lib/librte_vhost/vhost_rxtx.c

   1 /*-
   2  *   BSD LICENSE
   3  *
   4  *   Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
   5  *   All rights reserved.
   6  *
   7  *   Redistribution and use in source and binary forms, with or without
   8  *   modification, are permitted provided that the following conditions
   9  *   are met:
  10  *
  11  *     * Redistributions of source code must retain the above copyright
  12  *       notice, this list of conditions and the following disclaimer.
  13  *     * Redistributions in binary form must reproduce the above copyright
  14  *       notice, this list of conditions and the following disclaimer in
  15  *       the documentation and/or other materials provided with the
  16  *       distribution.
  17  *     * Neither the name of Intel Corporation nor the names of its
  18  *       contributors may be used to endorse or promote products derived
  19  *       from this software without specific prior written permission.
  20  *
  21  *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  24  *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  25  *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  26  *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  27  *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  28  *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  29  *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  30  *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  31  *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  32  */
  33
  34 #include <stdint.h>
  35 #include <linux/virtio_net.h>
  36
  37 #include <rte_mbuf.h>
  38 #include <rte_memcpy.h>
  39 #include <rte_virtio_net.h>
  40
  41 #include "vhost-net.h"
  42
  43 #define MAX_PKT_BURST 32
  44
  45 /**
  46  * This function adds buffers to the virtio devices RX virtqueue. Buffers can
  47  * be received from the physical port or from another virtio device. A packet
  48  * count is returned to indicate the number of packets that are succesfully
  49  * added to the RX queue. This function works when mergeable is disabled.
  50  */
  51 static inline uint32_t __attribute__((always_inline))
  52 virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
  53         struct rte_mbuf **pkts, uint32_t count)
  54 {
  55         struct vhost_virtqueue *vq;
  56         struct vring_desc *desc;
  57         struct rte_mbuf *buff;
  58         /* The virtio_hdr is initialised to 0. */
  59         struct virtio_net_hdr_mrg_rxbuf virtio_hdr = {{0, 0, 0, 0, 0, 0}, 0};
  60         uint64_t buff_addr = 0;
  61         uint64_t buff_hdr_addr = 0;
  62         uint32_t head[MAX_PKT_BURST], packet_len = 0;
  63         uint32_t head_idx, packet_success = 0;
  64         uint16_t avail_idx, res_cur_idx;
  65         uint16_t res_base_idx, res_end_idx;
  66         uint16_t free_entries;
  67         uint8_t success = 0;
  68
  69         LOG_DEBUG(VHOST_DATA, "(%"PRIu64") virtio_dev_rx()\n", dev->device_fh);
  70         if (unlikely(queue_id != VIRTIO_RXQ)) {
  71                 LOG_DEBUG(VHOST_DATA, "mq isn't supported in this version.\n");
  72                 return 0;
  73         }
  74
  75         vq = dev->virtqueue[VIRTIO_RXQ];
  76         count = (count > MAX_PKT_BURST) ? MAX_PKT_BURST : count;
  77
  78         /*
  79          * As many data cores may want access to available buffers,
  80          * they need to be reserved.
