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         /* Number of input buffers, and max we've ever had. */
  45         unsigned int num, max;
  46
  47         /* Receive & send queues. */
  48         struct sk_buff_head recv;
  49         struct sk_buff_head send;
  50 };
  51
  52 static inline struct virtio_net_hdr *skb_vnet_hdr(struct sk_buff *skb)
  53 {
  54         return (struct virtio_net_hdr *)skb->cb;
  55 }
  56
  57 static inline void vnet_hdr_to_sg(struct scatterlist *sg, struct sk_buff *skb)
  58 {
  59         sg_init_one(sg, skb_vnet_hdr(skb), sizeof(struct virtio_net_hdr));
  60 }
  61
  62 static void skb_xmit_done(struct virtqueue *svq)
  63 {
  64         struct virtnet_info *vi = svq->vdev->priv;
  65
  66         /* Suppress further interrupts. */
  67         svq->vq_ops->disable_cb(svq);
  68         /* We were waiting for more output buffers. */
  69         netif_wake_queue(vi->dev);
  70 }
  71
  72 static void receive_skb(struct net_device *dev, struct sk_buff *skb,
  73                         unsigned len)
  74 {
  75         struct virtio_net_hdr *hdr = skb_vnet_hdr(skb);
  76
  77         if (unlikely(len < sizeof(struct virtio_net_hdr) + ETH_HLEN)) {
  78                 pr_debug("%s: short packet %i\n", dev->name, len);
  79                 dev->stats.rx_length_errors++;
  80                 goto drop;
  81         }
  82         len -= sizeof(struct virtio_net_hdr);
  83         BUG_ON(len > MAX_PACKET_LEN);
  84
  85         skb_trim(skb, len);
  86         skb->protocol = eth_type_trans(skb, dev);
  87         pr_debug("Receiving skb proto 0x%04x len %i type %i\n",
  88                  ntohs(skb->protocol), skb->len, skb->pkt_type);
  89         dev->stats.rx_bytes += skb->len;
  90         dev->stats.rx_packets++;
  91
  92         if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
  93                 pr_debug("Needs csum!\n");
  94                 if (!skb_partial_csum_set(skb,hdr->csum_start,hdr->csum_offset))
  95                         goto frame_err;
  96         }
  97
  98         if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
  99                 pr_debug("GSO!\n");
 100                 switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
 101                 case VIRTIO_NET_HDR_GSO_TCPV4:
 102                         skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
 103                         break;
 104                 case VIRTIO_NET_HDR_GSO_UDP:
 105                         skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
 106                         break;
 107                 case VIRTIO_NET_HDR_GSO_TCPV6:
 108                         skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
 109                         break;
 110                 default:
 111                         if (net_ratelimit())
 112                                 printk(KERN_WARNING "%s: bad gso type %u.\n",
 113                                        dev->name, hdr->gso_type);
 114                         goto frame_err;
 115                 }
 116
 117                 if (hdr->gso_type & VIRTIO_NET_HDR_GSO_ECN)
 118                         skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
 119
 120                 skb_shinfo(skb)->gso_size = hdr->gso_size;
 121                 if (skb_shinfo(skb)->gso_size == 0) {
 122                         if (net_ratelimit())
 123                                 printk(KERN_WARNING "%s: zero gso size.\n",
 124                                        dev->name);
 125                         goto frame_err;
 126                 }
 127
 128                 /* Header must be checked, and gso_segs computed. */
 129                 skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
 130                 skb_shinfo(skb)->gso_segs = 0;
 131         }
 132
 133         netif_receive_skb(skb);
 134         return;
 135
 136 frame_err:
 137         dev->stats.rx_frame_errors++;
 138 drop:
 139         dev_kfree_skb(skb);
 140 }
 141
 142 static void try_fill_recv(struct virtnet_info *vi)
 143 {
 144         struct sk_buff *skb;
 145         struct scatterlist sg[1+MAX_SKB_FRAGS];
 146         int num, err;
