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 
38 #include <xen/events.h>
39 #include <asm/xen/hypercall.h>
40 
41 #define XENVIF_QUEUE_LENGTH 32
42 #define XENVIF_NAPI_WEIGHT  64
43 
44 int xenvif_schedulable(struct xenvif *vif)
45 {
46 	return netif_running(vif->dev) && netif_carrier_ok(vif->dev);
47 }
48 
49 static int xenvif_rx_schedulable(struct xenvif *vif)
50 {
51 	return xenvif_schedulable(vif) && !xenvif_rx_ring_full(vif);
52 }
53 
54 static irqreturn_t xenvif_tx_interrupt(int irq, void *dev_id)
55 {
56 	struct xenvif *vif = dev_id;
57 
58 	if (RING_HAS_UNCONSUMED_REQUESTS(&vif->tx))
59 		napi_schedule(&vif->napi);
60 
61 	return IRQ_HANDLED;
62 }
63 
64 static int xenvif_poll(struct napi_struct *napi, int budget)
65 {
66 	struct xenvif *vif = container_of(napi, struct xenvif, napi);
67 	int work_done;
68 
69 	work_done = xenvif_tx_action(vif, budget);
70 
71 	if (work_done < budget) {
72 		int more_to_do = 0;
73 		unsigned long flags;
74 
75 		/* It is necessary to disable IRQ before calling
76 		 * RING_HAS_UNCONSUMED_REQUESTS. Otherwise we might
77 		 * lose event from the frontend.
78 		 *
79 		 * Consider:
80 		 *   RING_HAS_UNCONSUMED_REQUESTS
81 		 *   <frontend generates event to trigger napi_schedule>
82 		 *   __napi_complete
83 		 *
84 		 * This handler is still in scheduled state so the
85 		 * event has no effect at all. After __napi_complete
86 		 * this handler is descheduled and cannot get
87 		 * scheduled again. We lose event in this case and the ring
88 		 * will be completely stalled.
89 		 */
90 
91 		local_irq_save(flags);
92 
93 		RING_FINAL_CHECK_FOR_REQUESTS(&vif->tx, more_to_do);
94 		if (!more_to_do)
95 			__napi_complete(napi);
96 
97 		local_irq_restore(flags);
98 	}
99 
100 	return work_done;
101 }
102 
103 static irqreturn_t xenvif_rx_interrupt(int irq, void *dev_id)
104 {
105 	struct xenvif *vif = dev_id;
106 
107 	if (xenvif_rx_schedulable(vif))
108 		netif_wake_queue(vif->dev);
109 
110 	return IRQ_HANDLED;
111 }
112 
113 static irqreturn_t xenvif_interrupt(int irq, void *dev_id)
114 {
115 	xenvif_tx_interrupt(irq, dev_id);
116 	xenvif_rx_interrupt(irq, dev_id);
117 
118 	return IRQ_HANDLED;
119 }
120 
121 static int xenvif_start_xmit(struct sk_buff *skb, struct net_device *dev)
122 {
123 	struct xenvif *vif = netdev_priv(dev);
124 
125 	BUG_ON(skb->dev != dev);
126 
127 	/* Drop the packet if vif is not ready */
128 	if (vif->task == NULL)
129 		goto drop;
130 
131 	/* Drop the packet if the target domain has no receive buffers. */
132 	if (!xenvif_rx_schedulable(vif))
133 		goto drop;
134 
135 	/* Reserve ring slots for the worst-case number of fragments. */
136 	vif->rx_req_cons_peek += xenvif_count_skb_slots(vif, skb);
137 
138 	if (vif->can_queue && xenvif_must_stop_queue(vif))
139 		netif_stop_queue(dev);
140 
141 	xenvif_queue_tx_skb(vif, skb);
142 
143 	return NETDEV_TX_OK;
144 
145  drop:
146 	vif->dev->stats.tx_dropped++;
147 	dev_kfree_skb(skb);
148 	return NETDEV_TX_OK;
149 }
150 
151 void xenvif_notify_tx_completion(struct xenvif *vif)
152 {
153 	if (netif_queue_stopped(vif->dev) && xenvif_rx_schedulable(vif))
154 		netif_wake_queue(vif->dev);
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 && !vif->gso_prefix)
218 		features &= ~NETIF_F_TSO;
219 	if (!vif->csum)
220 		features &= ~NETIF_F_IP_CSUM;
221 
222 	return features;
223 }
