virtio_net: Fix skb->csum_start computation
[linux-2.6.git] / 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         /* 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
98         dev->stats.rx_bytes += skb->len;
99         dev->stats.rx_packets++;
100
101         if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
102                 pr_debug("Needs csum!\n");
103                 if (!skb_partial_csum_set(skb,hdr->csum_start,hdr->csum_offset))
104                         goto frame_err;
105         }
106
107         skb->protocol = eth_type_trans(skb, dev);
108         pr_debug("Receiving skb proto 0x%04x len %i type %i\n",
109                  ntohs(skb->protocol), skb->len, skb->pkt_type);
110
111         if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
112                 pr_debug("GSO!\n");
113                 switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
114                 case VIRTIO_NET_HDR_GSO_TCPV4:
115                         skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
116                         break;
117                 case VIRTIO_NET_HDR_GSO_UDP:
118                         skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
119                         break;
120                 case VIRTIO_NET_HDR_GSO_TCPV6:
121                         skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
122                         break;
123                 default:
124                         if (net_ratelimit())
125                                 printk(KERN_WARNING "%s: bad gso type %u.\n",
126                                        dev->name, hdr->gso_type);
127                         goto frame_err;
128                 }
129
130                 if (hdr->gso_type & VIRTIO_NET_HDR_GSO_ECN)
131                         skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
132
133                 skb_shinfo(skb)->gso_size = hdr->gso_size;
134                 if (skb_shinfo(skb)->gso_size == 0) {
135                         if (net_ratelimit())
136                                 printk(KERN_WARNING "%s: zero gso size.\n",
137                                        dev->name);
138                         goto frame_err;
139                 }
140
141                 /* Header must be checked, and gso_segs computed. */
142                 skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
143                 skb_shinfo(skb)->gso_segs = 0;
144         }
145
146         netif_receive_skb(skb);
147         return;
148
149 frame_err:
150         dev->stats.rx_frame_errors++;
151 drop:
152         dev_kfree_skb(skb);
153 }
154
155 static void try_fill_recv(struct virtnet_info *vi)
156 {
157         struct sk_buff *skb;
158         struct scatterlist sg[2+MAX_SKB_FRAGS];
159         int num, err;
160
161         sg_init_table(sg, 2+MAX_SKB_FRAGS);
162         for (;;) {
163                 skb = netdev_alloc_skb(vi->dev, MAX_PACKET_LEN);
164                 if (unlikely(!skb))
165                         break;
166
167                 skb_put(skb, MAX_PACKET_LEN);
168                 vnet_hdr_to_sg(sg, skb);
169                 num = skb_to_sgvec(skb, sg+1, 0, skb->len) + 1;
170                 skb_queue_head(&vi->recv, skb);
171
172                 err = vi->rvq->vq_ops->add_buf(vi->rvq, sg, 0, num, skb);
173                 if (err) {
174                         skb_unlink(skb, &vi->recv);
175                         kfree_skb(skb);
176                         break;
177                 }
178                 vi->num++;
179         }
180         if (unlikely(vi->num > vi->max))
181                 vi->max = vi->num;
182         vi->rvq->vq_ops->kick(vi->rvq);
183 }
184
185 static void skb_recv_done(struct virtqueue *rvq)
186 {
187         struct virtnet_info *vi = rvq->vdev->priv;
188         /* Schedule NAPI, Suppress further interrupts if successful. */
189         if (netif_rx_schedule_prep(vi->dev, &vi->napi)) {
190                 rvq->vq_ops->disable_cb(rvq);
191                 __netif_rx_schedule(vi->dev, &vi->napi);
192         }
193 }
194
195 static int virtnet_poll(struct napi_struct *napi, int budget)
196 {
197         struct virtnet_info *vi = container_of(napi, struct virtnet_info, napi);
198         struct sk_buff *skb = NULL;
