Imported Upstream version 16.04

Change-Id: I77eadcd8538a9122e4773cbe55b24033dc451757
Signed-off-by: C.J. Collier <cjcollier@linuxfoundation.org>

3 files changed, 3331 insertions, 0 deletions

diff --git a/examples/vhost/Makefile b/examples/vhost/Makefile
new file mode 100644
index 00000000..e95c68ae
--- /dev/null
+++ b/examples/vhost/Makefile
@@ -0,0 +1,59 @@
+#   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 $(RTE_SDK)/mk/rte.vars.mk
+
+ifneq ($(CONFIG_RTE_EXEC_ENV),"linuxapp")
+$(info This application can only operate in a linuxapp environment, \
+please change the definition of the RTE_TARGET environment variable)
+all:
+else
+
+# binary name
+APP = vhost-switch
+
+# all source are stored in SRCS-y
+SRCS-y := main.c
+
+CFLAGS += -O2 -D_FILE_OFFSET_BITS=64
+CFLAGS += $(WERROR_FLAGS)
+CFLAGS += -D_GNU_SOURCE
+
+include $(RTE_SDK)/mk/rte.extapp.mk
+
+endif
diff --git a/examples/vhost/main.c b/examples/vhost/main.c
new file mode 100644
index 00000000..28c17afd
--- /dev/null
+++ b/examples/vhost/main.c
@@ -0,0 +1,3157 @@
+/*-
+ *   BSD LICENSE
+ *
+ *   Copyright(c) 2010-2015 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 <rte_ip.h>
+#include <rte_tcp.h>
+
+#include "main.h"
+
+#ifndef MAX_QUEUES
+#define MAX_QUEUES 128
+#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+1)*MBUF_CACHE_SIZE))
+
+#define MBUF_CACHE_SIZE	128
+#define MBUF_DATA_SIZE	RTE_MBUF_DEFAULT_BUF_SIZE
+
+/*
+ * 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	RTE_MBUF_DEFAULT_DATAROOM
+#define MBUF_DATA_SIZE_ZCP		RTE_MBUF_DEFAULT_BUF_SIZE
+#define MBUF_CACHE_SIZE_ZCP 0
+
+#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. */
+
+#define JUMBO_FRAME_MAX_SIZE    0x2600
+
+/* 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 (RTE_CACHE_LINE_SIZE / sizeof(struct vring_desc))
+
+#define MBUF_EXT_MEM(mb)   (rte_mbuf_from_indirect(mb) != (mb))
+
+/* mask of enabled ports */
+static uint32_t enabled_port_mask = 0;
+
+/* Promiscuous mode */
+static uint32_t promiscuous;
+
+/*Number of switching cores enabled*/
+static uint32_t num_switching_cores = 0;
+
+/* number of devices/queues to support*/
+static uint32_t num_queues = 0;
+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;
+
+/* Do vlan strip on host, enabled on default */
+static uint32_t vlan_strip = 1;
+
+/* 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. */
+typedef enum {
+	VM2VM_DISABLED = 0,
+	VM2VM_SOFTWARE = 1,
+	VM2VM_HARDWARE = 2,
+	VM2VM_LAST
+} vm2vm_type;
+static vm2vm_type vm2vm_mode = VM2VM_SOFTWARE;
+
+/* The type of host physical address translated from guest physical address. */
+typedef enum {
+	PHYS_ADDR_CONTINUOUS = 0,
+	PHYS_ADDR_CROSS_SUBREG = 1,
+	PHYS_ADDR_INVALID = 2,
+	PHYS_ADDR_LAST
+} hpa_type;
+
+/* Enable stats. */
+static uint32_t enable_stats = 0;
+/* Enable retries on RX. */
+static uint32_t enable_retry = 1;
+
+/* Disable TX checksum offload */
+static uint32_t enable_tx_csum;
+
+/* Disable TSO offload */
+static uint32_t enable_tso;
+
+/* 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";
+
+/* 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 = 0; /**< The number of ports specified in command line */
+static uint16_t num_pf_queues, num_vmdq_queues;
+static uint16_t vmdq_pool_base, vmdq_queue_base;
