[deb_dpdk.git] / examples / vhost_xen / main.c

/*-
 *   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_pause.h>

#include "main.h"
#include "virtio-net.h"
#include "xen_vhost.h"

#define MAX_QUEUES 128

/* the maximum number of external ports supported */
#define MAX_SUP_PORTS 1

/*
 * Calculate the number of buffers needed per port
 */
#define NUM_MBUFS_PER_PORT ((MAX_QUEUES*RTE_TEST_RX_DESC_DEFAULT) +             \
                                                        (num_switching_cores*MAX_PKT_BURST) +                   \
                                                        (num_switching_cores*RTE_TEST_TX_DESC_DEFAULT) +\
                                                        (num_switching_cores*MBUF_CACHE_SIZE))

#define MBUF_CACHE_SIZE 64

/*
 * RX and TX Prefetch, Host, and Write-back threshold values should be
 * carefully set for optimal performance. Consult the network
 * controller's datasheet and supporting DPDK documentation for guidance
 * on how these parameters should be set.
 */
#define RX_PTHRESH 8 /* Default values of RX prefetch threshold reg. */
#define RX_HTHRESH 8 /* Default values of RX host threshold reg. */
#define RX_WTHRESH 4 /* Default values of RX write-back threshold reg. */

/*
 * These default values are optimized for use with the Intel(R) 82599 10 GbE
 * Controller and the DPDK ixgbe PMD. Consider using other values for other
 * network controllers and/or network drivers.
 */
#define TX_PTHRESH 36 /* Default values of TX prefetch threshold reg. */
#define TX_HTHRESH 0  /* Default values of TX host threshold reg. */
#define TX_WTHRESH 0  /* Default values of TX write-back threshold reg. */

#define MAX_PKT_BURST 32                /* Max burst size for RX/TX */
#define MAX_MRG_PKT_BURST 16    /* Max burst for merge buffers. Set to 1 due to performance issue. */
#define BURST_TX_DRAIN_US 100   /* TX drain every ~100us */

/* State of virtio device. */
#define DEVICE_NOT_READY     0
#define DEVICE_READY         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 128
#define RTE_TEST_TX_DESC_DEFAULT 512

#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 long option length for option parsing. */
#define MAX_LONG_OPT_SZ 64

/* Used to compare MAC addresses. */
#define MAC_ADDR_CMP 0xFFFFFFFFFFFF

/* mask of enabled ports */
static uint32_t enabled_port_mask = 0;

/*Number of switching cores enabled*/
static uint32_t num_switching_cores = 0;

/* number of devices/queues to support*/
static uint32_t num_queues = 0;
uint32_t num_devices = 0;

/* Enable VM2VM communications. If this is disabled then the MAC address compare is skipped. */
static uint32_t enable_vm2vm = 1;
/* Enable stats. */
static uint32_t enable_stats = 0;

/* empty vmdq configuration structure. Filled in programatically */
static const 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   = 1, /**< 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 */

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];

/* 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;
        uint64_t tx;
        rte_atomic64_t rx;
} __rte_cache_aligned;
struct device_statistics dev_statistics[MAX_DEVICES];

/*
 * Builds up the correct configuration for VMDQ VLAN pool map
 * according to the pool & queue limits.
 */
static inline int
get_eth_conf(struct rte_eth_conf *eth_conf, uint32_t num_devices)
{
        struct rte_eth_vmdq_rx_conf conf;
        unsigned i;

        memset(&conf, 0, sizeof(conf));
        conf.nb_queue_pools = (enum rte_eth_nb_pools)num_devices;
        conf.nb_pool_maps = num_devices;

        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_mempool *mbuf_pool)
{
        struct rte_eth_dev_info dev_info;
        struct rte_eth_rxconf *rxconf;
        struct rte_eth_conf port_conf;
        uint16_t rx_rings, tx_rings = (uint16_t)rte_lcore_count();
        uint16_t rx_ring_size = RTE_TEST_RX_DESC_DEFAULT;
        uint16_t tx_ring_size = RTE_TEST_TX_DESC_DEFAULT;
        int retval;
        uint16_t q;