199         unsigned int len, received = 0;
200
201 again:
202         while (received < budget &&
203                (skb = vi->rvq->vq_ops->get_buf(vi->rvq, &len)) != NULL) {
204                 __skb_unlink(skb, &vi->recv);
205                 receive_skb(vi->dev, skb, len);
206                 vi->num--;
207                 received++;
208         }
209
210         /* FIXME: If we oom and completely run out of inbufs, we need
211          * to start a timer trying to fill more. */
212         if (vi->num < vi->max / 2)
213                 try_fill_recv(vi);
214
215         /* Out of packets? */
216         if (received < budget) {
217                 netif_rx_complete(vi->dev, napi);
218                 if (unlikely(!vi->rvq->vq_ops->enable_cb(vi->rvq))
219                     && napi_schedule_prep(napi)) {
220                         vi->rvq->vq_ops->disable_cb(vi->rvq);
221                         __netif_rx_schedule(vi->dev, napi);
222                         goto again;
223                 }
224         }
225
226         return received;
227 }
228
229 static void free_old_xmit_skbs(struct virtnet_info *vi)
230 {
231         struct sk_buff *skb;
232         unsigned int len;
233
234         while ((skb = vi->svq->vq_ops->get_buf(vi->svq, &len)) != NULL) {
235                 pr_debug("Sent skb %p\n", skb);
236                 __skb_unlink(skb, &vi->send);
237                 vi->dev->stats.tx_bytes += skb->len;
238                 vi->dev->stats.tx_packets++;
239                 kfree_skb(skb);
240         }
241 }
242
243 static int xmit_skb(struct virtnet_info *vi, struct sk_buff *skb)
244 {
245         int num;
246         struct scatterlist sg[2+MAX_SKB_FRAGS];
247         struct virtio_net_hdr *hdr;
248         const unsigned char *dest = ((struct ethhdr *)skb->data)->h_dest;
249
250         sg_init_table(sg, 2+MAX_SKB_FRAGS);
251
252         pr_debug("%s: xmit %p " MAC_FMT "\n", vi->dev->name, skb,
253                  dest[0], dest[1], dest[2],
254                  dest[3], dest[4], dest[5]);
255
256         /* Encode metadata header at front. */
257         hdr = skb_vnet_hdr(skb);
258         if (skb->ip_summed == CHECKSUM_PARTIAL) {
259                 hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
260                 hdr->csum_start = skb->csum_start - skb_headroom(skb);
261                 hdr->csum_offset = skb->csum_offset;
262         } else {
263                 hdr->flags = 0;
264                 hdr->csum_offset = hdr->csum_start = 0;
265         }
266
267         if (skb_is_gso(skb)) {
268                 hdr->hdr_len = skb_transport_header(skb) - skb->data;
269                 hdr->gso_size = skb_shinfo(skb)->gso_size;
270                 if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
271                         hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
272                 else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
273                         hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
274                 else if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP)
275                         hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP;
276                 else
277                         BUG();
278                 if (skb_shinfo(skb)->gso_type & SKB_GSO_TCP_ECN)
279                         hdr->gso_type |= VIRTIO_NET_HDR_GSO_ECN;
280         } else {
281                 hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
282                 hdr->gso_size = hdr->hdr_len = 0;
283         }
284
285         vnet_hdr_to_sg(sg, skb);
286         num = skb_to_sgvec(skb, sg+1, 0, skb->len) + 1;
287
288         return vi->svq->vq_ops->add_buf(vi->svq, sg, num, 0, skb);
289 }
290
291 static void xmit_tasklet(unsigned long data)
292 {
293         struct virtnet_info *vi = (void *)data;
294
295         netif_tx_lock_bh(vi->dev);
296         if (vi->last_xmit_skb && xmit_skb(vi, vi->last_xmit_skb) == 0) {
297                 vi->svq->vq_ops->kick(vi->svq);
298                 vi->last_xmit_skb = NULL;
299         }
300         netif_tx_unlock_bh(vi->dev);
301 }
302
303 static int start_xmit(struct sk_buff *skb, struct net_device *dev)
304 {
305         struct virtnet_info *vi = netdev_priv(dev);
306
307 again:
