
+	*(volatile uint16_t *)&vq->used->idx += 1;
+	vq->last_used_idx += 1;
+
+	/* Kick the guest if necessary. */
+	if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT))
+		eventfd_write((int)vq->kickfd, 1);
+}
+
+/*
+ * This function get available descriptor from vitio vring and un-attached mbuf
+ * from vpool->ring, and then attach them together. It needs adjust the offset
+ * for buff_addr and phys_addr accroding to PMD implementation, otherwise the
+ * frame data may be put to wrong location in mbuf.
+ */
+static inline void __attribute__((always_inline))
+attach_rxmbuf_zcp(struct virtio_net *dev)
+{
+	uint16_t res_base_idx, desc_idx;
+	uint64_t buff_addr, phys_addr;
+	struct vhost_virtqueue *vq;
+	struct vring_desc *desc;
+	struct rte_mbuf *mbuf = NULL;
+	struct vpool *vpool;
+	enum hpa_type addr_type;
+	struct vhost_dev *vdev = (struct vhost_dev *)dev->priv;
+
+	vpool = &vpool_array[vdev->vmdq_rx_q];
+	vq = dev->virtqueue[VIRTIO_RXQ];
+
+	do {
+		if (unlikely(get_available_ring_index_zcp(vdev->dev,
+				&res_base_idx, 1) != 1))
+			return;
+		desc_idx = vq->avail->ring[(res_base_idx) & (vq->size - 1)];
+
+		desc = &vq->desc[desc_idx];
+		if (desc->flags & VRING_DESC_F_NEXT) {
+			desc = &vq->desc[desc->next];
+			buff_addr = gpa_to_vva(dev, desc->addr);
+			phys_addr = gpa_to_hpa(vdev, desc->addr, desc->len,
+					&addr_type);
+		} else {
+			buff_addr = gpa_to_vva(dev,
+					desc->addr + vq->vhost_hlen);
+			phys_addr = gpa_to_hpa(vdev,
+					desc->addr + vq->vhost_hlen,
+					desc->len, &addr_type);
+		}
+
+		if (unlikely(addr_type == PHYS_ADDR_INVALID)) {
+			RTE_LOG(ERR, VHOST_DATA, "(%"PRIu64") Invalid frame "
+				"buffer address found when attaching RX frame "
+				"buffer address!\n", dev->device_fh);
+			put_desc_to_used_list_zcp(vq, desc_idx);
+			continue;
+		}
+
+		/*
+		 * Check if the frame buffer address from guest crosses
+		 * sub-region or not.
+		 */
+		if (unlikely(addr_type == PHYS_ADDR_CROSS_SUBREG)) {
+			RTE_LOG(ERR, VHOST_DATA,
+				"(%"PRIu64") Frame buffer address cross "
+				"sub-regioin found when attaching RX frame "
+				"buffer address!\n",
+				dev->device_fh);
+			put_desc_to_used_list_zcp(vq, desc_idx);
+			continue;
+		}
+	} while (unlikely(phys_addr == 0));
+
+	rte_ring_sc_dequeue(vpool->ring, (void **)&mbuf);
+	if (unlikely(mbuf == NULL)) {
+		LOG_DEBUG(VHOST_DATA,
+			"(%"PRIu64") in attach_rxmbuf_zcp: "
+			"ring_sc_dequeue fail.\n",
+			dev->device_fh);
+		put_desc_to_used_list_zcp(vq, desc_idx);
+		return;
+	}
+
+	if (unlikely(vpool->buf_size > desc->len)) {
+		LOG_DEBUG(VHOST_DATA,
+			"(%"PRIu64") in attach_rxmbuf_zcp: frame buffer "
+			"length(%d) of descriptor idx: %d less than room "
+			"size required: %d\n",
+			dev->device_fh, desc->len, desc_idx, vpool->buf_size);
+		put_desc_to_used_list_zcp(vq, desc_idx);
+		rte_ring_sp_enqueue(vpool->ring, (void *)mbuf);
+		return;
+	}
+
+	mbuf->buf_addr = (void *)(uintptr_t)(buff_addr - RTE_PKTMBUF_HEADROOM);
+	mbuf->pkt.data = (void *)(uintptr_t)(buff_addr);
+	mbuf->buf_physaddr = phys_addr - RTE_PKTMBUF_HEADROOM;
+	mbuf->pkt.data_len = desc->len;
+	MBUF_HEADROOM_UINT32(mbuf) = (uint32_t)desc_idx;
+
+	LOG_DEBUG(VHOST_DATA,
+		"(%"PRIu64") in attach_rxmbuf_zcp: res base idx:%d, "
+		"descriptor idx:%d\n",
+		dev->device_fh, res_base_idx, desc_idx);
+
+	__rte_mbuf_raw_free(mbuf);
+
+	return;
+}
+
+/*
+ * Detach an attched packet mbuf -
+ *  - restore original mbuf address and length values.
+ *  - reset pktmbuf data and data_len to their default values.
+ *  All other fields of the given packet mbuf will be left intact.
+ *
+ * @param m
+ *   The attached packet mbuf.
+ */
+static inline void
+pktmbuf_detach_zcp(struct rte_mbuf *m)
+{
+	const struct rte_mempool *mp = m->pool;
+	void *buf = RTE_MBUF_TO_BADDR(m);
+	uint32_t buf_ofs;
+	uint32_t buf_len = mp->elt_size - sizeof(*m);
+	m->buf_physaddr = rte_mempool_virt2phy(mp, m) + sizeof(*m);
+
+	m->buf_addr = buf;
+	m->buf_len = (uint16_t)buf_len;
+
+	buf_ofs = (RTE_PKTMBUF_HEADROOM <= m->buf_len) ?
+			RTE_PKTMBUF_HEADROOM : m->buf_len;
+	m->pkt.data = (char *) m->buf_addr + buf_ofs;
+
+	m->pkt.data_len = 0;
+}
+
+/*
+ * This function is called after packets have been transimited. It fetchs mbuf
+ * from vpool->pool, detached it and put into vpool->ring. It also update the
+ * used index and kick the guest if necessary.
+ */
+static inline uint32_t __attribute__((always_inline))
+txmbuf_clean_zcp(struct virtio_net *dev, struct vpool *vpool)
+{
+	struct rte_mbuf *mbuf;
+	struct vhost_virtqueue *vq = dev->virtqueue[VIRTIO_TXQ];
+	uint32_t used_idx = vq->last_used_idx & (vq->size - 1);
+	uint32_t index = 0;
+	uint32_t mbuf_count = rte_mempool_count(vpool->pool);
+
+	LOG_DEBUG(VHOST_DATA,
+		"(%"PRIu64") in txmbuf_clean_zcp: mbuf count in mempool before "
+		"clean is: %d\n",
+		dev->device_fh, mbuf_count);
+	LOG_DEBUG(VHOST_DATA,
+		"(%"PRIu64") in txmbuf_clean_zcp: mbuf count in  ring before "
+		"clean  is : %d\n",
+		dev->device_fh, rte_ring_count(vpool->ring));
+
+	for (index = 0; index < mbuf_count; index++) {
+		mbuf = __rte_mbuf_raw_alloc(vpool->pool);
+		if (likely(RTE_MBUF_INDIRECT(mbuf)))
+			pktmbuf_detach_zcp(mbuf);
+		rte_ring_sp_enqueue(vpool->ring, mbuf);
+
+		/* Update used index buffer information. */
+		vq->used->ring[used_idx].id = MBUF_HEADROOM_UINT32(mbuf);
+		vq->used->ring[used_idx].len = 0;
+
+		used_idx = (used_idx + 1) & (vq->size - 1);
+	}
+
+	LOG_DEBUG(VHOST_DATA,
+		"(%"PRIu64") in txmbuf_clean_zcp: mbuf count in mempool after "
+		"clean is: %d\n",
+		dev->device_fh, rte_mempool_count(vpool->pool));
+	LOG_DEBUG(VHOST_DATA,
+		"(%"PRIu64") in txmbuf_clean_zcp: mbuf count in  ring after "
+		"clean  is : %d\n",
+		dev->device_fh, rte_ring_count(vpool->ring));
+	LOG_DEBUG(VHOST_DATA,
+		"(%"PRIu64") in txmbuf_clean_zcp: before updated "
+		"vq->last_used_idx:%d\n",
+		dev->device_fh, vq->last_used_idx);
+
+	vq->last_used_idx += mbuf_count;
+
+	LOG_DEBUG(VHOST_DATA,
+		"(%"PRIu64") in txmbuf_clean_zcp: after updated "
+		"vq->last_used_idx:%d\n",
+		dev->device_fh, vq->last_used_idx);
+
+	rte_compiler_barrier();
+
+	*(volatile uint16_t *)&vq->used->idx += mbuf_count;
+
+	/* Kick guest if required. */
+	if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT))
+		eventfd_write((int)vq->kickfd, 1);
+
+	return 0;
+}
+
+/*
+ * This function is called when a virtio device is destroy.
+ * It fetchs mbuf from vpool->pool, and detached it, and put into vpool->ring.