+static uint16_t queues_per_pool;
+
+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 = NULL;
+static struct virtio_net_data_ll *ll_root_free = NULL;
+
+/* 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;
+};
+
+/* 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;
+	struct rte_eth_vmdq_rx_conf *def_conf =
+		&vmdq_conf_default.rx_adv_conf.vmdq_rx_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 = def_conf->enable_loop_back;
+	conf.rx_mode = def_conf->rx_mode;
+
+	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;
+	struct rte_eth_rxconf *rxconf;
+	struct rte_eth_txconf *txconf;
+	int16_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);
+
+	if (dev_info.max_rx_queues > MAX_QUEUES) {
+		rte_exit(EXIT_FAILURE,
+			"please define MAX_QUEUES no less than %u in %s\n",
+			dev_info.max_rx_queues, __FILE__);
+	}
+
+	rxconf = &dev_info.default_rxconf;
+	txconf = &dev_info.default_txconf;
+	rxconf->rx_drop_en = 1;
+
+	/* Enable vlan offload */
+	txconf->txq_flags &= ~ETH_TXQ_FLAGS_NOVLANOFFL;
+
+	/*
+	 * Zero copy defers queue RX/TX start to the time when guest
+	 * finishes its startup and packet buffers from that guest are
+	 * available.
+	 */
+	if (zero_copy) {
+		rxconf->rx_deferred_start = 1;
+		rxconf->rx_drop_en = 0;
+		txconf->tx_deferred_start = 1;
+	}
+
+	/*configure the number of supported virtio devices based on VMDQ limits */
+	num_devices = dev_info.max_vmdq_pools;
+
+	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;
+	/* NIC queues are divided into pf queues and vmdq queues.  */
+	num_pf_queues = dev_info.max_rx_queues - dev_info.vmdq_queue_num;
+	queues_per_pool = dev_info.vmdq_queue_num / dev_info.max_vmdq_pools;
+	num_vmdq_queues = num_devices * queues_per_pool;
+	num_queues = num_pf_queues + num_vmdq_queues;
+	vmdq_queue_base = dev_info.vmdq_queue_base;
+	vmdq_pool_base  = dev_info.vmdq_pool_base;
+	printf("pf queue num: %u, configured vmdq pool num: %u, each vmdq pool has %u queues\n",
+		num_pf_queues, num_devices, queues_per_pool);
+
+	if (port >= rte_eth_dev_count()) return -1;
+
+	if (enable_tx_csum == 0)
+		rte_vhost_feature_disable(1ULL << VIRTIO_NET_F_CSUM);
+
+	if (enable_tso == 0) {
+		rte_vhost_feature_disable(1ULL << VIRTIO_NET_F_HOST_TSO4);
+		rte_vhost_feature_disable(1ULL << VIRTIO_NET_F_HOST_TSO6);
+	}
+
+	rx_rings = (uint16_t)dev_info.max_rx_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),
+						rxconf,
+						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),
+						txconf);
+		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;
+	}
+
+	if (promiscuous)
+		rte_eth_promiscuous_enable(port);
+
+	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>\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"
+	"		--vlan-strip [0|1]: disable/enable(default) RX VLAN strip on host\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"
+	"		--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"
+	"		--tx-csum [0|1] disable/enable TX checksum offload.\n"
+	"		--tso [0|1] disable/enable TCP segment offload.\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},
+		{"vlan-strip", required_argument, NULL, 0},
+		{"stats", required_argument, NULL, 0},
+		{"dev-basename", required_argument, NULL, 0},
