examples/vhost: zero copy mode
[dpdk.git] / examples / vhost / main.c
index b86d57d..e911111 100644 (file)
@@ -48,6 +48,7 @@
 #include <rte_ethdev.h>
 #include <rte_log.h>
 #include <rte_string_fns.h>
+#include <rte_malloc.h>
 
 #include "main.h"
 #include "virtio-net.h"
 #define MBUF_CACHE_SIZE 128 
 #define MBUF_SIZE (2048 + sizeof(struct rte_mbuf) + RTE_PKTMBUF_HEADROOM)
 
+/*
+ * No frame data buffer allocated from host are required for zero copy
+ * implementation, guest will allocate the frame data buffer, and vhost
+ * directly use it.
+ */
+#define VIRTIO_DESCRIPTOR_LEN_ZCP 1518
+#define MBUF_SIZE_ZCP (VIRTIO_DESCRIPTOR_LEN_ZCP + sizeof(struct rte_mbuf) \
+       + RTE_PKTMBUF_HEADROOM)
+#define MBUF_CACHE_SIZE_ZCP 0
+
 /*
  * RX and TX Prefetch, Host, and Write-back threshold values should be
  * carefully set for optimal performance. Consult the network
 #define RTE_TEST_RX_DESC_DEFAULT 1024 
 #define RTE_TEST_TX_DESC_DEFAULT 512
 
+/*
+ * Need refine these 2 macros for legacy and DPDK based front end:
+ * Max vring avail descriptor/entries from guest - MAX_PKT_BURST
+ * And then adjust power 2.
+ */
+/*
+ * For legacy front end, 128 descriptors,
+ * half for virtio header, another half for mbuf.
+ */
+#define RTE_TEST_RX_DESC_DEFAULT_ZCP 32   /* legacy: 32, DPDK virt FE: 128. */
+#define RTE_TEST_TX_DESC_DEFAULT_ZCP 64   /* legacy: 64, DPDK virt FE: 64.  */
+
+/* Get first 4 bytes in mbuf headroom. */
+#define MBUF_HEADROOM_UINT32(mbuf) (*(uint32_t *)((uint8_t *)(mbuf) \
+               + sizeof(struct rte_mbuf)))
+
+/* true if x is a power of 2 */
+#define POWEROF2(x) ((((x)-1) & (x)) == 0)
+
 #define INVALID_PORT_ID 0xFF
 
 /* Max number of devices. Limited by vmdq. */
@@ -138,8 +168,42 @@ static uint32_t num_switching_cores = 0;
 static uint32_t num_queues = 0;
 uint32_t num_devices = 0;
 
+/*
+ * Enable zero copy, pkts buffer will directly dma to hw descriptor,
+ * disabled on default.
+ */
+static uint32_t zero_copy;
+
+/* number of descriptors to apply*/
+static uint32_t num_rx_descriptor = RTE_TEST_RX_DESC_DEFAULT_ZCP;
+static uint32_t num_tx_descriptor = RTE_TEST_TX_DESC_DEFAULT_ZCP;
+
+/* max ring descriptor, ixgbe, i40e, e1000 all are 4096. */
+#define MAX_RING_DESC 4096
+
+struct vpool {
+       struct rte_mempool *pool;
+       struct rte_ring *ring;
+       uint32_t buf_size;
+} vpool_array[MAX_QUEUES+MAX_QUEUES];
+
 /* Enable VM2VM communications. If this is disabled then the MAC address compare is skipped. */
-static uint32_t enable_vm2vm = 1;
+typedef enum {
+       VM2VM_DISABLED = 0,
+       VM2VM_SOFTWARE = 1,
+       VM2VM_HARDWARE = 2,
+       VM2VM_LAST
+} vm2vm_type;
+static vm2vm_type vm2vm_mode = VM2VM_SOFTWARE;
+
+/* The type of host physical address translated from guest physical address. */
+typedef enum {
+       PHYS_ADDR_CONTINUOUS = 0,
+       PHYS_ADDR_CROSS_SUBREG = 1,
+       PHYS_ADDR_INVALID = 2,
+       PHYS_ADDR_LAST
+} hpa_type;
+
 /* Enable stats. */
 static uint32_t enable_stats = 0;
 /* Enable retries on RX. */
@@ -159,7 +223,7 @@ static uint32_t dev_index = 0;
 extern uint64_t VHOST_FEATURES;
 
 /* Default configuration for rx and tx thresholds etc. */
-static const struct rte_eth_rxconf rx_conf_default = {
+static struct rte_eth_rxconf rx_conf_default = {
        .rx_thresh = {
                .pthresh = RX_PTHRESH,
                .hthresh = RX_HTHRESH,
@@ -173,7 +237,7 @@ static const struct rte_eth_rxconf rx_conf_default = {
  * Controller and the DPDK ixgbe/igb PMD. Consider using other values for other
  * network controllers and/or network drivers.
  */
-static const struct rte_eth_txconf tx_conf_default = {
+static struct rte_eth_txconf tx_conf_default = {
        .tx_thresh = {
                .pthresh = TX_PTHRESH,
                .hthresh = TX_HTHRESH,
@@ -184,7 +248,7 @@ static const struct rte_eth_txconf tx_conf_default = {
 };
 
 /* empty vmdq configuration structure. Filled in programatically */
-static const struct rte_eth_conf vmdq_conf_default = {
+static struct rte_eth_conf vmdq_conf_default = {
        .rxmode = {
                .mq_mode        = ETH_MQ_RX_VMDQ_ONLY,
                .split_hdr_size = 0,
@@ -223,6 +287,7 @@ static unsigned lcore_ids[RTE_MAX_LCORE];
 static uint8_t ports[RTE_MAX_ETHPORTS];
 static unsigned num_ports = 0; /**< The number of ports specified in command line */
 
+static const uint16_t external_pkt_default_vlan_tag = 2000;
 const uint16_t vlan_tags[] = {
        1000, 1001, 1002, 1003, 1004, 1005, 1006, 1007,
        1008, 1009, 1010, 1011, 1012, 1013, 1014, 1015,
@@ -254,6 +319,9 @@ struct mbuf_table {
 /* TX queue for each data core. */
 struct mbuf_table lcore_tx_queue[RTE_MAX_LCORE];
 
+/* TX queue fori each virtio device for zero copy. */
+struct mbuf_table tx_queue_zcp[MAX_QUEUES];
+
 /* Vlan header struct used to insert vlan tags on TX. */
 struct vlan_ethhdr {
        unsigned char   h_dest[ETH_ALEN];
@@ -263,6 +331,20 @@ struct vlan_ethhdr {
        __be16          h_vlan_encapsulated_proto;
 };
 
+/* IPv4 Header */
+struct ipv4_hdr {
+       uint8_t  version_ihl;           /**< version and header length */
+       uint8_t  type_of_service;       /**< type of service */
+       uint16_t total_length;          /**< length of packet */
+       uint16_t packet_id;             /**< packet ID */
+       uint16_t fragment_offset;       /**< fragmentation offset */
+       uint8_t  time_to_live;          /**< time to live */
+       uint8_t  next_proto_id;         /**< protocol ID */
+       uint16_t hdr_checksum;          /**< header checksum */
+       uint32_t src_addr;              /**< source address */
+       uint32_t dst_addr;              /**< destination address */
+} __attribute__((__packed__));
+
 /* Header lengths. */
 #define VLAN_HLEN       4
 #define VLAN_ETH_HLEN   18
@@ -270,9 +352,11 @@ struct vlan_ethhdr {
 /* Per-device statistics struct */
 struct device_statistics {
        uint64_t tx_total;
-       rte_atomic64_t rx_total;
+       rte_atomic64_t rx_total_atomic;
+       uint64_t rx_total;
        uint64_t tx;
-       rte_atomic64_t rx;
+       rte_atomic64_t rx_atomic;
+       uint64_t rx;
 } __rte_cache_aligned;
 struct device_statistics dev_statistics[MAX_DEVICES];
 
@@ -289,6 +373,8 @@ get_eth_conf(struct rte_eth_conf *eth_conf, uint32_t num_devices)
        memset(&conf, 0, sizeof(conf));
        conf.nb_queue_pools = (enum rte_eth_nb_pools)num_devices;
        conf.nb_pool_maps = num_devices;
+       conf.enable_loop_back =
+               vmdq_conf_default.rx_adv_conf.vmdq_rx_conf.enable_loop_back;
 
        for (i = 0; i < conf.nb_pool_maps; i++) {
                conf.pool_map[i].vlan_id = vlan_tags[ i ];
@@ -302,9 +388,9 @@ get_eth_conf(struct rte_eth_conf *eth_conf, uint32_t num_devices)
 }
 
 /*
- * 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.
+ * 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)
@@ -321,12 +407,12 @@ validate_num_devices(uint32_t max_nb_devices)
  * coming from the mbuf_pool passed as parameter
  */
 static inline int
-port_init(uint8_t port, struct rte_mempool *mbuf_pool)
+port_init(uint8_t port)
 {
        struct rte_eth_dev_info dev_info;
        struct rte_eth_conf port_conf;
-       uint16_t rx_rings, tx_rings = (uint16_t)rte_lcore_count();
-       const uint16_t rx_ring_size = RTE_TEST_RX_DESC_DEFAULT, tx_ring_size = RTE_TEST_TX_DESC_DEFAULT;
+       uint16_t rx_rings, tx_rings;
+       uint16_t rx_ring_size, tx_ring_size;
        int retval;
        uint16_t q;
 