  81          */
  82         do {
  83                 res_base_idx = vq->last_used_idx_res;
  84                 avail_idx = *((volatile uint16_t *)&vq->avail->idx);
  85
  86                 free_entries = (avail_idx - res_base_idx);
  87                 /*check that we have enough buffers*/
  88                 if (unlikely(count > free_entries))
  89                         count = free_entries;
  90
  91                 if (count == 0)
  92                         return 0;
  93
  94                 res_end_idx = res_base_idx + count;
  95                 /* vq->last_used_idx_res is atomically updated. */
  96                 /* TODO: Allow to disable cmpset if no concurrency in application. */
  97                 success = rte_atomic16_cmpset(&vq->last_used_idx_res,
  98                                 res_base_idx, res_end_idx);
  99         } while (unlikely(success == 0));
 100         res_cur_idx = res_base_idx;
 101         LOG_DEBUG(VHOST_DATA, "(%"PRIu64") Current Index %d| End Index %d\n",
 102                         dev->device_fh, res_cur_idx, res_end_idx);
 103
 104         /* Prefetch available ring to retrieve indexes. */
 105         rte_prefetch0(&vq->avail->ring[res_cur_idx & (vq->size - 1)]);
 106
 107         /* Retrieve all of the head indexes first to avoid caching issues. */
 108         for (head_idx = 0; head_idx < count; head_idx++)
 109                 head[head_idx] = vq->avail->ring[(res_cur_idx + head_idx) &
 110                                         (vq->size - 1)];
 111
 112         /*Prefetch descriptor index. */
 113         rte_prefetch0(&vq->desc[head[packet_success]]);
 114
 115         while (res_cur_idx != res_end_idx) {
 116                 /* Get descriptor from available ring */
 117                 desc = &vq->desc[head[packet_success]];
 118
 119                 buff = pkts[packet_success];
 120
 121                 /* Convert from gpa to vva (guest physical addr -> vhost virtual addr) */
 122                 buff_addr = gpa_to_vva(dev, desc->addr);
 123                 /* Prefetch buffer address. */
 124                 rte_prefetch0((void *)(uintptr_t)buff_addr);
 125
 126                 /* Copy virtio_hdr to packet and increment buffer address */
 127                 buff_hdr_addr = buff_addr;
 128                 packet_len = rte_pktmbuf_data_len(buff) + vq->vhost_hlen;
 129
 130                 /*
 131                  * If the descriptors are chained the header and data are
 132                  * placed in separate buffers.
 133                  */
 134                 if (desc->flags & VRING_DESC_F_NEXT) {
 135                         desc->len = vq->vhost_hlen;
 136                         desc = &vq->desc[desc->next];
 137                         /* Buffer address translation. */
 138                         buff_addr = gpa_to_vva(dev, desc->addr);
 139                         desc->len = rte_pktmbuf_data_len(buff);
 140                 } else {
 141                         buff_addr += vq->vhost_hlen;
 142                         desc->len = packet_len;
 143                 }
 144
 145                 /* Update used ring with desc information */
 146                 vq->used->ring[res_cur_idx & (vq->size - 1)].id =
 147                                                         head[packet_success];
 148                 vq->used->ring[res_cur_idx & (vq->size - 1)].len = packet_len;
 149
 150                 /* Copy mbuf data to buffer */
 151                 /* FIXME for sg mbuf and the case that desc couldn't hold the mbuf data */
 152                 rte_memcpy((void *)(uintptr_t)buff_addr,
 153                         rte_pktmbuf_mtod(buff, const void *),
 154                         rte_pktmbuf_data_len(buff));
 155                 PRINT_PACKET(dev, (uintptr_t)buff_addr,
 156                         rte_pktmbuf_data_len(buff), 0);
 157
 158                 res_cur_idx++;
 159                 packet_success++;
 160
 161                 rte_memcpy((void *)(uintptr_t)buff_hdr_addr,
 162                         (const void *)&virtio_hdr, vq->vhost_hlen);
 163
 164                 PRINT_PACKET(dev, (uintptr_t)buff_hdr_addr, vq->vhost_hlen, 1);
 165
 166                 if (res_cur_idx < res_end_idx) {
 167                         /* Prefetch descriptor index. */
 168                         rte_prefetch0(&vq->desc[head[packet_success]]);
 169                 }
 170         }
 171
 172         rte_compiler_barrier();
 173
 174         /* Wait until it's our turn to add our buffer to the used ring. */
 175         while (unlikely(vq->last_used_idx != res_base_idx))
 176                 rte_pause();