+ */
+static void
+mbuf_destroy_zcp(struct vpool *vpool)
+{
+	struct rte_mbuf *mbuf = NULL;
+	uint32_t index, mbuf_count = rte_mempool_count(vpool->pool);
+
+	LOG_DEBUG(VHOST_CONFIG,
+		"in mbuf_destroy_zcp: mbuf count in mempool before "
+		"mbuf_destroy_zcp is: %d\n",
+		mbuf_count);
+	LOG_DEBUG(VHOST_CONFIG,
+		"in mbuf_destroy_zcp: mbuf count in  ring before "
+		"mbuf_destroy_zcp  is : %d\n",
+		rte_ring_count(vpool->ring));
+
+	for (index = 0; index < mbuf_count; index++) {
+		mbuf = __rte_mbuf_raw_alloc(vpool->pool);
+		if (likely(mbuf != NULL)) {
+			if (likely(RTE_MBUF_INDIRECT(mbuf)))
+				pktmbuf_detach_zcp(mbuf);
+			rte_ring_sp_enqueue(vpool->ring, (void *)mbuf);
+		}
+	}
+
+	LOG_DEBUG(VHOST_CONFIG,
+		"in mbuf_destroy_zcp: mbuf count in mempool after "
+		"mbuf_destroy_zcp is: %d\n",
+		rte_mempool_count(vpool->pool));
+	LOG_DEBUG(VHOST_CONFIG,
+		"in mbuf_destroy_zcp: mbuf count in ring after "
+		"mbuf_destroy_zcp is : %d\n",
+		rte_ring_count(vpool->ring));
+}
+
+/*
+ * This function update the use flag and counter.
+ */
+static inline uint32_t __attribute__((always_inline))
+virtio_dev_rx_zcp(struct virtio_net *dev, struct rte_mbuf **pkts,
+	uint32_t count)
+{
+	struct vhost_virtqueue *vq;
+	struct vring_desc *desc;
+	struct rte_mbuf *buff;
+	/* The virtio_hdr is initialised to 0. */
+	struct virtio_net_hdr_mrg_rxbuf virtio_hdr
+		= {{0, 0, 0, 0, 0, 0}, 0};
+	uint64_t buff_hdr_addr = 0;
+	uint32_t head[MAX_PKT_BURST], packet_len = 0;
+	uint32_t head_idx, packet_success = 0;
+	uint16_t res_cur_idx;
+
+	LOG_DEBUG(VHOST_DATA, "(%"PRIu64") virtio_dev_rx()\n", dev->device_fh);
+
+	if (count == 0)
+		return 0;
+
+	vq = dev->virtqueue[VIRTIO_RXQ];
+	count = (count > MAX_PKT_BURST) ? MAX_PKT_BURST : count;
+
+	res_cur_idx = vq->last_used_idx;
+	LOG_DEBUG(VHOST_DATA, "(%"PRIu64") Current Index %d| End Index %d\n",
+		dev->device_fh, res_cur_idx, res_cur_idx + count);
+
+	/* Retrieve all of the head indexes first to avoid caching issues. */
+	for (head_idx = 0; head_idx < count; head_idx++)
+		head[head_idx] = MBUF_HEADROOM_UINT32(pkts[head_idx]);
+
+	/*Prefetch descriptor index. */
+	rte_prefetch0(&vq->desc[head[packet_success]]);
+
+	while (packet_success != count) {
+		/* Get descriptor from available ring */
+		desc = &vq->desc[head[packet_success]];
+
+		buff = pkts[packet_success];
+		LOG_DEBUG(VHOST_DATA,
+			"(%"PRIu64") in dev_rx_zcp: update the used idx for "
+			"pkt[%d] descriptor idx: %d\n",
+			dev->device_fh, packet_success,
+			MBUF_HEADROOM_UINT32(buff));
+
+		PRINT_PACKET(dev,
+			(uintptr_t)(((uint64_t)(uintptr_t)buff->buf_addr)
+			+ RTE_PKTMBUF_HEADROOM),
+			rte_pktmbuf_data_len(buff), 0);
+
+		/* Buffer address translation for virtio header. */
+		/* Could we buffer the translation for data in mbuf headroom */
+		buff_hdr_addr = gpa_to_vva(dev, desc->addr);
+		packet_len = rte_pktmbuf_data_len(buff) + vq->vhost_hlen;
+
+		/*
+		 * If the descriptors are chained the header and data are
+		 * placed in separate buffers.
+		 */
+		if (desc->flags & VRING_DESC_F_NEXT) {
+			desc->len = vq->vhost_hlen;
+			desc = &vq->desc[desc->next];
+			desc->len = rte_pktmbuf_data_len(buff);
+		} else {
+			desc->len = packet_len;
+		}
+
+		/* Update used ring with desc information */
+		vq->used->ring[res_cur_idx & (vq->size - 1)].id
+			= head[packet_success];
+		vq->used->ring[res_cur_idx & (vq->size - 1)].len
+			= packet_len;
+		res_cur_idx++;
+		packet_success++;
+
+		/* A header is required per buffer. */
+		rte_memcpy((void *)(uintptr_t)buff_hdr_addr,
+			(const void *)&virtio_hdr, vq->vhost_hlen);
+
+		PRINT_PACKET(dev, (uintptr_t)buff_hdr_addr, vq->vhost_hlen, 1);
+
+		if (likely(packet_success < count)) {
+			/* Prefetch descriptor index. */
+			rte_prefetch0(&vq->desc[head[packet_success]]);
+		}
+	}
+
+	rte_compiler_barrier();
+
+	LOG_DEBUG(VHOST_DATA,
+		"(%"PRIu64") in dev_rx_zcp: before update used idx: "
+		"vq.last_used_idx: %d, vq->used->idx: %d\n",
+		dev->device_fh, vq->last_used_idx, vq->used->idx);
+
+	*(volatile uint16_t *)&vq->used->idx += count;
+	vq->last_used_idx += count;
+
+	LOG_DEBUG(VHOST_DATA,
+		"(%"PRIu64") in dev_rx_zcp: after  update used idx: "
+		"vq.last_used_idx: %d, vq->used->idx: %d\n",
+		dev->device_fh, vq->last_used_idx, vq->used->idx);
+
+	/* Kick the guest if necessary. */
+	if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT))
+		eventfd_write((int)vq->kickfd, 1);
+
+	return count;
+}
+
+/*
+ * This function routes the TX packet to the correct interface.
+ * This may be a local device or the physical port.
+ */
+static inline void __attribute__((always_inline))
+virtio_tx_route_zcp(struct virtio_net *dev, struct rte_mbuf *m,
+	uint32_t desc_idx, uint8_t need_copy)
+{
+	struct mbuf_table *tx_q;
+	struct rte_mbuf **m_table;
+	struct rte_mbuf *mbuf = NULL;
+	unsigned len, ret, offset = 0;
+	struct vpool *vpool;
+	struct virtio_net_data_ll *dev_ll = ll_root_used;
+	struct ether_hdr *pkt_hdr = (struct ether_hdr *)m->pkt.data;
+	uint16_t vlan_tag = (uint16_t)vlan_tags[(uint16_t)dev->device_fh];
+	uint16_t vmdq_rx_q = ((struct vhost_dev *)dev->priv)->vmdq_rx_q;
+
+	/*Add packet to the port tx queue*/
+	tx_q = &tx_queue_zcp[vmdq_rx_q];
+	len = tx_q->len;
+
+	/* Allocate an mbuf and populate the structure. */
+	vpool = &vpool_array[MAX_QUEUES + vmdq_rx_q];
+	rte_ring_sc_dequeue(vpool->ring, (void **)&mbuf);
+	if (unlikely(mbuf == NULL)) {
+		struct vhost_virtqueue *vq = dev->virtqueue[VIRTIO_TXQ];
+		RTE_LOG(ERR, VHOST_DATA,
+			"(%"PRIu64") Failed to allocate memory for mbuf.\n",
+			dev->device_fh);
+		put_desc_to_used_list_zcp(vq, desc_idx);
+		return;
+	}
+
+	if (vm2vm_mode == VM2VM_HARDWARE) {
+		/* Avoid using a vlan tag from any vm for external pkt, such as
+		 * vlan_tags[dev->device_fh], oterwise, it conflicts when pool
+		 * selection, MAC address determines it as an external pkt
+		 * which should go to network, while vlan tag determine it as
+		 * a vm2vm pkt should forward to another vm. Hardware confuse
+		 * such a ambiguous situation, so pkt will lost.
+		 */
+		vlan_tag = external_pkt_default_vlan_tag;
+		while (dev_ll != NULL) {
+			if (likely(dev_ll->vdev->ready == DEVICE_RX) &&
+				ether_addr_cmp(&(pkt_hdr->d_addr),
+				&dev_ll->vdev->mac_address)) {
+
+				/*
+				 * Drop the packet if the TX packet is destined
+				 * for the TX device.
+				 */
+				if (unlikely(dev_ll->vdev->dev->device_fh
+					== dev->device_fh)) {
+					LOG_DEBUG(VHOST_DATA,
+					"(%"PRIu64") TX: Source and destination"
+					"MAC addresses are the same. Dropping "
+					"packet.\n",
+					dev_ll->dev->device_fh);
+					MBUF_HEADROOM_UINT32(mbuf)
+						= (uint32_t)desc_idx;
+					__rte_mbuf_raw_free(mbuf);
+					return;
+				}
+
+				/*
+				 * Packet length offset 4 bytes for HW vlan
+				 * strip when L2 switch back.
