drivers/net/virtio_net.c

   1 /* A simple network driver using virtio.
   2  *
   3  * Copyright 2007 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18  */
  19 //#define DEBUG
  20 #include <linux/netdevice.h>
  21 #include <linux/etherdevice.h>
  22 #include <linux/ethtool.h>
  23 #include <linux/module.h>
  24 #include <linux/virtio.h>
  25 #include <linux/virtio_net.h>
  26 #include <linux/scatterlist.h>
  27
  28 static int napi_weight = 128;
  29 module_param(napi_weight, int, 0444);
  30
  31 static int csum = 1, gso = 1;
  32 module_param(csum, bool, 0444);
  33 module_param(gso, bool, 0444);
  34
  35 /* FIXME: MTU in config. */
  36 #define MAX_PACKET_LEN (ETH_HLEN+ETH_DATA_LEN)
  37
  38 struct virtnet_info
  39 {
  40         struct virtio_device *vdev;
  41         struct virtqueue *rvq, *svq;
  42         struct net_device *dev;
  43         struct napi_struct napi;
  44
  45         /* The skb we couldn't send because buffers were full. */
  46         struct sk_buff *last_xmit_skb;
  47
  48         /* If we need to free in a timer, this is it. */
  49         struct timer_list xmit_free_timer;
  50
  51         /* Number of input buffers, and max we've ever had. */
  52         unsigned int num, max;
  53
  54         /* For cleaning up after transmission. */
  55         struct tasklet_struct tasklet;
  56         bool free_in_tasklet;
  57
  58         /* Receive & send queues. */
  59         struct sk_buff_head recv;
  60         struct sk_buff_head send;
  61 };
  62
  63 static inline struct virtio_net_hdr *skb_vnet_hdr(struct sk_buff *skb)
  64 {
  65         return (struct virtio_net_hdr *)skb->cb;
  66 }
  67
  68 static inline void vnet_hdr_to_sg(struct scatterlist *sg, struct sk_buff *skb)
  69 {
  70         sg_init_one(sg, skb_vnet_hdr(skb), sizeof(struct virtio_net_hdr));
  71 }
  72
  73 static void skb_xmit_done(struct virtqueue *svq)
  74 {
  75         struct virtnet_info *vi = svq->vdev->priv;
  76
  77         /* Suppress further interrupts. */
  78         svq->vq_ops->disable_cb(svq);
  79
  80         /* We were probably waiting for more output buffers. */
  81         netif_wake_queue(vi->dev);
  82
  83         /* Make sure we re-xmit last_xmit_skb: if there are no more packets
  84          * queued, start_xmit won't be called. */
  85         tasklet_schedule(&vi->tasklet);
  86 }
  87
  88 static void receive_skb(struct net_device *dev, struct sk_buff *skb,
  89                         unsigned len)
  90 {
  91         struct virtio_net_hdr *hdr = skb_vnet_hdr(skb);
  92
  93         if (unlikely(len < sizeof(struct virtio_net_hdr) + ETH_HLEN)) {
  94                 pr_debug("%s: short packet %i\n", dev->name, len);
  95                 dev->stats.rx_length_errors++;
  96                 goto drop;
  97         }
  98         len -= sizeof(struct virtio_net_hdr);
  99         BUG_ON(len > MAX_PACKET_LEN);
 100
 101         skb_trim(skb, len);
 102
 103         dev->stats.rx_bytes += skb->len;
 104         dev->stats.rx_packets++;
 105
 106         if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
 107                 pr_debug("Needs csum!\n");
 108                 if (!skb_partial_csum_set(skb,hdr->csum_start,hdr->csum_offset))
 109                         goto frame_err;
 110         }
 111
 112         skb->protocol = eth_type_trans(skb, dev);
 113         pr_debug("Receiving skb proto 0x%04x len %i type %i\n",
 114                  ntohs(skb->protocol), skb->len, skb->pkt_type);
 115
 116         if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
 117                 pr_debug("GSO!\n");