+		{"zero-copy", required_argument, NULL, 0},
+		{"rx-desc-num", required_argument, NULL, 0},
+		{"tx-desc-num", required_argument, NULL, 0},
+		{"tx-csum", required_argument, NULL, 0},
+		{"tso", required_argument, NULL, 0},
+		{NULL, 0, 0, 0},
+	};
+
+	/* Parse command line */
+	while ((opt = getopt_long(argc, argv, "p: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 'P':
+			promiscuous = 1;
+			vmdq_conf_default.rx_adv_conf.vmdq_rx_conf.rx_mode =
+				ETH_VMDQ_ACCEPT_BROADCAST |
+				ETH_VMDQ_ACCEPT_MULTICAST;
+			rte_vhost_feature_enable(1ULL << VIRTIO_NET_F_CTRL_RX);
+
+			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 = (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;
+				}
+			}
+
+			/* Enable/disable TX checksum offload. */
+			if (!strncmp(long_option[option_index].name, "tx-csum", MAX_LONG_OPT_SZ)) {
+				ret = parse_num_opt(optarg, 1);
+				if (ret == -1) {
+					RTE_LOG(INFO, VHOST_CONFIG, "Invalid argument for tx-csum [0|1]\n");
+					us_vhost_usage(prgname);
+					return -1;
+				} else
+					enable_tx_csum = ret;
+			}
+
+			/* Enable/disable TSO offload. */
+			if (!strncmp(long_option[option_index].name, "tso", MAX_LONG_OPT_SZ)) {
+				ret = parse_num_opt(optarg, 1);
+				if (ret == -1) {
+					RTE_LOG(INFO, VHOST_CONFIG, "Invalid argument for tso [0|1]\n");
+					us_vhost_usage(prgname);
+					return -1;
+				} else
+					enable_tso = 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;
+					if (ret) {
+						vmdq_conf_default.rxmode.jumbo_frame = 1;
+						vmdq_conf_default.rxmode.max_rx_pkt_len
+							= JUMBO_FRAME_MAX_SIZE;
+					}
+				}
+			}
+
+			/* Enable/disable RX VLAN strip on host. */
+			if (!strncmp(long_option[option_index].name,
+				"vlan-strip", MAX_LONG_OPT_SZ)) {
+				ret = parse_num_opt(optarg, 1);
+				if (ret == -1) {
+					RTE_LOG(INFO, VHOST_CONFIG,
+						"Invalid argument for VLAN strip [0|1]\n");
+					us_vhost_usage(prgname);
+					return -1;
+				} else {
+					vlan_strip = !!ret;
+					vmdq_conf_default.rxmode.hw_vlan_strip =
+						vlan_strip;
+				}
+			}
+
+			/* 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;
+			}
+
+			/* 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;
+	}
+
+	if ((zero_copy == 1) && (vmdq_conf_default.rxmode.jumbo_frame == 1)) {
+		RTE_LOG(INFO, VHOST_PORT,
+			"Vhost zero copy doesn't support jumbo frame,"
+			"please specify '--mergeable 0' to disable the "
+			"mergeable feature.\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 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, 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",
+		vdev->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 = rte_pktmbuf_mtod(m, struct ether_hdr *);
+
+	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. */
+	ret = rte_eth_dev_mac_addr_add(ports[0], &vdev->mac_address,
+				(uint32_t)dev->device_fh + vmdq_pool_base);
+	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. */
+	if (vlan_strip)
+		rte_eth_dev_set_vlan_strip_on_queue(ports[0],
+			(uint16_t)vdev->vmdq_rx_q, 1);
+
+	/* Set device as ready for RX. */
+	vdev->ready = DEVICE_RX;
+
+	return 0;
+}
+
+/*
+ * Removes MAC address and vlan tag from VMDQ. Ensures that nothing is adding buffers to the RX
+ * queue before disabling RX on the device.
