1 /*
2  * Network-device interface management.
3  *
4  * Copyright (c) 2004-2005, Keir Fraser
5  *
6  * This program is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU General Public License version 2
8  * as published by the Free Software Foundation; or, when distributed
9  * separately from the Linux kernel or incorporated into other
10  * software packages, subject to the following license:
11  *
12  * Permission is hereby granted, free of charge, to any person obtaining a copy
13  * of this source file (the "Software"), to deal in the Software without
14  * restriction, including without limitation the rights to use, copy, modify,
15  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
16  * and to permit persons to whom the Software is furnished to do so, subject to
17  * the following conditions:
18  *
19  * The above copyright notice and this permission notice shall be included in
20  * all copies or substantial portions of the Software.
21  *
22  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
23  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
24  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
25  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
26  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
27  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
28  * IN THE SOFTWARE.
29  */
30 
31 #include "common.h"
32 
33 #include <linux/kthread.h>
34 #include <linux/ethtool.h>
35 #include <linux/rtnetlink.h>
36 #include <linux/if_vlan.h>
37 #include <linux/vmalloc.h>
38 
39 #include <xen/events.h>
40 #include <asm/xen/hypercall.h>
41 
42 #define XENVIF_QUEUE_LENGTH 32
43 #define XENVIF_NAPI_WEIGHT  64
44 
45 int xenvif_schedulable(struct xenvif *vif)
46 {
47 	return netif_running(vif->dev) && netif_carrier_ok(vif->dev);
48 }
49 
50 static irqreturn_t xenvif_tx_interrupt(int irq, void *dev_id)
51 {
52 	struct xenvif *vif = dev_id;
53 
54 	if (RING_HAS_UNCONSUMED_REQUESTS(&vif->tx))
55 		napi_schedule(&vif->napi);
56 
57 	return IRQ_HANDLED;
58 }
59 
60 static int xenvif_poll(struct napi_struct *napi, int budget)
61 {
62 	struct xenvif *vif = container_of(napi, struct xenvif, napi);
63 	int work_done;
64 
65 	work_done = xenvif_tx_action(vif, budget);
66 
67 	if (work_done < budget) {
68 		int more_to_do = 0;
69 		unsigned long flags;
70 
71 		/* It is necessary to disable IRQ before calling
72 		 * RING_HAS_UNCONSUMED_REQUESTS. Otherwise we might
73 		 * lose event from the frontend.
74 		 *
75 		 * Consider:
76 		 *   RING_HAS_UNCONSUMED_REQUESTS
77 		 *   <frontend generates event to trigger napi_schedule>
78 		 *   __napi_complete
79 		 *
80 		 * This handler is still in scheduled state so the
81 		 * event has no effect at all. After __napi_complete
82 		 * this handler is descheduled and cannot get
83 		 * scheduled again. We lose event in this case and the ring
84 		 * will be completely stalled.
85 		 */
86 
87 		local_irq_save(flags);
88 
89 		RING_FINAL_CHECK_FOR_REQUESTS(&vif->tx, more_to_do);
90 		if (!more_to_do)
91 			__napi_complete(napi);
92 
93 		local_irq_restore(flags);
94 	}
95 
96 	return work_done;
97 }
98 
99 static irqreturn_t xenvif_rx_interrupt(int irq, void *dev_id)
100 {
101 	struct xenvif *vif = dev_id;
102 
103 	xenvif_kick_thread(vif);
104 
105 	return IRQ_HANDLED;
106 }
107 
108 static irqreturn_t xenvif_interrupt(int irq, void *dev_id)
109 {
110 	xenvif_tx_interrupt(irq, dev_id);
111 	xenvif_rx_interrupt(irq, dev_id);
112 
113 	return IRQ_HANDLED;
114 }
115 
116 static int xenvif_start_xmit(struct sk_buff *skb, struct net_device *dev)
117 {
118 	struct xenvif *vif = netdev_priv(dev);
119 	int min_slots_needed;
120 
121 	BUG_ON(skb->dev != dev);
122 
123 	/* Drop the packet if vif is not ready */
124 	if (vif->task == NULL || !xenvif_schedulable(vif))
125 		goto drop;
126 
127 	/* At best we'll need one slot for the header and one for each
128 	 * frag.
129 	 */
130 	min_slots_needed = 1 + skb_shinfo(skb)->nr_frags;
131 
132 	/* If the skb is GSO then we'll also need an extra slot for the
133 	 * metadata.
134 	 */
135 	if (skb_is_gso(skb))
136 		min_slots_needed++;
137 
138 	/* If the skb can't possibly fit in the remaining slots
139 	 * then turn off the queue to give the ring a chance to
140 	 * drain.
