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 /* FIXME: MTU in config. */
  28 #define MAX_PACKET_LEN (ETH_HLEN+ETH_DATA_LEN)
  29
  30 struct virtnet_info
  31 {
  32         struct virtio_device *vdev;
  33         struct virtqueue *rvq, *svq;
  34         struct net_device *dev;
  35         struct napi_struct napi;
  36
  37         /* Number of input buffers, and max we've ever had. */
  38         unsigned int num, max;
  39
  40         /* Receive & send queues. */
  41         struct sk_buff_head recv;
  42         struct sk_buff_head send;
  43 };
  44
  45 static inline struct virtio_net_hdr *skb_vnet_hdr(struct sk_buff *skb)
  46 {
  47         return (struct virtio_net_hdr *)skb->cb;
  48 }
  49
  50 static inline void vnet_hdr_to_sg(struct scatterlist *sg, struct sk_buff *skb)
  51 {
  52         sg_init_one(sg, skb_vnet_hdr(skb), sizeof(struct virtio_net_hdr));
  53 }
  54
  55 static bool skb_xmit_done(struct virtqueue *rvq)
  56 {
  57         struct virtnet_info *vi = rvq->vdev->priv;
  58
  59         /* In case we were waiting for output buffers. */
  60         netif_wake_queue(vi->dev);
  61         return true;
  62 }
  63
  64 static void receive_skb(struct net_device *dev, struct sk_buff *skb,
  65                         unsigned len)
  66 {
  67         struct virtio_net_hdr *hdr = skb_vnet_hdr(skb);
  68
  69         if (unlikely(len < sizeof(struct virtio_net_hdr) + ETH_HLEN)) {
  70                 pr_debug("%s: short packet %i\n", dev->name, len);
  71                 dev->stats.rx_length_errors++;
  72                 goto drop;
  73         }
  74         len -= sizeof(struct virtio_net_hdr);
  75         BUG_ON(len > MAX_PACKET_LEN);
  76
  77         skb_trim(skb, len);
  78         skb->protocol = eth_type_trans(skb, dev);
  79         pr_debug("Receiving skb proto 0x%04x len %i type %i\n",
  80                  ntohs(skb->protocol), skb->len, skb->pkt_type);
  81         dev->stats.rx_bytes += skb->len;
  82         dev->stats.rx_packets++;
  83
  84         if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
  85                 pr_debug("Needs csum!\n");
  86                 skb->ip_summed = CHECKSUM_PARTIAL;
  87                 skb->csum_start = hdr->csum_start;
  88                 skb->csum_offset = hdr->csum_offset;
  89                 if (skb->csum_start > skb->len - 2
  90                     || skb->csum_offset > skb->len - 2) {
  91                         if (net_ratelimit())
  92                                 printk(KERN_WARNING "%s: csum=%u/%u len=%u\n",
  93                                        dev->name, skb->csum_start,
  94                                        skb->csum_offset, skb->len);
  95                         goto frame_err;
  96                 }
  97         }
  98
  99         if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
 100                 pr_debug("GSO!\n");
 101                 switch (hdr->gso_type) {
 102                 case VIRTIO_NET_HDR_GSO_TCPV4:
 103                         skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
 104                         break;
 105                 case VIRTIO_NET_HDR_GSO_TCPV4_ECN:
 106                         skb_shinfo(skb)->gso_type = SKB_GSO_TCP_ECN;
 107                         break;
 108                 case VIRTIO_NET_HDR_GSO_UDP:
 109                         skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
 110                         break;
 111                 case VIRTIO_NET_HDR_GSO_TCPV6:
 112                         skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
 113                         break;
 114                 default:
 115                         if (net_ratelimit())
 116                                 printk(KERN_WARNING "%s: bad gso type %u.\n",
 117                                        dev->name, hdr->gso_type);
 118                         goto frame_err;
 119                 }
 120
 121                 skb_shinfo(skb)->gso_size = hdr->gso_size;
 122                 if (skb_shinfo(skb)->gso_size == 0) {
 123                         if (net_ratelimit())
 124                                 printk(KERN_WARNING "%s: zero gso size.\n",
 125                                        dev->name);
 126                         goto frame_err;
 127                 }
 128
 129                 /* Header must be checked, and gso_segs computed. */
 130                 skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
 131                 skb_shinfo(skb)->gso_segs = 0;
 132         }
 133
 134         netif_receive_skb(skb);
 135         return;
 136
 137 frame_err:
 138         dev->stats.rx_frame_errors++;
 139 drop:
 140         dev_kfree_skb(skb);
 141 }
 142
 143 static void try_fill_recv(struct virtnet_info *vi)
 144 {
 145         struct sk_buff *skb;
 146         struct scatterlist sg[1+MAX_SKB_FRAGS];
 147         int num, err;
 148
 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 bool skb_recv_done(struct virtqueue *rvq)