 118                 switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
 119                 case VIRTIO_NET_HDR_GSO_TCPV4:
 120                         skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
 121                         break;
 122                 case VIRTIO_NET_HDR_GSO_UDP:
 123                         skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
 124                         break;
 125                 case VIRTIO_NET_HDR_GSO_TCPV6:
 126                         skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
 127                         break;
 128                 default:
 129                         if (net_ratelimit())
 130                                 printk(KERN_WARNING "%s: bad gso type %u.\n",
 131                                        dev->name, hdr->gso_type);
 132                         goto frame_err;
 133                 }
 134
 135                 if (hdr->gso_type & VIRTIO_NET_HDR_GSO_ECN)
 136                         skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
 137
 138                 skb_shinfo(skb)->gso_size = hdr->gso_size;
 139                 if (skb_shinfo(skb)->gso_size == 0) {
 140                         if (net_ratelimit())
 141                                 printk(KERN_WARNING "%s: zero gso size.\n",
 142                                        dev->name);
 143                         goto frame_err;
 144                 }
 145
 146                 /* Header must be checked, and gso_segs computed. */
 147                 skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
 148                 skb_shinfo(skb)->gso_segs = 0;
 149         }
 150
 151         netif_receive_skb(skb);
 152         return;
 153
 154 frame_err:
 155         dev->stats.rx_frame_errors++;
 156 drop:
 157         dev_kfree_skb(skb);
 158 }
 159
 160 static void try_fill_recv(struct virtnet_info *vi)
 161 {
 162         struct sk_buff *skb;
 163         struct scatterlist sg[2+MAX_SKB_FRAGS];
 164         int num, err;
 165
 166         sg_init_table(sg, 2+MAX_SKB_FRAGS);
 167         for (;;) {
 168                 skb = netdev_alloc_skb(vi->dev, MAX_PACKET_LEN);
 169                 if (unlikely(!skb))
 170                         break;
 171
 172                 skb_put(skb, MAX_PACKET_LEN);
 173                 vnet_hdr_to_sg(sg, skb);
 174                 num = skb_to_sgvec(skb, sg+1, 0, skb->len) + 1;
 175                 skb_queue_head(&vi->recv, skb);
 176
 177                 err = vi->rvq->vq_ops->add_buf(vi->rvq, sg, 0, num, skb);
 178                 if (err) {
 179                         skb_unlink(skb, &vi->recv);
 180                         kfree_skb(skb);
 181                         break;
 182                 }
 183                 vi->num++;
 184         }
 185         if (unlikely(vi->num > vi->max))
 186                 vi->max = vi->num;
 187         vi->rvq->vq_ops->kick(vi->rvq);
 188 }
 189
 190 static void skb_recv_done(struct virtqueue *rvq)
 191 {
 192         struct virtnet_info *vi = rvq->vdev->priv;
 193         /* Schedule NAPI, Suppress further interrupts if successful. */
 194         if (netif_rx_schedule_prep(vi->dev, &vi->napi)) {
 195                 rvq->vq_ops->disable_cb(rvq);
 196                 __netif_rx_schedule(vi->dev, &vi->napi);
 197         }
 198 }
 199
 200 static int virtnet_poll(struct napi_struct *napi, int budget)
 201 {
 202         struct virtnet_info *vi = container_of(napi, struct virtnet_info, napi);
 203         struct sk_buff *skb = NULL;
 204         unsigned int len, received = 0;
 205
 206 again:
 207         while (received < budget &&