+ */
+static inline void
+unlink_vmdq(struct vhost_dev *vdev)
+{
+	unsigned i = 0;
+	unsigned rx_count;
+	struct rte_mbuf *pkts_burst[MAX_PKT_BURST];
+
+	if (vdev->ready == DEVICE_RX) {
+		/*clear MAC and VLAN settings*/
+		rte_eth_dev_mac_addr_remove(ports[0], &vdev->mac_address);
+		for (i = 0; i < 6; i++)
+			vdev->mac_address.addr_bytes[i] = 0;
+
+		vdev->vlan_tag = 0;
+
+		/*Clear out the receive buffers*/
+		rx_count = rte_eth_rx_burst(ports[0],
+					(uint16_t)vdev->vmdq_rx_q, pkts_burst, MAX_PKT_BURST);
+
+		while (rx_count) {
+			for (i = 0; i < rx_count; i++)
+				rte_pktmbuf_free(pkts_burst[i]);
+
+			rx_count = rte_eth_rx_burst(ports[0],
+					(uint16_t)vdev->vmdq_rx_q, pkts_burst, MAX_PKT_BURST);
+		}
+
+		vdev->ready = DEVICE_MAC_LEARNING;
+	}
+}
+
+/*
+ * Check if the packet destination MAC address is for a local device. If so 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;
+	uint64_t ret = 0;
+	struct virtio_net *dev = vdev->dev;
+	struct virtio_net *tdev; /* destination virito device */
+
+	pkt_hdr = rte_pktmbuf_mtod(m, struct ether_hdr *);
+
+	/*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[dev->device_fh].tx_total++;
+					dev_statistics[dev->device_fh].tx += ret;
+				}
+			}
+
+			return 0;
+		}
+		dev_ll = dev_ll->next;
+	}
+
+	return -1;
+}
+
+/*
+ * Check if the destination MAC of a packet is one local VM,
+ * and get its vlan tag, and offset if it is.
+ */
+static inline int __attribute__((always_inline))
+find_local_dest(struct virtio_net *dev, struct rte_mbuf *m,
+	uint32_t *offset, uint16_t *vlan_tag)
+{
+	struct virtio_net_data_ll *dev_ll = ll_root_used;
+	struct ether_hdr *pkt_hdr = rte_pktmbuf_mtod(m, struct ether_hdr *);
+
+	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->dev->device_fh);
+				return -1;
+			}
+
+			/*
+			 * HW vlan strip will reduce the packet length
+			 * by minus length of vlan tag, so need restore
+			 * the packet length by plus it.
+			 */
+			*offset = VLAN_HLEN;
+			*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,
+			(int)*vlan_tag);
+
+			break;
+		}
+		dev_ll = dev_ll->next;
+	}
+	return 0;
+}
+
+static uint16_t
+get_psd_sum(void *l3_hdr, uint64_t ol_flags)
+{
+	if (ol_flags & PKT_TX_IPV4)
+		return rte_ipv4_phdr_cksum(l3_hdr, ol_flags);
+	else /* assume ethertype == ETHER_TYPE_IPv6 */
+		return rte_ipv6_phdr_cksum(l3_hdr, ol_flags);
+}
+
+static void virtio_tx_offload(struct rte_mbuf *m)
+{
+	void *l3_hdr;
+	struct ipv4_hdr *ipv4_hdr = NULL;
+	struct tcp_hdr *tcp_hdr = NULL;
+	struct ether_hdr *eth_hdr = rte_pktmbuf_mtod(m, struct ether_hdr *);
+
+	l3_hdr = (char *)eth_hdr + m->l2_len;
+
+	if (m->ol_flags & PKT_TX_IPV4) {
+		ipv4_hdr = l3_hdr;
+		ipv4_hdr->hdr_checksum = 0;
+		m->ol_flags |= PKT_TX_IP_CKSUM;
+	}
+
+	tcp_hdr = (struct tcp_hdr *)((char *)l3_hdr + m->l3_len);
+	tcp_hdr->cksum = get_psd_sum(l3_hdr, m->ol_flags);
+}
+
+/*
+ * 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, 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 *dev = vdev->dev;
+	struct ether_hdr *nh;
+
+	/*check if destination is local VM*/
+	if ((vm2vm_mode == VM2VM_SOFTWARE) && (virtio_tx_local(vdev, m) == 0)) {
+		rte_pktmbuf_free(m);
+		return;
+	}
+
+	if (unlikely(vm2vm_mode == VM2VM_HARDWARE)) {
+		if (unlikely(find_local_dest(dev, m, &offset, &vlan_tag) != 0)) {
+			rte_pktmbuf_free(m);
+			return;
+		}
+	}
+
