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_shinfo(skb)->gso_type & SKB_GSO_TCPV4 ||
136 	    skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
137 		min_slots_needed++;
138 
139 	/* If the skb can't possibly fit in the remaining slots
140 	 * then turn off the queue to give the ring a chance to
141 	 * drain.
142 	 */
143 	if (!xenvif_rx_ring_slots_available(vif, min_slots_needed))
144 		xenvif_stop_queue(vif);
145 
146 	skb_queue_tail(&vif->rx_queue, skb);
147 	xenvif_kick_thread(vif);
148 
149 	return NETDEV_TX_OK;
150 
151  drop:
152 	vif->dev->stats.tx_dropped++;
153 	dev_kfree_skb(skb);
154 	return NETDEV_TX_OK;
155 }
156 
157 static struct net_device_stats *xenvif_get_stats(struct net_device *dev)
158 {
159 	struct xenvif *vif = netdev_priv(dev);
160 	return &vif->dev->stats;
161 }
162 
163 static void xenvif_up(struct xenvif *vif)
164 {
165 	napi_enable(&vif->napi);
166 	enable_irq(vif->tx_irq);
167 	if (vif->tx_irq != vif->rx_irq)
168 		enable_irq(vif->rx_irq);
169 	xenvif_check_rx_xenvif(vif);
170 }
171 
172 static void xenvif_down(struct xenvif *vif)
173 {
174 	napi_disable(&vif->napi);
175 	disable_irq(vif->tx_irq);
176 	if (vif->tx_irq != vif->rx_irq)
177 		disable_irq(vif->rx_irq);
178 	del_timer_sync(&vif->credit_timeout);
179 }
180 
181 static int xenvif_open(struct net_device *dev)
182 {
183 	struct xenvif *vif = netdev_priv(dev);
184 	if (netif_carrier_ok(dev))
185 		xenvif_up(vif);
186 	netif_start_queue(dev);
187 	return 0;
188 }
189 
190 static int xenvif_close(struct net_device *dev)
191 {
192 	struct xenvif *vif = netdev_priv(dev);
193 	if (netif_carrier_ok(dev))
194 		xenvif_down(vif);
195 	netif_stop_queue(dev);
196 	return 0;
197 }
198 
199 static int xenvif_change_mtu(struct net_device *dev, int mtu)
200 {
201 	struct xenvif *vif = netdev_priv(dev);
202 	int max = vif->can_sg ? 65535 - VLAN_ETH_HLEN : ETH_DATA_LEN;
203 
204 	if (mtu > max)
205 		return -EINVAL;
206 	dev->mtu = mtu;
207 	return 0;
208 }
209 
210 static netdev_features_t xenvif_fix_features(struct net_device *dev,
211 	netdev_features_t features)
212 {
213 	struct xenvif *vif = netdev_priv(dev);
214 
215 	if (!vif->can_sg)
216 		features &= ~NETIF_F_SG;
217 	if (~(vif->gso_mask | vif->gso_prefix_mask) & GSO_BIT(TCPV4))
218 		features &= ~NETIF_F_TSO;
219 	if (~(vif->gso_mask | vif->gso_prefix_mask) & GSO_BIT(TCPV6))
220 		features &= ~NETIF_F_TSO6;
221 	if (!vif->ip_csum)
222 		features &= ~NETIF_F_IP_CSUM;
223 	if (!vif->ipv6_csum)
224 		features &= ~NETIF_F_IPV6_CSUM;
225 
226 	return features;
227 }
228 
229 static const struct xenvif_stat {
230 	char name[ETH_GSTRING_LEN];
231 	u16 offset;
232 } xenvif_stats[] = {
233 	{
234 		"rx_gso_checksum_fixup",
235 		offsetof(struct xenvif, rx_gso_checksum_fixup)
236 	},
237 };
238 
239 static int xenvif_get_sset_count(struct net_device *dev, int string_set)
240 {
241 	switch (string_set) {
242 	case ETH_SS_STATS:
243 		return ARRAY_SIZE(xenvif_stats);
244 	default:
245 		return -EINVAL;
246 	}
247 }
248 
249 static void xenvif_get_ethtool_stats(struct net_device *dev,
250 				     struct ethtool_stats *stats, u64 * data)
251 {