308         /* Free up any pending old buffers before queueing new ones. */
309         free_old_xmit_skbs(vi);
310
311         /* If we has a buffer left over from last time, send it now. */
312         if (unlikely(vi->last_xmit_skb)) {
313                 if (xmit_skb(vi, vi->last_xmit_skb) != 0) {
314                         /* Drop this skb: we only queue one. */
315                         vi->dev->stats.tx_dropped++;
316                         kfree_skb(skb);
317                         skb = NULL;
318                         goto stop_queue;
319                 }
320                 vi->last_xmit_skb = NULL;
321         }
322
323         /* Put new one in send queue and do transmit */
324         if (likely(skb)) {
325                 __skb_queue_head(&vi->send, skb);
326                 if (xmit_skb(vi, skb) != 0) {
327                         vi->last_xmit_skb = skb;
328                         skb = NULL;
329                         goto stop_queue;
330                 }
331         }
332 done:
333         vi->svq->vq_ops->kick(vi->svq);
334         return NETDEV_TX_OK;
335
336 stop_queue:
337         pr_debug("%s: virtio not prepared to send\n", dev->name);
338         netif_stop_queue(dev);
339
340         /* Activate callback for using skbs: if this returns false it
341          * means some were used in the meantime. */
342         if (unlikely(!vi->svq->vq_ops->enable_cb(vi->svq))) {
343                 vi->svq->vq_ops->disable_cb(vi->svq);
344                 netif_start_queue(dev);
345                 goto again;
346         }
347         goto done;
348 }
349
350 #ifdef CONFIG_NET_POLL_CONTROLLER
351 static void virtnet_netpoll(struct net_device *dev)
352 {
353         struct virtnet_info *vi = netdev_priv(dev);
354
355         napi_schedule(&vi->napi);
356 }
357 #endif
358
359 static int virtnet_open(struct net_device *dev)
360 {
361         struct virtnet_info *vi = netdev_priv(dev);
362
363         napi_enable(&vi->napi);
364
365         /* If all buffers were filled by other side before we napi_enabled, we
366          * won't get another interrupt, so process any outstanding packets
367          * now.  virtnet_poll wants re-enable the queue, so we disable here.
368          * We synchronize against interrupts via NAPI_STATE_SCHED */
369         if (netif_rx_schedule_prep(dev, &vi->napi)) {
370                 vi->rvq->vq_ops->disable_cb(vi->rvq);
371                 __netif_rx_schedule(dev, &vi->napi);
372         }
373         return 0;
374 }
375
376 static int virtnet_close(struct net_device *dev)
377 {
378         struct virtnet_info *vi = netdev_priv(dev);
379
380         napi_disable(&vi->napi);
381
382         return 0;
383 }
384
385 static int virtnet_probe(struct virtio_device *vdev)
386 {
387         int err;
388         struct net_device *dev;
389         struct virtnet_info *vi;
390
391         /* Allocate ourselves a network device with room for our info */
392         dev = alloc_etherdev(sizeof(struct virtnet_info));
393         if (!dev)
394                 return -ENOMEM;
395
396         /* Set up network device as normal. */
397         dev->open = virtnet_open;
398         dev->stop = virtnet_close;
399         dev->hard_start_xmit = start_xmit;
400         dev->features = NETIF_F_HIGHDMA;
401 #ifdef CONFIG_NET_POLL_CONTROLLER
402         dev->poll_controller = virtnet_netpoll;
403 #endif
404         SET_NETDEV_DEV(dev, &vdev->dev);
405
406         /* Do we support "hardware" checksums? */
407         if (csum && virtio_has_feature(vdev, VIRTIO_NET_F_CSUM)) {
408                 /* This opens up the world of extra features. */
409                 dev->features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST;
410                 if (gso && virtio_has_feature(vdev, VIRTIO_NET_F_GSO)) {
411                         dev->features |= NETIF_F_TSO | NETIF_F_UFO
412                                 | NETIF_F_TSO_ECN | NETIF_F_TSO6;
413                 }
414                 /* Individual feature bits: what can host handle? */
415                 if (gso && virtio_has_feature(vdev, VIRTIO_NET_F_HOST_TSO4))
416                         dev->features |= NETIF_F_TSO;
417                 if (gso && virtio_has_feature(vdev, VIRTIO_NET_F_HOST_TSO6))
418                         dev->features |= NETIF_F_TSO6;
