[dpdk-dev,3/3] examples/vhost: add new vhost example
diff mbox

Message ID 1407254286-23972-4-git-send-email-huawei.xie@intel.com
State Superseded, archived
Headers show

Commit Message

Huawei Xie Aug. 5, 2014, 3:58 p.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               | 3047 +++++++++++++++++++++++++++++++++++
 examples/vhost/main.h               |  109 ++
 4 files changed, 3574 insertions(+)
 create mode 100644 examples/vhost/Makefile
 create mode 100755 examples/vhost/libvirt/qemu-wrap.py
 create mode 100644 examples/vhost/main.c
 create mode 100644 examples/vhost/main.h

Comments

Stephen Hemminger Aug. 6, 2014, 3:32 a.m. UTC | #1
> +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,
> +};

Why pre-compute table if it is just: vlan_tag = n + 1000?


> +
> +/* 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];

Doing per-core statistics would be faster than using atomic's
which have implicit lock.

> +/*
> + * 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);
> +	}
> +
> +	(void)(rte_memcpy(eth_conf, &vmdq_conf_default, sizeof(*eth_conf)));
> +	(void)(rte_memcpy(&eth_conf->rx_adv_conf.vmdq_rx_conf, &conf,
> +		   sizeof(eth_conf->rx_adv_conf.vmdq_rx_conf)));
> +	return 0;
> +}

If function always returns 0 just make it void.
No point in making non-fastpath code inline.
The cast to (void) is unnecessary and just makes things ugly.
Why not use structure assignment rather than memcpy() which is not type safe?
Huawei Xie Aug. 6, 2014, 5:34 a.m. UTC | #2
> -----Original Message-----
> From: Stephen Hemminger [mailto:stephen@networkplumber.org]
> Sent: Wednesday, August 06, 2014 11:33 AM
> To: Xie, Huawei
> Cc: dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH 3/3] examples/vhost: add new vhost example
> 
> 
> > +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,
> > +};
> 
> Why pre-compute table if it is just: vlan_tag = n + 1000?
This is inherited from old vhost example. For demonstration purpose, I feel it is ok. Besides, the purpose of this patch is to refactor the example using vhost library, so I prefer subsequent patches to fix those kind of problems.
> 
> 
> > +
> > +/* 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];
> 
> Doing per-core statistics would be faster than using atomic's
> which have implicit lock.
For software vm2vm mode, there is contention as two cores could enqueue the same virtio ring concurrently.
> 
> > +/*
> > + * 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);
> > +	}
> > +
> > +	(void)(rte_memcpy(eth_conf, &vmdq_conf_default, sizeof(*eth_conf)));
> > +	(void)(rte_memcpy(&eth_conf->rx_adv_conf.vmdq_rx_conf, &conf,
> > +		   sizeof(eth_conf->rx_adv_conf.vmdq_rx_conf)));
> > +	return 0;
> > +}
> 
> If function always returns 0 just make it void.
> No point in making non-fastpath code inline.
> The cast to (void) is unnecessary and just makes things ugly.
> Why not use structure assignment rather than memcpy() which is not type safe?
Agree. As stated above, I prefer subsequent patches to fix those issues inherited from old example. How do you think?

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 100755
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..2a8cdc9
--- /dev/null
+++ b/examples/vhost/main.c
@@ -0,0 +1,3047 @@ 
+/*-
+ *   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);
+	}
+
+	(void)(rte_memcpy(eth_conf, &vmdq_conf_default, sizeof(*eth_conf)));
+	(void)(rte_memcpy(&eth_conf->rx_adv_conf.vmdq_rx_conf, &conf,
+		   sizeof(eth_conf->rx_adv_conf.vmdq_rx_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;
+
+	/* The max pool number from dev_info will be used to validate the pool number specified in cmd line */
+	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);
+		/* TODO fixme */
+		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 then 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)) {
+
+			/* 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->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)) {
+				/* Drop the packet if the device is marked for removal*/
+				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_ */