+				 */
+				offset = 4;
+				vlan_tag =
+				(uint16_t)
+				vlan_tags[(uint16_t)dev_ll->vdev->dev->device_fh];
+
+				LOG_DEBUG(VHOST_DATA,
+				"(%"PRIu64") TX: pkt to local VM device id:"
+				"(%"PRIu64") vlan tag: %d.\n",
+				dev->device_fh, dev_ll->dev->device_fh,
+				vlan_tag);
+
+				break;
+			}
+			dev_ll = dev_ll->next;
+		}
+	}
+
+	mbuf->pkt.nb_segs = m->pkt.nb_segs;
+	mbuf->pkt.next = m->pkt.next;
+	mbuf->pkt.data_len = m->pkt.data_len + offset;
+	mbuf->pkt.pkt_len = mbuf->pkt.data_len;
+	if (unlikely(need_copy)) {
+		/* Copy the packet contents to the mbuf. */
+		rte_memcpy((void *)((uint8_t *)mbuf->pkt.data),
+			(const void *) ((uint8_t *)m->pkt.data),
+			m->pkt.data_len);
+	} else {
+		mbuf->pkt.data = m->pkt.data;
+		mbuf->buf_physaddr = m->buf_physaddr;
+		mbuf->buf_addr = m->buf_addr;
+	}
+	mbuf->ol_flags = PKT_TX_VLAN_PKT;
+	mbuf->pkt.vlan_macip.f.vlan_tci = vlan_tag;
+	mbuf->pkt.vlan_macip.f.l2_len = sizeof(struct ether_hdr);
+	mbuf->pkt.vlan_macip.f.l3_len = sizeof(struct ipv4_hdr);
+	MBUF_HEADROOM_UINT32(mbuf) = (uint32_t)desc_idx;
+
+	tx_q->m_table[len] = mbuf;
+	len++;
+
+	LOG_DEBUG(VHOST_DATA,
+		"(%"PRIu64") in tx_route_zcp: pkt: nb_seg: %d, next:%s\n",
+		dev->device_fh,
+		mbuf->pkt.nb_segs,
+		(mbuf->pkt.next == NULL) ? "null" : "non-null");
+
+	if (enable_stats) {
+		dev_statistics[dev->device_fh].tx_total++;
+		dev_statistics[dev->device_fh].tx++;
+	}
+
+	if (unlikely(len == MAX_PKT_BURST)) {
+		m_table = (struct rte_mbuf **)tx_q->m_table;
+		ret = rte_eth_tx_burst(ports[0],
+			(uint16_t)tx_q->txq_id, m_table, (uint16_t) len);
+
+		/*
+		 * Free any buffers not handled by TX and update
+		 * the port stats.
+		 */
+		if (unlikely(ret < len)) {
+			do {
+				rte_pktmbuf_free(m_table[ret]);
+			} while (++ret < len);
+		}
+
+		len = 0;
+		txmbuf_clean_zcp(dev, vpool);
+	}
+
+	tx_q->len = len;
+
+	return;
+}
+
+/*
+ * This function TX all available packets in virtio TX queue for one
+ * virtio-net device. If it is first packet, it learns MAC address and
+ * setup VMDQ.
+ */
+static inline void __attribute__((always_inline))
+virtio_dev_tx_zcp(struct virtio_net *dev)
+{
+	struct rte_mbuf m;
+	struct vring_desc *desc;
+	uint64_t buff_addr = 0, phys_addr;
+	uint32_t head[MAX_PKT_BURST];
+	uint32_t i;
+	uint16_t free_entries, packet_success = 0;
+	uint16_t avail_idx;
+	uint8_t need_copy = 0;
+	enum hpa_type addr_type;
+	struct vhost_dev *vdev = (struct vhost_dev *)dev->priv;
+	struct vhost_virtqueue *vq = dev->virtqueue[VIRTIO_TXQ];
+
+	avail_idx =  *((volatile uint16_t *)&vq->avail->idx);
+
+	/* If there are no available buffers then return. */
+	if (vq->last_used_idx_res == avail_idx)
+		return;
+
+	LOG_DEBUG(VHOST_DATA, "(%"PRIu64") virtio_dev_tx()\n", dev->device_fh);
+
+	/* Prefetch available ring to retrieve head indexes. */
+	rte_prefetch0(&vq->avail->ring[vq->last_used_idx_res & (vq->size - 1)]);
+
+	/* Get the number of free entries in the ring */
+	free_entries = (avail_idx - vq->last_used_idx_res);
+
+	/* Limit to MAX_PKT_BURST. */
+	free_entries
+		= (free_entries > MAX_PKT_BURST) ? MAX_PKT_BURST : free_entries;
+
+	LOG_DEBUG(VHOST_DATA, "(%"PRIu64") Buffers available %d\n",
+		dev->device_fh, free_entries);
+
+	/* Retrieve all of the head indexes first to avoid caching issues. */
+	for (i = 0; i < free_entries; i++)
+		head[i]
+			= vq->avail->ring[(vq->last_used_idx_res + i)
+			& (vq->size - 1)];
+
+	vq->last_used_idx_res += free_entries;
+
+	/* Prefetch descriptor index. */
+	rte_prefetch0(&vq->desc[head[packet_success]]);
+	rte_prefetch0(&vq->used->ring[vq->last_used_idx & (vq->size - 1)]);
+
+	while (packet_success < free_entries) {
+		desc = &vq->desc[head[packet_success]];
+
+		/* Discard first buffer as it is the virtio header */
+		desc = &vq->desc[desc->next];
+
+		/* Buffer address translation. */
+		buff_addr = gpa_to_vva(dev, desc->addr);
+		phys_addr = gpa_to_hpa(vdev, desc->addr, desc->len, &addr_type);
+
+		if (likely(packet_success < (free_entries - 1)))
+			/* Prefetch descriptor index. */
+			rte_prefetch0(&vq->desc[head[packet_success + 1]]);
+
+		if (unlikely(addr_type == PHYS_ADDR_INVALID)) {
+			RTE_LOG(ERR, VHOST_DATA,
+				"(%"PRIu64") Invalid frame buffer address found"
+				"when TX packets!\n",
+				dev->device_fh);
+			packet_success++;
+			continue;
+		}
+
+		/* Prefetch buffer address. */
+		rte_prefetch0((void *)(uintptr_t)buff_addr);
+
+		/*
+		 * Setup dummy mbuf. This is copied to a real mbuf if
+		 * transmitted out the physical port.
+		 */
+		m.pkt.data_len = desc->len;
+		m.pkt.nb_segs = 1;
+		m.pkt.next = NULL;
+		m.pkt.data = (void *)(uintptr_t)buff_addr;
+		m.buf_addr = m.pkt.data;
+		m.buf_physaddr = phys_addr;
+
+		/*
+		 * Check if the frame buffer address from guest crosses
+		 * sub-region or not.
+		 */
+		if (unlikely(addr_type == PHYS_ADDR_CROSS_SUBREG)) {
+			RTE_LOG(ERR, VHOST_DATA,
+				"(%"PRIu64") Frame buffer address cross "
+				"sub-regioin found when attaching TX frame "
+				"buffer address!\n",
+				dev->device_fh);
+			need_copy = 1;
+		} else
+			need_copy = 0;
+
+		PRINT_PACKET(dev, (uintptr_t)buff_addr, desc->len, 0);
+
+		/*
+		 * If this is the first received packet we need to learn
+		 * the MAC and setup VMDQ
+		 */
+		if (unlikely(vdev->ready == DEVICE_MAC_LEARNING)) {
+			if (vdev->remove || (link_vmdq(vdev, &m) == -1)) {
+				/*
+				 * Discard frame if device is scheduled for
+				 * removal or a duplicate MAC address is found.
+				 */
+				packet_success += free_entries;
+				vq->last_used_idx += packet_success;
+				break;
+			}
+		}
+
+		virtio_tx_route_zcp(dev, &m, head[packet_success], need_copy);
+		packet_success++;
+	}
+}
+
+/*
+ * This function is called by each data core. It handles all RX/TX registered
+ * with the core. For TX the specific lcore linked list is used. For RX, MAC
+ * addresses are compared with all devices in the main linked list.
+ */
+static int
+switch_worker_zcp(__attribute__((unused)) void *arg)
+{
+	struct virtio_net *dev = NULL;
+	struct vhost_dev  *vdev = NULL;
+	struct rte_mbuf *pkts_burst[MAX_PKT_BURST];
+	struct virtio_net_data_ll *dev_ll;
+	struct mbuf_table *tx_q;
+	volatile struct lcore_ll_info *lcore_ll;
+	const uint64_t drain_tsc
+		= (rte_get_tsc_hz() + US_PER_S - 1) / US_PER_S
+		* BURST_TX_DRAIN_US;
+	uint64_t prev_tsc, diff_tsc, cur_tsc, ret_count = 0;
+	unsigned ret;
+	const uint16_t lcore_id = rte_lcore_id();
+	uint16_t count_in_ring, rx_count = 0;
+
+	RTE_LOG(INFO, VHOST_DATA, "Procesing on Core %u started\n", lcore_id);
+
+	lcore_ll = lcore_info[lcore_id].lcore_ll;
+	prev_tsc = 0;
+
+	while (1) {
+		cur_tsc = rte_rdtsc();
+
+		/* TX burst queue drain */
+		diff_tsc = cur_tsc - prev_tsc;
+		if (unlikely(diff_tsc > drain_tsc)) {
+			/*
+			 * Get mbuf from vpool.pool and detach mbuf and
+			 * put back into vpool.ring.