@@ -337,6 +423,16 @@ port_init(uint8_t port, struct rte_mempool *mbuf_pool)
        num_devices = dev_info.max_vmdq_pools;
        num_queues = dev_info.max_rx_queues;
 
+       if (zero_copy) {
+               rx_ring_size = num_rx_descriptor;
+               tx_ring_size = num_tx_descriptor;
+               tx_rings = dev_info.max_tx_queues;
+       } else {
+               rx_ring_size = RTE_TEST_RX_DESC_DEFAULT;
+               tx_ring_size = RTE_TEST_TX_DESC_DEFAULT;
+               tx_rings = (uint16_t)rte_lcore_count();
+       }
+
        retval = validate_num_devices(MAX_DEVICES);
        if (retval < 0)
                return retval;
@@ -358,7 +454,7 @@ port_init(uint8_t port, struct rte_mempool *mbuf_pool)
        for (q = 0; q < rx_rings; q ++) {
                retval = rte_eth_rx_queue_setup(port, q, rx_ring_size,
                                                rte_eth_dev_socket_id(port), &rx_conf_default,
-                                               mbuf_pool);
+                                               vpool_array[q].pool);
                if (retval < 0)
                        return retval;
        }
@@ -371,8 +467,10 @@ port_init(uint8_t port, struct rte_mempool *mbuf_pool)
 
        /* Start the device. */
        retval  = rte_eth_dev_start(port);
-       if (retval < 0)
+       if (retval < 0) {
+               RTE_LOG(ERR, DATA, "Failed to start the device.\n");
                return retval;
+       }
 
        rte_eth_macaddr_get(port, &vmdq_ports_eth_addr[port]);
        RTE_LOG(INFO, PORT, "Max virtio devices supported: %u\n", num_devices);
@@ -457,16 +555,26 @@ parse_num_opt(const char *q_arg, uint32_t max_valid_value)
 static void
 us_vhost_usage(const char *prgname)
 {
-       RTE_LOG(INFO, CONFIG, "%s [EAL options] -- -p PORTMASK --vm2vm [0|1] --rx_retry [0|1] --mergeable [0|1] --stats [0-N] --dev-basename <name> --dev-index [0-N] --nb-devices ND\n"
+       RTE_LOG(INFO, CONFIG, "%s [EAL options] -- -p PORTMASK\n"
+       "               --vm2vm [0|1|2]\n"
+       "               --rx_retry [0|1] --mergeable [0|1] --stats [0-N]\n"
+       "               --dev-basename <name> --dev-index [0-N]\n"
+       "               --nb-devices ND\n"
        "               -p PORTMASK: Set mask for ports to be used by application\n"
-       "               --vm2vm [0|1]: disable/enable(default) vm2vm comms\n"
+       "               --vm2vm [0|1|2]: disable/software(default)/hardware vm2vm comms\n"
        "               --rx-retry [0|1]: disable/enable(default) retries on rx. Enable retry if destintation queue is full\n"
        "               --rx-retry-delay [0-N]: timeout(in usecond) between retries on RX. This makes effect only if retries on rx enabled\n"
        "               --rx-retry-num [0-N]: the number of retries on rx. This makes effect only if retries on rx enabled\n"
        "               --mergeable [0|1]: disable(default)/enable RX mergeable buffers\n"
        "               --stats [0-N]: 0: Disable stats, N: Time in seconds to print stats\n"
        "               --dev-basename: The basename to be used for the character device.\n"
-       "               --dev-index [0-N]: Defaults to zero if not used. Index is appended to basename.\n",
+       "               --dev-index [0-N]: Defaults to zero if not used. Index is appended to basename.\n"
+       "               --zero-copy [0|1]: disable(default)/enable rx/tx "
+                       "zero copy\n"
+       "               --rx-desc-num [0-N]: the number of descriptors on rx, "
+                       "used only when zero copy is enabled.\n"
+       "               --tx-desc-num [0-N]: the number of descriptors on tx, "
+                       "used only when zero copy is enabled.\n",
               prgname);
 }
 
@@ -489,7 +597,10 @@ us_vhost_parse_args(int argc, char **argv)
                {"stats", required_argument, NULL, 0},
                {"dev-basename", required_argument, NULL, 0},
                {"dev-index", required_argument, NULL, 0},
-               {NULL, 0, 0, 0}
+               {"zero-copy", required_argument, NULL, 0},
+               {"rx-desc-num", required_argument, NULL, 0},
+               {"tx-desc-num", required_argument, NULL, 0},
+               {NULL, 0, 0, 0},
        };
 
        /* Parse command line */
@@ -507,14 +618,17 @@ us_vhost_parse_args(int argc, char **argv)
 
                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 (!strncmp(long_option[option_index].name, "vm2vm",
+                               MAX_LONG_OPT_SZ)) {
+                               ret = parse_num_opt(optarg, (VM2VM_LAST - 1));
                                if (ret == -1) {
-                                       RTE_LOG(INFO, CONFIG, "Invalid argument for vm2vm [0|1]\n");
+                                       RTE_LOG(INFO, CONFIG,
+                                               "Invalid argument for "
+                                               "vm2vm [0|1|2]\n");
                                        us_vhost_usage(prgname);
                                        return -1;
                                } else {
-                                       enable_vm2vm = ret;
+                                       vm2vm_mode = (vm2vm_type)ret;
                                }
                        }
 
@@ -595,8 +709,64 @@ us_vhost_parse_args(int argc, char **argv)
                                        RTE_LOG(INFO, CONFIG, "Invalid argument for character device index [0..N]\n");
                                        us_vhost_usage(prgname);
                                        return -1;
-                               } else {
+                               } else
                                        dev_index = ret;
+                       }
+
+                       /* Enable/disable rx/tx zero copy. */
+                       if (!strncmp(long_option[option_index].name,
+                               "zero-copy", MAX_LONG_OPT_SZ)) {
+                               ret = parse_num_opt(optarg, 1);
+                               if (ret == -1) {
+                                       RTE_LOG(INFO, CONFIG,
+                                               "Invalid argument"
+                                               " for zero-copy [0|1]\n");
+                                       us_vhost_usage(prgname);
+                                       return -1;
+                               } else
+                                       zero_copy = ret;
+
+                               if (zero_copy) {
+#ifdef RTE_MBUF_SCATTER_GATHER
+                                       RTE_LOG(ERR, CONFIG, "Before running "
+                                       "zero copy vhost APP, please "
+                                       "disable RTE_MBUF_SCATTER_GATHER\n"
+                                       "in config file and then rebuild DPDK "
+                                       "core lib!\n"
+                                       "Otherwise please disable zero copy "
+                                       "flag in command line!\n");
+                                       return -1;
+#endif
+                               }
+                       }
+
+                       /* Specify the descriptor number on RX. */
+                       if (!strncmp(long_option[option_index].name,
+                               "rx-desc-num", MAX_LONG_OPT_SZ)) {
+                               ret = parse_num_opt(optarg, MAX_RING_DESC);
+                               if ((ret == -1) || (!POWEROF2(ret))) {
+                                       RTE_LOG(INFO, CONFIG,
+                                       "Invalid argument for rx-desc-num[0-N],"
+                                       "power of 2 required.\n");
+                                       us_vhost_usage(prgname);
+                                       return -1;
+                               } else {
+                                       num_rx_descriptor = ret;
+                               }
+                       }
+
+                       /* Specify the descriptor number on TX. */
+                       if (!strncmp(long_option[option_index].name,
+                               "tx-desc-num", MAX_LONG_OPT_SZ)) {
+                               ret = parse_num_opt(optarg, MAX_RING_DESC);
+                               if ((ret == -1) || (!POWEROF2(ret))) {
+                                       RTE_LOG(INFO, CONFIG,
+                                       "Invalid argument for tx-desc-num [0-N],"
+                                       "power of 2 required.\n");
+                                       us_vhost_usage(prgname);
+                                       return -1;
+                               } else {
+                                       num_tx_descriptor = ret;
                                }
                        }
 
@@ -620,6 +790,13 @@ us_vhost_parse_args(int argc, char **argv)
                return -1;
        }
 
+       if ((zero_copy == 1) && (vm2vm_mode == VM2VM_SOFTWARE)) {
+               RTE_LOG(INFO, PORT,
+                       "Vhost zero copy doesn't support software vm2vm,"
+                       "please specify 'vm2vm 2' to use hardware vm2vm.\n");
+               return -1;
+       }
+
        return 0;
 }
 
@@ -700,6 +877,41 @@ gpa_to_vva(struct virtio_net *dev, uint64_t guest_pa)
        return vhost_va;
 }
 