 147
 148         sg_init_table(sg, 1+MAX_SKB_FRAGS);
 149         for (;;) {
 150                 skb = netdev_alloc_skb(vi->dev, MAX_PACKET_LEN);
 151                 if (unlikely(!skb))
 152                         break;
 153
 154                 skb_put(skb, MAX_PACKET_LEN);
 155                 vnet_hdr_to_sg(sg, skb);
 156                 num = skb_to_sgvec(skb, sg+1, 0, skb->len) + 1;
 157                 skb_queue_head(&vi->recv, skb);
 158
 159                 err = vi->rvq->vq_ops->add_buf(vi->rvq, sg, 0, num, skb);
 160                 if (err) {
 161                         skb_unlink(skb, &vi->recv);
 162                         kfree_skb(skb);
 163                         break;
 164                 }
 165                 vi->num++;
 166         }
 167         if (unlikely(vi->num > vi->max))
 168                 vi->max = vi->num;
 169         vi->rvq->vq_ops->kick(vi->rvq);
 170 }
 171
 172 static void skb_recv_done(struct virtqueue *rvq)
 173 {
 174         struct virtnet_info *vi = rvq->vdev->priv;
 175         /* Schedule NAPI, Suppress further interrupts if successful. */
 176         if (netif_rx_schedule_prep(vi->dev, &vi->napi)) {
 177                 rvq->vq_ops->disable_cb(rvq);
 178                 __netif_rx_schedule(vi->dev, &vi->napi);
 179         }
 180 }
 181
 182 static int virtnet_poll(struct napi_struct *napi, int budget)
 183 {
 184         struct virtnet_info *vi = container_of(napi, struct virtnet_info, napi);
 185         struct sk_buff *skb = NULL;
 186         unsigned int len, received = 0;
 187
 188 again:
 189         while (received < budget &&
 190                (skb = vi->rvq->vq_ops->get_buf(vi->rvq, &len)) != NULL) {
 191                 __skb_unlink(skb, &vi->recv);
 192                 receive_skb(vi->dev, skb, len);
 193                 vi->num--;
 194                 received++;
 195         }
 196
 197         /* FIXME: If we oom and completely run out of inbufs, we need
 198          * to start a timer trying to fill more. */
 199         if (vi->num < vi->max / 2)
 200                 try_fill_recv(vi);
 201
 202         /* Out of packets? */
 203         if (received < budget) {
 204                 netif_rx_complete(vi->dev, napi);
 205                 if (unlikely(!vi->rvq->vq_ops->enable_cb(vi->rvq))
 206                     && napi_schedule_prep(napi)) {
 207                         vi->rvq->vq_ops->disable_cb(vi->rvq);
 208                         __netif_rx_schedule(vi->dev, napi);
 209                         goto again;
 210                 }
 211         }
 212
 213         return received;
 214 }
 215
 216 static void free_old_xmit_skbs(struct virtnet_info *vi)
 217 {
 218         struct sk_buff *skb;
 219         unsigned int len;
 220
 221         while ((skb = vi->svq->vq_ops->get_buf(vi->svq, &len)) != NULL) {
 222                 pr_debug("Sent skb %p\n", skb);
 223                 __skb_unlink(skb, &vi->send);
 224                 vi->dev->stats.tx_bytes += len;
 225                 vi->dev->stats.tx_packets++;
 226                 kfree_skb(skb);
 227         }
 228 }
 229
 230 static int start_xmit(struct sk_buff *skb, struct net_device *dev)
 231 {
 232         struct virtnet_info *vi = netdev_priv(dev);
 233         int num, err;
 234         struct scatterlist sg[1+MAX_SKB_FRAGS];
 235         struct virtio_net_hdr *hdr;
 236         const unsigned char *dest = ((struct ethhdr *)skb->data)->h_dest;
 237
 238         sg_init_table(sg, 1+MAX_SKB_FRAGS);
 239
 240         pr_debug("%s: xmit %p " MAC_FMT "\n", dev->name, skb,
 241                  dest[0], dest[1], dest[2],
 242                  dest[3], dest[4], dest[5]);
 243
 244         /* Encode metadata header at front. */
 245         hdr = skb_vnet_hdr(skb);
 246         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 247                 hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
 248                 hdr->csum_start = skb->csum_start - skb_headroom(skb);
 249                 hdr->csum_offset = skb->csum_offset;
 250         } else {
 251                 hdr->flags = 0;
 252                 hdr->csum_offset = hdr->csum_start = 0;
 253         }
 254
 255         if (skb_is_gso(skb)) {