 173 {
 174         struct virtnet_info *vi = rvq->vdev->priv;
 175         netif_rx_schedule(vi->dev, &vi->napi);
 176         /* Suppress further interrupts. */
 177         return false;
 178 }
 179
 180 static int virtnet_poll(struct napi_struct *napi, int budget)
 181 {
 182         struct virtnet_info *vi = container_of(napi, struct virtnet_info, napi);
 183         struct sk_buff *skb = NULL;
 184         unsigned int len, received = 0;
 185
 186 again:
 187         while (received < budget &&
 188                (skb = vi->rvq->vq_ops->get_buf(vi->rvq, &len)) != NULL) {
 189                 __skb_unlink(skb, &vi->recv);
 190                 receive_skb(vi->dev, skb, len);
 191                 vi->num--;
 192                 received++;
 193         }
 194
 195         /* FIXME: If we oom and completely run out of inbufs, we need
 196          * to start a timer trying to fill more. */
 197         if (vi->num < vi->max / 2)
 198                 try_fill_recv(vi);
 199
 200         /* All done? */
 201         if (!skb) {
 202                 netif_rx_complete(vi->dev, napi);
 203                 if (unlikely(!vi->rvq->vq_ops->restart(vi->rvq))
 204                     && netif_rx_reschedule(vi->dev, napi))
 205                         goto again;
 206         }
 207
 208         return received;
 209 }
 210
 211 static void free_old_xmit_skbs(struct virtnet_info *vi)
 212 {
 213         struct sk_buff *skb;
 214         unsigned int len;
 215
 216         while ((skb = vi->svq->vq_ops->get_buf(vi->svq, &len)) != NULL) {
 217                 pr_debug("Sent skb %p\n", skb);
 218                 __skb_unlink(skb, &vi->send);
 219                 vi->dev->stats.tx_bytes += len;
 220                 vi->dev->stats.tx_packets++;
 221                 kfree_skb(skb);
 222         }
 223 }
 224
 225 static int start_xmit(struct sk_buff *skb, struct net_device *dev)
 226 {
 227         struct virtnet_info *vi = netdev_priv(dev);
 228         int num, err;
 229         struct scatterlist sg[1+MAX_SKB_FRAGS];
 230         struct virtio_net_hdr *hdr;
 231         const unsigned char *dest = ((struct ethhdr *)skb->data)->h_dest;
 232         DECLARE_MAC_BUF(mac);
 233
 234         pr_debug("%s: xmit %p %s\n", dev->name, skb, print_mac(mac, dest));
 235
 236         free_old_xmit_skbs(vi);
 237
 238         /* Encode metadata header at front. */
 239         hdr = skb_vnet_hdr(skb);
 240         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 241                 hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
 242                 hdr->csum_start = skb->csum_start - skb_headroom(skb);
 243                 hdr->csum_offset = skb->csum_offset;
 244         } else {
 245                 hdr->flags = 0;
 246                 hdr->csum_offset = hdr->csum_start = 0;
 247         }
 248
 249         if (skb_is_gso(skb)) {
 250                 hdr->gso_size = skb_shinfo(skb)->gso_size;
 251                 if (skb_shinfo(skb)->gso_type & SKB_GSO_TCP_ECN)
 252                         hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4_ECN;
 253                 else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
 254                         hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
 255                 else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
 256                         hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
 257                 else if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP)
 258                         hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP;
 259                 else
 260                         BUG();
 261         } else {
 262                 hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
 263                 hdr->gso_size = 0;
 264         }
 265
 266         vnet_hdr_to_sg(sg, skb);
 267         num = skb_to_sgvec(skb, sg+1, 0, skb->len) + 1;
 268         __skb_queue_head(&vi->send, skb);
 269         err = vi->svq->vq_ops->add_buf(vi->svq, sg, num, 0, skb);
 270         if (err) {
 271                 pr_debug("%s: virtio not prepared to send\n", dev->name);
 272                 skb_unlink(skb, &vi->send);
 273                 netif_stop_queue(dev);
 274                 return NETDEV_TX_BUSY;
 275         }
 276         vi->svq->vq_ops->kick(vi->svq);
 277
 278         return 0;
 279 }
 280
 281 static int virtnet_open(struct net_device *dev)
 282 {
 283         struct virtnet_info *vi = netdev_priv(dev);
 284
 285         try_fill_recv(vi);
 286
 287         /* If we didn't even get one input buffer, we're useless. */
 288         if (vi->num == 0)
 289                 return -ENOMEM;
 290
 291         napi_enable(&vi->napi);
 292         return 0;
 293 }
 294
 295 static int virtnet_close(struct net_device *dev)
 296 {
 297         struct virtnet_info *vi = netdev_priv(dev);
 298         struct sk_buff *skb;
 299
 300         napi_disable(&vi->napi);