+/*
+ * Function to convert guest physical addresses to vhost physical addresses.
+ * This is used to convert virtio buffer addresses.
+ */
+static inline uint64_t __attribute__((always_inline))
+gpa_to_hpa(struct virtio_net *dev, uint64_t guest_pa,
+       uint32_t buf_len, hpa_type *addr_type)
+{
+       struct virtio_memory_regions_hpa *region;
+       uint32_t regionidx;
+       uint64_t vhost_pa = 0;
+
+       *addr_type = PHYS_ADDR_INVALID;
+
+       for (regionidx = 0; regionidx < dev->mem->nregions_hpa; regionidx++) {
+               region = &dev->mem->regions_hpa[regionidx];
+               if ((guest_pa >= region->guest_phys_address) &&
+                       (guest_pa <= region->guest_phys_address_end)) {
+                       vhost_pa = region->host_phys_addr_offset + guest_pa;
+                       if (likely((guest_pa + buf_len - 1)
+                               <= region->guest_phys_address_end))
+                               *addr_type = PHYS_ADDR_CONTINUOUS;
+                       else
+                               *addr_type = PHYS_ADDR_CROSS_SUBREG;
+                       break;
+               }
+       }
+
+       LOG_DEBUG(DATA, "(%"PRIu64") GPA %p| HPA %p\n",
+               dev->device_fh, (void *)(uintptr_t)guest_pa,
+               (void *)(uintptr_t)vhost_pa);
+
+       return vhost_pa;
+}
+
 /*
  * 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
@@ -894,7 +1106,6 @@ link_vmdq(struct virtio_net *dev, struct rte_mbuf *m)
 
        /* 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, DATA, "(%"PRIu64") MAC_ADDRESS %02x:%02x:%02x:%02x:%02x:%02x and VLAN_TAG %d registered\n",
@@ -991,8 +1202,12 @@ virtio_tx_local(struct virtio_net *dev, struct rte_mbuf *m)
                                /*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);
+                                       rte_atomic64_add(
+                                       &dev_statistics[dev_ll->dev->device_fh].rx_total_atomic,
+                                       1);
+                                       rte_atomic64_add(
+                                       &dev_statistics[dev_ll->dev->device_fh].rx_atomic,
+                                       ret);
                                        dev_statistics[dev->device_fh].tx_total++;
                                        dev_statistics[dev->device_fh].tx += ret;
                                }
@@ -1017,12 +1232,47 @@ virtio_tx_route(struct virtio_net* dev, struct rte_mbuf *m, struct rte_mempool *
        struct vlan_ethhdr *vlan_hdr;
        struct rte_mbuf **m_table;
        struct rte_mbuf *mbuf;
-       unsigned len, ret;
+       unsigned len, ret, offset = 0;
        const uint16_t lcore_id = rte_lcore_id();
+       struct virtio_net_data_ll *dev_ll = ll_root_used;
+       struct ether_hdr *pkt_hdr = (struct ether_hdr *)m->pkt.data;
 
        /*check if destination is local VM*/
-       if (enable_vm2vm && (virtio_tx_local(dev, m) == 0)) {
+       if ((vm2vm_mode == VM2VM_SOFTWARE) && (virtio_tx_local(dev, m) == 0))
                return;
+
+       if (vm2vm_mode == VM2VM_HARDWARE) {
+               while (dev_ll != NULL) {
+                       if ((dev_ll->dev->ready == DEVICE_RX)
+                               && 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(DATA,
+                                       "(%"PRIu64") TX: Source and destination"
+                                       " MAC addresses are the same. Dropping "
+                                       "packet.\n",
+                                       dev_ll->dev->device_fh);
+                                       return;
+                               }
+                               offset = 4;
+                               vlan_tag =
+                               (uint16_t)
+                               vlan_tags[(uint16_t)dev_ll->dev->device_fh];
+
+                               LOG_DEBUG(DATA,
+                               "(%"PRIu64") TX: pkt to local VM device id:"
+                               "(%"PRIu64") vlan tag: %d.\n",
+                               dev->device_fh, dev_ll->dev->device_fh,
+                               vlan_tag);
+
+                               break;
+                       }
+                       dev_ll = dev_ll->next;
+               }
        }
 
        LOG_DEBUG(DATA, "(%"PRIu64") TX: MAC address is external\n", dev->device_fh);
@@ -1038,7 +1288,7 @@ virtio_tx_route(struct virtio_net* dev, struct rte_mbuf *m, struct rte_mempool *
                return;
        }
 
-       mbuf->pkt.data_len = m->pkt.data_len + VLAN_HLEN;
+       mbuf->pkt.data_len = m->pkt.data_len + VLAN_HLEN + offset;
        mbuf->pkt.pkt_len = mbuf->pkt.data_len;
 
        /* Copy ethernet header to mbuf. */
@@ -1262,8 +1512,11 @@ switch_worker(__attribute__((unused)) void *arg)
                                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);
+                                               rte_atomic64_add(
+                                               &dev_statistics[dev_ll->dev->device_fh].rx_total_atomic,
+                                               rx_count);
+                                               rte_atomic64_add(
+                                               &dev_statistics[dev_ll->dev->device_fh].rx_atomic, ret_count);
                                        }
                                        while (likely(rx_count)) {
                                                rx_count--;
@@ -1286,11 +1539,866 @@ switch_worker(__attribute__((unused)) void *arg)
 }
 
