Imported Upstream version 16.04
[deb_dpdk.git] / examples / vhost_xen / main.c
diff --git a/examples/vhost_xen/main.c b/examples/vhost_xen/main.c
new file mode 100644 (file)
index 0000000..d83138d
--- /dev/null
@@ -0,0 +1,1530 @@
+/*-
+ *   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 "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   = 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 */
+
+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();
+       const uint16_t rx_ring_size = RTE_TEST_RX_DESC_DEFAULT, 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;
+
+       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;
+}
+
+/*
+ * 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 virtual addresses. This
+ * is used to convert virtio buffer addresses.
+ */
+static inline uint64_t __attribute__((always_inline))
+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;
+               }
+       }
+       LOG_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 succesfully
+ * added to the RX queue.
+ */
+static inline uint32_t __attribute__((always_inline))
+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;
+
+       LOG_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;
+       LOG_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 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 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 inline unsigned __attribute__((always_inline))
+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) {
+                               LOG_DEBUG(VHOST_DATA, "(%"PRIu64") TX: Source and destination MAC addresses are the same. Dropping packet.\n",
+                                                       dev_ll->dev->device_fh);
+                               return 0;
+                       }
+
+
+                       LOG_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*/
+                               LOG_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 inline void __attribute__((always_inline))
+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;
+       }
+
+       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;
+
+       /* 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 inline void __attribute__((always_inline))
+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;
+
+       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 & (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;
+
+       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 + 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) {
+                               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;
+
+               }
+
+               /*
+                * 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. The CUSE
+ * device is also registered here to handle the IOCTLs.
+ */
+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();
+       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;
+       }
+
+       /* 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");
+
+       /* 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, 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(ERR, 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;
+}