 208                (skb = vi->rvq->vq_ops->get_buf(vi->rvq, &len)) != NULL) {
 209                 __skb_unlink(skb, &vi->recv);
 210                 receive_skb(vi->dev, skb, len);
 211                 vi->num--;
 212                 received++;
 213         }
 214
 215         /* FIXME: If we oom and completely run out of inbufs, we need
 216          * to start a timer trying to fill more. */
 217         if (vi->num < vi->max / 2)
 218                 try_fill_recv(vi);
 219
 220         /* Out of packets? */
 221         if (received < budget) {
 222                 netif_rx_complete(vi->dev, napi);
 223                 if (unlikely(!vi->rvq->vq_ops->enable_cb(vi->rvq))
 224                     && napi_schedule_prep(napi)) {
 225                         vi->rvq->vq_ops->disable_cb(vi->rvq);
 226                         __netif_rx_schedule(vi->dev, napi);
 227                         goto again;
 228                 }
 229         }
 230
 231         return received;
 232 }
 233
 234 static void free_old_xmit_skbs(struct virtnet_info *vi)
 235 {
 236         struct sk_buff *skb;
 237         unsigned int len;
 238
 239         while ((skb = vi->svq->vq_ops->get_buf(vi->svq, &len)) != NULL) {
 240                 pr_debug("Sent skb %p\n", skb);
 241                 __skb_unlink(skb, &vi->send);
 242                 vi->dev->stats.tx_bytes += skb->len;
 243                 vi->dev->stats.tx_packets++;
 244                 kfree_skb(skb);
 245         }
 246 }
 247
 248 /* If the virtio transport doesn't always notify us when all in-flight packets
 249  * are consumed, we fall back to using this function on a timer to free them. */
 250 static void xmit_free(unsigned long data)
 251 {
 252         struct virtnet_info *vi = (void *)data;
 253
 254         netif_tx_lock(vi->dev);
 255
 256         free_old_xmit_skbs(vi);
 257
 258         if (!skb_queue_empty(&vi->send))
 259                 mod_timer(&vi->xmit_free_timer, jiffies + (HZ/10));
 260
 261         netif_tx_unlock(vi->dev);
 262 }
 263
 264 static int xmit_skb(struct virtnet_info *vi, struct sk_buff *skb)
 265 {
 266         int num, err;
 267         struct scatterlist sg[2+MAX_SKB_FRAGS];
 268         struct virtio_net_hdr *hdr;
 269         const unsigned char *dest = ((struct ethhdr *)skb->data)->h_dest;
 270
 271         sg_init_table(sg, 2+MAX_SKB_FRAGS);
 272
 273         pr_debug("%s: xmit %p " MAC_FMT "\n", vi->dev->name, skb,
 274                  dest[0], dest[1], dest[2],
 275                  dest[3], dest[4], dest[5]);
 276
 277         /* Encode metadata header at front. */
 278         hdr = skb_vnet_hdr(skb);
 279         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 280                 hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
 281                 hdr->csum_start = skb->csum_start - skb_headroom(skb);
 282                 hdr->csum_offset = skb->csum_offset;
 283         } else {
 284                 hdr->flags = 0;
 285                 hdr->csum_offset = hdr->csum_start = 0;
 286         }
 287
 288         if (skb_is_gso(skb)) {
 289                 hdr->hdr_len = skb_transport_header(skb) - skb->data;
 290                 hdr->gso_size = skb_shinfo(skb)->gso_size;
 291                 if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
 292                         hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
 293                 else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
 294                         hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
 295                 else if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP)