 256                 hdr->hdr_len = skb_transport_header(skb) - skb->data;
 257                 hdr->gso_size = skb_shinfo(skb)->gso_size;
 258                 if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
 259                         hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
 260                 else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
 261                         hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
 262                 else if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP)
 263                         hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP;
 264                 else
 265                         BUG();
 266                 if (skb_shinfo(skb)->gso_type & SKB_GSO_TCP_ECN)
 267                         hdr->gso_type |= VIRTIO_NET_HDR_GSO_ECN;
 268         } else {
 269                 hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
 270                 hdr->gso_size = hdr->hdr_len = 0;
 271         }
 272
 273         vnet_hdr_to_sg(sg, skb);
 274         num = skb_to_sgvec(skb, sg+1, 0, skb->len) + 1;
 275         __skb_queue_head(&vi->send, skb);
 276
 277 again:
 278         /* Free up any pending old buffers before queueing new ones. */
 279         free_old_xmit_skbs(vi);
 280         err = vi->svq->vq_ops->add_buf(vi->svq, sg, num, 0, skb);
 281         if (err) {
 282                 pr_debug("%s: virtio not prepared to send\n", dev->name);
 283                 netif_stop_queue(dev);
 284
 285                 /* Activate callback for using skbs: if this returns false it
 286                  * means some were used in the meantime. */
 287                 if (unlikely(!vi->svq->vq_ops->enable_cb(vi->svq))) {
 288                         printk("Unlikely: restart svq race\n");
 289                         vi->svq->vq_ops->disable_cb(vi->svq);
 290                         netif_start_queue(dev);
 291                         goto again;
 292                 }
 293                 __skb_unlink(skb, &vi->send);
 294
 295                 return NETDEV_TX_BUSY;
 296         }
 297         vi->svq->vq_ops->kick(vi->svq);
 298
 299         return 0;
 300 }
 301
 302 #ifdef CONFIG_NET_POLL_CONTROLLER
 303 static void virtnet_netpoll(struct net_device *dev)
 304 {
 305         struct virtnet_info *vi = netdev_priv(dev);
 306
 307         napi_schedule(&vi->napi);
 308 }
 309 #endif
 310
 311 static int virtnet_open(struct net_device *dev)
 312 {
 313         struct virtnet_info *vi = netdev_priv(dev);
 314
 315         napi_enable(&vi->napi);
 316
 317         /* If all buffers were filled by other side before we napi_enabled, we
 318          * won't get another interrupt, so process any outstanding packets
 319          * now.  virtnet_poll wants re-enable the queue, so we disable here.
 320          * We synchronize against interrupts via NAPI_STATE_SCHED */
 321         if (netif_rx_schedule_prep(dev, &vi->napi)) {
 322                 vi->rvq->vq_ops->disable_cb(vi->rvq);
 323                 __netif_rx_schedule(dev, &vi->napi);
 324         }
 325         return 0;
 326 }
 327
 328 static int virtnet_close(struct net_device *dev)
 329 {
 330         struct virtnet_info *vi = netdev_priv(dev);
 331
 332         napi_disable(&vi->napi);
 333
 334         return 0;
 335 }
 336
 337 static int virtnet_probe(struct virtio_device *vdev)
 338 {
 339         int err;
 340         struct net_device *dev;
 341         struct virtnet_info *vi;
 342
 343         /* Allocate ourselves a network device with room for our info */
 344         dev = alloc_etherdev(sizeof(struct virtnet_info));
 345         if (!dev)
 346                 return -ENOMEM;
 347
 348         /* Set up network device as normal. */
 349         dev->open = virtnet_open;
 350         dev->stop = virtnet_close;
 351         dev->hard_start_xmit = start_xmit;
 352         dev->features = NETIF_F_HIGHDMA;
 353 #ifdef CONFIG_NET_POLL_CONTROLLER
 354         dev->poll_controller = virtnet_netpoll;
 355 #endif
 356         SET_NETDEV_DEV(dev, &vdev->dev);
 357
 358         /* Do we support "hardware" checksums? */
 359         if (csum && vdev->config->feature(vdev, VIRTIO_NET_F_CSUM)) {