 177
 178         *(volatile uint16_t *)&vq->used->idx += count;
 179         vq->last_used_idx = res_end_idx;
 180
 181         /* flush used->idx update before we read avail->flags. */
 182         rte_mb();
 183
 184         /* Kick the guest if necessary. */
 185         if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT))
 186                 eventfd_write((int)vq->callfd, 1);
 187         return count;
 188 }
 189
 190 static inline uint32_t __attribute__((always_inline))
 191 copy_from_mbuf_to_vring(struct virtio_net *dev, uint16_t res_base_idx,
 192         uint16_t res_end_idx, struct rte_mbuf *pkt)
 193 {
 194         uint32_t vec_idx = 0;
 195         uint32_t entry_success = 0;
 196         struct vhost_virtqueue *vq;
 197         /* The virtio_hdr is initialised to 0. */
 198         struct virtio_net_hdr_mrg_rxbuf virtio_hdr = {
 199                 {0, 0, 0, 0, 0, 0}, 0};
 200         uint16_t cur_idx = res_base_idx;
 201         uint64_t vb_addr = 0;
 202         uint64_t vb_hdr_addr = 0;
 203         uint32_t seg_offset = 0;
 204         uint32_t vb_offset = 0;
 205         uint32_t seg_avail;
 206         uint32_t vb_avail;
 207         uint32_t cpy_len, entry_len;
 208
 209         if (pkt == NULL)
 210                 return 0;
 211
 212         LOG_DEBUG(VHOST_DATA, "(%"PRIu64") Current Index %d| "
 213                 "End Index %d\n",
 214                 dev->device_fh, cur_idx, res_end_idx);
 215
 216         /*
 217          * Convert from gpa to vva
 218          * (guest physical addr -> vhost virtual addr)
 219          */
 220         vq = dev->virtqueue[VIRTIO_RXQ];
 221         vb_addr =
 222                 gpa_to_vva(dev, vq->buf_vec[vec_idx].buf_addr);
 223         vb_hdr_addr = vb_addr;
 224
 225         /* Prefetch buffer address. */
 226         rte_prefetch0((void *)(uintptr_t)vb_addr);
 227
 228         virtio_hdr.num_buffers = res_end_idx - res_base_idx;
 229
 230         LOG_DEBUG(VHOST_DATA, "(%"PRIu64") RX: Num merge buffers %d\n",
 231                 dev->device_fh, virtio_hdr.num_buffers);
 232
 233         rte_memcpy((void *)(uintptr_t)vb_hdr_addr,
 234                 (const void *)&virtio_hdr, vq->vhost_hlen);
 235
 236         PRINT_PACKET(dev, (uintptr_t)vb_hdr_addr, vq->vhost_hlen, 1);
 237
 238         seg_avail = rte_pktmbuf_data_len(pkt);
 239         vb_offset = vq->vhost_hlen;
 240         vb_avail =
 241                 vq->buf_vec[vec_idx].buf_len - vq->vhost_hlen;
 242
 243         entry_len = vq->vhost_hlen;
 244
 245         if (vb_avail == 0) {
 246                 uint32_t desc_idx =
 247                         vq->buf_vec[vec_idx].desc_idx;
 248                 vq->desc[desc_idx].len = vq->vhost_hlen;
 249
 250                 if ((vq->desc[desc_idx].flags
 251                         & VRING_DESC_F_NEXT) == 0) {
 252                         /* Update used ring with desc information */
 253                         vq->used->ring[cur_idx & (vq->size - 1)].id
 254                                 = vq->buf_vec[vec_idx].desc_idx;
 255                         vq->used->ring[cur_idx & (vq->size - 1)].len
 256                                 = entry_len;
 257
 258                         entry_len = 0;
 259                         cur_idx++;
 260                         entry_success++;
 261                 }
 262
 263                 vec_idx++;
 264                 vb_addr =
 265                         gpa_to_vva(dev, vq->buf_vec[vec_idx].buf_addr);
 266
 267                 /* Prefetch buffer address. */
 268                 rte_prefetch0((void *)(uintptr_t)vb_addr);
 269                 vb_offset = 0;
 270                 vb_avail = vq->buf_vec[vec_idx].buf_len;
 271         }
 272
 273         cpy_len = RTE_MIN(vb_avail, seg_avail);
 274
 275         while (cpy_len > 0) {
 276                 /* Copy mbuf data to vring buffer */
 277                 rte_memcpy((void *)(uintptr_t)(vb_addr + vb_offset),
 278                         (const void *)(rte_pktmbuf_mtod(pkt, char*) + seg_offset),
 279                         cpy_len);
 280
 281                 PRINT_PACKET(dev,
 282                         (uintptr_t)(vb_addr + vb_offset),
 283                         cpy_len, 0);
 284
 285                 seg_offset += cpy_len;
 286                 vb_offset += cpy_len;
 287                 seg_avail -= cpy_len;
 288                 vb_avail -= cpy_len;
 289                 entry_len += cpy_len;
 290
 291                 if (seg_avail != 0) {
 292                         /*
 293                          * The virtio buffer in this vring
 294                          * entry reach to its end.