        /* The max pool number from dev_info will be used to validate the pool number specified in cmd line */
        rte_eth_dev_info_get (port, &dev_info);

        /*configure the number of supported virtio devices based on VMDQ limits */
        num_devices = dev_info.max_vmdq_pools;
        num_queues = dev_info.max_rx_queues;

        retval = validate_num_devices(MAX_DEVICES);
        if (retval < 0)
                return retval;

        /* Get port configuration. */
        retval = get_eth_conf(&port_conf, num_devices);
        if (retval < 0)
                return retval;

        if (port >= rte_eth_dev_count()) return -1;

        rx_rings = (uint16_t)num_queues,
        /* Configure ethernet device. */
        retval = rte_eth_dev_configure(port, rx_rings, tx_rings, &port_conf);
        if (retval != 0)
                return retval;

        retval = rte_eth_dev_adjust_nb_rx_tx_desc(port, &rx_ring_size,
                &tx_ring_size);
        if (retval != 0)
                return retval;
        if (rx_ring_size > RTE_TEST_RX_DESC_DEFAULT ||
                tx_ring_size > RTE_TEST_TX_DESC_DEFAULT) {
                RTE_LOG(ERR, VHOST_PORT, "Mbuf pool has an insufficient size for "
                        "port %u.\n", port);
                return -1;
        }

        rte_eth_dev_info_get(port, &dev_info);
        rxconf = &dev_info.default_rxconf;
        rxconf->rx_drop_en = 1;
        /* 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,
                                                mbuf_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),
                                                NULL);
                if (retval < 0)
                        return retval;
        }

        /* Start the device. */
        retval  = rte_eth_dev_start(port);
        if (retval < 0)
                return retval;

        rte_eth_macaddr_get(port, &vmdq_ports_eth_addr[port]);
        RTE_LOG(INFO, VHOST_PORT, "Max virtio devices supported: %u\n", num_devices);
        RTE_LOG(INFO, VHOST_PORT, "Port %u MAC: %02"PRIx8" %02"PRIx8" %02"PRIx8
                        " %02"PRIx8" %02"PRIx8" %02"PRIx8"\n",
                        (unsigned)port,
                        vmdq_ports_eth_addr[port].addr_bytes[0],
                        vmdq_ports_eth_addr[port].addr_bytes[1],
                        vmdq_ports_eth_addr[port].addr_bytes[2],
                        vmdq_ports_eth_addr[port].addr_bytes[3],
                        vmdq_ports_eth_addr[port].addr_bytes[4],
                        vmdq_ports_eth_addr[port].addr_bytes[5]);

        return 0;
}

/*
 * 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 --vm2vm [0|1] --stats [0-N] --nb-devices ND\n"
        "               -p PORTMASK: Set mask for ports to be used by application\n"
        "               --vm2vm [0|1]: disable/enable(default) vm2vm comms\n"
        "               --stats [0-N]: 0: Disable stats, N: Time in seconds to print stats\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},
                {"stats", required_argument, NULL, 0},
                {NULL, 0, 0, 0}
        };

        /* Parse command line */
        while ((opt = getopt_long(argc, argv, "p:",long_option, &option_index)) != EOF) {
                switch (opt) {
                /* Portmask */
                case 'p':
                        enabled_port_mask = parse_portmask(optarg);
                        if (enabled_port_mask == 0) {
                                RTE_LOG(INFO, VHOST_CONFIG, "Invalid portmask\n");
                                us_vhost_usage(prgname);
                                return -1;
                        }
                        break;

                case 0:
                        /* Enable/disable vm2vm comms. */
                        if (!strncmp(long_option[option_index].name, "vm2vm", MAX_LONG_OPT_SZ)) {
                                ret = parse_num_opt(optarg, 1);
                                if (ret == -1) {
                                        RTE_LOG(INFO, VHOST_CONFIG, "Invalid argument for vm2vm [0|1]\n");
                                        us_vhost_usage(prgname);
                                        return -1;
                                } else {
                                        enable_vm2vm = ret;
                                }
                        }