+			 */
+			dev_ll = lcore_ll->ll_root_used;
+			while ((dev_ll != NULL) && (dev_ll->vdev != NULL)) {
+				/* Get virtio device ID */
+				vdev = dev_ll->vdev;
+				dev = vdev->dev;
+
+				if (likely(!vdev->remove)) {
+					tx_q = &tx_queue_zcp[(uint16_t)vdev->vmdq_rx_q];
+					if (tx_q->len) {
+						LOG_DEBUG(VHOST_DATA,
+						"TX queue drained after timeout"
+						" with burst size %u\n",
+						tx_q->len);
+
+						/*
+						 * Tx any packets in the queue
+						 */
+						ret = rte_eth_tx_burst(
+							ports[0],
+							(uint16_t)tx_q->txq_id,
+							(struct rte_mbuf **)
+							tx_q->m_table,
+							(uint16_t)tx_q->len);
+						if (unlikely(ret < tx_q->len)) {
+							do {
+								rte_pktmbuf_free(
+									tx_q->m_table[ret]);
+							} while (++ret < tx_q->len);
+						}
+						tx_q->len = 0;
+
+						txmbuf_clean_zcp(dev,
+							&vpool_array[MAX_QUEUES + vdev->vmdq_rx_q]);
+					}
+				}
+				dev_ll = dev_ll->next;
+			}
+			prev_tsc = cur_tsc;
+		}
+
+		rte_prefetch0(lcore_ll->ll_root_used);
+
+		/*
+		 * Inform the configuration core that we have exited the linked
+		 * list and that no devices are in use if requested.
+		 */
+		if (lcore_ll->dev_removal_flag == REQUEST_DEV_REMOVAL)
+			lcore_ll->dev_removal_flag = ACK_DEV_REMOVAL;
+
+		/* Process devices */
+		dev_ll = lcore_ll->ll_root_used;
+
+		while ((dev_ll != NULL) && (dev_ll->vdev != NULL)) {
+			vdev = dev_ll->vdev;
+			dev  = vdev->dev;
+			if (unlikely(vdev->remove)) {
+				dev_ll = dev_ll->next;
+				unlink_vmdq(vdev);
+				vdev->ready = DEVICE_SAFE_REMOVE;
+				continue;
+			}
+
+			if (likely(vdev->ready == DEVICE_RX)) {
+				uint32_t index = vdev->vmdq_rx_q;
+				uint16_t i;
+				count_in_ring
+				= rte_ring_count(vpool_array[index].ring);
+				uint16_t free_entries
+				= (uint16_t)get_available_ring_num_zcp(dev);
+
+				/*
+				 * Attach all mbufs in vpool.ring and put back
+				 * into vpool.pool.
+				 */
+				for (i = 0;
+				i < RTE_MIN(free_entries,
+				RTE_MIN(count_in_ring, MAX_PKT_BURST));
+				i++)
+					attach_rxmbuf_zcp(dev);
+
+				/* Handle guest RX */
+				rx_count = rte_eth_rx_burst(ports[0],
+					vdev->vmdq_rx_q, pkts_burst,
+					MAX_PKT_BURST);
+
+				if (rx_count) {
+					ret_count = virtio_dev_rx_zcp(dev,
+							pkts_burst, rx_count);
+					if (enable_stats) {
+						dev_statistics[dev->device_fh].rx_total
+							+= rx_count;
+						dev_statistics[dev->device_fh].rx
+							+= ret_count;
+					}
+					while (likely(rx_count)) {
+						rx_count--;
+						pktmbuf_detach_zcp(
+							pkts_burst[rx_count]);
+						rte_ring_sp_enqueue(
+							vpool_array[index].ring,
+							(void *)pkts_burst[rx_count]);
+					}
+				}
+			}
+
+			if (likely(!vdev->remove))
+				/* Handle guest TX */
+				virtio_dev_tx_zcp(dev);
+
+			/* Move to the next device in the list */
+			dev_ll = dev_ll->next;
+		}
+	}
+
+	return 0;
+}
+
+
+/*
+ * Add an entry to a used linked list. A free entry must first be found
+ * in the free linked list using get_data_ll_free_entry();
+ */
+static void
+add_data_ll_entry(struct virtio_net_data_ll **ll_root_addr,
+	struct virtio_net_data_ll *ll_dev)
+{
+	struct virtio_net_data_ll *ll = *ll_root_addr;
+
+	/* Set next as NULL and use a compiler barrier to avoid reordering. */
+	ll_dev->next = NULL;
+	rte_compiler_barrier();
+
+	/* If ll == NULL then this is the first device. */
+	if (ll) {
+		/* Increment to the tail of the linked list. */
+		while ((ll->next != NULL))
+			ll = ll->next;
+
+		ll->next = ll_dev;
+	} else {
+		*ll_root_addr = ll_dev;
+	}
+}
+
+/*
+ * Remove an entry from a used linked list. The entry must then be added to
+ * the free linked list using put_data_ll_free_entry().
+ */
+static void
+rm_data_ll_entry(struct virtio_net_data_ll **ll_root_addr,
+	struct virtio_net_data_ll *ll_dev,
+	struct virtio_net_data_ll *ll_dev_last)
+{
+	struct virtio_net_data_ll *ll = *ll_root_addr;
+
+	if (unlikely((ll == NULL) || (ll_dev == NULL)))
+		return;
+
+	if (ll_dev == ll)
+		*ll_root_addr = ll_dev->next;
+	else
+		if (likely(ll_dev_last != NULL))
+			ll_dev_last->next = ll_dev->next;
+		else
+			RTE_LOG(ERR, VHOST_CONFIG,
+				"Remove entry form ll failed.\n");
+}
+
+/*
+ * Find and return an entry from the free linked list.
+ */
+static struct virtio_net_data_ll *
+get_data_ll_free_entry(struct virtio_net_data_ll **ll_root_addr)
+{
+	struct virtio_net_data_ll *ll_free = *ll_root_addr;
+	struct virtio_net_data_ll *ll_dev;
+
+	if (ll_free == NULL)
+		return NULL;
+
+	ll_dev = ll_free;
+	*ll_root_addr = ll_free->next;
+
+	return ll_dev;
+}
+
+/*
+ * Place an entry back on to the free linked list.
+ */
+static void
+put_data_ll_free_entry(struct virtio_net_data_ll **ll_root_addr,
+	struct virtio_net_data_ll *ll_dev)
+{
+	struct virtio_net_data_ll *ll_free = *ll_root_addr;
+
+	if (ll_dev == NULL)
+		return;
+
+	ll_dev->next = ll_free;
+	*ll_root_addr = ll_dev;
+}
+
+/*
+ * Creates a linked list of a given size.
+ */
+static struct virtio_net_data_ll *
+alloc_data_ll(uint32_t size)
+{
+	struct virtio_net_data_ll *ll_new;
+	uint32_t i;
+
+	/* Malloc and then chain the linked list. */
+	ll_new = rte_zmalloc("vhost ll",
+			size * sizeof(struct virtio_net_data_ll), 0);
+	if (ll_new == NULL) {
+		RTE_LOG(ERR, VHOST_CONFIG,
+			"Failed to allocate memory for ll_new.\n");
+		return NULL;
+	}
+
+	for (i = 0; i < size - 1; i++) {
+		ll_new[i].vdev = NULL;
+		ll_new[i].next = &ll_new[i+1];
+	}
+	ll_new[i].next = NULL;
+
+	return ll_new;
+}
+
+/*
+ * Create the main linked list along with each individual cores linked list.
+ * A used and a free list are created to manage entries.
+ */
+static int
+init_data_ll(void)
+{
+	int lcore;
+
+	RTE_LCORE_FOREACH_SLAVE(lcore) {
+		lcore_info[lcore].lcore_ll = rte_zmalloc("vhost lcore_ll_info",
+					sizeof(struct lcore_ll_info), 0);
+		if (lcore_info[lcore].lcore_ll == NULL) {
+			RTE_LOG(ERR, VHOST_CONFIG,
+				"Failed to allocate memory for lcore_ll.\n");
+			return -1;
+		}
+
+		lcore_info[lcore].lcore_ll->device_num = 0;
+		lcore_info[lcore].lcore_ll->dev_removal_flag = ACK_DEV_REMOVAL;
+		lcore_info[lcore].lcore_ll->ll_root_used = NULL;
+		if (num_devices % num_switching_cores)
+			lcore_info[lcore].lcore_ll->ll_root_free =
+			alloc_data_ll((num_devices / num_switching_cores) + 1);
+		else
+			lcore_info[lcore].lcore_ll->ll_root_free =
+			alloc_data_ll(num_devices / num_switching_cores);
+	}
+
+	/* Allocate devices up to a maximum of MAX_DEVICES. */
+	ll_root_free = alloc_data_ll(MIN((num_devices), MAX_DEVICES));
+
+	return 0;
+}
+
+/*
+ * Remove a device from the specific data core linked list and from the main
+ * linked list. Synchonization occurs through the use of the lcore
+ * dev_removal_flag. Device is made volatile here to avoid re-ordering
+ * of dev->remove=1 which can cause an infinite loop in the rte_pause loop.