224 
225 static const struct xenvif_stat {
226 	char name[ETH_GSTRING_LEN];
227 	u16 offset;
228 } xenvif_stats[] = {
229 	{
230 		"rx_gso_checksum_fixup",
231 		offsetof(struct xenvif, rx_gso_checksum_fixup)
232 	},
233 };
234 
235 static int xenvif_get_sset_count(struct net_device *dev, int string_set)
236 {
237 	switch (string_set) {
238 	case ETH_SS_STATS:
239 		return ARRAY_SIZE(xenvif_stats);
240 	default:
241 		return -EINVAL;
242 	}
243 }
244 
245 static void xenvif_get_ethtool_stats(struct net_device *dev,
246 				     struct ethtool_stats *stats, u64 * data)
247 {
248 	void *vif = netdev_priv(dev);
249 	int i;
250 
251 	for (i = 0; i < ARRAY_SIZE(xenvif_stats); i++)
252 		data[i] = *(unsigned long *)(vif + xenvif_stats[i].offset);
253 }
254 
255 static void xenvif_get_strings(struct net_device *dev, u32 stringset, u8 * data)
256 {
257 	int i;
258 
259 	switch (stringset) {
260 	case ETH_SS_STATS:
261 		for (i = 0; i < ARRAY_SIZE(xenvif_stats); i++)
262 			memcpy(data + i * ETH_GSTRING_LEN,
263 			       xenvif_stats[i].name, ETH_GSTRING_LEN);
264 		break;
265 	}
266 }
267 
268 static const struct ethtool_ops xenvif_ethtool_ops = {
269 	.get_link	= ethtool_op_get_link,
270 
271 	.get_sset_count = xenvif_get_sset_count,
272 	.get_ethtool_stats = xenvif_get_ethtool_stats,
273 	.get_strings = xenvif_get_strings,
274 };
275 
276 static const struct net_device_ops xenvif_netdev_ops = {
277 	.ndo_start_xmit	= xenvif_start_xmit,
278 	.ndo_get_stats	= xenvif_get_stats,
279 	.ndo_open	= xenvif_open,
280 	.ndo_stop	= xenvif_close,
281 	.ndo_change_mtu	= xenvif_change_mtu,
282 	.ndo_fix_features = xenvif_fix_features,
283 	.ndo_set_mac_address = eth_mac_addr,
284 	.ndo_validate_addr   = eth_validate_addr,
285 };
286 
287 struct xenvif *xenvif_alloc(struct device *parent, domid_t domid,
288 			    unsigned int handle)
289 {
290 	int err;
291 	struct net_device *dev;
292 	struct xenvif *vif;
293 	char name[IFNAMSIZ] = {};
294 	int i;
295 
296 	snprintf(name, IFNAMSIZ - 1, "vif%u.%u", domid, handle);
297 	dev = alloc_netdev(sizeof(struct xenvif), name, ether_setup);
298 	if (dev == NULL) {
299 		pr_warn("Could not allocate netdev for %s\n", name);
300 		return ERR_PTR(-ENOMEM);
301 	}
302 
303 	SET_NETDEV_DEV(dev, parent);
304 
305 	vif = netdev_priv(dev);
306 	vif->domid  = domid;
307 	vif->handle = handle;
308 	vif->can_sg = 1;
309 	vif->csum = 1;
310 	vif->dev = dev;
311 
312 	vif->credit_bytes = vif->remaining_credit = ~0UL;
313 	vif->credit_usec  = 0UL;
314 	init_timer(&vif->credit_timeout);
315 	vif->credit_window_start = get_jiffies_64();
316 
317 	dev->netdev_ops	= &xenvif_netdev_ops;
318 	dev->hw_features = NETIF_F_SG | NETIF_F_IP_CSUM | NETIF_F_TSO;
319 	dev->features = dev->hw_features;
320 	SET_ETHTOOL_OPS(dev, &xenvif_ethtool_ops);
321 
322 	dev->tx_queue_len = XENVIF_QUEUE_LENGTH;
323 
324 	skb_queue_head_init(&vif->rx_queue);
325 	skb_queue_head_init(&vif->tx_queue);
326 
327 	vif->pending_cons = 0;
328 	vif->pending_prod = MAX_PENDING_REQS;
329 	for (i = 0; i < MAX_PENDING_REQS; i++)
330 		vif->pending_ring[i] = i;
331 	for (i = 0; i < MAX_PENDING_REQS; i++)
332 		vif->mmap_pages[i] = NULL;
333 
334 	/*
335 	 * Initialise a dummy MAC address. We choose the numerically
336 	 * largest non-broadcast address to prevent the address getting
337 	 * stolen by an Ethernet bridge for STP purposes.