                        /* Enable/disable stats. */
                        if (!strncmp(long_option[option_index].name, "stats", MAX_LONG_OPT_SZ)) {
                                ret = parse_num_opt(optarg, INT32_MAX);
                                if (ret == -1) {
                                        RTE_LOG(INFO, VHOST_CONFIG, "Invalid argument for stats [0..N]\n");
                                        us_vhost_usage(prgname);
                                        return -1;
                                } else {
                                        enable_stats = ret;
                                }
                        }
                        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;
        }

        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;
}

/*
 * Function to convert guest physical addresses to vhost virtual addresses. This
 * is used to convert virtio buffer addresses.
 */
static __rte_always_inline uint64_t
gpa_to_vva(struct virtio_net *dev, uint64_t guest_pa)
{
        struct virtio_memory_regions *region;
        uint32_t regionidx;
        uint64_t vhost_va = 0;

        for (regionidx = 0; regionidx < dev->mem->nregions; regionidx++) {
                region = &dev->mem->regions[regionidx];
                if ((guest_pa >= region->guest_phys_address) &&
                        (guest_pa <= region->guest_phys_address_end)) {
                        vhost_va = region->address_offset + guest_pa;
                        break;
                }
        }
        RTE_LOG_DP(DEBUG, VHOST_DATA, "(%" PRIu64 ") GPA %p| VVA %p\n",
                dev->device_fh, (void*)(uintptr_t)guest_pa, (void*)(uintptr_t)vhost_va);

        return vhost_va;
}

/*
 * This function adds buffers to the virtio devices RX virtqueue. Buffers can
 * be received from the physical port or from another virtio device. A packet
 * count is returned to indicate the number of packets that were successfully
 * added to the RX queue.
 */
static __rte_always_inline uint32_t
virtio_dev_rx(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_addr = 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 avail_idx, res_cur_idx;
        uint16_t res_base_idx, res_end_idx;
        uint16_t free_entries;
        uint8_t success = 0;
        void *userdata;

        RTE_LOG_DP(DEBUG, VHOST_DATA, "(%" PRIu64 ") virtio_dev_rx()\n", dev->device_fh);
        vq = dev->virtqueue_rx;
        count = (count > MAX_PKT_BURST) ? MAX_PKT_BURST : count;
        /* As many data cores may want access to available buffers, they need to be reserved. */
        do {

                res_base_idx = vq->last_used_idx_res;

                avail_idx = *((volatile uint16_t *)&vq->avail->idx);

                free_entries = (avail_idx - res_base_idx);

                /*check that we have enough buffers*/
                if (unlikely(count > free_entries))
                        count = free_entries;

                if (count == 0)
                        return 0;

                res_end_idx = res_base_idx + count;
                /* vq->last_used_idx_res is atomically updated. */
                success = rte_atomic16_cmpset(&vq->last_used_idx_res, res_base_idx,
                                                                        res_end_idx);
        } while (unlikely(success == 0));
        res_cur_idx = res_base_idx;
        RTE_LOG_DP(DEBUG, VHOST_DATA, "(%" PRIu64 ") Current Index %d| End Index %d\n",
                dev->device_fh, res_cur_idx, res_end_idx);

        /* Prefetch available ring to retrieve indexes. */
        rte_prefetch0(&vq->avail->ring[res_cur_idx & (vq->size - 1)]);

        /* Retrieve all of the head indexes first to avoid caching issues. */
        for (head_idx = 0; head_idx < count; head_idx++)
                head[head_idx] = vq->avail->ring[(res_cur_idx + head_idx) & (vq->size - 1)];

        /*Prefetch descriptor index. */
        rte_prefetch0(&vq->desc[head[packet_success]]);

        while (res_cur_idx != res_end_idx) {
                /* Get descriptor from available ring */
                desc = &vq->desc[head[packet_success]];
                /* Prefetch descriptor address. */
                rte_prefetch0(desc);

                buff = pkts[packet_success];

                /* Convert from gpa to vva (guest physical addr -> vhost virtual addr) */
                buff_addr = gpa_to_vva(dev, desc->addr);
                /* Prefetch buffer address. */
                rte_prefetch0((void*)(uintptr_t)buff_addr);