 296                         hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP;
 297                 else
 298                         BUG();
 299                 if (skb_shinfo(skb)->gso_type & SKB_GSO_TCP_ECN)
 300                         hdr->gso_type |= VIRTIO_NET_HDR_GSO_ECN;
 301         } else {
 302                 hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
 303                 hdr->gso_size = hdr->hdr_len = 0;
 304         }
 305
 306         vnet_hdr_to_sg(sg, skb);
 307         num = skb_to_sgvec(skb, sg+1, 0, skb->len) + 1;
 308
 309         err = vi->svq->vq_ops->add_buf(vi->svq, sg, num, 0, skb);
 310         if (!err && !vi->free_in_tasklet)
 311                 mod_timer(&vi->xmit_free_timer, jiffies + (HZ/10));
 312
 313         return err;
 314 }
 315
 316 static void xmit_tasklet(unsigned long data)
 317 {
 318         struct virtnet_info *vi = (void *)data;
 319
 320         netif_tx_lock_bh(vi->dev);
 321         if (vi->last_xmit_skb && xmit_skb(vi, vi->last_xmit_skb) == 0) {
 322                 vi->svq->vq_ops->kick(vi->svq);
 323                 vi->last_xmit_skb = NULL;
 324         }
 325         if (vi->free_in_tasklet)
 326                 free_old_xmit_skbs(vi);
 327         netif_tx_unlock_bh(vi->dev);
 328 }
 329
 330 static int start_xmit(struct sk_buff *skb, struct net_device *dev)
 331 {
 332         struct virtnet_info *vi = netdev_priv(dev);
 333
 334 again:
 335         /* Free up any pending old buffers before queueing new ones. */
 336         free_old_xmit_skbs(vi);
 337
 338         /* If we has a buffer left over from last time, send it now. */
 339         if (unlikely(vi->last_xmit_skb) &&
 340             xmit_skb(vi, vi->last_xmit_skb) != 0)
 341                 goto stop_queue;
 342
 343         vi->last_xmit_skb = NULL;
 344
 345         /* Put new one in send queue and do transmit */
 346         if (likely(skb)) {
 347                 __skb_queue_head(&vi->send, skb);
 348                 if (xmit_skb(vi, skb) != 0) {
 349                         vi->last_xmit_skb = skb;
 350                         skb = NULL;
 351                         goto stop_queue;
 352                 }
 353         }
 354 done:
 355         vi->svq->vq_ops->kick(vi->svq);
 356         return NETDEV_TX_OK;
 357
 358 stop_queue:
 359         pr_debug("%s: virtio not prepared to send\n", dev->name);
 360         netif_stop_queue(dev);
 361
 362         /* Activate callback for using skbs: if this returns false it
 363          * means some were used in the meantime. */
 364         if (unlikely(!vi->svq->vq_ops->enable_cb(vi->svq))) {
 365                 vi->svq->vq_ops->disable_cb(vi->svq);
 366                 netif_start_queue(dev);
 367                 goto again;
 368         }
 369         if (skb) {
 370                 /* Drop this skb: we only queue one. */
 371                 vi->dev->stats.tx_dropped++;
 372                 kfree_skb(skb);
 373         }
 374         goto done;
 375 }
 376
 377 #ifdef CONFIG_NET_POLL_CONTROLLER
 378 static void virtnet_netpoll(struct net_device *dev)
 379 {
 380         struct virtnet_info *vi = netdev_priv(dev);
 381
 382         napi_schedule(&vi->napi);
 383 }
 384 #endif
 385
 386 static int virtnet_open(struct net_device *dev)
 387 {
 388         struct virtnet_info *vi = netdev_priv(dev);
 389
 390         napi_enable(&vi->napi);
 391
 392         /* If all buffers were filled by other side before we napi_enabled, we
 393          * won't get another interrupt, so process any outstanding packets
 394          * now.  virtnet_poll wants re-enable the queue, so we disable here.