+ */
+static void
+destroy_device(struct virtio_net *dev)
+{
+	struct virtio_net_data_ll *ll_lcore_dev_cur;
+	struct virtio_net_data_ll *ll_main_dev_cur;
+	struct virtio_net_data_ll *ll_lcore_dev_last = NULL;
+	struct virtio_net_data_ll *ll_main_dev_last = NULL;
+	struct vhost_dev *vdev;
+	int lcore;
+
+	dev->flags &= ~VIRTIO_DEV_RUNNING;
+
+	vdev = (struct vhost_dev *)dev->priv;
+	/* Set the remove flag. */
+	vdev->remove = 1;
+	while (vdev->ready != DEVICE_SAFE_REMOVE)
+		rte_pause();
+
+	/* Search for entry to be removed from lcore ll */
+	ll_lcore_dev_cur = lcore_info[vdev->coreid].lcore_ll->ll_root_used;
+	while (ll_lcore_dev_cur != NULL) {
+		if (ll_lcore_dev_cur->vdev == vdev) {
+			break;
+		} else {
+			ll_lcore_dev_last = ll_lcore_dev_cur;
+			ll_lcore_dev_cur = ll_lcore_dev_cur->next;
+		}
+	}
+
+	if (ll_lcore_dev_cur == NULL) {
+		RTE_LOG(ERR, VHOST_CONFIG,
+			"(%"PRIu64") Failed to find the dev to be destroy.\n",
+			dev->device_fh);
+		return;
+	}
+
+	/* Search for entry to be removed from main ll */
+	ll_main_dev_cur = ll_root_used;
+	ll_main_dev_last = NULL;
+	while (ll_main_dev_cur != NULL) {
+		if (ll_main_dev_cur->vdev == vdev) {
+			break;
+		} else {
+			ll_main_dev_last = ll_main_dev_cur;
+			ll_main_dev_cur = ll_main_dev_cur->next;
+		}
+	}
+
+	/* Remove entries from the lcore and main ll. */
+	rm_data_ll_entry(&lcore_info[vdev->coreid].lcore_ll->ll_root_used,
+		ll_lcore_dev_cur, ll_lcore_dev_last);
+	rm_data_ll_entry(&ll_root_used, ll_main_dev_cur, ll_main_dev_last);
+
+	/* Set the dev_removal_flag on each lcore. */
+	RTE_LCORE_FOREACH_SLAVE(lcore) {
+		lcore_info[lcore].lcore_ll->dev_removal_flag =
+			REQUEST_DEV_REMOVAL;
+	}
+
+	/*
+	 * Once each core has set the dev_removal_flag to ACK_DEV_REMOVAL we
+	 * can be sure that they can no longer access the device removed from
+	 * the linked lists and that the devices are no longer in use.
+	 */
+	RTE_LCORE_FOREACH_SLAVE(lcore) {
+		while (lcore_info[lcore].lcore_ll->dev_removal_flag !=
+			ACK_DEV_REMOVAL)
+			rte_pause();
+	}
+
+	/* Add the entries back to the lcore and main free ll.*/
+	put_data_ll_free_entry(&lcore_info[vdev->coreid].lcore_ll->ll_root_free,
+				ll_lcore_dev_cur);
+	put_data_ll_free_entry(&ll_root_free, ll_main_dev_cur);
+
+	/* Decrement number of device on the lcore. */
+	lcore_info[vdev->coreid].lcore_ll->device_num--;
+
+	RTE_LOG(INFO, VHOST_DATA,
+		"(%"PRIu64") Device has been removed from data core\n",
+		dev->device_fh);
+
+	if (zero_copy) {
+		struct vpool *vpool = &vpool_array[vdev->vmdq_rx_q];
+
+		/* Stop the RX queue. */
+		if (rte_eth_dev_rx_queue_stop(ports[0], vdev->vmdq_rx_q) != 0) {
+			LOG_DEBUG(VHOST_CONFIG,
+				"(%"PRIu64") In destroy_device: Failed to stop "
+				"rx queue:%d\n",
+				dev->device_fh,
+				dev->vmdq_rx_q);
+		}
+
+		LOG_DEBUG(VHOST_CONFIG,
+			"(%"PRIu64") in destroy_device: Start put mbuf in "
+			"mempool back to ring for RX queue: %d\n",
+			dev->device_fh, dev->vmdq_rx_q);
+
+		mbuf_destroy_zcp(vpool);
+
+		/* Stop the TX queue. */
+		if (rte_eth_dev_tx_queue_stop(ports[0], vdev->vmdq_rx_q) != 0) {
+			LOG_DEBUG(VHOST_CONFIG,
+				"(%"PRIu64") In destroy_device: Failed to "
+				"stop tx queue:%d\n",
+				dev->device_fh, dev->vmdq_rx_q);
+		}
+
+		vpool = &vpool_array[vdev->vmdq_rx_q + MAX_QUEUES];
+
+		LOG_DEBUG(VHOST_CONFIG,
+			"(%"PRIu64") destroy_device: Start put mbuf in mempool "
+			"back to ring for TX queue: %d, dev:(%"PRIu64")\n",
+			dev->device_fh, (vdev->vmdq_rx_q + MAX_QUEUES),
+			dev->device_fh);
+
+		mbuf_destroy_zcp(vpool);
+		rte_free(vdev->regions_hpa);
+	}
+	rte_free(vdev);
+
+}
+
+/*
+ * Calculate the region count of physical continous regions for one particular
+ * region of whose vhost virtual address is continous. The particular region
+ * start from vva_start, with size of 'size' in argument.
+ */
+static uint32_t
+check_hpa_regions(uint64_t vva_start, uint64_t size)
+{
+	uint32_t i, nregions = 0, page_size = getpagesize();
+	uint64_t cur_phys_addr = 0, next_phys_addr = 0;
+	if (vva_start % page_size) {
+		LOG_DEBUG(VHOST_CONFIG,
+			"in check_countinous: vva start(%p) mod page_size(%d) "
+			"has remainder\n",
+			(void *)(uintptr_t)vva_start, page_size);
+		return 0;
+	}
+	if (size % page_size) {
+		LOG_DEBUG(VHOST_CONFIG,
+			"in check_countinous: "
+			"size((%"PRIu64")) mod page_size(%d) has remainder\n",
+			size, page_size);
+		return 0;
+	}
+	for (i = 0; i < size - page_size; i = i + page_size) {
+		cur_phys_addr
+			= rte_mem_virt2phy((void *)(uintptr_t)(vva_start + i));
+		next_phys_addr = rte_mem_virt2phy(
+			(void *)(uintptr_t)(vva_start + i + page_size));
+		if ((cur_phys_addr + page_size) != next_phys_addr) {
+			++nregions;
+			LOG_DEBUG(VHOST_CONFIG,
+				"in check_continuous: hva addr:(%p) is not "
+				"continuous with hva addr:(%p), diff:%d\n",
+				(void *)(uintptr_t)(vva_start + (uint64_t)i),
+				(void *)(uintptr_t)(vva_start + (uint64_t)i
+				+ page_size), page_size);
+			LOG_DEBUG(VHOST_CONFIG,
+				"in check_continuous: hpa addr:(%p) is not "
+				"continuous with hpa addr:(%p), "
+				"diff:(%"PRIu64")\n",
+				(void *)(uintptr_t)cur_phys_addr,
+				(void *)(uintptr_t)next_phys_addr,
+				(next_phys_addr-cur_phys_addr));
+		}
+	}
+	return nregions;
+}
+
+/*
+ * Divide each region whose vhost virtual address is continous into a few
+ * sub-regions, make sure the physical address within each sub-region are
+ * continous. And fill offset(to GPA) and size etc. information of each
+ * sub-region into regions_hpa.
