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         sg_init_table(sg, 1+MAX_SKB_FRAGS);
 150         for (;;) {
 151                 skb = netdev_alloc_skb(vi->dev, MAX_PACKET_LEN);
 152                 if (unlikely(!skb))
 153                         break;
 154
 155                 skb_put(skb, MAX_PACKET_LEN);
 156                 vnet_hdr_to_sg(sg, skb);
 157                 num = skb_to_sgvec(skb, sg+1, 0, skb->len) + 1;
 158                 skb_queue_head(&vi->recv, skb);
 159
 160                 err = vi->rvq->vq_ops->add_buf(vi->rvq, sg, 0, num, skb);
 161                 if (err) {
 162                         skb_unlink(skb, &vi->recv);
 163                         kfree_skb(skb);
 164                         break;
 165                 }
 166                 vi->num++;
 167         }
 168         if (unlikely(vi->num > vi->max))
 169                 vi->max = vi->num;
 170         vi->rvq->vq_ops->kick(vi->rvq);
 171 }
 172
 173 static bool skb_recv_done(struct virtqueue *rvq)
 174 {
 175         struct virtnet_info *vi = rvq->vdev->priv;
 176         netif_rx_schedule(vi->dev, &vi->napi);
 177         /* Suppress further interrupts. */
 178         return false;
 179 }
 180
 181 static int virtnet_poll(struct napi_struct *napi, int budget)
 182 {
 183         struct virtnet_info *vi = container_of(napi, struct virtnet_info, napi);
 184         struct sk_buff *skb = NULL;
 185         unsigned int len, received = 0;
 186
 187 again:
 188         while (received < budget &&
 189                (skb = vi->rvq->vq_ops->get_buf(vi->rvq, &len)) != NULL) {
 190                 __skb_unlink(skb, &vi->recv);
 191                 receive_skb(vi->dev, skb, len);
 192                 vi->num--;
 193                 received++;
 194         }
 195
 196         /* FIXME: If we oom and completely run out of inbufs, we need
 197          * to start a timer trying to fill more. */
 198         if (vi->num < vi->max / 2)
 199                 try_fill_recv(vi);
 200
 201         /* All done? */
 202         if (!skb) {
 203                 netif_rx_complete(vi->dev, napi);
 204                 if (unlikely(!vi->rvq->vq_ops->restart(vi->rvq))
 205                     && netif_rx_reschedule(vi->dev, napi))
 206                         goto again;
 207         }
 208
 209         return received;
 210 }
 211
 212 static void free_old_xmit_skbs(struct virtnet_info *vi)
 213 {
 214         struct sk_buff *skb;
 215         unsigned int len;
 216
 217         while ((skb = vi->svq->vq_ops->get_buf(vi->svq, &len)) != NULL) {
 218                 pr_debug("Sent skb %p\n", skb);
 219                 __skb_unlink(skb, &vi->send);
 220                 vi->dev->stats.tx_bytes += len;
 221                 vi->dev->stats.tx_packets++;
 222                 kfree_skb(skb);
 223         }
 224 }
 225
 226 static int start_xmit(struct sk_buff *skb, struct net_device *dev)
 227 {
 228         struct virtnet_info *vi = netdev_priv(dev);
 229         int num, err;
 230         struct scatterlist sg[1+MAX_SKB_FRAGS];
 231         struct virtio_net_hdr *hdr;
 232         const unsigned char *dest = ((struct ethhdr *)skb->data)->h_dest;
 233         DECLARE_MAC_BUF(mac);
 234
 235         sg_init_table(sg, 1+MAX_SKB_FRAGS);
 236
 237         pr_debug("%s: xmit %p %s\n", dev->name, skb, print_mac(mac, dest));
 238
 239         free_old_xmit_skbs(vi);
 240
 241         /* Encode metadata header at front. */
 242         hdr = skb_vnet_hdr(skb);
 243         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 244                 hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
 245                 hdr->csum_start = skb->csum_start - skb_headroom(skb);
 246                 hdr->csum_offset = skb->csum_offset;
 247         } else {
 248                 hdr->flags = 0;
 249                 hdr->csum_offset = hdr->csum_start = 0;
 250         }
 251
 252         if (skb_is_gso(skb)) {
 253                 hdr->gso_size = skb_shinfo(skb)->gso_size;
 254                 if (skb_shinfo(skb)->gso_type & SKB_GSO_TCP_ECN)
 255                         hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4_ECN;
 256                 else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
 257                         hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
 258                 else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
 259                         hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
 260                 else if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP)
 261                         hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP;
 262                 else
 263                         BUG();
 264         } else {
 265                 hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
 266                 hdr->gso_size = 0;
 267         }
 268
 269         vnet_hdr_to_sg(sg, skb);
 270         num = skb_to_sgvec(skb, sg+1, 0, skb->len) + 1;
 271         __skb_queue_head(&vi->send, skb);
 272         err = vi->svq->vq_ops->add_buf(vi->svq, sg, num, 0, skb);
 273         if (err) {
 274                 pr_debug("%s: virtio not prepared to send\n", dev->name);
 275                 skb_unlink(skb, &vi->send);
 276                 netif_stop_queue(dev);
 277                 return NETDEV_TX_BUSY;
 278         }
 279         vi->svq->vq_ops->kick(vi->svq);
 280
 281         return 0;
 282 }
 283
 284 static int virtnet_open(struct net_device *dev)