 /*
- * 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();
+ * This function gets available ring number for zero copy rx.
+ * Only one thread will call this funciton for a paticular virtio device,
+ * so, it is designed as non-thread-safe function.
+ */
+static inline uint32_t __attribute__((always_inline))
+get_available_ring_num_zcp(struct virtio_net *dev)
+{
+       struct vhost_virtqueue *vq = dev->virtqueue[VIRTIO_RXQ];
+       uint16_t avail_idx;
+
+       avail_idx = *((volatile uint16_t *)&vq->avail->idx);
+       return (uint32_t)(avail_idx - vq->last_used_idx_res);
+}
+
+/*
+ * This function gets available ring index for zero copy rx,
+ * it will retry 'burst_rx_retry_num' times till it get enough ring index.
+ * Only one thread will call this funciton for a paticular virtio device,
+ * so, it is designed as non-thread-safe function.
+ */
+static inline uint32_t __attribute__((always_inline))
+get_available_ring_index_zcp(struct virtio_net *dev,
+       uint16_t *res_base_idx, uint32_t count)
+{
+       struct vhost_virtqueue *vq = dev->virtqueue[VIRTIO_RXQ];
+       uint16_t avail_idx;
+       uint32_t retry = 0;
+       uint16_t free_entries;
+
+       *res_base_idx = vq->last_used_idx_res;
+       avail_idx = *((volatile uint16_t *)&vq->avail->idx);
+       free_entries = (avail_idx - *res_base_idx);
+
+       LOG_DEBUG(DATA, "(%"PRIu64") in get_available_ring_index_zcp: "
+                       "avail idx: %d, "
+                       "res base idx:%d, free entries:%d\n",
+                       dev->device_fh, avail_idx, *res_base_idx,
+                       free_entries);
+
+       /*
+        * If retry is enabled and the queue is full then we wait
+        * and retry to avoid packet loss.
+        */
+       if (enable_retry && unlikely(count > free_entries)) {
+               for (retry = 0; retry < burst_rx_retry_num; retry++) {
+                       rte_delay_us(burst_rx_delay_time);
+                       avail_idx = *((volatile uint16_t *)&vq->avail->idx);
+                       free_entries = (avail_idx - *res_base_idx);
+                       if (count <= free_entries)
+                               break;
+               }
+       }
+
+       /*check that we have enough buffers*/
+       if (unlikely(count > free_entries))
+               count = free_entries;
+
+       if (unlikely(count == 0)) {
+               LOG_DEBUG(DATA,
+                       "(%"PRIu64") Fail in get_available_ring_index_zcp: "
+                       "avail idx: %d, res base idx:%d, free entries:%d\n",
+                       dev->device_fh, avail_idx,
+                       *res_base_idx, free_entries);
+               return 0;
+       }
+
+       vq->last_used_idx_res = *res_base_idx + count;
+
+       return count;
+}
+
+/*
+ * This function put descriptor back to used list.
+ */
+static inline void __attribute__((always_inline))
+put_desc_to_used_list_zcp(struct vhost_virtqueue *vq, uint16_t desc_idx)
+{
+       uint16_t res_cur_idx = vq->last_used_idx;
+       vq->used->ring[res_cur_idx & (vq->size - 1)].id = (uint32_t)desc_idx;
+       vq->used->ring[res_cur_idx & (vq->size - 1)].len = 0;
+       rte_compiler_barrier();
+       *(volatile uint16_t *)&vq->used->idx += 1;
+       vq->last_used_idx += 1;
+
+       /* Kick the guest if necessary. */
+       if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT))
+               eventfd_write((int)vq->kickfd, 1);
+}
+
+/*
+ * This function get available descriptor from vitio vring and un-attached mbuf
+ * from vpool->ring, and then attach them together. It needs adjust the offset
+ * for buff_addr and phys_addr accroding to PMD implementation, otherwise the
+ * frame data may be put to wrong location in mbuf.
+ */
+static inline void __attribute__((always_inline))
+attach_rxmbuf_zcp(struct virtio_net *dev)
+{
+       uint16_t res_base_idx, desc_idx;
+       uint64_t buff_addr, phys_addr;
+       struct vhost_virtqueue *vq;
+       struct vring_desc *desc;
+       struct rte_mbuf *mbuf = NULL;
+       struct vpool *vpool;
+       hpa_type addr_type;
+
+       vpool = &vpool_array[dev->vmdq_rx_q];
+       vq = dev->virtqueue[VIRTIO_RXQ];
+
+       do {
+               if (unlikely(get_available_ring_index_zcp(dev, &res_base_idx,
+                               1) != 1))
+                       return;
+               desc_idx = vq->avail->ring[(res_base_idx) & (vq->size - 1)];
+
+               desc = &vq->desc[desc_idx];
+               if (desc->flags & VRING_DESC_F_NEXT) {
+                       desc = &vq->desc[desc->next];
+                       buff_addr = gpa_to_vva(dev, desc->addr);
+                       phys_addr = gpa_to_hpa(dev, desc->addr, desc->len,
+                                       &addr_type);
+               } else {
+                       buff_addr = gpa_to_vva(dev,
+                                       desc->addr + vq->vhost_hlen);
+                       phys_addr = gpa_to_hpa(dev,
+                                       desc->addr + vq->vhost_hlen,
+                                       desc->len, &addr_type);
+               }
+
+               if (unlikely(addr_type == PHYS_ADDR_INVALID)) {
+                       RTE_LOG(ERR, DATA, "(%"PRIu64") Invalid frame buffer"
+                               " address found when attaching RX frame buffer"
+                               " address!\n", dev->device_fh);
+                       put_desc_to_used_list_zcp(vq, desc_idx);
+                       continue;
+               }
+
+               /*
+                * Check if the frame buffer address from guest crosses
+                * sub-region or not.
+                */
+               if (unlikely(addr_type == PHYS_ADDR_CROSS_SUBREG)) {
+                       RTE_LOG(ERR, DATA,
+                               "(%"PRIu64") Frame buffer address cross "
+                               "sub-regioin found when attaching RX frame "
+                               "buffer address!\n",
+                               dev->device_fh);
+                       put_desc_to_used_list_zcp(vq, desc_idx);
+                       continue;
+               }
+       } while (unlikely(phys_addr == 0));
+
+       rte_ring_sc_dequeue(vpool->ring, (void **)&mbuf);
+       if (unlikely(mbuf == NULL)) {
+               LOG_DEBUG(DATA,
+                       "(%"PRIu64") in attach_rxmbuf_zcp: "
+                       "ring_sc_dequeue fail.\n",
+                       dev->device_fh);
+               put_desc_to_used_list_zcp(vq, desc_idx);
+               return;
+       }
+
+       if (unlikely(vpool->buf_size > desc->len)) {
+               LOG_DEBUG(DATA,
+                       "(%"PRIu64") in attach_rxmbuf_zcp: frame buffer "
+                       "length(%d) of descriptor idx: %d less than room "
+                       "size required: %d\n",
+                       dev->device_fh, desc->len, desc_idx, vpool->buf_size);
+               put_desc_to_used_list_zcp(vq, desc_idx);
+               rte_ring_sp_enqueue(vpool->ring, (void *)mbuf);
+               return;
+       }
+
+       mbuf->buf_addr = (void *)(uintptr_t)(buff_addr - RTE_PKTMBUF_HEADROOM);
+       mbuf->pkt.data = (void *)(uintptr_t)(buff_addr);
+       mbuf->buf_physaddr = phys_addr - RTE_PKTMBUF_HEADROOM;
+       mbuf->pkt.data_len = desc->len;
+       MBUF_HEADROOM_UINT32(mbuf) = (uint32_t)desc_idx;
+
+       LOG_DEBUG(DATA,
+               "(%"PRIu64") in attach_rxmbuf_zcp: res base idx:%d, "
+               "descriptor idx:%d\n",
+               dev->device_fh, res_base_idx, desc_idx);
+
+       __rte_mbuf_raw_free(mbuf);
+
+       return;
+}
+
+/*
+ * Detach an attched packet mbuf -
+ *  - restore original mbuf address and length values.
+ *  - reset pktmbuf data and data_len to their default values.
+ *  All other fields of the given packet mbuf will be left intact.
+ *
+ * @param m
+ *   The attached packet mbuf.
+ */
+static inline void pktmbuf_detach_zcp(struct rte_mbuf *m)
+{
+       const struct rte_mempool *mp = m->pool;
+       void *buf = RTE_MBUF_TO_BADDR(m);
+       uint32_t buf_ofs;
+       uint32_t buf_len = mp->elt_size - sizeof(*m);
+       m->buf_physaddr = rte_mempool_virt2phy(mp, m) + sizeof(*m);
+
+       m->buf_addr = buf;
+       m->buf_len = (uint16_t)buf_len;
+
+       buf_ofs = (RTE_PKTMBUF_HEADROOM <= m->buf_len) ?
+                       RTE_PKTMBUF_HEADROOM : m->buf_len;
+       m->pkt.data = (char *) m->buf_addr + buf_ofs;
+
+       m->pkt.data_len = 0;
+}
+
+/*
+ * This function is called after packets have been transimited. It fetchs mbuf
+ * from vpool->pool, detached it and put into vpool->ring. It also update the
+ * used index and kick the guest if necessary.
+ */
+static inline uint32_t __attribute__((always_inline))
+txmbuf_clean_zcp(struct virtio_net *dev, struct vpool *vpool)
+{
+       struct rte_mbuf *mbuf;
+       struct vhost_virtqueue *vq = dev->virtqueue[VIRTIO_TXQ];
+       uint32_t used_idx = vq->last_used_idx & (vq->size - 1);
+       uint32_t index = 0;
+       uint32_t mbuf_count = rte_mempool_count(vpool->pool);
+
+       LOG_DEBUG(DATA,
+               "(%"PRIu64") in txmbuf_clean_zcp: mbuf count in mempool before "
+               "clean is: %d\n",
+               dev->device_fh, mbuf_count);
+       LOG_DEBUG(DATA,
+               "(%"PRIu64") in txmbuf_clean_zcp: mbuf count in  ring before "
+               "clean  is : %d\n",
+               dev->device_fh, rte_ring_count(vpool->ring));
+
+       for (index = 0; index < mbuf_count; index++) {
+               mbuf = __rte_mbuf_raw_alloc(vpool->pool);
+               if (likely(RTE_MBUF_INDIRECT(mbuf)))
+                       pktmbuf_detach_zcp(mbuf);
+               rte_ring_sp_enqueue(vpool->ring, mbuf);
+
+               /* Update used index buffer information. */
+               vq->used->ring[used_idx].id = MBUF_HEADROOM_UINT32(mbuf);
+               vq->used->ring[used_idx].len = 0;
+
+               used_idx = (used_idx + 1) & (vq->size - 1);
+       }
+
+       LOG_DEBUG(DATA,
+               "(%"PRIu64") in txmbuf_clean_zcp: mbuf count in mempool after "
+               "clean is: %d\n",
+               dev->device_fh, rte_mempool_count(vpool->pool));
+       LOG_DEBUG(DATA,
+               "(%"PRIu64") in txmbuf_clean_zcp: mbuf count in  ring after "
+               "clean  is : %d\n",
+               dev->device_fh, rte_ring_count(vpool->ring));
+       LOG_DEBUG(DATA,
+               "(%"PRIu64") in txmbuf_clean_zcp: before updated "
+               "vq->last_used_idx:%d\n",
+               dev->device_fh, vq->last_used_idx);
+
+       vq->last_used_idx += mbuf_count;
+
+       LOG_DEBUG(DATA,
+               "(%"PRIu64") in txmbuf_clean_zcp: after updated "
+               "vq->last_used_idx:%d\n",
+               dev->device_fh, vq->last_used_idx);
+
+       rte_compiler_barrier();
+
+       *(volatile uint16_t *)&vq->used->idx += mbuf_count;
+
+       /* Kick guest if required. */
+       if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT))
+               eventfd_write((int)vq->kickfd, 1);
+
+       return 0;
+}
+
+/*
+ * This function is called when a virtio device is destroy.
+ * It fetchs mbuf from vpool->pool, and detached it, and put into vpool->ring.
+ */
+static void mbuf_destroy_zcp(struct vpool *vpool)
+{
+       struct rte_mbuf *mbuf = NULL;
+       uint32_t index, mbuf_count = rte_mempool_count(vpool->pool);
+
+       LOG_DEBUG(CONFIG,
+               "in mbuf_destroy_zcp: mbuf count in mempool before "
+               "mbuf_destroy_zcp is: %d\n",
+               mbuf_count);
+       LOG_DEBUG(CONFIG,