+ */
+static uint32_t
+fill_hpa_memory_regions(struct virtio_memory_regions_hpa *mem_region_hpa,
+			struct virtio_memory *virtio_memory)
+{
+	uint32_t regionidx, regionidx_hpa = 0, i, k, page_size = getpagesize();
+	uint64_t cur_phys_addr = 0, next_phys_addr = 0, vva_start;
+
+	if (mem_region_hpa == NULL)
+		return 0;
+
+	for (regionidx = 0; regionidx < virtio_memory->nregions; regionidx++) {
+		vva_start = virtio_memory->regions[regionidx].guest_phys_address +
+			virtio_memory->regions[regionidx].address_offset;
+		mem_region_hpa[regionidx_hpa].guest_phys_address =
+			virtio_memory->regions[regionidx].guest_phys_address;
+		mem_region_hpa[regionidx_hpa].host_phys_addr_offset =
+			rte_mem_virt2phy((void *)(uintptr_t)(vva_start)) -
+			mem_region_hpa[regionidx_hpa].guest_phys_address;
+		LOG_DEBUG(VHOST_CONFIG,
+			"in fill_hpa_regions: guest phys addr start[%d]:(%p)\n",
+			regionidx_hpa,
+			(void *)(uintptr_t)
+			(mem_region_hpa[regionidx_hpa].guest_phys_address));
+		LOG_DEBUG(VHOST_CONFIG,
+			"in fill_hpa_regions: host  phys addr start[%d]:(%p)\n",
+			regionidx_hpa,
+			(void *)(uintptr_t)
+			(mem_region_hpa[regionidx_hpa].host_phys_addr_offset));
+		for (i = 0, k = 0;
+			i < virtio_memory->regions[regionidx].memory_size -
+				page_size;
+			i += page_size) {
+			cur_phys_addr = rte_mem_virt2phy(
+					(void *)(uintptr_t)(vva_start + i));
+			next_phys_addr = rte_mem_virt2phy(
+					(void *)(uintptr_t)(vva_start +
+					i + page_size));
+			if ((cur_phys_addr + page_size) != next_phys_addr) {
+				mem_region_hpa[regionidx_hpa].guest_phys_address_end =
+					mem_region_hpa[regionidx_hpa].guest_phys_address +
+					k + page_size;
+				mem_region_hpa[regionidx_hpa].memory_size
+					= k + page_size;
+				LOG_DEBUG(VHOST_CONFIG, "in fill_hpa_regions: "
+					"guest phys addr end  [%d]:(%p)\n",
+					regionidx_hpa,
+					(void *)(uintptr_t)
+					(mem_region_hpa[regionidx_hpa].guest_phys_address_end));
+				LOG_DEBUG(VHOST_CONFIG,
+					"in fill_hpa_regions: guest phys addr "
+					"size [%d]:(%p)\n",
+					regionidx_hpa,
+					(void *)(uintptr_t)
+					(mem_region_hpa[regionidx_hpa].memory_size));
+				mem_region_hpa[regionidx_hpa + 1].guest_phys_address
+					= mem_region_hpa[regionidx_hpa].guest_phys_address_end;
+				++regionidx_hpa;
+				mem_region_hpa[regionidx_hpa].host_phys_addr_offset =
+					next_phys_addr -
+					mem_region_hpa[regionidx_hpa].guest_phys_address;
+				LOG_DEBUG(VHOST_CONFIG, "in fill_hpa_regions: "
+					"guest phys addr start[%d]:(%p)\n",
+					regionidx_hpa,
+					(void *)(uintptr_t)
+					(mem_region_hpa[regionidx_hpa].guest_phys_address));
+				LOG_DEBUG(VHOST_CONFIG,
+					"in fill_hpa_regions: host  phys addr "
+					"start[%d]:(%p)\n",
+					regionidx_hpa,
+					(void *)(uintptr_t)
+					(mem_region_hpa[regionidx_hpa].host_phys_addr_offset));
+				k = 0;
+			} else {
+				k += page_size;
+			}
+		}
+		mem_region_hpa[regionidx_hpa].guest_phys_address_end
+			= mem_region_hpa[regionidx_hpa].guest_phys_address
+			+ k + page_size;
+		mem_region_hpa[regionidx_hpa].memory_size = k + page_size;
+		LOG_DEBUG(VHOST_CONFIG, "in fill_hpa_regions: guest phys addr "
+			"end [%d]:(%p)\n", regionidx_hpa,
+			(void *)(uintptr_t)
+			(mem_region_hpa[regionidx_hpa].guest_phys_address_end));
+		LOG_DEBUG(VHOST_CONFIG, "in fill_hpa_regions: guest phys addr "
+			"size [%d]:(%p)\n", regionidx_hpa,
+			(void *)(uintptr_t)
+			(mem_region_hpa[regionidx_hpa].memory_size));
+		++regionidx_hpa;
+	}
+	return regionidx_hpa;
+}
+
+/*
+ * A new device is added to a data core. First the device is added to the main
+ * linked list and then allocated to a specific data core.
+ */
+static int
+new_device(struct virtio_net *dev)
+{
+	struct virtio_net_data_ll *ll_dev;
+	int lcore, core_add = 0;
+	uint32_t device_num_min = num_devices;
+	struct vhost_dev *vdev;
+	uint32_t regionidx;
+
+	vdev = rte_zmalloc("vhost device", sizeof(*vdev), CACHE_LINE_SIZE);
+	if (vdev == NULL) {
+		RTE_LOG(INFO, VHOST_DATA,
+		"(%"PRIu64") Couldn't allocate memory for vhost dev\n",
+			dev->device_fh);
+		return -1;
+	}
+	vdev->dev = dev;
+	dev->priv = vdev;
+
+	if (zero_copy) {
+		vdev->nregions_hpa = dev->mem->nregions;
+		for (regionidx = 0; regionidx < dev->mem->nregions;
+			regionidx++) {
+			vdev->nregions_hpa
+				+= check_hpa_regions(
+					dev->mem->regions[regionidx].guest_phys_address +
+					dev->mem->regions[regionidx].address_offset,
+					dev->mem->regions[regionidx].memory_size);
+
+		}
+
+		vdev->regions_hpa = (struct virtio_memory_regions_hpa *)
+			rte_zmalloc("vhost hpa region",
+			sizeof(struct virtio_memory_regions_hpa) *
+			vdev->nregions_hpa, CACHE_LINE_SIZE);
+		if (vdev->regions_hpa == NULL) {
+			RTE_LOG(ERR, VHOST_CONFIG,
+				"Cannot allocate memory for hpa region\n");
+			rte_free(vdev);
+			return -1;
+		}
+
+
+		if (fill_hpa_memory_regions(
+			vdev->regions_hpa, dev->mem) !=
+			vdev->nregions_hpa) {
+
+			RTE_LOG(ERR, VHOST_CONFIG,
+				"hpa memory regions number mismatch: "
+				"[%d]\n", vdev->nregions_hpa);
+			rte_free(vdev->regions_hpa);
+			rte_free(vdev);
+			return -1;
+		}
+	}
+
+
+	/* Add device to main linked list */
+	ll_dev = get_data_ll_free_entry(&ll_root_free);
+	if (ll_dev == NULL) {
+		RTE_LOG(INFO, VHOST_DATA,
+			"(%"PRIu64") No free entry found in linked list. "
+			"Device limit of %d devices per core has been "
+			"reached\n",
+			dev->device_fh, num_devices);
+		if (vdev->regions_hpa)
+			rte_free(vdev->regions_hpa);
+		rte_free(vdev);
+		return -1;
+	}
+	ll_dev->vdev = vdev;
+	add_data_ll_entry(&ll_root_used, ll_dev);
+
+	/* Allocate the vmdq receive queue for this virtio device */
+	vdev->vmdq_rx_q = dev->device_fh *  (num_queues / num_devices);
+
+	if (zero_copy) {
+		uint16_t vmdq_rx_q = vdev->vmdq_rx_q;
+		uint32_t count_in_ring, i;
+		struct mbuf_table *tx_q;
+
+		count_in_ring = rte_ring_count(vpool_array[vmdq_rx_q].ring);
+
+		LOG_DEBUG(VHOST_CONFIG,
+			"(%"PRIu64") in new_device: mbuf count in mempool "
+			"before attach is: %d\n",
+			dev->device_fh,
+			rte_mempool_count(vpool_array[vmdq_rx_q].pool));
+		LOG_DEBUG(VHOST_CONFIG,
+			"(%"PRIu64") in new_device: mbuf count in  ring "
+			"before attach  is : %d\n",
+			dev->device_fh, count_in_ring);
+
+
+		/*
+		 * Attach all mbufs in vpool.ring and put back into vpool.pool.
