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