+               "in mbuf_destroy_zcp: mbuf count in  ring before "
+               "mbuf_destroy_zcp  is : %d\n",
+               rte_ring_count(vpool->ring));
+
+       for (index = 0; index < mbuf_count; index++) {
+               mbuf = __rte_mbuf_raw_alloc(vpool->pool);
+               if (likely(mbuf != NULL)) {
+                       if (likely(RTE_MBUF_INDIRECT(mbuf)))
+                               pktmbuf_detach_zcp(mbuf);
+                       rte_ring_sp_enqueue(vpool->ring, (void *)mbuf);
+               }
+       }
+
+       LOG_DEBUG(CONFIG,
+               "in mbuf_destroy_zcp: mbuf count in mempool after "
+               "mbuf_destroy_zcp is: %d\n",
+               rte_mempool_count(vpool->pool));
+       LOG_DEBUG(CONFIG,
+               "in mbuf_destroy_zcp: mbuf count in ring after "
+               "mbuf_destroy_zcp is : %d\n",
+               rte_ring_count(vpool->ring));
+}
+
+/*
+ * This function update the use flag and counter.
+ */
+static inline uint32_t __attribute__((always_inline))
+virtio_dev_rx_zcp(struct virtio_net *dev, struct rte_mbuf **pkts,
+       uint32_t count)
+{
+       struct vhost_virtqueue *vq;
+       struct vring_desc *desc;
+       struct rte_mbuf *buff;
+       /* The virtio_hdr is initialised to 0. */
+       struct virtio_net_hdr_mrg_rxbuf virtio_hdr
+               = {{0, 0, 0, 0, 0, 0}, 0};
+       uint64_t buff_hdr_addr = 0;
+       uint32_t head[MAX_PKT_BURST], packet_len = 0;
+       uint32_t head_idx, packet_success = 0;
+       uint16_t res_cur_idx;
+
+       LOG_DEBUG(DATA, "(%"PRIu64") virtio_dev_rx()\n", dev->device_fh);
+
+       if (count == 0)
+               return 0;
+
+       vq = dev->virtqueue[VIRTIO_RXQ];
+       count = (count > MAX_PKT_BURST) ? MAX_PKT_BURST : count;
+
+       res_cur_idx = vq->last_used_idx;
+       LOG_DEBUG(DATA, "(%"PRIu64") Current Index %d| End Index %d\n",
+               dev->device_fh, res_cur_idx, res_cur_idx + count);
+
+       /* Retrieve all of the head indexes first to avoid caching issues. */
+       for (head_idx = 0; head_idx < count; head_idx++)
+               head[head_idx] = MBUF_HEADROOM_UINT32(pkts[head_idx]);
+
+       /*Prefetch descriptor index. */
+       rte_prefetch0(&vq->desc[head[packet_success]]);
+
+       while (packet_success != count) {
+               /* Get descriptor from available ring */
+               desc = &vq->desc[head[packet_success]];
+
+               buff = pkts[packet_success];
+               LOG_DEBUG(DATA,
+                       "(%"PRIu64") in dev_rx_zcp: update the used idx for "
+                       "pkt[%d] descriptor idx: %d\n",
+                       dev->device_fh, packet_success,
+                       MBUF_HEADROOM_UINT32(buff));
+
+               PRINT_PACKET(dev,
+                       (uintptr_t)(((uint64_t)(uintptr_t)buff->buf_addr)
+                       + RTE_PKTMBUF_HEADROOM),
+                       rte_pktmbuf_data_len(buff), 0);
+
+               /* Buffer address translation for virtio header. */
+               buff_hdr_addr = gpa_to_vva(dev, desc->addr);
+               packet_len = rte_pktmbuf_data_len(buff) + vq->vhost_hlen;
+
+               /*
+                * If the descriptors are chained the header and data are
+                * placed in separate buffers.
+                */
+               if (desc->flags & VRING_DESC_F_NEXT) {
+                       desc->len = vq->vhost_hlen;
+                       desc = &vq->desc[desc->next];
+                       desc->len = rte_pktmbuf_data_len(buff);
+               } else {
+                       desc->len = packet_len;
+               }
+
+               /* Update used ring with desc information */
+               vq->used->ring[res_cur_idx & (vq->size - 1)].id
+                       = head[packet_success];
+               vq->used->ring[res_cur_idx & (vq->size - 1)].len
+                       = packet_len;
+               res_cur_idx++;
+               packet_success++;
+
+               /* A header is required per buffer. */
+               rte_memcpy((void *)(uintptr_t)buff_hdr_addr,
+                       (const void *)&virtio_hdr, vq->vhost_hlen);
+
+               PRINT_PACKET(dev, (uintptr_t)buff_hdr_addr, vq->vhost_hlen, 1);
+
+               if (likely(packet_success < count)) {
+                       /* Prefetch descriptor index. */
+                       rte_prefetch0(&vq->desc[head[packet_success]]);
+               }
+       }
+
+       rte_compiler_barrier();
+
+       LOG_DEBUG(DATA,
+               "(%"PRIu64") in dev_rx_zcp: before update used idx: "
+               "vq.last_used_idx: %d, vq->used->idx: %d\n",
+               dev->device_fh, vq->last_used_idx, vq->used->idx);
+
+       *(volatile uint16_t *)&vq->used->idx += count;
+       vq->last_used_idx += count;
+
+       LOG_DEBUG(DATA,
+               "(%"PRIu64") in dev_rx_zcp: after  update used idx: "
+               "vq.last_used_idx: %d, vq->used->idx: %d\n",
+               dev->device_fh, vq->last_used_idx, vq->used->idx);
+
+       /* Kick the guest if necessary. */
+       if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT))
+               eventfd_write((int)vq->kickfd, 1);
+
+       return count;
+}
+
+/*
+ * This function routes the TX packet to the correct interface.
+ * This may be a local device or the physical port.
+ */
+static inline void __attribute__((always_inline))
+virtio_tx_route_zcp(struct virtio_net *dev, struct rte_mbuf *m,
+       uint32_t desc_idx, uint8_t need_copy)
+{
+       struct mbuf_table *tx_q;
+       struct rte_mbuf **m_table;
+       struct rte_mbuf *mbuf = NULL;
+       unsigned len, ret, offset = 0;
+       struct vpool *vpool;
+       struct virtio_net_data_ll *dev_ll = ll_root_used;
+       struct ether_hdr *pkt_hdr = (struct ether_hdr *)m->pkt.data;
+       uint16_t vlan_tag = (uint16_t)vlan_tags[(uint16_t)dev->device_fh];
+
+       /*Add packet to the port tx queue*/
+       tx_q = &tx_queue_zcp[(uint16_t)dev->vmdq_rx_q];
+       len = tx_q->len;
+
+       /* Allocate an mbuf and populate the structure. */
+       vpool = &vpool_array[MAX_QUEUES + (uint16_t)dev->vmdq_rx_q];
+       rte_ring_sc_dequeue(vpool->ring, (void **)&mbuf);
+       if (unlikely(mbuf == NULL)) {
+               struct vhost_virtqueue *vq = dev->virtqueue[VIRTIO_TXQ];
+               RTE_LOG(ERR, DATA,
+                       "(%"PRIu64") Failed to allocate memory for mbuf.\n",
+                       dev->device_fh);
+               put_desc_to_used_list_zcp(vq, desc_idx);
+               return;
+       }
+
+       if (vm2vm_mode == VM2VM_HARDWARE) {
+               /* Avoid using a vlan tag from any vm for external pkt, such as
+                * vlan_tags[dev->device_fh], oterwise, it conflicts when pool
+                * selection, MAC address determines it as an external pkt
+                * which should go to network, while vlan tag determine it as
+                * a vm2vm pkt should forward to another vm. Hardware confuse
+                * such a ambiguous situation, so pkt will lost.
+                */
+               vlan_tag = external_pkt_default_vlan_tag;
+               while (dev_ll != NULL) {
+                       if (likely(dev_ll->dev->ready == DEVICE_RX) &&
+                               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 (unlikely(dev_ll->dev->device_fh
+                                       == dev->device_fh)) {
+                                       LOG_DEBUG(DATA,
+                                       "(%"PRIu64") TX: Source and destination"
+                                       "MAC addresses are the same. Dropping "
+                                       "packet.\n",
+                                       dev_ll->dev->device_fh);
+                                       MBUF_HEADROOM_UINT32(mbuf)
+                                               = (uint32_t)desc_idx;
+                                       __rte_mbuf_raw_free(mbuf);
+                                       return;
+                               }
+
+                               /*
+                                * Packet length offset 4 bytes for HW vlan
+                                * strip when L2 switch back.
+                                */
+                               offset = 4;
+                               vlan_tag =
+                               (uint16_t)
+                               vlan_tags[(uint16_t)dev_ll->dev->device_fh];
+
+                               LOG_DEBUG(DATA,
+                               "(%"PRIu64") TX: pkt to local VM device id:"
+                               "(%"PRIu64") vlan tag: %d.\n",
+                               dev->device_fh, dev_ll->dev->device_fh,
+                               vlan_tag);
+
+                               break;
+                       }
+                       dev_ll = dev_ll->next;
+               }
+       }
+
+       mbuf->pkt.nb_segs = m->pkt.nb_segs;
+       mbuf->pkt.next = m->pkt.next;
+       mbuf->pkt.data_len = m->pkt.data_len + offset;
+       mbuf->pkt.pkt_len = mbuf->pkt.data_len;
+       if (unlikely(need_copy)) {
+               /* Copy the packet contents to the mbuf. */
+               rte_memcpy((void *)((uint8_t *)mbuf->pkt.data),
+                       (const void *) ((uint8_t *)m->pkt.data),
+                       m->pkt.data_len);
+       } else {
+               mbuf->pkt.data = m->pkt.data;
+               mbuf->buf_physaddr = m->buf_physaddr;
+               mbuf->buf_addr = m->buf_addr;
+       }
+       mbuf->ol_flags = PKT_TX_VLAN_PKT;
+       mbuf->pkt.vlan_macip.f.vlan_tci = vlan_tag;
+       mbuf->pkt.vlan_macip.f.l2_len = sizeof(struct ether_hdr);
+       mbuf->pkt.vlan_macip.f.l3_len = sizeof(struct ipv4_hdr);
+       MBUF_HEADROOM_UINT32(mbuf) = (uint32_t)desc_idx;
+
+       tx_q->m_table[len] = mbuf;
+       len++;
+
+       LOG_DEBUG(DATA,
+               "(%"PRIu64") in tx_route_zcp: pkt: nb_seg: %d, next:%s\n",
+               dev->device_fh,
+               mbuf->pkt.nb_segs,
+               (mbuf->pkt.next == NULL) ? "null" : "non-null");
+
+       if (enable_stats) {
+               dev_statistics[dev->device_fh].tx_total++;
+               dev_statistics[dev->device_fh].tx++;
+       }
+
+       if (unlikely(len == MAX_PKT_BURST)) {
+               m_table = (struct rte_mbuf **)tx_q->m_table;
+               ret = rte_eth_tx_burst(ports[0],
+                       (uint16_t)tx_q->txq_id, m_table, (uint16_t) len);
+
+               /*
+                * Free any buffers not handled by TX and update
+                * the port stats.
+                */
+               if (unlikely(ret < len)) {
+                       do {
+                               rte_pktmbuf_free(m_table[ret]);
+                       } while (++ret < len);
+               }
+
+               len = 0;
+               txmbuf_clean_zcp(dev, vpool);
+       }
+
+       tx_q->len = len;
+
+       return;
+}
+
+/*
+ * This function TX all available packets in virtio TX queue for one
+ * virtio-net device. If it is first packet, it learns MAC address and
+ * setup VMDQ.
+ */
+static inline void __attribute__((always_inline))
+virtio_dev_tx_zcp(struct virtio_net *dev)
+{
+       struct rte_mbuf m;
+       struct vhost_virtqueue *vq;
+       struct vring_desc *desc;
+       uint64_t buff_addr = 0, phys_addr;
+       uint32_t head[MAX_PKT_BURST];
+       uint32_t i;
+       uint16_t free_entries, packet_success = 0;
+       uint16_t avail_idx;
+       uint8_t need_copy = 0;
+       hpa_type addr_type;
+
+       vq = dev->virtqueue[VIRTIO_TXQ];