 295                          * But the segment doesn't complete.
 296                          */
 297                         if ((vq->desc[vq->buf_vec[vec_idx].desc_idx].flags &
 298                                 VRING_DESC_F_NEXT) == 0) {
 299                                 /* Update used ring with desc information */
 300                                 vq->used->ring[cur_idx & (vq->size - 1)].id
 301                                         = vq->buf_vec[vec_idx].desc_idx;
 302                                 vq->used->ring[cur_idx & (vq->size - 1)].len
 303                                         = entry_len;
 304                                 entry_len = 0;
 305                                 cur_idx++;
 306                                 entry_success++;
 307                         }
 308
 309                         vec_idx++;
 310                         vb_addr = gpa_to_vva(dev,
 311                                 vq->buf_vec[vec_idx].buf_addr);
 312                         vb_offset = 0;
 313                         vb_avail = vq->buf_vec[vec_idx].buf_len;
 314                         cpy_len = RTE_MIN(vb_avail, seg_avail);
 315                 } else {
 316                         /*
 317                          * This current segment complete, need continue to
 318                          * check if the whole packet complete or not.
 319                          */
 320                         pkt = pkt->next;
 321                         if (pkt != NULL) {
 322                                 /*
 323                                  * There are more segments.
 324                                  */
 325                                 if (vb_avail == 0) {
 326                                         /*
 327                                          * This current buffer from vring is
 328                                          * used up, need fetch next buffer
 329                                          * from buf_vec.
 330                                          */
 331                                         uint32_t desc_idx =
 332                                                 vq->buf_vec[vec_idx].desc_idx;
 333                                         vq->desc[desc_idx].len = vb_offset;
 334
 335                                         if ((vq->desc[desc_idx].flags &
 336                                                 VRING_DESC_F_NEXT) == 0) {
 337                                                 uint16_t wrapped_idx =
 338                                                         cur_idx & (vq->size - 1);
 339                                                 /*
 340                                                  * Update used ring with the
 341                                                  * descriptor information
 342                                                  */
 343                                                 vq->used->ring[wrapped_idx].id
 344                                                         = desc_idx;
 345                                                 vq->used->ring[wrapped_idx].len
 346                                                         = entry_len;
 347                                                 entry_success++;
 348                                                 entry_len = 0;
 349                                                 cur_idx++;
 350                                         }
 351
 352                                         /* Get next buffer from buf_vec. */
 353                                         vec_idx++;
 354                                         vb_addr = gpa_to_vva(dev,
 355                                                 vq->buf_vec[vec_idx].buf_addr);
 356                                         vb_avail =
 357                                                 vq->buf_vec[vec_idx].buf_len;
 358                                         vb_offset = 0;
 359                                 }
 360
 361                                 seg_offset = 0;
 362                                 seg_avail = rte_pktmbuf_data_len(pkt);
 363                                 cpy_len = RTE_MIN(vb_avail, seg_avail);
 364                         } else {
 365                                 /*
 366                                  * This whole packet completes.