+	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;
+
+	nh = rte_pktmbuf_mtod(m, struct ether_hdr *);
+	if (unlikely(nh->ether_type == rte_cpu_to_be_16(ETHER_TYPE_VLAN))) {
+		/* Guest has inserted the vlan tag. */
+		struct vlan_hdr *vh = (struct vlan_hdr *) (nh + 1);
+		uint16_t vlan_tag_be = rte_cpu_to_be_16(vlan_tag);
+		if ((vm2vm_mode == VM2VM_HARDWARE) &&
+			(vh->vlan_tci != vlan_tag_be))
+			vh->vlan_tci = vlan_tag_be;
+	} else {
+		m->ol_flags |= PKT_TX_VLAN_PKT;
+
+		/*
+		 * Find the right seg to adjust the data len when offset is
+		 * bigger than tail room size.
+		 */
+		if (unlikely(vm2vm_mode == VM2VM_HARDWARE)) {
+			if (likely(offset <= rte_pktmbuf_tailroom(m)))
+				m->data_len += offset;
+			else {
+				struct rte_mbuf *seg = m;
+
+				while ((seg->next != NULL) &&
+					(offset > rte_pktmbuf_tailroom(seg)))
+					seg = seg->next;
+
+				seg->data_len += offset;
+			}
+			m->pkt_len += offset;
+		}
+
+		m->vlan_tci = vlan_tag;
+	}
+
+	if (m->ol_flags & PKT_TX_TCP_SEG)
+		virtio_tx_offload(m);
+
+	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 (dev_ll != NULL) {
+			/*get virtio device ID*/
+			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(pkts_burst[rx_count]);
+					}
+
+				}
+			}
+
+			if (likely(!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]);
+					}
+				}
+				for (i = 0; i < tx_count; ++i) {
+					virtio_tx_route(vdev, pkts_burst[i],
+						vlan_tags[(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(vq->callfd, (eventfd_t)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;
+	void *obj = NULL;
+	struct rte_mbuf *mbuf;
+	struct vpool *vpool;
+	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, &obj);
+	mbuf = obj;
+	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, obj);
+		return;
+	}
+
+	mbuf->buf_addr = (void *)(uintptr_t)(buff_addr - RTE_PKTMBUF_HEADROOM);
+	mbuf->data_off = RTE_PKTMBUF_HEADROOM;
+	mbuf->buf_physaddr = phys_addr - RTE_PKTMBUF_HEADROOM;
+	mbuf->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->data_off = buf_ofs;
+
+	m->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(MBUF_EXT_MEM(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(vq->callfd, (eventfd_t)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(MBUF_EXT_MEM(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. */
+		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(vq->callfd, (eventfd_t)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;
+	void *obj = NULL;
+	struct rte_mbuf *mbuf;
+	unsigned len, ret, offset = 0;
+	struct vpool *vpool;
+	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, &obj);
+	mbuf = obj;
+	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;
+		if (find_local_dest(dev, m, &offset, &vlan_tag) != 0) {
+			MBUF_HEADROOM_UINT32(mbuf) = (uint32_t)desc_idx;
+			__rte_mbuf_raw_free(mbuf);
+			return;
+		}
+	}
+
+	mbuf->nb_segs = m->nb_segs;
+	mbuf->next = m->next;
+	mbuf->data_len = m->data_len + offset;
+	mbuf->pkt_len = mbuf->data_len;
+	if (unlikely(need_copy)) {
+		/* Copy the packet contents to the mbuf. */
+		rte_memcpy(rte_pktmbuf_mtod(mbuf, void *),
+			rte_pktmbuf_mtod(m, void *),
+			m->data_len);
+	} else {
+		mbuf->data_off = m->data_off;
+		mbuf->buf_physaddr = m->buf_physaddr;
+		mbuf->buf_addr = m->buf_addr;
+	}
+	mbuf->ol_flags |= PKT_TX_VLAN_PKT;
+	mbuf->vlan_tci = vlan_tag;