                {
                        /* Copy virtio_hdr to packet and increment buffer address */
                        buff_hdr_addr = buff_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];
                                /* Buffer address translation. */
                                buff_addr = gpa_to_vva(dev, desc->addr);
                                desc->len = rte_pktmbuf_data_len(buff);
                        } else {
                                buff_addr += vq->vhost_hlen;
                                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;

                /* Copy mbuf data to buffer */
                userdata = rte_pktmbuf_mtod(buff, void *);
                rte_memcpy((void *)(uintptr_t)buff_addr, userdata, rte_pktmbuf_data_len(buff));

                res_cur_idx++;
                packet_success++;

                /* mergeable is disabled then a header is required per buffer. */
                rte_memcpy((void *)(uintptr_t)buff_hdr_addr, (const void *)&virtio_hdr, vq->vhost_hlen);
                if (res_cur_idx < res_end_idx) {
                        /* Prefetch descriptor index. */
                        rte_prefetch0(&vq->desc[head[packet_success]]);
                }
        }

        rte_compiler_barrier();

        /* Wait until it's our turn to add our buffer to the used ring. */
        while (unlikely(vq->last_used_idx != res_base_idx))
                rte_pause();

        *(volatile uint16_t *)&vq->used->idx += count;

        vq->last_used_idx = res_end_idx;

        return count;
}

/*
 * Compares a packet destination MAC address to a device MAC address.
 */
static __rte_always_inline int
ether_addr_cmp(struct ether_addr *ea, struct ether_addr *eb)
{
        return ((*(uint64_t *)ea ^ *(uint64_t *)eb) & MAC_ADDR_CMP) == 0;
}

/*
 * This function registers mac along with a
 * vlan tag to a VMDQ.
 */
static int
link_vmdq(struct virtio_net *dev)
{
        int ret;
        struct virtio_net_data_ll *dev_ll;

        dev_ll = ll_root_used;

        while (dev_ll != NULL) {
                if ((dev != dev_ll->dev) && ether_addr_cmp(&dev->mac_address, &dev_ll->dev->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;
        }

        /* vlan_tag currently uses the device_id. */
        dev->vlan_tag = vlan_tags[dev->device_fh];
        dev->vmdq_rx_q = dev->device_fh * (num_queues/num_devices);

        /* 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,
                dev->mac_address.addr_bytes[0], dev->mac_address.addr_bytes[1],
                dev->mac_address.addr_bytes[2], dev->mac_address.addr_bytes[3],
                dev->mac_address.addr_bytes[4], dev->mac_address.addr_bytes[5],
                dev->vlan_tag);

        /* Register the MAC address. */
        ret = rte_eth_dev_mac_addr_add(ports[0], &dev->mac_address, (uint32_t)dev->device_fh);
        if (ret) {
                RTE_LOG(ERR, VHOST_DATA, "(%"PRIu64") Failed to add device MAC address to VMDQ\n",
                                                                                dev->device_fh);
                return -1;
        }

        /* Enable stripping of the vlan tag as we handle routing. */
        rte_eth_dev_set_vlan_strip_on_queue(ports[0], dev->vmdq_rx_q, 1);

        rte_compiler_barrier();
        /* Set device as ready for RX. */
        dev->ready = DEVICE_READY;

        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 virtio_net *dev)
{
        unsigned i = 0;
        unsigned rx_count;
        struct rte_mbuf *pkts_burst[MAX_PKT_BURST];

        if (dev->ready == DEVICE_READY) {
                /*clear MAC and VLAN settings*/
                rte_eth_dev_mac_addr_remove(ports[0], &dev->mac_address);
                for (i = 0; i < 6; i++)
                        dev->mac_address.addr_bytes[i] = 0;

                dev->vlan_tag = 0;