+		 */
+		for (i = 0; i < count_in_ring; i++)
+			attach_rxmbuf_zcp(dev);
+
+		LOG_DEBUG(VHOST_CONFIG, "(%"PRIu64") in new_device: "
+			"mbuf count in mempool after attach is: %d\n",
+			dev->device_fh,
+			rte_mempool_count(vpool_array[vmdq_rx_q].pool));
+		LOG_DEBUG(VHOST_CONFIG, "(%"PRIu64") in new_device: "
+			"mbuf count in ring after attach  is : %d\n",
+			dev->device_fh,
+			rte_ring_count(vpool_array[vmdq_rx_q].ring));
+
+		tx_q = &tx_queue_zcp[vmdq_rx_q];
+		tx_q->txq_id = vmdq_rx_q;
+
+		if (rte_eth_dev_tx_queue_start(ports[0], vmdq_rx_q) != 0) {
+			struct vpool *vpool = &vpool_array[vmdq_rx_q];
+
+			LOG_DEBUG(VHOST_CONFIG,
+				"(%"PRIu64") In new_device: Failed to start "
+				"tx queue:%d\n",
+				dev->device_fh, vmdq_rx_q);
+
+			mbuf_destroy_zcp(vpool);
+			rte_free(vdev->regions_hpa);
+			rte_free(vdev);
+			return -1;
+		}
+
+		if (rte_eth_dev_rx_queue_start(ports[0], vmdq_rx_q) != 0) {
+			struct vpool *vpool = &vpool_array[vmdq_rx_q];
+
+			LOG_DEBUG(VHOST_CONFIG,
+				"(%"PRIu64") In new_device: Failed to start "
+				"rx queue:%d\n",
+				dev->device_fh, vmdq_rx_q);
+
+			/* Stop the TX queue. */
+			if (rte_eth_dev_tx_queue_stop(ports[0],
+				vmdq_rx_q) != 0) {
+				LOG_DEBUG(VHOST_CONFIG,
+					"(%"PRIu64") In new_device: Failed to "
+					"stop tx queue:%d\n",
+					dev->device_fh, vmdq_rx_q);
+			}
+
+			mbuf_destroy_zcp(vpool);
+			rte_free(vdev->regions_hpa);
+			rte_free(vdev);
+			return -1;
+		}
+	}
+
+	/* Reset ready flag*/
+	vdev->ready = DEVICE_MAC_LEARNING;
+	vdev->remove = 0;
+
+	/* Find a suitable lcore to add the device. */
+	RTE_LCORE_FOREACH_SLAVE(lcore) {
+		if (lcore_info[lcore].lcore_ll->device_num < device_num_min) {
+			device_num_min = lcore_info[lcore].lcore_ll->device_num;
+			core_add = lcore;
+		}
+	}
+	/* Add device to per core linked list */
+	ll_dev =
+	get_data_ll_free_entry(&lcore_info[core_add].lcore_ll->ll_root_free);
+	if (ll_dev == NULL) {
+		RTE_LOG(INFO, VHOST_DATA,
+		"(%"PRIu64") Failed to add device to data core\n",
+		dev->device_fh);
+		vdev->ready = DEVICE_SAFE_REMOVE;
+		destroy_device(dev);
+		if (vdev->regions_hpa)
+			rte_free(vdev->regions_hpa);
+		rte_free(vdev);
+		return -1;
+	}
+	ll_dev->vdev = vdev;
+	vdev->coreid = core_add;
+
+
+
+	add_data_ll_entry(&lcore_info[vdev->coreid].lcore_ll->ll_root_used,
+			ll_dev);
+
+	/* Initialize device stats */
+	memset(&dev_statistics[dev->device_fh], 0,
+		sizeof(struct device_statistics));
+
+	/* Disable notifications. */
+	rte_vhost_enable_guest_notification(dev, VIRTIO_RXQ, 0);
+	rte_vhost_enable_guest_notification(dev, VIRTIO_TXQ, 0);
+	lcore_info[vdev->coreid].lcore_ll->device_num++;
+	dev->flags |= VIRTIO_DEV_RUNNING;
+
+	RTE_LOG(INFO, VHOST_DATA,
+		"(%"PRIu64") Device has been added to data core %d\n",
+		dev->device_fh, vdev->coreid);
+
+	return 0;
+}
+
+/*
+ * These callback allow devices to be added to the data core when configuration
+ * has been fully complete.
+ */
+static const struct virtio_net_device_ops virtio_net_device_ops = {
+	.new_device =  new_device,
+	.destroy_device = destroy_device,
+};
+
+/*
+ * This is a thread will wake up after a period to print stats if the user has
+ * enabled them.
+ */
+static void
+print_stats(void)
+{
+	struct virtio_net_data_ll *dev_ll;
+	uint64_t tx_dropped, rx_dropped;
+	uint64_t tx, tx_total, rx, rx_total;
+	uint32_t device_fh;
+	const char clr[] = { 27, '[', '2', 'J', '\0' };
+	const char top_left[] = { 27, '[', '1', ';', '1', 'H', '\0' };
+
+	while (1) {
+		sleep(enable_stats);
+
+		/*  Clear screen and move to top left */
+		printf("%s%s", clr, top_left);
+
+		printf("\nDevice statistics "
+			"====================================");
+
+		dev_ll = ll_root_used;
+		while (dev_ll != NULL) {
+			device_fh = (uint32_t)dev_ll->vdev->dev->device_fh;
+			tx_total = dev_statistics[device_fh].tx_total;
+			tx = dev_statistics[device_fh].tx;
+			tx_dropped = tx_total - tx;
+			if (zero_copy == 0) {
+				rx_total = rte_atomic64_read(
+					&dev_statistics[device_fh].rx_total_atomic);
+				rx = rte_atomic64_read(
+					&dev_statistics[device_fh].rx_atomic);
+			} else {
+				rx_total = dev_statistics[device_fh].rx_total;
+				rx = dev_statistics[device_fh].rx;
+			}
+			rx_dropped = rx_total - rx;
+
+			printf("\nStatistics for device %"PRIu32" "
+				"------------------------------\n"
+					"TX total:       %"PRIu64"\n"
+					"TX dropped:     %"PRIu64"\n"
+					"TX successful:  %"PRIu64"\n"
+					"RX total:       %"PRIu64"\n"
+					"RX dropped:     %"PRIu64"\n"
+					"RX successful:  %"PRIu64"",
+					device_fh,
+					tx_total,
+					tx_dropped,
+					tx,
+					rx_total,
+					rx_dropped,
+					rx);
+
+			dev_ll = dev_ll->next;
+		}
+		printf("\n======================================================\n");
+	}
+}
+
+static void
+setup_mempool_tbl(int socket, uint32_t index, char *pool_name,
+	char *ring_name, uint32_t nb_mbuf)
+{
+	uint16_t roomsize = VIRTIO_DESCRIPTOR_LEN_ZCP + RTE_PKTMBUF_HEADROOM;
+	vpool_array[index].pool
+		= rte_mempool_create(pool_name, nb_mbuf, MBUF_SIZE_ZCP,
+		MBUF_CACHE_SIZE_ZCP, sizeof(struct rte_pktmbuf_pool_private),
+		rte_pktmbuf_pool_init, (void *)(uintptr_t)roomsize,
+		rte_pktmbuf_init, NULL, socket, 0);
+	if (vpool_array[index].pool != NULL) {
+		vpool_array[index].ring
+			= rte_ring_create(ring_name,
+				rte_align32pow2(nb_mbuf + 1),
+				socket, RING_F_SP_ENQ | RING_F_SC_DEQ);
+		if (likely(vpool_array[index].ring != NULL)) {
+			LOG_DEBUG(VHOST_CONFIG,
+				"in setup_mempool_tbl: mbuf count in "
+				"mempool is: %d\n",
+				rte_mempool_count(vpool_array[index].pool));
+			LOG_DEBUG(VHOST_CONFIG,
+				"in setup_mempool_tbl: mbuf count in "
+				"ring   is: %d\n",
+				rte_ring_count(vpool_array[index].ring));
+		} else {
+			rte_exit(EXIT_FAILURE, "ring_create(%s) failed",
+				ring_name);
+		}
+
+		/* Need consider head room. */
+		vpool_array[index].buf_size = roomsize - RTE_PKTMBUF_HEADROOM;
+	} else {
+		rte_exit(EXIT_FAILURE, "mempool_create(%s) failed", pool_name);
+	}
+}
+
+/*
+ * Main function, does initialisation and calls the per-lcore functions.
+ * The CUSE device is also registered here to handle the IOCTLs.