 367                                  */
 368                                 uint32_t desc_idx =
 369                                         vq->buf_vec[vec_idx].desc_idx;
 370                                 vq->desc[desc_idx].len = vb_offset;
 371
 372                                 while (vq->desc[desc_idx].flags &
 373                                         VRING_DESC_F_NEXT) {
 374                                         desc_idx = vq->desc[desc_idx].next;
 375                                          vq->desc[desc_idx].len = 0;
 376                                 }
 377
 378                                 /* Update used ring with desc information */
 379                                 vq->used->ring[cur_idx & (vq->size - 1)].id
 380                                         = vq->buf_vec[vec_idx].desc_idx;
 381                                 vq->used->ring[cur_idx & (vq->size - 1)].len
 382                                         = entry_len;
 383                                 entry_len = 0;
 384                                 cur_idx++;
 385                                 entry_success++;
 386                                 seg_avail = 0;
 387                                 cpy_len = RTE_MIN(vb_avail, seg_avail);
 388                         }
 389                 }
 390         }
 391
 392         return entry_success;
 393 }
 394
 395 /*
 396  * This function works for mergeable RX.
 397  */
 398 static inline uint32_t __attribute__((always_inline))
 399 virtio_dev_merge_rx(struct virtio_net *dev, uint16_t queue_id,
 400         struct rte_mbuf **pkts, uint32_t count)
 401 {
 402         struct vhost_virtqueue *vq;
 403         uint32_t pkt_idx = 0, entry_success = 0;
 404         uint16_t avail_idx, res_cur_idx;
 405         uint16_t res_base_idx, res_end_idx;
 406         uint8_t success = 0;
 407
 408         LOG_DEBUG(VHOST_DATA, "(%"PRIu64") virtio_dev_merge_rx()\n",
 409                 dev->device_fh);
 410         if (unlikely(queue_id != VIRTIO_RXQ)) {
 411                 LOG_DEBUG(VHOST_DATA, "mq isn't supported in this version.\n");
 412         }
 413
 414         vq = dev->virtqueue[VIRTIO_RXQ];
 415         count = RTE_MIN((uint32_t)MAX_PKT_BURST, count);
 416
 417         if (count == 0)
 418                 return 0;
 419
 420         for (pkt_idx = 0; pkt_idx < count; pkt_idx++) {
 421                 uint32_t secure_len = 0;
 422                 uint16_t need_cnt;
 423                 uint32_t vec_idx = 0;
 424                 uint32_t pkt_len = pkts[pkt_idx]->pkt_len + vq->vhost_hlen;
 425                 uint16_t i, id;
 426
 427                 do {
 428                         /*
 429                          * As many data cores may want access to available
 430                          * buffers, they need to be reserved.