                /*Clear out the receive buffers*/
                rx_count = rte_eth_rx_burst(ports[0],
                                        (uint16_t)dev->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)dev->vmdq_rx_q, pkts_burst, MAX_PKT_BURST);
                }

                dev->ready = DEVICE_NOT_READY;
        }
}

/*
 * 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 __rte_always_inline unsigned
virtio_tx_local(struct virtio_net *dev, struct rte_mbuf *m)
{
        struct virtio_net_data_ll *dev_ll;
        struct ether_hdr *pkt_hdr;
        uint64_t ret = 0;

        pkt_hdr = rte_pktmbuf_mtod(m, struct ether_hdr *);

        /*get the used devices list*/
        dev_ll = ll_root_used;

        while (dev_ll != NULL) {
                if (likely(dev_ll->dev->ready == DEVICE_READY) && ether_addr_cmp(&(pkt_hdr->d_addr),
                                          &dev_ll->dev->mac_address)) {

                        /* Drop the packet if the TX packet is destined for the TX device. */
                        if (dev_ll->dev->device_fh == dev->device_fh) {
                                RTE_LOG_DP(DEBUG, VHOST_DATA, "(%" PRIu64 ") TX: "
                                        "Source and destination MAC addresses are the same. "
                                        "Dropping packet.\n",
                                        dev_ll->dev->device_fh);
                                return 0;
                        }


                        RTE_LOG_DP(DEBUG, VHOST_DATA, "(%" PRIu64 ") TX: "
                                "MAC address is local\n", dev_ll->dev->device_fh);

                        if (dev_ll->dev->remove) {
                                /*drop the packet if the device is marked for removal*/
                                RTE_LOG_DP(DEBUG, VHOST_DATA, "(%" PRIu64 ") "
                                        "Device is marked for removal\n",
                                        dev_ll->dev->device_fh);
                        } else {
                                /*send the packet to the local virtio device*/
                                ret = virtio_dev_rx(dev_ll->dev, &m, 1);
                                if (enable_stats) {
                                        rte_atomic64_add(&dev_statistics[dev_ll->dev->device_fh].rx_total, 1);
                                        rte_atomic64_add(&dev_statistics[dev_ll->dev->device_fh].rx, ret);
                                        dev_statistics[dev->device_fh].tx_total++;
                                        dev_statistics[dev->device_fh].tx += ret;
                                }
                        }

                        return 0;
                }
                dev_ll = dev_ll->next;
        }

        return -1;
}

/*
 * This function routes the TX packet to the correct interface. This may be a local device
 * or the physical port.
 */
static __rte_always_inline void
virtio_tx_route(struct virtio_net* dev, struct rte_mbuf *m, struct rte_mempool *mbuf_pool, uint16_t vlan_tag)
{
        struct mbuf_table *tx_q;
        struct vlan_ethhdr *vlan_hdr;
        struct rte_mbuf **m_table;
        struct rte_mbuf *mbuf;
        unsigned len, ret;
        const uint16_t lcore_id = rte_lcore_id();

        /*check if destination is local VM*/
        if (enable_vm2vm && (virtio_tx_local(dev, m) == 0)) {
                return;
        }

        RTE_LOG_DP(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;

        /* Allocate an mbuf and populate the structure. */
        mbuf = rte_pktmbuf_alloc(mbuf_pool);
        if(!mbuf)
                return;

        mbuf->data_len = m->data_len + VLAN_HLEN;
        mbuf->pkt_len = mbuf->data_len;

        /* Copy ethernet header to mbuf. */
        rte_memcpy(rte_pktmbuf_mtod(mbuf, void*),
                        rte_pktmbuf_mtod(m, const void*), ETH_HLEN);


        /* Setup vlan header. Bytes need to be re-ordered for network with htons()*/
        vlan_hdr = rte_pktmbuf_mtod(mbuf, struct vlan_ethhdr *);
        vlan_hdr->h_vlan_encapsulated_proto = vlan_hdr->h_vlan_proto;
        vlan_hdr->h_vlan_proto = htons(ETH_P_8021Q);
        vlan_hdr->h_vlan_TCI = htons(vlan_tag);