141 	 */
142 	if (!xenvif_rx_ring_slots_available(vif, min_slots_needed))
143 		xenvif_stop_queue(vif);
144 
145 	skb_queue_tail(&vif->rx_queue, skb);
146 	xenvif_kick_thread(vif);
147 
148 	return NETDEV_TX_OK;
149 
150  drop:
151 	vif->dev->stats.tx_dropped++;
152 	dev_kfree_skb(skb);
153 	return NETDEV_TX_OK;
154 }
155 
156 static struct net_device_stats *xenvif_get_stats(struct net_device *dev)
157 {
158 	struct xenvif *vif = netdev_priv(dev);
159 	return &vif->dev->stats;
160 }
161 
162 static void xenvif_up(struct xenvif *vif)
163 {
164 	napi_enable(&vif->napi);
165 	enable_irq(vif->tx_irq);
166 	if (vif->tx_irq != vif->rx_irq)
167 		enable_irq(vif->rx_irq);
168 	xenvif_check_rx_xenvif(vif);
169 }
170 
171 static void xenvif_down(struct xenvif *vif)
172 {
173 	napi_disable(&vif->napi);
174 	disable_irq(vif->tx_irq);
175 	if (vif->tx_irq != vif->rx_irq)
176 		disable_irq(vif->rx_irq);
177 	del_timer_sync(&vif->credit_timeout);
178 }
179 
180 static int xenvif_open(struct net_device *dev)
181 {
182 	struct xenvif *vif = netdev_priv(dev);
183 	if (netif_carrier_ok(dev))
184 		xenvif_up(vif);
185 	netif_start_queue(dev);
186 	return 0;
187 }
188 
189 static int xenvif_close(struct net_device *dev)
190 {
191 	struct xenvif *vif = netdev_priv(dev);
192 	if (netif_carrier_ok(dev))
193 		xenvif_down(vif);
194 	netif_stop_queue(dev);
195 	return 0;
196 }
197 
198 static int xenvif_change_mtu(struct net_device *dev, int mtu)
199 {
200 	struct xenvif *vif = netdev_priv(dev);
201 	int max = vif->can_sg ? 65535 - VLAN_ETH_HLEN : ETH_DATA_LEN;
202 
203 	if (mtu > max)
204 		return -EINVAL;
205 	dev->mtu = mtu;
206 	return 0;
207 }
208 
209 static netdev_features_t xenvif_fix_features(struct net_device *dev,
210 	netdev_features_t features)
211 {
212 	struct xenvif *vif = netdev_priv(dev);
213 
214 	if (!vif->can_sg)
215 		features &= ~NETIF_F_SG;
216 	if (~(vif->gso_mask | vif->gso_prefix_mask) & GSO_BIT(TCPV4))
217 		features &= ~NETIF_F_TSO;
218 	if (~(vif->gso_mask | vif->gso_prefix_mask) & GSO_BIT(TCPV6))
219 		features &= ~NETIF_F_TSO6;
220 	if (!vif->ip_csum)
221 		features &= ~NETIF_F_IP_CSUM;
222 	if (!vif->ipv6_csum)
223 		features &= ~NETIF_F_IPV6_CSUM;
224 
225 	return features;
226 }
227 
228 static const struct xenvif_stat {
229 	char name[ETH_GSTRING_LEN];
230 	u16 offset;
231 } xenvif_stats[] = {
232 	{
233 		"rx_gso_checksum_fixup",
234 		offsetof(struct xenvif, rx_gso_checksum_fixup)
235 	},
236 };
237 
238 static int xenvif_get_sset_count(struct net_device *dev, int string_set)
239 {
240 	switch (string_set) {
241 	case ETH_SS_STATS:
242 		return ARRAY_SIZE(xenvif_stats);
243 	default:
244 		return -EINVAL;
245 	}
246 }
247 
248 static void xenvif_get_ethtool_stats(struct net_device *dev,
249 				     struct ethtool_stats *stats, u64 * data)
250 {
251 	void *vif = netdev_priv(dev);
252 	int i;
253 
254 	for (i = 0; i < ARRAY_SIZE(xenvif_stats); i++)
255 		data[i] = *(unsigned long *)(vif + xenvif_stats[i].offset);