 301
 302         /* networking core has neutered skb_xmit_done/skb_recv_done, so don't
 303          * worry about races vs. get(). */
 304         vi->rvq->vq_ops->shutdown(vi->rvq);
 305         while ((skb = __skb_dequeue(&vi->recv)) != NULL) {
 306                 kfree_skb(skb);
 307                 vi->num--;
 308         }
 309         vi->svq->vq_ops->shutdown(vi->svq);
 310         while ((skb = __skb_dequeue(&vi->send)) != NULL)
 311                 kfree_skb(skb);
 312
 313         BUG_ON(vi->num != 0);
 314         return 0;
 315 }
 316
 317 static int virtnet_probe(struct virtio_device *vdev)
 318 {
 319         int err;
 320         unsigned int len;
 321         struct net_device *dev;
 322         struct virtnet_info *vi;
 323         void *token;
 324
 325         /* Allocate ourselves a network device with room for our info */
 326         dev = alloc_etherdev(sizeof(struct virtnet_info));
 327         if (!dev)
 328                 return -ENOMEM;
 329
 330         /* Set up network device as normal. */
 331         ether_setup(dev);
 332         dev->open = virtnet_open;
 333         dev->stop = virtnet_close;
 334         dev->hard_start_xmit = start_xmit;
 335         dev->features = NETIF_F_HIGHDMA;
 336         SET_NETDEV_DEV(dev, &vdev->dev);
 337
 338         /* Do we support "hardware" checksums? */
 339         token = vdev->config->find(vdev, VIRTIO_CONFIG_NET_F, &len);
 340         if (virtio_use_bit(vdev, token, len, VIRTIO_NET_F_NO_CSUM)) {
 341                 /* This opens up the world of extra features. */
 342                 dev->features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST;
 343                 if (virtio_use_bit(vdev, token, len, VIRTIO_NET_F_TSO4))
 344                         dev->features |= NETIF_F_TSO;
 345                 if (virtio_use_bit(vdev, token, len, VIRTIO_NET_F_UFO))
 346                         dev->features |= NETIF_F_UFO;
 347                 if (virtio_use_bit(vdev, token, len, VIRTIO_NET_F_TSO4_ECN))
 348                         dev->features |= NETIF_F_TSO_ECN;
 349                 if (virtio_use_bit(vdev, token, len, VIRTIO_NET_F_TSO6))
 350                         dev->features |= NETIF_F_TSO6;
 351         }
 352
 353         /* Configuration may specify what MAC to use.  Otherwise random. */
 354         token = vdev->config->find(vdev, VIRTIO_CONFIG_NET_MAC_F, &len);
 355         if (token) {
 356                 dev->addr_len = len;
 357                 vdev->config->get(vdev, token, dev->dev_addr, len);
 358         } else
 359                 random_ether_addr(dev->dev_addr);
 360
 361         /* Set up our device-specific information */
 362         vi = netdev_priv(dev);
 363         netif_napi_add(dev, &vi->napi, virtnet_poll, 16);
 364         vi->dev = dev;
 365         vi->vdev = vdev;
 366
 367         /* We expect two virtqueues, receive then send. */
 368         vi->rvq = vdev->config->find_vq(vdev, skb_recv_done);
 369         if (IS_ERR(vi->rvq)) {
 370                 err = PTR_ERR(vi->rvq);
 371                 goto free;
 372         }
 373
 374         vi->svq = vdev->config->find_vq(vdev, skb_xmit_done);
 375         if (IS_ERR(vi->svq)) {
 376                 err = PTR_ERR(vi->svq);
 377                 goto free_recv;
 378         }
 379
 380         /* Initialize our empty receive and send queues. */
 381         skb_queue_head_init(&vi->recv);
 382         skb_queue_head_init(&vi->send);
 383
 384         err = register_netdev(dev);
 385         if (err) {
 386                 pr_debug("virtio_net: registering device failed\n");
 387                 goto free_send;
 388         }
 389         pr_debug("virtnet: registered device %s\n", dev->name);
 390         vdev->priv = vi;
 391         return 0;
 392
 393 free_send:
 394         vdev->config->del_vq(vi->svq);
 395 free_recv:
 396         vdev->config->del_vq(vi->rvq);
 397 free:
 398         free_netdev(dev);
 399         return err;
 400 }
 401
 402 static void virtnet_remove(struct virtio_device *vdev)
 403 {
 404         unregister_netdev(vdev->priv);
 405         free_netdev(vdev->priv);
 406 }
 407
 408 static struct virtio_device_id id_table[] = {
 409         { VIRTIO_ID_NET, VIRTIO_DEV_ANY_ID },
 410         { 0 },
 411 };
 412
 413 static struct virtio_driver virtio_net = {
 414         .driver.name =  KBUILD_MODNAME,
 415         .driver.owner = THIS_MODULE,
 416         .id_table =     id_table,
 417         .probe =        virtnet_probe,
 418         .remove =       __devexit_p(virtnet_remove),
 419 };
 420
 421 static int __init init(void)
 422 {
 423         return register_virtio_driver(&virtio_net);
 424 }
 425
 426 static void __exit fini(void)
 427 {
 428         unregister_virtio_driver(&virtio_net);
 429 }
 430 module_init(init);
 431 module_exit(fini);
 432
 433 MODULE_DEVICE_TABLE(virtio, id_table);
 434 MODULE_DESCRIPTION("Virtio network driver");
 435 MODULE_LICENSE("GPL");