419                 if (gso && virtio_has_feature(vdev, VIRTIO_NET_F_HOST_ECN))
420                         dev->features |= NETIF_F_TSO_ECN;
421                 if (gso && virtio_has_feature(vdev, VIRTIO_NET_F_HOST_UFO))
422                         dev->features |= NETIF_F_UFO;
423         }
424
425         /* Configuration may specify what MAC to use.  Otherwise random. */
426         if (virtio_has_feature(vdev, VIRTIO_NET_F_MAC)) {
427                 vdev->config->get(vdev,
428                                   offsetof(struct virtio_net_config, mac),
429                                   dev->dev_addr, dev->addr_len);
430         } else
431                 random_ether_addr(dev->dev_addr);
432
433         /* Set up our device-specific information */
434         vi = netdev_priv(dev);
435         netif_napi_add(dev, &vi->napi, virtnet_poll, napi_weight);
436         vi->dev = dev;
437         vi->vdev = vdev;
438         vdev->priv = vi;
439
440         /* We expect two virtqueues, receive then send. */
441         vi->rvq = vdev->config->find_vq(vdev, 0, skb_recv_done);
442         if (IS_ERR(vi->rvq)) {
443                 err = PTR_ERR(vi->rvq);
444                 goto free;
445         }
446
447         vi->svq = vdev->config->find_vq(vdev, 1, skb_xmit_done);
448         if (IS_ERR(vi->svq)) {
449                 err = PTR_ERR(vi->svq);
450                 goto free_recv;
451         }
452
453         /* Initialize our empty receive and send queues. */
454         skb_queue_head_init(&vi->recv);
455         skb_queue_head_init(&vi->send);
456
457         tasklet_init(&vi->tasklet, xmit_tasklet, (unsigned long)vi);
458
459         err = register_netdev(dev);
460         if (err) {
461                 pr_debug("virtio_net: registering device failed\n");
462                 goto free_send;
463         }
464
465         /* Last of all, set up some receive buffers. */
466         try_fill_recv(vi);
467
468         /* If we didn't even get one input buffer, we're useless. */
469         if (vi->num == 0) {
470                 err = -ENOMEM;
471                 goto unregister;
472         }
473
474         pr_debug("virtnet: registered device %s\n", dev->name);
475         return 0;
476
477 unregister:
478         unregister_netdev(dev);
479 free_send:
480         vdev->config->del_vq(vi->svq);
481 free_recv:
482         vdev->config->del_vq(vi->rvq);
483 free:
484         free_netdev(dev);
485         return err;
486 }
487
488 static void virtnet_remove(struct virtio_device *vdev)
489 {
490         struct virtnet_info *vi = vdev->priv;
491         struct sk_buff *skb;
492
493         /* Stop all the virtqueues. */
494         vdev->config->reset(vdev);
495
496         /* Free our skbs in send and recv queues, if any. */
497         while ((skb = __skb_dequeue(&vi->recv)) != NULL) {
498                 kfree_skb(skb);
499                 vi->num--;
500         }
501         __skb_queue_purge(&vi->send);
502
503         BUG_ON(vi->num != 0);
504
505         vdev->config->del_vq(vi->svq);
506         vdev->config->del_vq(vi->rvq);
507         unregister_netdev(vi->dev);
508         free_netdev(vi->dev);
509 }
510
511 static struct virtio_device_id id_table[] = {
512         { VIRTIO_ID_NET, VIRTIO_DEV_ANY_ID },
513         { 0 },
514 };
515
516 static unsigned int features[] = {
517         VIRTIO_NET_F_CSUM, VIRTIO_NET_F_GSO, VIRTIO_NET_F_MAC,
518         VIRTIO_NET_F_HOST_TSO4, VIRTIO_NET_F_HOST_UFO, VIRTIO_NET_F_HOST_TSO6,
519         VIRTIO_NET_F_HOST_ECN,
520 };
521
522 static struct virtio_driver virtio_net = {
523         .feature_table = features,
524         .feature_table_size = ARRAY_SIZE(features),
525         .driver.name =  KBUILD_MODNAME,
526         .driver.owner = THIS_MODULE,
527         .id_table =     id_table,
528         .probe =        virtnet_probe,
529         .remove =       __devexit_p(virtnet_remove),
530 };
531
532 static int __init init(void)
533 {
534         return register_virtio_driver(&virtio_net);
535 }
536
537 static void __exit fini(void)
538 {
539         unregister_virtio_driver(&virtio_net);
540 }
541 module_init(init);
542 module_exit(fini);
543
544 MODULE_DEVICE_TABLE(virtio, id_table);
545 MODULE_DESCRIPTION("Virtio network driver");
546 MODULE_LICENSE("GPL");