 360                 /* This opens up the world of extra features. */
 361                 dev->features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST;
 362                 if (gso && vdev->config->feature(vdev, VIRTIO_NET_F_GSO)) {
 363                         dev->features |= NETIF_F_TSO | NETIF_F_UFO
 364                                 | NETIF_F_TSO_ECN | NETIF_F_TSO6;
 365                 }
 366         }
 367
 368         /* Configuration may specify what MAC to use.  Otherwise random. */
 369         if (vdev->config->feature(vdev, VIRTIO_NET_F_MAC)) {
 370                 vdev->config->get(vdev,
 371                                   offsetof(struct virtio_net_config, mac),
 372                                   dev->dev_addr, dev->addr_len);
 373         } else
 374                 random_ether_addr(dev->dev_addr);
 375
 376         /* Set up our device-specific information */
 377         vi = netdev_priv(dev);
 378         netif_napi_add(dev, &vi->napi, virtnet_poll, napi_weight);
 379         vi->dev = dev;
 380         vi->vdev = vdev;
 381         vdev->priv = vi;
 382
 383         /* We expect two virtqueues, receive then send. */
 384         vi->rvq = vdev->config->find_vq(vdev, 0, skb_recv_done);
 385         if (IS_ERR(vi->rvq)) {
 386                 err = PTR_ERR(vi->rvq);
 387                 goto free;
 388         }
 389
 390         vi->svq = vdev->config->find_vq(vdev, 1, skb_xmit_done);
 391         if (IS_ERR(vi->svq)) {
 392                 err = PTR_ERR(vi->svq);
 393                 goto free_recv;
 394         }
 395
 396         /* Initialize our empty receive and send queues. */
 397         skb_queue_head_init(&vi->recv);
 398         skb_queue_head_init(&vi->send);
 399
 400         err = register_netdev(dev);
 401         if (err) {
 402                 pr_debug("virtio_net: registering device failed\n");
 403                 goto free_send;
 404         }
 405
 406         /* Last of all, set up some receive buffers. */
 407         try_fill_recv(vi);
 408
 409         /* If we didn't even get one input buffer, we're useless. */
 410         if (vi->num == 0) {
 411                 err = -ENOMEM;
 412                 goto unregister;
 413         }
 414
 415         pr_debug("virtnet: registered device %s\n", dev->name);
 416         return 0;
 417
 418 unregister:
 419         unregister_netdev(dev);
 420 free_send:
 421         vdev->config->del_vq(vi->svq);
 422 free_recv:
 423         vdev->config->del_vq(vi->rvq);
 424 free:
 425         free_netdev(dev);
 426         return err;
 427 }
 428
 429 static void virtnet_remove(struct virtio_device *vdev)
 430 {
 431         struct virtnet_info *vi = vdev->priv;
 432         struct sk_buff *skb;
 433
 434         /* Stop all the virtqueues. */
 435         vdev->config->reset(vdev);
 436
 437         /* Free our skbs in send and recv queues, if any. */
 438         while ((skb = __skb_dequeue(&vi->recv)) != NULL) {
 439                 kfree_skb(skb);
 440                 vi->num--;
 441         }
 442         while ((skb = __skb_dequeue(&vi->send)) != NULL)
 443                 kfree_skb(skb);
 444
 445         BUG_ON(vi->num != 0);
 446
 447         vdev->config->del_vq(vi->svq);
 448         vdev->config->del_vq(vi->rvq);
 449         unregister_netdev(vi->dev);
 450         free_netdev(vi->dev);
 451 }
 452
 453 static struct virtio_device_id id_table[] = {
 454         { VIRTIO_ID_NET, VIRTIO_DEV_ANY_ID },
 455         { 0 },
 456 };
 457
 458 static struct virtio_driver virtio_net = {
 459         .driver.name =  KBUILD_MODNAME,
 460         .driver.owner = THIS_MODULE,
 461         .id_table =     id_table,
 462         .probe =        virtnet_probe,
 463         .remove =       __devexit_p(virtnet_remove),
 464 };
 465
 466 static int __init init(void)
 467 {
 468         return register_virtio_driver(&virtio_net);
 469 }
 470
 471 static void __exit fini(void)
 472 {
 473         unregister_virtio_driver(&virtio_net);
 474 }
 475 module_init(init);
 476 module_exit(fini);
 477
 478 MODULE_DEVICE_TABLE(virtio, id_table);
 479 MODULE_DESCRIPTION("Virtio network driver");
 480 MODULE_LICENSE("GPL");