 395          * We synchronize against interrupts via NAPI_STATE_SCHED */
 396         if (netif_rx_schedule_prep(dev, &vi->napi)) {
 397                 vi->rvq->vq_ops->disable_cb(vi->rvq);
 398                 __netif_rx_schedule(dev, &vi->napi);
 399         }
 400         return 0;
 401 }
 402
 403 static int virtnet_close(struct net_device *dev)
 404 {
 405         struct virtnet_info *vi = netdev_priv(dev);
 406
 407         napi_disable(&vi->napi);
 408
 409         return 0;
 410 }
 411
 412 static int virtnet_set_tx_csum(struct net_device *dev, u32 data)
 413 {
 414         struct virtnet_info *vi = netdev_priv(dev);
 415         struct virtio_device *vdev = vi->vdev;
 416
 417         if (data && !virtio_has_feature(vdev, VIRTIO_NET_F_CSUM))
 418                 return -ENOSYS;
 419
 420         return ethtool_op_set_tx_hw_csum(dev, data);
 421 }
 422
 423 static struct ethtool_ops virtnet_ethtool_ops = {
 424         .set_tx_csum = virtnet_set_tx_csum,
 425         .set_sg = ethtool_op_set_sg,
 426 };
 427
 428 static int virtnet_probe(struct virtio_device *vdev)
 429 {
 430         int err;
 431         struct net_device *dev;
 432         struct virtnet_info *vi;
 433
 434         /* Allocate ourselves a network device with room for our info */
 435         dev = alloc_etherdev(sizeof(struct virtnet_info));
 436         if (!dev)
 437                 return -ENOMEM;
 438
 439         /* Set up network device as normal. */
 440         dev->open = virtnet_open;
 441         dev->stop = virtnet_close;
 442         dev->hard_start_xmit = start_xmit;
 443         dev->features = NETIF_F_HIGHDMA;
 444 #ifdef CONFIG_NET_POLL_CONTROLLER
 445         dev->poll_controller = virtnet_netpoll;
 446 #endif
 447         SET_ETHTOOL_OPS(dev, &virtnet_ethtool_ops);
 448         SET_NETDEV_DEV(dev, &vdev->dev);
 449
 450         /* Do we support "hardware" checksums? */
 451         if (csum && virtio_has_feature(vdev, VIRTIO_NET_F_CSUM)) {
 452                 /* This opens up the world of extra features. */
 453                 dev->features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST;
 454                 if (gso && virtio_has_feature(vdev, VIRTIO_NET_F_GSO)) {
 455                         dev->features |= NETIF_F_TSO | NETIF_F_UFO
 456                                 | NETIF_F_TSO_ECN | NETIF_F_TSO6;
 457                 }
 458                 /* Individual feature bits: what can host handle? */
 459                 if (gso && virtio_has_feature(vdev, VIRTIO_NET_F_HOST_TSO4))
 460                         dev->features |= NETIF_F_TSO;
 461                 if (gso && virtio_has_feature(vdev, VIRTIO_NET_F_HOST_TSO6))
 462                         dev->features |= NETIF_F_TSO6;
 463                 if (gso && virtio_has_feature(vdev, VIRTIO_NET_F_HOST_ECN))
 464                         dev->features |= NETIF_F_TSO_ECN;
 465                 if (gso && virtio_has_feature(vdev, VIRTIO_NET_F_HOST_UFO))
 466                         dev->features |= NETIF_F_UFO;
 467         }
 468
 469         /* Configuration may specify what MAC to use.  Otherwise random. */
 470         if (virtio_has_feature(vdev, VIRTIO_NET_F_MAC)) {
 471                 vdev->config->get(vdev,
 472                                   offsetof(struct virtio_net_config, mac),
 473                                   dev->dev_addr, dev->addr_len);
 474         } else
 475                 random_ether_addr(dev->dev_addr);
 476
 477         /* Set up our device-specific information */
 478         vi = netdev_priv(dev);
 479         netif_napi_add(dev, &vi->napi, virtnet_poll, napi_weight);
 480         vi->dev = dev;
 481         vi->vdev = vdev;
 482         vdev->priv = vi;
 483
 484         /* If they give us a callback when all buffers are done, we don't need
 485          * the timer. */