+       avail_idx =  *((volatile uint16_t *)&vq->avail->idx);
+
+       /* If there are no available buffers then return. */
+       if (vq->last_used_idx_res == avail_idx)
+               return;
+
+       LOG_DEBUG(DATA, "(%"PRIu64") virtio_dev_tx()\n", dev->device_fh);
+
+       /* Prefetch available ring to retrieve head indexes. */
+       rte_prefetch0(&vq->avail->ring[vq->last_used_idx_res & (vq->size - 1)]);
+
+       /* Get the number of free entries in the ring */
+       free_entries = (avail_idx - vq->last_used_idx_res);
+
+       /* Limit to MAX_PKT_BURST. */
+       free_entries
+               = (free_entries > MAX_PKT_BURST) ? MAX_PKT_BURST : free_entries;
+
+       LOG_DEBUG(DATA, "(%"PRIu64") Buffers available %d\n",
+               dev->device_fh, free_entries);
+
+       /* Retrieve all of the head indexes first to avoid caching issues. */
+       for (i = 0; i < free_entries; i++)
+               head[i]
+                       = vq->avail->ring[(vq->last_used_idx_res + i)
+                       & (vq->size - 1)];
+
+       vq->last_used_idx_res += free_entries;
+
+       /* Prefetch descriptor index. */
+       rte_prefetch0(&vq->desc[head[packet_success]]);
+       rte_prefetch0(&vq->used->ring[vq->last_used_idx & (vq->size - 1)]);
+
+       while (packet_success < free_entries) {
+               desc = &vq->desc[head[packet_success]];
+
+               /* Discard first buffer as it is the virtio header */
+               desc = &vq->desc[desc->next];
+
+               /* Buffer address translation. */
+               buff_addr = gpa_to_vva(dev, desc->addr);
+               phys_addr = gpa_to_hpa(dev, desc->addr, desc->len, &addr_type);
+
+               if (likely(packet_success < (free_entries - 1)))
+                       /* Prefetch descriptor index. */
+                       rte_prefetch0(&vq->desc[head[packet_success + 1]]);
+
+               if (unlikely(addr_type == PHYS_ADDR_INVALID)) {
+                       RTE_LOG(ERR, DATA,
+                               "(%"PRIu64") Invalid frame buffer address found"
+                               "when TX packets!\n",
+                               dev->device_fh);
+                       packet_success++;
+                       continue;
+               }
+
+               /* Prefetch buffer address. */
+               rte_prefetch0((void *)(uintptr_t)buff_addr);
+
+               /*
+                * Setup dummy mbuf. This is copied to a real mbuf if
+                * transmitted out the physical port.
+                */
+               m.pkt.data_len = desc->len;
+               m.pkt.nb_segs = 1;
+               m.pkt.next = NULL;
+               m.pkt.data = (void *)(uintptr_t)buff_addr;
+               m.buf_addr = m.pkt.data;
+               m.buf_physaddr = phys_addr;
+
+               /*
+                * Check if the frame buffer address from guest crosses
+                * sub-region or not.
+                */
+               if (unlikely(addr_type == PHYS_ADDR_CROSS_SUBREG)) {
+                       RTE_LOG(ERR, DATA,
+                               "(%"PRIu64") Frame buffer address cross "
+                               "sub-regioin found when attaching TX frame "
+                               "buffer address!\n",
+                               dev->device_fh);
+                       need_copy = 1;
+               } else
+                       need_copy = 0;
+
+               PRINT_PACKET(dev, (uintptr_t)buff_addr, desc->len, 0);
+
+               /*
+                * If this is the first received packet we need to learn
+                * the MAC and setup VMDQ
+                */
+               if (unlikely(dev->ready == DEVICE_MAC_LEARNING)) {
+                       if (dev->remove || (link_vmdq(dev, &m) == -1)) {
+                               /*
+                                * Discard frame if device is scheduled for
+                                * removal or a duplicate MAC address is found.
+                                */
+                               packet_success += free_entries;
+                               vq->last_used_idx += packet_success;
+                               break;
+                       }
+               }
+
+               virtio_tx_route_zcp(dev, &m, head[packet_success], need_copy);
+               packet_success++;
+       }
+}
+
+/*
+ * This function is called by each data core. It handles all RX/TX registered
+ * with the core. For TX the specific lcore linked list is used. For RX, MAC
+ * addresses are compared with all devices in the main linked list.
+ */
+static int
+switch_worker_zcp(__attribute__((unused)) void *arg)
+{
+       struct virtio_net *dev = NULL;
+       struct rte_mbuf *pkts_burst[MAX_PKT_BURST];
+       struct virtio_net_data_ll *dev_ll;
+       struct mbuf_table *tx_q;
+       volatile struct lcore_ll_info *lcore_ll;
+       const uint64_t drain_tsc
+               = (rte_get_tsc_hz() + US_PER_S - 1) / US_PER_S
+               * BURST_TX_DRAIN_US;
+       uint64_t prev_tsc, diff_tsc, cur_tsc, ret_count = 0;
+       unsigned ret;
+       const uint16_t lcore_id = rte_lcore_id();
+       uint16_t count_in_ring, rx_count = 0;
+
+       RTE_LOG(INFO, DATA, "Procesing on Core %u started\n", lcore_id);
+
+       lcore_ll = lcore_info[lcore_id].lcore_ll;
+       prev_tsc = 0;
+
+       while (1) {
+               cur_tsc = rte_rdtsc();
+
+               /* TX burst queue drain */
+               diff_tsc = cur_tsc - prev_tsc;
+               if (unlikely(diff_tsc > drain_tsc)) {
+                       /*
+                        * Get mbuf from vpool.pool and detach mbuf and
+                        * put back into vpool.ring.
+                        */
+                       dev_ll = lcore_ll->ll_root_used;
+                       while ((dev_ll != NULL) && (dev_ll->dev != NULL)) {
+                               /* Get virtio device ID */
+                               dev = dev_ll->dev;
+
+                               if (likely(!dev->remove)) {
+                                       tx_q = &tx_queue_zcp[(uint16_t)dev->vmdq_rx_q];
+                                       if (tx_q->len) {
+                                               LOG_DEBUG(DATA,
+                                               "TX queue drained after timeout"
+                                               " with burst size %u\n",
+                                               tx_q->len);
+
+                                               /*
+                                                * Tx any packets in the queue
+                                                */
+                                               ret = rte_eth_tx_burst(
+                                                       ports[0],
+                                                       (uint16_t)tx_q->txq_id,
+                                                       (struct rte_mbuf **)
+                                                       tx_q->m_table,
+                                                       (uint16_t)tx_q->len);
+                                               if (unlikely(ret < tx_q->len)) {
+                                                       do {
+                                                               rte_pktmbuf_free(
+                                                                       tx_q->m_table[ret]);
+                                                       } while (++ret < tx_q->len);
+                                               }
+                                               tx_q->len = 0;
+
+                                               txmbuf_clean_zcp(dev,
+                                                       &vpool_array[MAX_QUEUES+dev->vmdq_rx_q]);
+                                       }
+                               }
+                               dev_ll = dev_ll->next;
+                       }
+                       prev_tsc = cur_tsc;
+               }
+
+               rte_prefetch0(lcore_ll->ll_root_used);
+
+               /*
+                * Inform the configuration core that we have exited the linked
+                * list and that no devices are in use if requested.
+                */
+               if (lcore_ll->dev_removal_flag == REQUEST_DEV_REMOVAL)
+                       lcore_ll->dev_removal_flag = ACK_DEV_REMOVAL;
+
+               /* Process devices */
+               dev_ll = lcore_ll->ll_root_used;
+
+               while ((dev_ll != NULL) && (dev_ll->dev != NULL)) {
+                       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_RX)) {
+                               uint32_t index = dev->vmdq_rx_q;
+                               uint16_t i;
+                               count_in_ring
+                               = rte_ring_count(vpool_array[index].ring);
+                               uint16_t free_entries
+                               = (uint16_t)get_available_ring_num_zcp(dev);
+
+                               /*
+                                * Attach all mbufs in vpool.ring and put back
+                                * into vpool.pool.
+                                */
+                               for (i = 0;
+                               i < RTE_MIN(free_entries,
+                               RTE_MIN(count_in_ring, MAX_PKT_BURST));
+                               i++)
+                                       attach_rxmbuf_zcp(dev);
+
+                               /* Handle guest RX */
+                               rx_count = rte_eth_rx_burst(ports[0],
+                                       (uint16_t)dev->vmdq_rx_q, pkts_burst,
+                                       MAX_PKT_BURST);
+
+                               if (rx_count) {
+                                       ret_count = virtio_dev_rx_zcp(dev,
+                                                       pkts_burst, rx_count);
+                                       if (enable_stats) {
+                                               dev_statistics[dev->device_fh].rx_total
+                                                       += rx_count;
+                                               dev_statistics[dev->device_fh].rx
+                                                       += ret_count;
+                                       }
+                                       while (likely(rx_count)) {
+                                               rx_count--;
+                                               pktmbuf_detach_zcp(
+                                                       pkts_burst[rx_count]);
+                                               rte_ring_sp_enqueue(
+                                                       vpool_array[index].ring,
+                                                       (void *)pkts_burst[rx_count]);
+                                       }
+                               }
+                       }
+
+                       if (likely(!dev->remove))
+                               /* Handle guest TX */
+                               virtio_dev_tx_zcp(dev);
+
+                       /* Move to the next device in the list */
+                       dev_ll = dev_ll->next;
+               }
+       }
+
+       return 0;
+}
+
+
+/*
+ * Add an entry to a used linked list. A free entry must first be found
+ * in the free linked list using get_data_ll_free_entry();
  */
 static void
-add_data_ll_entry(struct virtio_net_data_ll **ll_root_addr, struct virtio_net_data_ll *ll_dev)
+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;
 