252 	void *vif = netdev_priv(dev);
253 	int i;
254 
255 	for (i = 0; i < ARRAY_SIZE(xenvif_stats); i++)
256 		data[i] = *(unsigned long *)(vif + xenvif_stats[i].offset);
257 }
258 
259 static void xenvif_get_strings(struct net_device *dev, u32 stringset, u8 * data)
260 {
261 	int i;
262 
263 	switch (stringset) {
264 	case ETH_SS_STATS:
265 		for (i = 0; i < ARRAY_SIZE(xenvif_stats); i++)
266 			memcpy(data + i * ETH_GSTRING_LEN,
267 			       xenvif_stats[i].name, ETH_GSTRING_LEN);
268 		break;
269 	}
270 }
271 
272 static const struct ethtool_ops xenvif_ethtool_ops = {
273 	.get_link	= ethtool_op_get_link,
274 
275 	.get_sset_count = xenvif_get_sset_count,
276 	.get_ethtool_stats = xenvif_get_ethtool_stats,
277 	.get_strings = xenvif_get_strings,
278 };
279 
280 static const struct net_device_ops xenvif_netdev_ops = {
281 	.ndo_start_xmit	= xenvif_start_xmit,
282 	.ndo_get_stats	= xenvif_get_stats,
283 	.ndo_open	= xenvif_open,
284 	.ndo_stop	= xenvif_close,
285 	.ndo_change_mtu	= xenvif_change_mtu,
286 	.ndo_fix_features = xenvif_fix_features,
287 	.ndo_set_mac_address = eth_mac_addr,
288 	.ndo_validate_addr   = eth_validate_addr,
289 };
290 
291 struct xenvif *xenvif_alloc(struct device *parent, domid_t domid,
292 			    unsigned int handle)
293 {
294 	int err;
295 	struct net_device *dev;
296 	struct xenvif *vif;
297 	char name[IFNAMSIZ] = {};
298 	int i;
299 
300 	snprintf(name, IFNAMSIZ - 1, "vif%u.%u", domid, handle);
301 	dev = alloc_netdev(sizeof(struct xenvif), name, ether_setup);
302 	if (dev == NULL) {
303 		pr_warn("Could not allocate netdev for %s\n", name);
304 		return ERR_PTR(-ENOMEM);
305 	}
306 
307 	SET_NETDEV_DEV(dev, parent);
308 
309 	vif = netdev_priv(dev);
310 
311 	vif->grant_copy_op = vmalloc(sizeof(struct gnttab_copy) *
312 				     MAX_GRANT_COPY_OPS);
313 	if (vif->grant_copy_op == NULL) {
314 		pr_warn("Could not allocate grant copy space for %s\n", name);
315 		free_netdev(dev);
316 		return ERR_PTR(-ENOMEM);
317 	}
318 
319 	vif->domid  = domid;
320 	vif->handle = handle;
321 	vif->can_sg = 1;
322 	vif->ip_csum = 1;
323 	vif->dev = dev;
324 
325 	vif->credit_bytes = vif->remaining_credit = ~0UL;
326 	vif->credit_usec  = 0UL;
327 	init_timer(&vif->credit_timeout);
328 	vif->credit_window_start = get_jiffies_64();
329 
330 	dev->netdev_ops	= &xenvif_netdev_ops;
331 	dev->hw_features = NETIF_F_SG |
332 		NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM |
333 		NETIF_F_TSO | NETIF_F_TSO6;
334 	dev->features = dev->hw_features | NETIF_F_RXCSUM;
335 	SET_ETHTOOL_OPS(dev, &xenvif_ethtool_ops);
336 
337 	dev->tx_queue_len = XENVIF_QUEUE_LENGTH;
338 
339 	skb_queue_head_init(&vif->rx_queue);
340 	skb_queue_head_init(&vif->tx_queue);
341 
342 	vif->pending_cons = 0;
343 	vif->pending_prod = MAX_PENDING_REQS;
344 	for (i = 0; i < MAX_PENDING_REQS; i++)
345 		vif->pending_ring[i] = i;
346 	for (i = 0; i < MAX_PENDING_REQS; i++)
347 		vif->mmap_pages[i] = NULL;
348 
349 	/*
350 	 * Initialise a dummy MAC address. We choose the numerically
351 	 * largest non-broadcast address to prevent the address getting
352 	 * stolen by an Ethernet bridge for STP purposes.