256 }
257 
258 static void xenvif_get_strings(struct net_device *dev, u32 stringset, u8 * data)
259 {
260 	int i;
261 
262 	switch (stringset) {
263 	case ETH_SS_STATS:
264 		for (i = 0; i < ARRAY_SIZE(xenvif_stats); i++)
265 			memcpy(data + i * ETH_GSTRING_LEN,
266 			       xenvif_stats[i].name, ETH_GSTRING_LEN);
267 		break;
268 	}
269 }
270 
271 static const struct ethtool_ops xenvif_ethtool_ops = {
272 	.get_link	= ethtool_op_get_link,
273 
274 	.get_sset_count = xenvif_get_sset_count,
275 	.get_ethtool_stats = xenvif_get_ethtool_stats,
276 	.get_strings = xenvif_get_strings,
277 };
278 
279 static const struct net_device_ops xenvif_netdev_ops = {
280 	.ndo_start_xmit	= xenvif_start_xmit,
281 	.ndo_get_stats	= xenvif_get_stats,
282 	.ndo_open	= xenvif_open,
283 	.ndo_stop	= xenvif_close,
284 	.ndo_change_mtu	= xenvif_change_mtu,
285 	.ndo_fix_features = xenvif_fix_features,
286 	.ndo_set_mac_address = eth_mac_addr,
287 	.ndo_validate_addr   = eth_validate_addr,
288 };
289 
290 struct xenvif *xenvif_alloc(struct device *parent, domid_t domid,
291 			    unsigned int handle)
292 {
293 	int err;
294 	struct net_device *dev;
295 	struct xenvif *vif;
296 	char name[IFNAMSIZ] = {};
297 	int i;
298 
299 	snprintf(name, IFNAMSIZ - 1, "vif%u.%u", domid, handle);
300 	dev = alloc_netdev(sizeof(struct xenvif), name, ether_setup);
301 	if (dev == NULL) {
302 		pr_warn("Could not allocate netdev for %s\n", name);
303 		return ERR_PTR(-ENOMEM);
304 	}
305 
306 	SET_NETDEV_DEV(dev, parent);
307 
308 	vif = netdev_priv(dev);
309 
310 	vif->grant_copy_op = vmalloc(sizeof(struct gnttab_copy) *
311 				     MAX_GRANT_COPY_OPS);
312 	if (vif->grant_copy_op == NULL) {
313 		pr_warn("Could not allocate grant copy space for %s\n", name);
314 		free_netdev(dev);
315 		return ERR_PTR(-ENOMEM);
316 	}
317 
318 	vif->domid  = domid;
319 	vif->handle = handle;
320 	vif->can_sg = 1;
321 	vif->ip_csum = 1;
322 	vif->dev = dev;
323 
324 	vif->credit_bytes = vif->remaining_credit = ~0UL;
325 	vif->credit_usec  = 0UL;
326 	init_timer(&vif->credit_timeout);
327 	vif->credit_window_start = get_jiffies_64();
328 
329 	dev->netdev_ops	= &xenvif_netdev_ops;
330 	dev->hw_features = NETIF_F_SG |
331 		NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM |
332 		NETIF_F_TSO | NETIF_F_TSO6;
333 	dev->features = dev->hw_features | NETIF_F_RXCSUM;
334 	SET_ETHTOOL_OPS(dev, &xenvif_ethtool_ops);
335 
336 	dev->tx_queue_len = XENVIF_QUEUE_LENGTH;
337 
338 	skb_queue_head_init(&vif->rx_queue);
339 	skb_queue_head_init(&vif->tx_queue);
340 
341 	vif->pending_cons = 0;
342 	vif->pending_prod = MAX_PENDING_REQS;
343 	for (i = 0; i < MAX_PENDING_REQS; i++)
344 		vif->pending_ring[i] = i;
345 	for (i = 0; i < MAX_PENDING_REQS; i++)
346 		vif->mmap_pages[i] = NULL;
347 
348 	/*
349 	 * Initialise a dummy MAC address. We choose the numerically
350 	 * largest non-broadcast address to prevent the address getting
351 	 * stolen by an Ethernet bridge for STP purposes.