 431                          */
 432                         res_base_idx = vq->last_used_idx_res;
 433                         res_cur_idx = res_base_idx;
 434
 435                         do {
 436                                 avail_idx = *((volatile uint16_t *)&vq->avail->idx);
 437                                 if (unlikely(res_cur_idx == avail_idx)) {
 438                                         LOG_DEBUG(VHOST_DATA,
 439                                                 "(%"PRIu64") Failed "
 440                                                 "to get enough desc from "
 441                                                 "vring\n",
 442                                                 dev->device_fh);
 443                                         return pkt_idx;
 444                                 } else {
 445                                         uint16_t wrapped_idx =
 446                                                 (res_cur_idx) & (vq->size - 1);
 447                                         uint32_t idx =
 448                                                 vq->avail->ring[wrapped_idx];
 449                                         uint8_t next_desc;
 450
 451                                         do {
 452                                                 next_desc = 0;
 453                                                 secure_len += vq->desc[idx].len;
 454                                                 if (vq->desc[idx].flags &
 455                                                         VRING_DESC_F_NEXT) {
 456                                                         idx = vq->desc[idx].next;
 457                                                         next_desc = 1;
 458                                                 }
 459                                         } while (next_desc);
 460
 461                                         res_cur_idx++;
 462                                 }
 463                         } while (pkt_len > secure_len);
 464
 465                         /* vq->last_used_idx_res is atomically updated. */
 466                         success = rte_atomic16_cmpset(&vq->last_used_idx_res,
 467                                                         res_base_idx,
 468                                                         res_cur_idx);
 469                 } while (success == 0);
 470
 471                 id = res_base_idx;
 472                 need_cnt = res_cur_idx - res_base_idx;
 473
 474                 for (i = 0; i < need_cnt; i++, id++) {
 475                         uint16_t wrapped_idx = id & (vq->size - 1);
 476                         uint32_t idx = vq->avail->ring[wrapped_idx];
 477                         uint8_t next_desc;
 478                         do {
 479                                 next_desc = 0;
 480                                 vq->buf_vec[vec_idx].buf_addr =
 481                                         vq->desc[idx].addr;
 482                                 vq->buf_vec[vec_idx].buf_len =
 483                                         vq->desc[idx].len;
 484                                 vq->buf_vec[vec_idx].desc_idx = idx;
 485                                 vec_idx++;
 486
 487                                 if (vq->desc[idx].flags & VRING_DESC_F_NEXT) {
 488                                         idx = vq->desc[idx].next;
 489                                         next_desc = 1;
 490                                 }
 491                         } while (next_desc);
 492                 }
 493
 494                 res_end_idx = res_cur_idx;
 495
 496                 entry_success = copy_from_mbuf_to_vring(dev, res_base_idx,
 497                         res_end_idx, pkts[pkt_idx]);
 498
 499                 rte_compiler_barrier();
 500
 501                 /*
 502                  * Wait until it's our turn to add our buffer
 503                  * to the used ring.
 504                  */
 505                 while (unlikely(vq->last_used_idx != res_base_idx))
 506                         rte_pause();
 507
 508                 *(volatile uint16_t *)&vq->used->idx += entry_success;
 509                 vq->last_used_idx = res_end_idx;
 510
 511                 /* flush used->idx update before we read avail->flags. */
 512                 rte_mb();
 513
 514                 /* Kick the guest if necessary. */
 515                 if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT))
 516                         eventfd_write((int)vq->callfd, 1);
 517         }
 518
 519         return count;
 520 }
 521
 522 uint16_t
 523 rte_vhost_enqueue_burst(struct virtio_net *dev, uint16_t queue_id,
 524         struct rte_mbuf **pkts, uint16_t count)
 525 {
 526         if (unlikely(dev->features & (1 << VIRTIO_NET_F_MRG_RXBUF)))
 527                 return virtio_dev_merge_rx(dev, queue_id, pkts, count);
 528         else
 529                 return virtio_dev_rx(dev, queue_id, pkts, count);
 530 }
 531
 532 uint16_t