@@ -1311,14 +2419,16 @@ add_data_ll_entry(struct virtio_net_data_ll **ll_root_addr, struct virtio_net_da
 }
 
 /*
- * 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().
+ * 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)
+rm_data_ll_entry(struct virtio_net_data_ll **ll_root_addr,
+       struct virtio_net_data_ll *ll_dev,
+       struct virtio_net_data_ll *ll_dev_last)
 {
        struct virtio_net_data_ll *ll = *ll_root_addr;
-       
+
        if (unlikely((ll == NULL) || (ll_dev == NULL)))
                return;
 
@@ -1353,7 +2463,8 @@ get_data_ll_free_entry(struct virtio_net_data_ll **ll_root_addr)
  * 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)
+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;
 
@@ -1465,7 +2576,9 @@ destroy_device (volatile struct virtio_net *dev)
        }
 
        if (ll_lcore_dev_cur == NULL) {
-               RTE_LOG(ERR, CONFIG, "Failed to find the dev to be destroy.\n");
+               RTE_LOG(ERR, CONFIG,
+                       "(%"PRIu64") Failed to find the dev to be destroy.\n",
+                       dev->device_fh);
                return;
        }
 
@@ -1509,6 +2622,45 @@ destroy_device (volatile struct virtio_net *dev)
        lcore_info[ll_lcore_dev_cur->dev->coreid].lcore_ll->device_num--;
        
        RTE_LOG(INFO, DATA, "(%"PRIu64") Device has been removed from data core\n", dev->device_fh);
+
+       if (zero_copy) {
+               struct vpool *vpool = &vpool_array[dev->vmdq_rx_q];
+
+               /* Stop the RX queue. */
+               if (rte_eth_dev_rx_queue_stop(ports[0], dev->vmdq_rx_q) != 0) {
+                       LOG_DEBUG(CONFIG,
+                               "(%"PRIu64") In destroy_device: Failed to stop "
+                               "rx queue:%d\n",
+                               dev->device_fh,
+                               dev->vmdq_rx_q);
+               }
+
+               LOG_DEBUG(CONFIG,
+                       "(%"PRIu64") in destroy_device: Start put mbuf in "
+                       "mempool back to ring for RX queue: %d\n",
+                       dev->device_fh, dev->vmdq_rx_q);
+
+               mbuf_destroy_zcp(vpool);
+
+               /* Stop the TX queue. */
+               if (rte_eth_dev_tx_queue_stop(ports[0], dev->vmdq_rx_q) != 0) {
+                       LOG_DEBUG(CONFIG,
+                               "(%"PRIu64") In destroy_device: Failed to "
+                               "stop tx queue:%d\n",
+                               dev->device_fh, dev->vmdq_rx_q);
+               }
+
+               vpool = &vpool_array[dev->vmdq_rx_q + MAX_QUEUES];
+
+               LOG_DEBUG(CONFIG,
+                       "(%"PRIu64") destroy_device: Start put mbuf in mempool "
+                       "back to ring for TX queue: %d, dev:(%"PRIu64")\n",
+                       dev->device_fh, (dev->vmdq_rx_q + MAX_QUEUES),
+                       dev->device_fh);
+
+               mbuf_destroy_zcp(vpool);
+       }
+
 }
 
 /*
@@ -1532,6 +2684,78 @@ new_device (struct virtio_net *dev)
        }
        ll_dev->dev = dev;
        add_data_ll_entry(&ll_root_used, ll_dev);
+       ll_dev->dev->vmdq_rx_q
+               = ll_dev->dev->device_fh * (num_queues / num_devices);
+
+       if (zero_copy) {
+               uint32_t index = ll_dev->dev->vmdq_rx_q;
+               uint32_t count_in_ring, i;
+               struct mbuf_table *tx_q;
+
+               count_in_ring = rte_ring_count(vpool_array[index].ring);
+
+               LOG_DEBUG(CONFIG,
+                       "(%"PRIu64") in new_device: mbuf count in mempool "
+                       "before attach is: %d\n",
+                       dev->device_fh,
+                       rte_mempool_count(vpool_array[index].pool));
+               LOG_DEBUG(CONFIG,
+                       "(%"PRIu64") in new_device: mbuf count in  ring "
+                       "before attach  is : %d\n",
+                       dev->device_fh, count_in_ring);
+
+               /*
+                * Attach all mbufs in vpool.ring and put back intovpool.pool.
+                */
+               for (i = 0; i < count_in_ring; i++)
+                       attach_rxmbuf_zcp(dev);
+
+               LOG_DEBUG(CONFIG, "(%"PRIu64") in new_device: mbuf count in "
+                       "mempool after attach is: %d\n",
+                       dev->device_fh,
+                       rte_mempool_count(vpool_array[index].pool));
+               LOG_DEBUG(CONFIG, "(%"PRIu64") in new_device: mbuf count in "
+                       "ring after attach  is : %d\n",
+                       dev->device_fh,
+                       rte_ring_count(vpool_array[index].ring));
+
+               tx_q = &tx_queue_zcp[(uint16_t)dev->vmdq_rx_q];
+               tx_q->txq_id = dev->vmdq_rx_q;
+
+               if (rte_eth_dev_tx_queue_start(ports[0], dev->vmdq_rx_q) != 0) {
+                       struct vpool *vpool = &vpool_array[dev->vmdq_rx_q];
+
+                       LOG_DEBUG(CONFIG,
+                               "(%"PRIu64") In new_device: Failed to start "
+                               "tx queue:%d\n",
+                               dev->device_fh, dev->vmdq_rx_q);
+
+                       mbuf_destroy_zcp(vpool);
+                       return -1;
+               }
+
+               if (rte_eth_dev_rx_queue_start(ports[0], dev->vmdq_rx_q) != 0) {
+                       struct vpool *vpool = &vpool_array[dev->vmdq_rx_q];
+
+                       LOG_DEBUG(CONFIG,
+                               "(%"PRIu64") In new_device: Failed to start "
+                               "rx queue:%d\n",
+                               dev->device_fh, dev->vmdq_rx_q);
+
+                       /* Stop the TX queue. */
+                       if (rte_eth_dev_tx_queue_stop(ports[0],
+                               dev->vmdq_rx_q) != 0) {
+                               LOG_DEBUG(CONFIG,
+                                       "(%"PRIu64") In new_device: Failed to "
+                                       "stop tx queue:%d\n",
+                                       dev->device_fh, dev->vmdq_rx_q);
+                       }
+
+                       mbuf_destroy_zcp(vpool);
+                       return -1;
+               }
+
+       }
 
        /*reset ready flag*/
        dev->ready = DEVICE_MAC_LEARNING;
@@ -1549,6 +2773,7 @@ new_device (struct virtio_net *dev)
        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, DATA, "(%"PRIu64") Failed to add device to data core\n", dev->device_fh);
+               dev->ready = DEVICE_SAFE_REMOVE;
                destroy_device(dev);
                return -1;
        }
@@ -1606,8 +2831,15 @@ print_stats(void)
                        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);
+                       if (zero_copy == 0) {
+                               rx_total = rte_atomic64_read(
+                                       &dev_statistics[device_fh].rx_total_atomic);
+                               rx = rte_atomic64_read(
+                                       &dev_statistics[device_fh].rx_atomic);
+                       } else {
+                               rx_total = dev_statistics[device_fh].rx_total;
+                               rx = dev_statistics[device_fh].rx;
+                       }
                        rx_dropped = rx_total - rx;
 