+	mbuf->l2_len = sizeof(struct ether_hdr);
+	mbuf->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->nb_segs,
+		(mbuf->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 vhost_virtqueue *vq;
+	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;
+	hpa_type addr_type;
+	struct vhost_dev *vdev = (struct vhost_dev *)dev->priv;
+
+	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);
+		/* Need check extra VLAN_HLEN size for inserting VLAN tag */
+		phys_addr = gpa_to_hpa(vdev, desc->addr, desc->len + VLAN_HLEN,
+			&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.data_len = desc->len;
+		m.nb_segs = 1;
+		m.next = NULL;
+		m.data_off = 0;
+		m.buf_addr = (void *)(uintptr_t)buff_addr;
+		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 = malloc(size * sizeof(struct virtio_net_data_ll));
+	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 = malloc(sizeof(struct lcore_ll_info));
+		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 (volatile 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,
+				vdev->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, vdev->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, vdev->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 the 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), RTE_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 = rte_calloc("vhost hpa region",
+					       vdev->nregions_hpa,
+					       sizeof(struct virtio_memory_regions_hpa),
+					       RTE_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 ll */
+	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);
+	vdev->vmdq_rx_q
+		= dev->device_fh * queues_per_pool + vmdq_queue_base;
+
+	if (zero_copy) {
+		uint32_t index = vdev->vmdq_rx_q;
+		uint32_t count_in_ring, i;
+		struct mbuf_table *tx_q;
+
+		count_in_ring = rte_ring_count(vpool_array[index].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[index].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 intovpool.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[index].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[index].ring));
+
+		tx_q = &tx_queue_zcp[(uint16_t)vdev->vmdq_rx_q];
+		tx_q->txq_id = vdev->vmdq_rx_q;
+
+		if (rte_eth_dev_tx_queue_start(ports[0], vdev->vmdq_rx_q) != 0) {
+			struct vpool *vpool = &vpool_array[vdev->vmdq_rx_q];
+
+			LOG_DEBUG(VHOST_CONFIG,
+				"(%"PRIu64") In new_device: Failed to start "
+				"tx queue:%d\n",
+				dev->device_fh, vdev->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], vdev->vmdq_rx_q) != 0) {
+			struct vpool *vpool = &vpool_array[vdev->vmdq_rx_q];
+
+			LOG_DEBUG(VHOST_CONFIG,
+				"(%"PRIu64") In new_device: Failed to start "
+				"rx queue:%d\n",
+				dev->device_fh, vdev->vmdq_rx_q);
+
+			/* Stop the TX queue. */
+			if (rte_eth_dev_tx_queue_stop(ports[0],
+				vdev->vmdq_rx_q) != 0) {
+				LOG_DEBUG(VHOST_CONFIG,
+					"(%"PRIu64") In new_device: Failed to "
+					"stop tx queue:%d\n",
+					dev->device_fh, vdev->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 lcore ll */
+	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);
+		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" ------------------------------"
+					"\nTX total: 		%"PRIu64""
+					"\nTX dropped: 		%"PRIu64""
+					"\nTX successful: 		%"PRIu64""
+					"\nRX total: 		%"PRIu64""
+					"\nRX dropped: 		%"PRIu64""