 533 rte_vhost_dequeue_burst(struct virtio_net *dev, uint16_t queue_id,
 534         struct rte_mempool *mbuf_pool, struct rte_mbuf **pkts, uint16_t count)
 535 {
 536         struct rte_mbuf *m, *prev;
 537         struct vhost_virtqueue *vq;
 538         struct vring_desc *desc;
 539         uint64_t vb_addr = 0;
 540         uint32_t head[MAX_PKT_BURST];
 541         uint32_t used_idx;
 542         uint32_t i;
 543         uint16_t free_entries, entry_success = 0;
 544         uint16_t avail_idx;
 545
 546         if (unlikely(queue_id != VIRTIO_TXQ)) {
 547                 LOG_DEBUG(VHOST_DATA, "mq isn't supported in this version.\n");
 548                 return 0;
 549         }
 550
 551         vq = dev->virtqueue[VIRTIO_TXQ];
 552         avail_idx =  *((volatile uint16_t *)&vq->avail->idx);
 553
 554         /* If there are no available buffers then return. */
 555         if (vq->last_used_idx == avail_idx)
 556                 return 0;
 557
 558         LOG_DEBUG(VHOST_DATA, "%s (%"PRIu64")\n", __func__,
 559                 dev->device_fh);
 560
 561         /* Prefetch available ring to retrieve head indexes. */
 562         rte_prefetch0(&vq->avail->ring[vq->last_used_idx & (vq->size - 1)]);
 563
 564         /*get the number of free entries in the ring*/
 565         free_entries = (avail_idx - vq->last_used_idx);
 566
 567         free_entries = RTE_MIN(free_entries, count);
 568         /* Limit to MAX_PKT_BURST. */
 569         free_entries = RTE_MIN(free_entries, MAX_PKT_BURST);
 570
 571         LOG_DEBUG(VHOST_DATA, "(%"PRIu64") Buffers available %d\n",
 572                         dev->device_fh, free_entries);
 573         /* Retrieve all of the head indexes first to avoid caching issues. */
 574         for (i = 0; i < free_entries; i++)
 575                 head[i] = vq->avail->ring[(vq->last_used_idx + i) & (vq->size - 1)];
 576
 577         /* Prefetch descriptor index. */
 578         rte_prefetch0(&vq->desc[head[entry_success]]);
 579         rte_prefetch0(&vq->used->ring[vq->last_used_idx & (vq->size - 1)]);
 580
 581         while (entry_success < free_entries) {
 582                 uint32_t vb_avail, vb_offset;
 583                 uint32_t seg_avail, seg_offset;
 584                 uint32_t cpy_len;
 585                 uint32_t seg_num = 0;
 586                 struct rte_mbuf *cur;
 587                 uint8_t alloc_err = 0;
 588
 589                 desc = &vq->desc[head[entry_success]];
 590
 591                 /* Discard first buffer as it is the virtio header */
 592                 desc = &vq->desc[desc->next];
 593
 594                 /* Buffer address translation. */
 595                 vb_addr = gpa_to_vva(dev, desc->addr);
 596                 /* Prefetch buffer address. */
 597                 rte_prefetch0((void *)(uintptr_t)vb_addr);
 598
 599                 used_idx = vq->last_used_idx & (vq->size - 1);
 600
 601                 if (entry_success < (free_entries - 1)) {
 602                         /* Prefetch descriptor index. */
 603                         rte_prefetch0(&vq->desc[head[entry_success+1]]);
 604                         rte_prefetch0(&vq->used->ring[(used_idx + 1) & (vq->size - 1)]);
 605                 }
 606
 607                 /* Update used index buffer information. */
 608                 vq->used->ring[used_idx].id = head[entry_success];
 609                 vq->used->ring[used_idx].len = 0;
 610
 611                 vb_offset = 0;
 612                 vb_avail = desc->len;
 613                 /* Allocate an mbuf and populate the structure. */
 614                 m = rte_pktmbuf_alloc(mbuf_pool);
 615                 if (unlikely(m == NULL)) {
 616                         RTE_LOG(ERR, VHOST_DATA,
 617                                 "Failed to allocate memory for mbuf.\n");
 618                         break;
 619                 }
 620                 seg_offset = 0;
 621                 seg_avail = m->buf_len - RTE_PKTMBUF_HEADROOM;
 622                 cpy_len = RTE_MIN(vb_avail, seg_avail);
 623
 624                 PRINT_PACKET(dev, (uintptr_t)vb_addr, desc->len, 0);
 625
 626                 seg_num++;
 627                 cur = m;
 628                 prev = m;
 629                 while (cpy_len != 0) {
 630                         rte_memcpy((void *)(rte_pktmbuf_mtod(cur, char *) + seg_offset),
 631                                 (void *)((uintptr_t)(vb_addr + vb_offset)),
 632                                 cpy_len);
 633
 634                         seg_offset += cpy_len;
 635                         vb_offset += cpy_len;
 636                         vb_avail -= cpy_len;
 637                         seg_avail -= cpy_len;
 638
 639                         if (vb_avail != 0) {
 640                                 /*
 641                                  * The segment reachs to its end,
 642                                  * while the virtio buffer in TX vring has
 643                                  * more data to be copied.