        /* Copy the remaining packet contents to the mbuf. */
        rte_memcpy(rte_pktmbuf_mtod_offset(mbuf, void *, VLAN_ETH_HLEN),
                rte_pktmbuf_mtod_offset(m, const void *, ETH_HLEN),
                (m->data_len - ETH_HLEN));
        tx_q->m_table[len] = mbuf;
        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;
}

static __rte_always_inline void
virtio_dev_tx(struct virtio_net* dev, struct rte_mempool *mbuf_pool)
{
        struct rte_mbuf m;
        struct vhost_virtqueue *vq;
        struct vring_desc *desc;
        uint64_t buff_addr = 0;
        uint32_t head[MAX_PKT_BURST];
        uint32_t used_idx;
        uint32_t i;
        uint16_t free_entries, packet_success = 0;
        uint16_t avail_idx;

        vq = dev->virtqueue_tx;
        avail_idx = *((volatile uint16_t *)&vq->avail->idx);

        /* If there are no available buffers then return. */
        if (vq->last_used_idx == avail_idx)
                return;

        RTE_LOG_DP(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 & (vq->size - 1)]);

        /*get the number of free entries in the ring*/
        free_entries = avail_idx - vq->last_used_idx;
        free_entries = unlikely(free_entries < MAX_PKT_BURST) ? free_entries : MAX_PKT_BURST;

        RTE_LOG_DP(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 + i) & (vq->size - 1)];

        /* Prefetch descriptor index. */
        rte_prefetch0(&vq->desc[head[packet_success]]);

        while (packet_success < free_entries) {
                desc = &vq->desc[head[packet_success]];
                /* Prefetch descriptor address. */
                rte_prefetch0(desc);

                if (packet_success < (free_entries - 1)) {
                        /* Prefetch descriptor index. */
                        rte_prefetch0(&vq->desc[head[packet_success+1]]);
                }

                /* Update used index buffer information. */
                used_idx = vq->last_used_idx & (vq->size - 1);
                vq->used->ring[used_idx].id = head[packet_success];
                vq->used->ring[used_idx].len = 0;

                /* 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);
                /* 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.data_off = 0;
                m.nb_segs = 1;

                virtio_tx_route(dev, &m, mbuf_pool, 0);

                vq->last_used_idx++;
                packet_success++;
        }

        rte_compiler_barrier();
        vq->used->idx += packet_success;
        /* Kick guest if required. */
}

/*
 * 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 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;

        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) {
                                RTE_LOG_DP(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;

                }

                /*
                 * 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*/
                        dev = dev_ll->dev;

                        if (unlikely(dev->remove)) {
                                dev_ll = dev_ll->next;
                                unlink_vmdq(dev);
                                dev->ready = DEVICE_SAFE_REMOVE;
                                continue;
                        }
                        if (likely(dev->ready == DEVICE_READY)) {
                                /*Handle guest RX*/
                                rx_count = rte_eth_rx_burst(ports[0],
                                        (uint16_t)dev->vmdq_rx_q, pkts_burst, MAX_PKT_BURST);

                                if (rx_count) {
                                        ret_count = virtio_dev_rx(dev, pkts_burst, rx_count);
                                        if (enable_stats) {
                                                rte_atomic64_add(&dev_statistics[dev_ll->dev->device_fh].rx_total, rx_count);
                                                rte_atomic64_add(&dev_statistics[dev_ll->dev->device_fh].rx, ret_count);
                                        }
                                        while (likely(rx_count)) {
                                                rx_count--;
                                                rte_pktmbuf_free_seg(pkts_burst[rx_count]);
                                        }

                                }
                        }

                        if (likely(!dev->remove))
                                /*Handle guest TX*/
                                virtio_dev_tx(dev, mbuf_pool);

                        /*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 (ll_dev == ll)
                *ll_root_addr = ll_dev->next;
        else
                ll_dev_last->next = ll_dev->next;
}

/*
 * 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;

        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].dev = 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. The
 * rx/tx thread must be set the flag to indicate that it is safe to remove the device.
 * used.
 */
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;
        int lcore;

        dev->flags &= ~VIRTIO_DEV_RUNNING;