 285 {
 286         struct virtnet_info *vi = netdev_priv(dev);
 287
 288         try_fill_recv(vi);
 289
 290         /* If we didn't even get one input buffer, we're useless. */
 291         if (vi->num == 0)
 292                 return -ENOMEM;
 293
 294         napi_enable(&vi->napi);
 295         return 0;
 296 }
 297
 298 static int virtnet_close(struct net_device *dev)
 299 {
 300         struct virtnet_info *vi = netdev_priv(dev);
 301         struct sk_buff *skb;
 302
 303         napi_disable(&vi->napi);
 304
 305         /* networking core has neutered skb_xmit_done/skb_recv_done, so don't
 306          * worry about races vs. get(). */
 307         vi->rvq->vq_ops->shutdown(vi->rvq);
 308         while ((skb = __skb_dequeue(&vi->recv)) != NULL) {
 309                 kfree_skb(skb);
 310                 vi->num--;
 311         }
 312         vi->svq->vq_ops->shutdown(vi->svq);
 313         while ((skb = __skb_dequeue(&vi->send)) != NULL)
 314                 kfree_skb(skb);
 315
 316         BUG_ON(vi->num != 0);
 317         return 0;
 318 }
 319
 320 static int virtnet_probe(struct virtio_device *vdev)
 321 {
 322         int err;
 323         unsigned int len;
 324         struct net_device *dev;
 325         struct virtnet_info *vi;
 326         void *token;
 327
 328         /* Allocate ourselves a network device with room for our info */
 329         dev = alloc_etherdev(sizeof(struct virtnet_info));
 330         if (!dev)
 331                 return -ENOMEM;
 332
 333         /* Set up network device as normal. */
 334         ether_setup(dev);
 335         dev->open = virtnet_open;
 336         dev->stop = virtnet_close;
 337         dev->hard_start_xmit = start_xmit;
 338         dev->features = NETIF_F_HIGHDMA;
 339         SET_NETDEV_DEV(dev, &vdev->dev);
 340
 341         /* Do we support "hardware" checksums? */
 342         token = vdev->config->find(vdev, VIRTIO_CONFIG_NET_F, &len);
 343         if (virtio_use_bit(vdev, token, len, VIRTIO_NET_F_NO_CSUM)) {
 344                 /* This opens up the world of extra features. */
 345                 dev->features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST;
 346                 if (virtio_use_bit(vdev, token, len, VIRTIO_NET_F_TSO4))
 347                         dev->features |= NETIF_F_TSO;
 348                 if (virtio_use_bit(vdev, token, len, VIRTIO_NET_F_UFO))
 349                         dev->features |= NETIF_F_UFO;
 350                 if (virtio_use_bit(vdev, token, len, VIRTIO_NET_F_TSO4_ECN))
 351                         dev->features |= NETIF_F_TSO_ECN;
 352                 if (virtio_use_bit(vdev, token, len, VIRTIO_NET_F_TSO6))
 353                         dev->features |= NETIF_F_TSO6;
 354         }
 355
 356         /* Configuration may specify what MAC to use.  Otherwise random. */
 357         token = vdev->config->find(vdev, VIRTIO_CONFIG_NET_MAC_F, &len);
 358         if (token) {
 359                 dev->addr_len = len;
 360                 vdev->config->get(vdev, token, dev->dev_addr, len);
 361         } else
 362                 random_ether_addr(dev->dev_addr);
 363
 364         /* Set up our device-specific information */
 365         vi = netdev_priv(dev);
 366         netif_napi_add(dev, &vi->napi, virtnet_poll, 16);
 367         vi->dev = dev;
 368         vi->vdev = vdev;
 369
 370         /* We expect two virtqueues, receive then send. */
 371         vi->rvq = vdev->config->find_vq(vdev, skb_recv_done);
 372         if (IS_ERR(vi->rvq)) {
 373                 err = PTR_ERR(vi->rvq);
 374                 goto free;
 375         }
 376
 377         vi->svq = vdev->config->find_vq(vdev, skb_xmit_done);
 378         if (IS_ERR(vi->svq)) {
 379                 err = PTR_ERR(vi->svq);
 380                 goto free_recv;
 381         }
 382
 383         /* Initialize our empty receive and send queues. */
 384         skb_queue_head_init(&vi->recv);
 385         skb_queue_head_init(&vi->send);
 386
 387         err = register_netdev(dev);
 388         if (err) {
 389                 pr_debug("virtio_net: registering device failed\n");
 390                 goto free_send;
 391         }
 392         pr_debug("virtnet: registered device %s\n", dev->name);
 393         vdev->priv = vi;
 394         return 0;
 395
 396 free_send:
 397         vdev->config->del_vq(vi->svq);
 398 free_recv:
 399         vdev->config->del_vq(vi->rvq);
 400 free:
 401         free_netdev(dev);
 402         return err;
 403 }
 404
 405 static void virtnet_remove(struct virtio_device *vdev)
 406 {
 407         unregister_netdev(vdev->priv);
 408         free_netdev(vdev->priv);
 409 }
 410
 411 static struct virtio_device_id id_table[] = {
 412         { VIRTIO_ID_NET, VIRTIO_DEV_ANY_ID },
 413         { 0 },
 414 };
 415
 416 static struct virtio_driver virtio_net = {
 417         .driver.name =  KBUILD_MODNAME,
 418         .driver.owner = THIS_MODULE,
 419         .id_table =     id_table,
 420         .probe =        virtnet_probe,
 421         .remove =       __devexit_p(virtnet_remove),
 422 };
 423
 424 static int __init init(void)
 425 {
 426         return register_virtio_driver(&virtio_net);
 427 }
 428
 429 static void __exit fini(void)
 430 {
 431         unregister_virtio_driver(&virtio_net);
 432 }
 433 module_init(init);
 434 module_exit(fini);
 435
 436 MODULE_DEVICE_TABLE(virtio, id_table);
 437 MODULE_DESCRIPTION("Virtio network driver");
 438 MODULE_LICENSE("GPL");