 644                                  */
 645                                 cur->data_len = seg_offset;
 646                                 m->pkt_len += seg_offset;
 647                                 /* Allocate mbuf and populate the structure. */
 648                                 cur = rte_pktmbuf_alloc(mbuf_pool);
 649                                 if (unlikely(cur == NULL)) {
 650                                         RTE_LOG(ERR, VHOST_DATA, "Failed to "
 651                                                 "allocate memory for mbuf.\n");
 652                                         rte_pktmbuf_free(m);
 653                                         alloc_err = 1;
 654                                         break;
 655                                 }
 656
 657                                 seg_num++;
 658                                 prev->next = cur;
 659                                 prev = cur;
 660                                 seg_offset = 0;
 661                                 seg_avail = cur->buf_len - RTE_PKTMBUF_HEADROOM;
 662                         } else {
 663                                 if (desc->flags & VRING_DESC_F_NEXT) {
 664                                         /*
 665                                          * There are more virtio buffers in
 666                                          * same vring entry need to be copied.
 667                                          */
 668                                         if (seg_avail == 0) {
 669                                                 /*
 670                                                  * The current segment hasn't
 671                                                  * room to accomodate more
 672                                                  * data.
 673                                                  */
 674                                                 cur->data_len = seg_offset;
 675                                                 m->pkt_len += seg_offset;
 676                                                 /*
 677                                                  * Allocate an mbuf and
 678                                                  * populate the structure.
 679                                                  */
 680                                                 cur = rte_pktmbuf_alloc(mbuf_pool);
 681                                                 if (unlikely(cur == NULL)) {
 682                                                         RTE_LOG(ERR,
 683                                                                 VHOST_DATA,
 684                                                                 "Failed to "
 685                                                                 "allocate memory "
 686                                                                 "for mbuf\n");
 687                                                         rte_pktmbuf_free(m);
 688                                                         alloc_err = 1;
 689                                                         break;
 690                                                 }
 691                                                 seg_num++;
 692                                                 prev->next = cur;
 693                                                 prev = cur;
 694                                                 seg_offset = 0;
 695                                                 seg_avail = cur->buf_len - RTE_PKTMBUF_HEADROOM;
 696                                         }
 697
 698                                         desc = &vq->desc[desc->next];
 699
 700                                         /* Buffer address translation. */
 701                                         vb_addr = gpa_to_vva(dev, desc->addr);
 702                                         /* Prefetch buffer address. */
 703                                         rte_prefetch0((void *)(uintptr_t)vb_addr);
 704                                         vb_offset = 0;
 705                                         vb_avail = desc->len;
 706
 707                                         PRINT_PACKET(dev, (uintptr_t)vb_addr,
 708                                                 desc->len, 0);
 709                                 } else {
 710                                         /* The whole packet completes. */
 711                                         cur->data_len = seg_offset;
 712                                         m->pkt_len += seg_offset;
 713                                         vb_avail = 0;
 714                                 }
 715                         }
 716
 717                         cpy_len = RTE_MIN(vb_avail, seg_avail);
 718                 }
 719
 720                 if (unlikely(alloc_err == 1))
 721                         break;
 722
 723                 m->nb_segs = seg_num;
 724
 725                 pkts[entry_success] = m;
 726                 vq->last_used_idx++;
 727                 entry_success++;
 728         }
 729
 730         rte_compiler_barrier();
 731         vq->used->idx += entry_success;
 732         /* Kick guest if required. */
 733         if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT))
 734                 eventfd_write((int)vq->callfd, 1);
 735         return entry_success;
 736 }