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