+ */
+int
+MAIN(int argc, char *argv[])
+{
+	struct rte_mempool *mbuf_pool = NULL;
+	unsigned lcore_id, core_id = 0;
+	unsigned nb_ports, valid_num_ports;
+	int ret;
+	uint8_t portid, queue_id = 0;
+	static pthread_t tid;
+
+	/* init EAL */
+	ret = rte_eal_init(argc, argv);
+	if (ret < 0)
+		rte_exit(EXIT_FAILURE, "Error with EAL initialization\n");
+	argc -= ret;
+	argv += ret;
+
+	/* parse app arguments */
+	ret = us_vhost_parse_args(argc, argv);
+	if (ret < 0)
+		rte_exit(EXIT_FAILURE, "Invalid argument\n");
+
+	if (rte_eal_pci_probe() != 0)
+		rte_exit(EXIT_FAILURE,
+			"Error with NIC driver initialization\n");
+
+	for (lcore_id = 0; lcore_id < RTE_MAX_LCORE; lcore_id++)
+		if (rte_lcore_is_enabled(lcore_id))
+			lcore_ids[core_id++] = lcore_id;
+
+	if (rte_lcore_count() > RTE_MAX_LCORE)
+		rte_exit(EXIT_FAILURE, "Not enough cores\n");
+
+	/*set the number of swithcing cores available*/
+	num_switching_cores = rte_lcore_count()-1;
+
+	/* Get the number of physical ports. */
+	nb_ports = rte_eth_dev_count();
+	if (nb_ports > RTE_MAX_ETHPORTS)
+		nb_ports = RTE_MAX_ETHPORTS;
+
+	/*
+	 * Update the global var NUM_PORTS and global array PORTS
+	 * and get value of var VALID_NUM_PORTS according to system ports number
+	 */
+	valid_num_ports = check_ports_num(nb_ports);
+
+	if ((valid_num_ports ==  0) || (valid_num_ports > MAX_SUP_PORTS)) {
+		RTE_LOG(INFO, VHOST_PORT, "Current enabled port number is %u,"
+			"but only %u port can be enabled\n",
+			num_ports, MAX_SUP_PORTS);
+		return -1;
+	}
+
+	if (zero_copy == 0) {
+		/* Create the mbuf pool. */
+		mbuf_pool = rte_mempool_create(
+				"MBUF_POOL",
+				NUM_MBUFS_PER_PORT
+				* valid_num_ports,
+				MBUF_SIZE, MBUF_CACHE_SIZE,
+				sizeof(struct rte_pktmbuf_pool_private),
+				rte_pktmbuf_pool_init, NULL,
+				rte_pktmbuf_init, NULL,
+				rte_socket_id(), 0);
+		if (mbuf_pool == NULL)
+			rte_exit(EXIT_FAILURE, "Cannot create mbuf pool\n");
+
+		for (queue_id = 0; queue_id < MAX_QUEUES + 1; queue_id++)
+			vpool_array[queue_id].pool = mbuf_pool;
+
+		if (vm2vm_mode == VM2VM_HARDWARE) {
+			/* Enable VT loop back to let L2 switch to do it. */
+			vmdq_conf_default.rx_adv_conf.vmdq_rx_conf.enable_loop_back = 1;
+			LOG_DEBUG(VHOST_CONFIG,
+				"Enable loop back for L2 switch in vmdq.\n");
+		}
+	} else {
+		uint32_t nb_mbuf;
+		char pool_name[RTE_MEMPOOL_NAMESIZE];
+		char ring_name[RTE_MEMPOOL_NAMESIZE];
+
+		rx_conf_default.start_rx_per_q = (uint8_t)zero_copy;
+		rx_conf_default.rx_drop_en = 0;
+		tx_conf_default.start_tx_per_q = (uint8_t)zero_copy;
+		nb_mbuf = num_rx_descriptor
+			+ num_switching_cores * MBUF_CACHE_SIZE_ZCP
+			+ num_switching_cores * MAX_PKT_BURST;
+
+		for (queue_id = 0; queue_id < MAX_QUEUES; queue_id++) {
+			snprintf(pool_name, sizeof(pool_name),
+				"rxmbuf_pool_%u", queue_id);
+			snprintf(ring_name, sizeof(ring_name),
+				"rxmbuf_ring_%u", queue_id);
+			setup_mempool_tbl(rte_socket_id(), queue_id,
+				pool_name, ring_name, nb_mbuf);
+		}
+
+		nb_mbuf = num_tx_descriptor
+				+ num_switching_cores * MBUF_CACHE_SIZE_ZCP
+				+ num_switching_cores * MAX_PKT_BURST;
+
+		for (queue_id = 0; queue_id < MAX_QUEUES; queue_id++) {
+			snprintf(pool_name, sizeof(pool_name),
+				"txmbuf_pool_%u", queue_id);
+			snprintf(ring_name, sizeof(ring_name),
+				"txmbuf_ring_%u", queue_id);
+			setup_mempool_tbl(rte_socket_id(),
+				(queue_id + MAX_QUEUES),
+				pool_name, ring_name, nb_mbuf);
+		}
+
+		if (vm2vm_mode == VM2VM_HARDWARE) {
+			/* Enable VT loop back to let L2 switch to do it. */
+			vmdq_conf_default.rx_adv_conf.vmdq_rx_conf.enable_loop_back = 1;
+			LOG_DEBUG(VHOST_CONFIG,
+				"Enable loop back for L2 switch in vmdq.\n");
+		}
+	}
+	/* Set log level. */
+	rte_set_log_level(LOG_LEVEL);
+
+	/* initialize all ports */
+	for (portid = 0; portid < nb_ports; portid++) {
+		/* skip ports that are not enabled */
+		if ((enabled_port_mask & (1 << portid)) == 0) {
+			RTE_LOG(INFO, VHOST_PORT,
+				"Skipping disabled port %d\n", portid);
+			continue;
+		}
+		if (port_init(portid) != 0)
+			rte_exit(EXIT_FAILURE,
+				"Cannot initialize network ports\n");
+	}
+
+	/* Initialise all linked lists. */
+	if (init_data_ll() == -1)
+		rte_exit(EXIT_FAILURE, "Failed to initialize linked list\n");
+
+	/* Initialize device stats */
+	memset(&dev_statistics, 0, sizeof(dev_statistics));
+
+	/* Enable stats if the user option is set. */
+	if (enable_stats)
+		pthread_create(&tid, NULL, (void *)print_stats, NULL);
+
+	/* Launch all data cores. */
+	if (zero_copy == 0) {
+		RTE_LCORE_FOREACH_SLAVE(lcore_id) {
+			rte_eal_remote_launch(switch_worker,
+				mbuf_pool, lcore_id);
+		}
+	} else {
+		uint32_t count_in_mempool, index, i;
+		for (index = 0; index < 2 * MAX_QUEUES; index++) {
+			/* For all RX and TX queues. */
+			count_in_mempool
+				= rte_mempool_count(vpool_array[index].pool);
+
+			/*
+			 * Transfer all un-attached mbufs from vpool.pool
+			 * to vpoo.ring.
+			 */
+			for (i = 0; i < count_in_mempool; i++) {
+				struct rte_mbuf *mbuf
+					= __rte_mbuf_raw_alloc(
+						vpool_array[index].pool);
+				rte_ring_sp_enqueue(vpool_array[index].ring,
+						(void *)mbuf);
+			}
+
+			LOG_DEBUG(VHOST_CONFIG,
+				"in MAIN: mbuf count in mempool at initial "
+				"is: %d\n", count_in_mempool);
+			LOG_DEBUG(VHOST_CONFIG,
+				"in MAIN: mbuf count in  ring at initial  is :"
+				" %d\n",
+				rte_ring_count(vpool_array[index].ring));
+		}
+
+		RTE_LCORE_FOREACH_SLAVE(lcore_id)
+			rte_eal_remote_launch(switch_worker_zcp, NULL,
+				lcore_id);
+	}
+
+	if (mergeable == 0)
+		rte_vhost_feature_disable(1ULL << VIRTIO_NET_F_MRG_RXBUF);
+
+	/* Register CUSE device to handle IOCTLs. */
+	ret = rte_vhost_driver_register((char *)&dev_basename);
+	if (ret != 0)
+		rte_exit(EXIT_FAILURE, "CUSE device setup failure.\n");
+
+	rte_vhost_driver_callback_register(&virtio_net_device_ops);
+
+	/* Start CUSE session. */
+	rte_vhost_driver_session_start();
+
+	return 0;
+
+}
diff --git a/examples/vhost/main.h b/examples/vhost/main.h
new file mode 100644
index 0000000..866ba3a
--- /dev/null
+++ b/examples/vhost/main.h
@@ -0,0 +1,109 @@ 
+/*-
+ *   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.
+ */
+
+#ifndef _MAIN_H_
+#define _MAIN_H_
+
+#ifdef RTE_EXEC_ENV_BAREMETAL
+#define MAIN _main
+#else
+#define MAIN main
+#endif
+
+/**
+ * Information relating to memory regions including offsets to
+ * addresses in host physical space.
+ */
+struct virtio_memory_regions_hpa {
+	/**< Base guest physical address of region. */
+	uint64_t    guest_phys_address;
+	/**< End guest physical address of region. */
+	uint64_t    guest_phys_address_end;
+	/**< Size of region. */
+	uint64_t    memory_size;
+	/**< Offset of region for gpa to hpa translation. */
+	uint64_t    host_phys_addr_offset;
+};
+
+/**
+ * Device linked list structure for data path.
+ */
+struct vhost_dev {
+	/**< Pointer to device created by vhost lib. */
+	struct virtio_net      *dev;
+	/**< Number of memory regions for gpa to hpa translation. */
+	uint32_t nregions_hpa;
+	/**< Memory region information for gpa to hpa translation. */
+	struct virtio_memory_regions_hpa *regions_hpa;
+	/**< Device MAC address (Obtained on first TX packet). */
+	struct ether_addr mac_address;
+	/**< RX VMDQ queue number. */
+	uint16_t vmdq_rx_q;
+	/**< Vlan tag assigned to the pool */
+	uint32_t vlan_tag;
+	/**< Data core that the device is added to. */
+	uint16_t coreid;
+	/**< A device is set as ready if the MAC address has been set. */
+	volatile uint8_t ready;
+	/**< Device is marked for removal from the data core. */
+	volatile uint8_t remove;
+} __rte_cache_aligned;
+
+struct virtio_net_data_ll {
+	/* Pointer to device created by configuration core. */
+	struct vhost_dev		*vdev;
+	/* Pointer to next device in linked list. */
+	struct virtio_net_data_ll	*next;
+};
+
+/**
+ * Structure containing data core specific information.
+ */
+struct lcore_ll_info {
+	/**< Pointer to head in free linked list. */
+	struct virtio_net_data_ll *ll_root_free;
+	/**< Pointer to head of used linked list. */
+	struct virtio_net_data_ll *ll_root_used;
+	/**< Number of devices on lcore. */
+	uint32_t device_num;
+	/**< Flag to synchronize device removal. */
+	volatile uint8_t  dev_removal_flag;
+};
+
+struct lcore_info {
+	/* Pointer to data core specific lcore_ll_info struct */
+	struct lcore_ll_info *lcore_ll;
+};
+
+int MAIN(int argc, char **argv);
+#endif /* _MAIN_H_ */