352 	 * (FE:FF:FF:FF:FF:FF)
353 	 */
354 	memset(dev->dev_addr, 0xFF, ETH_ALEN);
355 	dev->dev_addr[0] &= ~0x01;
356 
357 	netif_napi_add(dev, &vif->napi, xenvif_poll, XENVIF_NAPI_WEIGHT);
358 
359 	netif_carrier_off(dev);
360 
361 	err = register_netdev(dev);
362 	if (err) {
363 		netdev_warn(dev, "Could not register device: err=%d\n", err);
364 		free_netdev(dev);
365 		return ERR_PTR(err);
366 	}
367 
368 	netdev_dbg(dev, "Successfully created xenvif\n");
369 
370 	__module_get(THIS_MODULE);
371 
372 	return vif;
373 }
374 
375 int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref,
376 		   unsigned long rx_ring_ref, unsigned int tx_evtchn,
377 		   unsigned int rx_evtchn)
378 {
379 	struct task_struct *task;
380 	int err = -ENOMEM;
381 
382 	BUG_ON(vif->tx_irq);
383 	BUG_ON(vif->task);
384 
385 	err = xenvif_map_frontend_rings(vif, tx_ring_ref, rx_ring_ref);
386 	if (err < 0)
387 		goto err;
388 
389 	init_waitqueue_head(&vif->wq);
390 
391 	if (tx_evtchn == rx_evtchn) {
392 		/* feature-split-event-channels == 0 */
393 		err = bind_interdomain_evtchn_to_irqhandler(
394 			vif->domid, tx_evtchn, xenvif_interrupt, 0,
395 			vif->dev->name, vif);
396 		if (err < 0)
397 			goto err_unmap;
398 		vif->tx_irq = vif->rx_irq = err;
399 		disable_irq(vif->tx_irq);
400 	} else {
401 		/* feature-split-event-channels == 1 */
402 		snprintf(vif->tx_irq_name, sizeof(vif->tx_irq_name),
403 			 "%s-tx", vif->dev->name);
404 		err = bind_interdomain_evtchn_to_irqhandler(
405 			vif->domid, tx_evtchn, xenvif_tx_interrupt, 0,
406 			vif->tx_irq_name, vif);
407 		if (err < 0)
408 			goto err_unmap;
409 		vif->tx_irq = err;
410 		disable_irq(vif->tx_irq);
411 
412 		snprintf(vif->rx_irq_name, sizeof(vif->rx_irq_name),
413 			 "%s-rx", vif->dev->name);
414 		err = bind_interdomain_evtchn_to_irqhandler(
415 			vif->domid, rx_evtchn, xenvif_rx_interrupt, 0,
416 			vif->rx_irq_name, vif);
417 		if (err < 0)
418 			goto err_tx_unbind;
419 		vif->rx_irq = err;
420 		disable_irq(vif->rx_irq);
421 	}
422 
423 	task = kthread_create(xenvif_kthread,
424 			      (void *)vif, "%s", vif->dev->name);
425 	if (IS_ERR(task)) {
426 		pr_warn("Could not allocate kthread for %s\n", vif->dev->name);
427 		err = PTR_ERR(task);
428 		goto err_rx_unbind;
429 	}
430 
431 	vif->task = task;
432 
433 	rtnl_lock();
434 	if (!vif->can_sg && vif->dev->mtu > ETH_DATA_LEN)
435 		dev_set_mtu(vif->dev, ETH_DATA_LEN);
436 	netdev_update_features(vif->dev);
437 	netif_carrier_on(vif->dev);
438 	if (netif_running(vif->dev))
439 		xenvif_up(vif);
440 	rtnl_unlock();
441 
442 	wake_up_process(vif->task);
443 
444 	return 0;
445 
446 err_rx_unbind:
447 	unbind_from_irqhandler(vif->rx_irq, vif);
448 	vif->rx_irq = 0;
449 err_tx_unbind:
450 	unbind_from_irqhandler(vif->tx_irq, vif);
451 	vif->tx_irq = 0;
452 err_unmap:
453 	xenvif_unmap_frontend_rings(vif);
454 err:
455 	module_put(THIS_MODULE);
456 	return err;
457 }
458 
459 void xenvif_carrier_off(struct xenvif *vif)
460 {
461 	struct net_device *dev = vif->dev;
462 
463 	rtnl_lock();
464 	netif_carrier_off(dev); /* discard queued packets */
465 	if (netif_running(dev))
466 		xenvif_down(vif);
467 	rtnl_unlock();
468 }
469 
470 void xenvif_disconnect(struct xenvif *vif)
471 {
472 	if (netif_carrier_ok(vif->dev))
473 		xenvif_carrier_off(vif);
474 
475 	if (vif->task) {
476 		kthread_stop(vif->task);
477 		vif->task = NULL;
478 	}
479 
480 	if (vif->tx_irq) {
481 		if (vif->tx_irq == vif->rx_irq)
482 			unbind_from_irqhandler(vif->tx_irq, vif);
483 		else {
484 			unbind_from_irqhandler(vif->tx_irq, vif);
485 			unbind_from_irqhandler(vif->rx_irq, vif);
486 		}
487 		vif->tx_irq = 0;
488 	}
489 
490 	xenvif_unmap_frontend_rings(vif);
491 }
492 
493 void xenvif_free(struct xenvif *vif)
494 {
495 	netif_napi_del(&vif->napi);
496 
497 	unregister_netdev(vif->dev);
498 
499 	vfree(vif->grant_copy_op);
500 	free_netdev(vif->dev);
501 
502 	module_put(THIS_MODULE);
503 }
504