                        printf("\nStatistics for device %"PRIu32" ------------------------------"
@@ -1631,6 +2863,43 @@ print_stats(void)
        }
 }
 
+static void
+setup_mempool_tbl(int socket, uint32_t index, char *pool_name,
+       char *ring_name, uint32_t nb_mbuf)
+{
+       uint16_t roomsize = VIRTIO_DESCRIPTOR_LEN_ZCP + RTE_PKTMBUF_HEADROOM;
+       vpool_array[index].pool
+               = rte_mempool_create(pool_name, nb_mbuf, MBUF_SIZE_ZCP,
+               MBUF_CACHE_SIZE_ZCP, sizeof(struct rte_pktmbuf_pool_private),
+               rte_pktmbuf_pool_init, (void *)(uintptr_t)roomsize,
+               rte_pktmbuf_init, NULL, socket, 0);
+       if (vpool_array[index].pool != NULL) {
+               vpool_array[index].ring
+                       = rte_ring_create(ring_name,
+                               rte_align32pow2(nb_mbuf + 1),
+                               socket, RING_F_SP_ENQ | RING_F_SC_DEQ);
+               if (likely(vpool_array[index].ring != NULL)) {
+                       LOG_DEBUG(CONFIG,
+                               "in setup_mempool_tbl: mbuf count in "
+                               "mempool is: %d\n",
+                               rte_mempool_count(vpool_array[index].pool));
+                       LOG_DEBUG(CONFIG,
+                               "in setup_mempool_tbl: mbuf count in "
+                               "ring   is: %d\n",
+                               rte_ring_count(vpool_array[index].ring));
+               } else {
+                       rte_exit(EXIT_FAILURE, "ring_create(%s) failed",
+                               ring_name);
+               }
+
+               /* Need consider head room. */
+               vpool_array[index].buf_size = roomsize - RTE_PKTMBUF_HEADROOM;
+       } else {
+               rte_exit(EXIT_FAILURE, "mempool_create(%s) failed", pool_name);
+       }
+}
+
+
 /*
  * Main function, does initialisation and calls the per-lcore functions. The CUSE
  * device is also registered here to handle the IOCTLs.
@@ -1638,11 +2907,11 @@ print_stats(void)
 int
 MAIN(int argc, char *argv[])
 {
-       struct rte_mempool *mbuf_pool;
+       struct rte_mempool *mbuf_pool = NULL;
        unsigned lcore_id, core_id = 0;
        unsigned nb_ports, valid_num_ports;
        int ret;
-       uint8_t portid;
+       uint8_t portid, queue_id = 0;
        static pthread_t tid;
 
        /* init EAL */
@@ -1687,16 +2956,71 @@ MAIN(int argc, char *argv[])
                return -1;
        }
 
-       /* Create the mbuf pool. */
-       mbuf_pool = rte_mempool_create("MBUF_POOL", NUM_MBUFS_PER_PORT * valid_num_ports,
-                                      MBUF_SIZE, MBUF_CACHE_SIZE,
-                                      sizeof(struct rte_pktmbuf_pool_private),
-                                      rte_pktmbuf_pool_init, NULL,
-                                      rte_pktmbuf_init, NULL,
-                                      rte_socket_id(), 0);
-       if (mbuf_pool == NULL)
-               rte_exit(EXIT_FAILURE, "Cannot create mbuf pool\n");
+       if (zero_copy == 0) {
+               /* Create the mbuf pool. */
+               mbuf_pool = rte_mempool_create(
+                               "MBUF_POOL",
+                               NUM_MBUFS_PER_PORT
+                               * valid_num_ports,
+                               MBUF_SIZE, MBUF_CACHE_SIZE,
+                               sizeof(struct rte_pktmbuf_pool_private),
+                               rte_pktmbuf_pool_init, NULL,
+                               rte_pktmbuf_init, NULL,
+                               rte_socket_id(), 0);
+               if (mbuf_pool == NULL)
+                       rte_exit(EXIT_FAILURE, "Cannot create mbuf pool\n");
+
+               for (queue_id = 0; queue_id < MAX_QUEUES + 1; queue_id++)
+                       vpool_array[queue_id].pool = mbuf_pool;
+
+               if (vm2vm_mode == VM2VM_HARDWARE) {
+                       /* Enable VT loop back to let L2 switch to do it. */
+                       vmdq_conf_default.rx_adv_conf.vmdq_rx_conf.enable_loop_back = 1;
+                       LOG_DEBUG(CONFIG,
+                               "Enable loop back for L2 switch in vmdq.\n");
+               }
+       } else {
+               uint32_t nb_mbuf;
+               char pool_name[RTE_MEMPOOL_NAMESIZE];
+               char ring_name[RTE_MEMPOOL_NAMESIZE];
+
+               rx_conf_default.start_rx_per_q = (uint8_t)zero_copy;
+               rx_conf_default.rx_drop_en = 0;
+               tx_conf_default.start_tx_per_q = (uint8_t)zero_copy;
+               nb_mbuf = num_rx_descriptor
+                       + num_switching_cores * MBUF_CACHE_SIZE_ZCP
+                       + num_switching_cores * MAX_PKT_BURST;
+
+               for (queue_id = 0; queue_id < MAX_QUEUES; queue_id++) {
+                       rte_snprintf(pool_name, sizeof(pool_name),
+                               "rxmbuf_pool_%u", queue_id);
+                       rte_snprintf(ring_name, sizeof(ring_name),
+                               "rxmbuf_ring_%u", queue_id);
+                       setup_mempool_tbl(rte_socket_id(), queue_id,
+                               pool_name, ring_name, nb_mbuf);
+               }
+
+               nb_mbuf = num_tx_descriptor
+                               + num_switching_cores * MBUF_CACHE_SIZE_ZCP
+                               + num_switching_cores * MAX_PKT_BURST;
+
+               for (queue_id = 0; queue_id < MAX_QUEUES; queue_id++) {
+                       rte_snprintf(pool_name, sizeof(pool_name),
+                               "txmbuf_pool_%u", queue_id);
+                       rte_snprintf(ring_name, sizeof(ring_name),
+                               "txmbuf_ring_%u", queue_id);
+                       setup_mempool_tbl(rte_socket_id(),
+                               (queue_id + MAX_QUEUES),
+                               pool_name, ring_name, nb_mbuf);
+               }
 
+               if (vm2vm_mode == VM2VM_HARDWARE) {
+                       /* Enable VT loop back to let L2 switch to do it. */
+                       vmdq_conf_default.rx_adv_conf.vmdq_rx_conf.enable_loop_back = 1;
+                       LOG_DEBUG(CONFIG,
+                               "Enable loop back for L2 switch in vmdq.\n");
+               }
+       }
        /* Set log level. */
        rte_set_log_level(LOG_LEVEL);
 
@@ -1704,11 +3028,13 @@ MAIN(int argc, char *argv[])
        for (portid = 0; portid < nb_ports; portid++) {
                /* skip ports that are not enabled */
                if ((enabled_port_mask & (1 << portid)) == 0) {
-                       RTE_LOG(INFO, PORT, "Skipping disabled port %d\n", portid);
+                       RTE_LOG(INFO, PORT,
+                               "Skipping disabled port %d\n", portid);
                        continue;
                }
-               if (port_init(portid, mbuf_pool) != 0)
-                       rte_exit(EXIT_FAILURE, "Cannot initialize network ports\n");
+               if (port_init(portid) != 0)
+                       rte_exit(EXIT_FAILURE,
+                               "Cannot initialize network ports\n");
        }
 
        /* Initialise all linked lists. */
@@ -1723,8 +3049,42 @@ MAIN(int argc, char *argv[])
                pthread_create(&tid, NULL, (void*)print_stats, NULL );
 
        /* Launch all data cores. */
-       RTE_LCORE_FOREACH_SLAVE(lcore_id) {
-               rte_eal_remote_launch(switch_worker, mbuf_pool, lcore_id);
+       if (zero_copy == 0) {
+               RTE_LCORE_FOREACH_SLAVE(lcore_id) {
+                       rte_eal_remote_launch(switch_worker,
+                               mbuf_pool, lcore_id);
+               }
+       } else {
+               uint32_t count_in_mempool, index, i;
+               for (index = 0; index < 2*MAX_QUEUES; index++) {
+                       /* For all RX and TX queues. */
+                       count_in_mempool
+                               = rte_mempool_count(vpool_array[index].pool);
+
+                       /*
+                        * Transfer all un-attached mbufs from vpool.pool
+                        * to vpoo.ring.
+                        */
+                       for (i = 0; i < count_in_mempool; i++) {
+                               struct rte_mbuf *mbuf
+                                       = __rte_mbuf_raw_alloc(
+                                               vpool_array[index].pool);
+                               rte_ring_sp_enqueue(vpool_array[index].ring,
+                                               (void *)mbuf);
+                       }
+
+                       LOG_DEBUG(CONFIG,
+                               "in MAIN: mbuf count in mempool at initial "
+                               "is: %d\n", count_in_mempool);
+                       LOG_DEBUG(CONFIG,
+                               "in MAIN: mbuf count in  ring at initial  is :"
+                               " %d\n",
+                               rte_ring_count(vpool_array[index].ring));
+               }
+
+               RTE_LCORE_FOREACH_SLAVE(lcore_id)
+                       rte_eal_remote_launch(switch_worker_zcp, NULL,
+                               lcore_id);
        }
 
        /* Register CUSE device to handle IOCTLs. */