        /*set the remove flag. */
        dev->remove = 1;

        while(dev->ready != DEVICE_SAFE_REMOVE) {
                rte_pause();
        }

        /* Search for entry to be removed from lcore ll */
        ll_lcore_dev_cur = lcore_info[dev->coreid].lcore_ll->ll_root_used;
        while (ll_lcore_dev_cur != NULL) {
                if (ll_lcore_dev_cur->dev == dev) {
                        break;
                } else {
                        ll_lcore_dev_last = ll_lcore_dev_cur;
                        ll_lcore_dev_cur = ll_lcore_dev_cur->next;
                }
        }

        /* 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->dev == dev) {
                        break;
                } else {
                        ll_main_dev_last = ll_main_dev_cur;
                        ll_main_dev_cur = ll_main_dev_cur->next;
                }
        }

        if (ll_lcore_dev_cur == NULL || ll_main_dev_cur == NULL) {
                RTE_LOG(ERR, XENHOST, "%s: could find device in per_cpu list or main_list\n", __func__);
                return;
        }

        /* Remove entries from the lcore and main ll. */
        rm_data_ll_entry(&lcore_info[ll_lcore_dev_cur->dev->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[ll_lcore_dev_cur->dev->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[ll_lcore_dev_cur->dev->coreid].lcore_ll->device_num--;

        RTE_LOG(INFO, VHOST_DATA, "  #####(%"PRIu64") Device has been removed from data core\n", dev->device_fh);
}

/*
 * 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;

        /* 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);
                return -1;
        }
        ll_dev->dev = dev;
        add_data_ll_entry(&ll_root_used, ll_dev);

        /*reset ready flag*/
        dev->ready = DEVICE_NOT_READY;
        dev->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->dev->coreid = core_add;
        ll_dev = get_data_ll_free_entry(&lcore_info[ll_dev->dev->coreid].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);
                destroy_device(dev);
                return -1;
        }
        ll_dev->dev = dev;
        add_data_ll_entry(&lcore_info[ll_dev->dev->coreid].lcore_ll->ll_root_used, ll_dev);

        /* Initialize device stats */
        memset(&dev_statistics[dev->device_fh], 0, sizeof(struct device_statistics));

        lcore_info[ll_dev->dev->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, dev->coreid);

        link_vmdq(dev);

        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->dev->device_fh;
                        tx_total = dev_statistics[device_fh].tx_total;
                        tx = dev_statistics[device_fh].tx;
                        tx_dropped = tx_total - tx;
                        rx_total = rte_atomic64_read(&dev_statistics[device_fh].rx_total);
                        rx = rte_atomic64_read(&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");
        }
}


int init_virtio_net(struct virtio_net_device_ops const * const ops);

/*
 * Main function, does initialisation and calls the per-lcore functions.
 */
int
main(int argc, char *argv[])
{
        struct rte_mempool *mbuf_pool;
        unsigned lcore_id, core_id = 0;
        unsigned nb_ports, valid_num_ports;
        int ret;
        uint8_t portid;
        static pthread_t tid;
        char thread_name[RTE_MAX_THREAD_NAME_LEN];

        /* 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();

        /*
         * 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;
        }

        /* Create the mbuf pool. */
        mbuf_pool = rte_pktmbuf_pool_create("MBUF_POOL",
                NUM_MBUFS_PER_PORT * valid_num_ports, MBUF_CACHE_SIZE, 0,
                RTE_MBUF_DEFAULT_BUF_SIZE, rte_socket_id());
        if (mbuf_pool == NULL)
                rte_exit(EXIT_FAILURE, "Cannot create mbuf pool\n");

        /* 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, mbuf_pool) != 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-xen-stats");
                ret = rte_thread_setname(tid, thread_name);
                if (ret != 0)
                        RTE_LOG(DEBUG, VHOST_CONFIG,
                                "Cannot set print-stats name\n");
        }

        /* Launch all data cores. */
        RTE_LCORE_FOREACH_SLAVE(lcore_id) {
                rte_eal_remote_launch(switch_worker, mbuf_pool, lcore_id);
        }

        init_virtio_xen(&virtio_net_device_ops);

        virtio_monitor_loop();
        return 0;
}