 486         vi->free_in_tasklet = virtio_has_feature(vdev,VIRTIO_F_NOTIFY_ON_EMPTY);
 487
 488         /* We expect two virtqueues, receive then send. */
 489         vi->rvq = vdev->config->find_vq(vdev, 0, skb_recv_done);
 490         if (IS_ERR(vi->rvq)) {
 491                 err = PTR_ERR(vi->rvq);
 492                 goto free;
 493         }
 494
 495         vi->svq = vdev->config->find_vq(vdev, 1, skb_xmit_done);
 496         if (IS_ERR(vi->svq)) {
 497                 err = PTR_ERR(vi->svq);
 498                 goto free_recv;
 499         }
 500
 501         /* Initialize our empty receive and send queues. */
 502         skb_queue_head_init(&vi->recv);
 503         skb_queue_head_init(&vi->send);
 504
 505         tasklet_init(&vi->tasklet, xmit_tasklet, (unsigned long)vi);
 506
 507         if (!vi->free_in_tasklet)
 508                 setup_timer(&vi->xmit_free_timer, xmit_free, (unsigned long)vi);
 509
 510         err = register_netdev(dev);
 511         if (err) {
 512                 pr_debug("virtio_net: registering device failed\n");
 513                 goto free_send;
 514         }
 515
 516         /* Last of all, set up some receive buffers. */
 517         try_fill_recv(vi);
 518
 519         /* If we didn't even get one input buffer, we're useless. */
 520         if (vi->num == 0) {
 521                 err = -ENOMEM;
 522                 goto unregister;
 523         }
 524
 525         pr_debug("virtnet: registered device %s\n", dev->name);
 526         return 0;
 527
 528 unregister:
 529         unregister_netdev(dev);
 530 free_send:
 531         vdev->config->del_vq(vi->svq);
 532 free_recv:
 533         vdev->config->del_vq(vi->rvq);
 534 free:
 535         free_netdev(dev);
 536         return err;
 537 }
 538
 539 static void virtnet_remove(struct virtio_device *vdev)
 540 {
 541         struct virtnet_info *vi = vdev->priv;
 542         struct sk_buff *skb;
 543
 544         /* Stop all the virtqueues. */
 545         vdev->config->reset(vdev);
 546
 547         if (!vi->free_in_tasklet)
 548                 del_timer_sync(&vi->xmit_free_timer);
 549
 550         /* Free our skbs in send and recv queues, if any. */
 551         while ((skb = __skb_dequeue(&vi->recv)) != NULL) {
 552                 kfree_skb(skb);
 553                 vi->num--;
 554         }
 555         __skb_queue_purge(&vi->send);
 556
 557         BUG_ON(vi->num != 0);
 558
 559         vdev->config->del_vq(vi->svq);
 560         vdev->config->del_vq(vi->rvq);
 561         unregister_netdev(vi->dev);
 562         free_netdev(vi->dev);
 563 }
 564
 565 static struct virtio_device_id id_table[] = {
 566         { VIRTIO_ID_NET, VIRTIO_DEV_ANY_ID },
 567         { 0 },
 568 };
 569
 570 static unsigned int features[] = {
 571         VIRTIO_NET_F_CSUM, VIRTIO_NET_F_GUEST_CSUM,
 572         VIRTIO_NET_F_GSO, VIRTIO_NET_F_MAC,
 573         VIRTIO_NET_F_HOST_TSO4, VIRTIO_NET_F_HOST_UFO, VIRTIO_NET_F_HOST_TSO6,
 574         VIRTIO_NET_F_HOST_ECN, VIRTIO_F_NOTIFY_ON_EMPTY,
 575 };
 576
 577 static struct virtio_driver virtio_net = {
 578         .feature_table = features,
 579         .feature_table_size = ARRAY_SIZE(features),
 580         .driver.name =  KBUILD_MODNAME,
 581         .driver.owner = THIS_MODULE,
 582         .id_table =     id_table,
 583         .probe =        virtnet_probe,
 584         .remove =       __devexit_p(virtnet_remove),
 585 };
 586
 587 static int __init init(void)
 588 {
 589         return register_virtio_driver(&virtio_net);
 590 }
 591
 592 static void __exit fini(void)
 593 {
 594         unregister_virtio_driver(&virtio_net);
 595 }
 596 module_init(init);
 597 module_exit(fini);
 598
 599 MODULE_DEVICE_TABLE(virtio, id_table);
 600 MODULE_DESCRIPTION("Virtio network driver");
 601 MODULE_LICENSE("GPL");