+					"\nRX 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)
+{
+	vpool_array[index].pool	= rte_pktmbuf_pool_create(pool_name, nb_mbuf,
+		MBUF_CACHE_SIZE_ZCP, 0, MBUF_DATA_SIZE_ZCP, socket);
+	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 = VIRTIO_DESCRIPTOR_LEN_ZCP;
+	} else {
+		rte_exit(EXIT_FAILURE, "mempool_create(%s) failed", pool_name);
+	}
+}
+
+/* When we receive a INT signal, unregister vhost driver */
+static void
+sigint_handler(__rte_unused int signum)
+{
+	/* Unregister vhost driver. */
+	int ret = rte_vhost_driver_unregister((char *)&dev_basename);
+	if (ret != 0)
+		rte_exit(EXIT_FAILURE, "vhost driver unregister failure.\n");
+	exit(0);
+}
+
+/*
+ * 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;
+	uint16_t queue_id;
+	static pthread_t tid;
+	char thread_name[RTE_MAX_THREAD_NAME_LEN];
+
+	signal(SIGINT, sigint_handler);
+
+	/* 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");
+
+	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_pktmbuf_pool_create("MBUF_POOL",
+			NUM_MBUFS_PER_PORT * valid_num_ports, MBUF_CACHE_SIZE,
+			0, MBUF_DATA_SIZE, rte_socket_id());
+		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];
+
+		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) {
+		ret = pthread_create(&tid, NULL, (void *)print_stats, NULL);
+		if (ret != 0)
+			rte_exit(EXIT_FAILURE,
+				"Cannot create print-stats thread\n");
+
+		/* Set thread_name for aid in debugging.  */
+		snprintf(thread_name, RTE_MAX_THREAD_NAME_LEN, "print-stats");
+		ret = rte_thread_setname(tid, thread_name);
+		if (ret != 0)
+			RTE_LOG(ERR, VHOST_CONFIG,
+				"Cannot set print-stats name\n");
+	}
+
+	/* 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 vhost(cuse or user) driver to handle vhost messages. */
+	ret = rte_vhost_driver_register((char *)&dev_basename);
+	if (ret != 0)
+		rte_exit(EXIT_FAILURE, "vhost driver register 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 00000000..d04e2be2
--- /dev/null
+++ b/examples/vhost/main.h
@@ -0,0 +1,115 @@
+/*-
+ *   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_
+
+//#define DEBUG
+
+#ifdef DEBUG
+#define LOG_LEVEL RTE_LOG_DEBUG
+#define LOG_DEBUG(log_type, fmt, args...) do {	\
+	RTE_LOG(DEBUG, log_type, fmt, ##args);		\
+} while (0)
+#else
+#define LOG_LEVEL RTE_LOG_INFO
+#define LOG_DEBUG(log_type, fmt, args...) do{} while(0)
+#endif
+
+/* Macros for printing using RTE_LOG */
+#define RTE_LOGTYPE_VHOST_CONFIG RTE_LOGTYPE_USER1
+#define RTE_LOGTYPE_VHOST_DATA   RTE_LOGTYPE_USER2
+#define RTE_LOGTYPE_VHOST_PORT   RTE_LOGTYPE_USER3
+
+/**
+ * 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
+{
+	struct vhost_dev		*vdev;	/* Pointer to device created by configuration core. */
+	struct virtio_net_data_ll	*next;  /* Pointer to next device in linked list. */
+};
+
+/*
+ * Structure containing data core specific information.
+ */
+struct lcore_ll_info
+{
+	struct virtio_net_data_ll	*ll_root_free; 		/* Pointer to head in free linked list. */
+	struct virtio_net_data_ll	*ll_root_used;		/* Pointer to head of used linked list. */
+	uint32_t 					device_num;			/* Number of devices on lcore. */
+	volatile uint8_t			dev_removal_flag;	/* Flag to synchronize device removal. */
+};
+
+struct lcore_info
+{
+	struct lcore_ll_info	*lcore_ll;	/* Pointer to data core specific lcore_ll_info struct */
+};
+
+#endif /* _MAIN_H_ */