353 	 * (FE:FF:FF:FF:FF:FF)
354 	 */
355 	memset(dev->dev_addr, 0xFF, ETH_ALEN);
356 	dev->dev_addr[0] &= ~0x01;
357 
358 	netif_napi_add(dev, &vif->napi, xenvif_poll, XENVIF_NAPI_WEIGHT);
359 
360 	netif_carrier_off(dev);
361 
362 	err = register_netdev(dev);
363 	if (err) {
364 		netdev_warn(dev, "Could not register device: err=%d\n", err);
365 		free_netdev(dev);
366 		return ERR_PTR(err);
367 	}
368 
369 	netdev_dbg(dev, "Successfully created xenvif\n");
370 
371 	__module_get(THIS_MODULE);
372 
373 	return vif;
374 }
375 
376 int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref,
377 		   unsigned long rx_ring_ref, unsigned int tx_evtchn,
378 		   unsigned int rx_evtchn)
379 {
380 	struct task_struct *task;
381 	int err = -ENOMEM;
382 
383 	BUG_ON(vif->tx_irq);
384 	BUG_ON(vif->task);
385 
386 	err = xenvif_map_frontend_rings(vif, tx_ring_ref, rx_ring_ref);
387 	if (err < 0)
388 		goto err;
389 
390 	init_waitqueue_head(&vif->wq);
391 
392 	if (tx_evtchn == rx_evtchn) {
393 		/* feature-split-event-channels == 0 */
394 		err = bind_interdomain_evtchn_to_irqhandler(
395 			vif->domid, tx_evtchn, xenvif_interrupt, 0,
396 			vif->dev->name, vif);
397 		if (err < 0)
398 			goto err_unmap;
399 		vif->tx_irq = vif->rx_irq = err;
400 		disable_irq(vif->tx_irq);
401 	} else {
402 		/* feature-split-event-channels == 1 */
403 		snprintf(vif->tx_irq_name, sizeof(vif->tx_irq_name),
404 			 "%s-tx", vif->dev->name);
405 		err = bind_interdomain_evtchn_to_irqhandler(
406 			vif->domid, tx_evtchn, xenvif_tx_interrupt, 0,
407 			vif->tx_irq_name, vif);
408 		if (err < 0)
409 			goto err_unmap;
410 		vif->tx_irq = err;
411 		disable_irq(vif->tx_irq);
412 
413 		snprintf(vif->rx_irq_name, sizeof(vif->rx_irq_name),
414 			 "%s-rx", vif->dev->name);
415 		err = bind_interdomain_evtchn_to_irqhandler(
416 			vif->domid, rx_evtchn, xenvif_rx_interrupt, 0,
417 			vif->rx_irq_name, vif);
418 		if (err < 0)
419 			goto err_tx_unbind;
420 		vif->rx_irq = err;
421 		disable_irq(vif->rx_irq);
422 	}
423 
424 	task = kthread_create(xenvif_kthread,
425 			      (void *)vif, "%s", vif->dev->name);
426 	if (IS_ERR(task)) {
427 		pr_warn("Could not allocate kthread for %s\n", vif->dev->name);
428 		err = PTR_ERR(task);
429 		goto err_rx_unbind;
430 	}
431 
432 	vif->task = task;
433 
434 	rtnl_lock();
435 	if (!vif->can_sg && vif->dev->mtu > ETH_DATA_LEN)
436 		dev_set_mtu(vif->dev, ETH_DATA_LEN);
437 	netdev_update_features(vif->dev);
438 	netif_carrier_on(vif->dev);
439 	if (netif_running(vif->dev))
440 		xenvif_up(vif);
441 	rtnl_unlock();
442 
443 	wake_up_process(vif->task);
444 
445 	return 0;
446 
447 err_rx_unbind:
448 	unbind_from_irqhandler(vif->rx_irq, vif);
449 	vif->rx_irq = 0;
450 err_tx_unbind:
451 	unbind_from_irqhandler(vif->tx_irq, vif);
452 	vif->tx_irq = 0;
453 err_unmap:
454 	xenvif_unmap_frontend_rings(vif);
455 err:
456 	module_put(THIS_MODULE);
457 	return err;
458 }
459 
460 void xenvif_carrier_off(struct xenvif *vif)
461 {
462 	struct net_device *dev = vif->dev;
463 
464 	rtnl_lock();
465 	netif_carrier_off(dev); /* discard queued packets */
466 	if (netif_running(dev))
467 		xenvif_down(vif);
468 	rtnl_unlock();
469 }
470 
471 void xenvif_disconnect(struct xenvif *vif)
472 {
473 	if (netif_carrier_ok(vif->dev))
474 		xenvif_carrier_off(vif);
475 
476 	if (vif->task) {
477 		kthread_stop(vif->task);
478 		vif->task = NULL;
479 	}
480 
481 	if (vif->tx_irq) {
482 		if (vif->tx_irq == vif->rx_irq)
483 			unbind_from_irqhandler(vif->tx_irq, vif);
484 		else {
485 			unbind_from_irqhandler(vif->tx_irq, vif);
486 			unbind_from_irqhandler(vif->rx_irq, vif);
487 		}
488 		vif->tx_irq = 0;
489 	}
490 
491 	xenvif_unmap_frontend_rings(vif);
492 }
493 
494 void xenvif_free(struct xenvif *vif)
495 {
496 	netif_napi_del(&vif->napi);
497 
498 	unregister_netdev(vif->dev);
499 
500 	vfree(vif->grant_copy_op);
501 	free_netdev(vif->dev);
502 
503 	module_put(THIS_MODULE);
504 }
505