338 	 * (FE:FF:FF:FF:FF:FF)
339 	 */
340 	memset(dev->dev_addr, 0xFF, ETH_ALEN);
341 	dev->dev_addr[0] &= ~0x01;
342 
343 	netif_napi_add(dev, &vif->napi, xenvif_poll, XENVIF_NAPI_WEIGHT);
344 
345 	netif_carrier_off(dev);
346 
347 	err = register_netdev(dev);
348 	if (err) {
349 		netdev_warn(dev, "Could not register device: err=%d\n", err);
350 		free_netdev(dev);
351 		return ERR_PTR(err);
352 	}
353 
354 	netdev_dbg(dev, "Successfully created xenvif\n");
355 
356 	__module_get(THIS_MODULE);
357 
358 	return vif;
359 }
360 
361 int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref,
362 		   unsigned long rx_ring_ref, unsigned int tx_evtchn,
363 		   unsigned int rx_evtchn)
364 {
365 	int err = -ENOMEM;
366 
367 	/* Already connected through? */
368 	if (vif->tx_irq)
369 		return 0;
370 
371 	err = xenvif_map_frontend_rings(vif, tx_ring_ref, rx_ring_ref);
372 	if (err < 0)
373 		goto err;
374 
375 	if (tx_evtchn == rx_evtchn) {
376 		/* feature-split-event-channels == 0 */
377 		err = bind_interdomain_evtchn_to_irqhandler(
378 			vif->domid, tx_evtchn, xenvif_interrupt, 0,
379 			vif->dev->name, vif);
380 		if (err < 0)
381 			goto err_unmap;
382 		vif->tx_irq = vif->rx_irq = err;
383 		disable_irq(vif->tx_irq);
384 	} else {
385 		/* feature-split-event-channels == 1 */
386 		snprintf(vif->tx_irq_name, sizeof(vif->tx_irq_name),
387 			 "%s-tx", vif->dev->name);
388 		err = bind_interdomain_evtchn_to_irqhandler(
389 			vif->domid, tx_evtchn, xenvif_tx_interrupt, 0,
390 			vif->tx_irq_name, vif);
391 		if (err < 0)
392 			goto err_unmap;
393 		vif->tx_irq = err;
394 		disable_irq(vif->tx_irq);
395 
396 		snprintf(vif->rx_irq_name, sizeof(vif->rx_irq_name),
397 			 "%s-rx", vif->dev->name);
398 		err = bind_interdomain_evtchn_to_irqhandler(
399 			vif->domid, rx_evtchn, xenvif_rx_interrupt, 0,
400 			vif->rx_irq_name, vif);
401 		if (err < 0)
402 			goto err_tx_unbind;
403 		vif->rx_irq = err;
404 		disable_irq(vif->rx_irq);
405 	}
406 
407 	init_waitqueue_head(&vif->wq);
408 	vif->task = kthread_create(xenvif_kthread,
409 				   (void *)vif, "%s", vif->dev->name);
410 	if (IS_ERR(vif->task)) {
411 		pr_warn("Could not allocate kthread for %s\n", vif->dev->name);
412 		err = PTR_ERR(vif->task);
413 		goto err_rx_unbind;
414 	}
415 
416 	rtnl_lock();
417 	if (!vif->can_sg && vif->dev->mtu > ETH_DATA_LEN)
418 		dev_set_mtu(vif->dev, ETH_DATA_LEN);
419 	netdev_update_features(vif->dev);
420 	netif_carrier_on(vif->dev);
421 	if (netif_running(vif->dev))
422 		xenvif_up(vif);
423 	rtnl_unlock();
424 
425 	wake_up_process(vif->task);
426 
427 	return 0;
428 
429 err_rx_unbind:
430 	unbind_from_irqhandler(vif->rx_irq, vif);
431 	vif->rx_irq = 0;
432 err_tx_unbind:
433 	unbind_from_irqhandler(vif->tx_irq, vif);
434 	vif->tx_irq = 0;
435 err_unmap:
436 	xenvif_unmap_frontend_rings(vif);
437 err:
438 	module_put(THIS_MODULE);
439 	return err;
440 }
441 
442 void xenvif_carrier_off(struct xenvif *vif)
443 {
444 	struct net_device *dev = vif->dev;
445 
446 	rtnl_lock();
447 	netif_carrier_off(dev); /* discard queued packets */
448 	if (netif_running(dev))
449 		xenvif_down(vif);
450 	rtnl_unlock();
451 }
452 
453 void xenvif_disconnect(struct xenvif *vif)
454 {
455 	if (netif_carrier_ok(vif->dev))
456 		xenvif_carrier_off(vif);
457 
458 	if (vif->tx_irq) {
459 		if (vif->tx_irq == vif->rx_irq)
460 			unbind_from_irqhandler(vif->tx_irq, vif);
461 		else {
462 			unbind_from_irqhandler(vif->tx_irq, vif);
463 			unbind_from_irqhandler(vif->rx_irq, vif);
464 		}
465 		vif->tx_irq = 0;
466 	}
467 
468 	if (vif->task)
469 		kthread_stop(vif->task);
470 
471 	xenvif_unmap_frontend_rings(vif);
472 }
473 
474 void xenvif_free(struct xenvif *vif)
475 {
476 	netif_napi_del(&vif->napi);
477 
478 	unregister_netdev(vif->dev);
479 
480 	free_netdev(vif->dev);
481 
482 	module_put(THIS_MODULE);
483 }
484