hvc_xen.c revision 6a07cbc4ef9cea9f9eabc676fd6b8c03c11f51cc 
1/*
2 * xen console driver interface to hvc_console.c
3 *
4 * (c) 2007 Gerd Hoffmann <kraxel@suse.de>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
19 */
20
21#include <linux/console.h>
22#include <linux/delay.h>
23#include <linux/err.h>
24#include <linux/init.h>
25#include <linux/types.h>
26#include <linux/list.h>
27
28#include <asm/io.h>
29#include <asm/xen/hypervisor.h>
30
31#include <xen/xen.h>
32#include <xen/interface/xen.h>
33#include <xen/hvm.h>
34#include <xen/grant_table.h>
35#include <xen/page.h>
36#include <xen/events.h>
37#include <xen/interface/io/console.h>
38#include <xen/hvc-console.h>
39#include <xen/xenbus.h>
40
41#include "hvc_console.h"
42
43#define HVC_COOKIE   0x58656e /* "Xen" in hex */
44
45struct xencons_info {
46	struct list_head list;
47	struct xenbus_device *xbdev;
48	struct xencons_interface *intf;
49	unsigned int evtchn;
50	struct hvc_struct *hvc;
51	int irq;
52	int vtermno;
53	grant_ref_t gntref;
54};
55
56static LIST_HEAD(xenconsoles);
57static DEFINE_SPINLOCK(xencons_lock);
58
59/* ------------------------------------------------------------------ */
60
61static struct xencons_info *vtermno_to_xencons(int vtermno)
62{
63	struct xencons_info *entry, *n, *ret = NULL;
64
65	if (list_empty(&xenconsoles))
66			return NULL;
67
68	list_for_each_entry_safe(entry, n, &xenconsoles, list) {
69		if (entry->vtermno == vtermno) {
70			ret  = entry;
71			break;
72		}
73	}
74
75	return ret;
76}
77
78static inline int xenbus_devid_to_vtermno(int devid)
79{
80	return devid + HVC_COOKIE;
81}
82
83static inline void notify_daemon(struct xencons_info *cons)
84{
85	/* Use evtchn: this is called early, before irq is set up. */
86	notify_remote_via_evtchn(cons->evtchn);
87}
88
89static int __write_console(struct xencons_info *xencons,
90		const char *data, int len)
91{
92	XENCONS_RING_IDX cons, prod;
93	struct xencons_interface *intf = xencons->intf;
94	int sent = 0;
95
96	cons = intf->out_cons;
97	prod = intf->out_prod;
98	mb();			/* update queue values before going on */
99	BUG_ON((prod - cons) > sizeof(intf->out));
100
101	while ((sent < len) && ((prod - cons) < sizeof(intf->out)))
102		intf->out[MASK_XENCONS_IDX(prod++, intf->out)] = data[sent++];
103
104	wmb();			/* write ring before updating pointer */
105	intf->out_prod = prod;
106
107	if (sent)
108		notify_daemon(xencons);
109	return sent;
110}
111
112static int domU_write_console(uint32_t vtermno, const char *data, int len)
113{
114	int ret = len;
115	struct xencons_info *cons = vtermno_to_xencons(vtermno);
116	if (cons == NULL)
117		return -EINVAL;
118
119	/*
120	 * Make sure the whole buffer is emitted, polling if
121	 * necessary.  We don't ever want to rely on the hvc daemon
122	 * because the most interesting console output is when the
123	 * kernel is crippled.
124	 */
125	while (len) {
126		int sent = __write_console(cons, data, len);
127
128		data += sent;
129		len -= sent;
130
131		if (unlikely(len))
132			HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
133	}
134
135	return ret;
136}
137
138static int domU_read_console(uint32_t vtermno, char *buf, int len)
139{
140	struct xencons_interface *intf;
141	XENCONS_RING_IDX cons, prod;
142	int recv = 0;
143	struct xencons_info *xencons = vtermno_to_xencons(vtermno);
144	if (xencons == NULL)
145		return -EINVAL;
146	intf = xencons->intf;
147
148	cons = intf->in_cons;
149	prod = intf->in_prod;
150	mb();			/* get pointers before reading ring */
151	BUG_ON((prod - cons) > sizeof(intf->in));
152
153	while (cons != prod && recv < len)
154		buf[recv++] = intf->in[MASK_XENCONS_IDX(cons++, intf->in)];
155
156	mb();			/* read ring before consuming */
157	intf->in_cons = cons;
158
159	notify_daemon(xencons);
160	return recv;
161}
162
163static struct hv_ops domU_hvc_ops = {
164	.get_chars = domU_read_console,
165	.put_chars = domU_write_console,
166	.notifier_add = notifier_add_irq,
167	.notifier_del = notifier_del_irq,
168	.notifier_hangup = notifier_hangup_irq,
169};
170
171static int dom0_read_console(uint32_t vtermno, char *buf, int len)
172{
173	return HYPERVISOR_console_io(CONSOLEIO_read, len, buf);
174}
175
176/*
177 * Either for a dom0 to write to the system console, or a domU with a
178 * debug version of Xen
179 */
180static int dom0_write_console(uint32_t vtermno, const char *str, int len)
181{
182	int rc = HYPERVISOR_console_io(CONSOLEIO_write, len, (char *)str);
183	if (rc < 0)
184		return 0;
185
186	return len;
187}
188
189static struct hv_ops dom0_hvc_ops = {
190	.get_chars = dom0_read_console,
191	.put_chars = dom0_write_console,
192	.notifier_add = notifier_add_irq,
193	.notifier_del = notifier_del_irq,
194	.notifier_hangup = notifier_hangup_irq,
195};
196
197static int xen_hvm_console_init(void)
198{
199	int r;
200	uint64_t v = 0;
201	unsigned long mfn;
202	struct xencons_info *info;
203
204	if (!xen_hvm_domain())
205		return -ENODEV;
206
207	info = vtermno_to_xencons(HVC_COOKIE);
208	if (!info) {
209		info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL | __GFP_ZERO);
210		if (!info)
211			return -ENOMEM;
212	}
213
214	/* already configured */
215	if (info->intf != NULL)
216		return 0;
217
218	r = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v);
219	if (r < 0)
220		goto err;
221	info->evtchn = v;
222	hvm_get_parameter(HVM_PARAM_CONSOLE_PFN, &v);
223	if (r < 0)
224		goto err;
225	mfn = v;
226	info->intf = ioremap(mfn << PAGE_SHIFT, PAGE_SIZE);
227	if (info->intf == NULL)
228		goto err;
229	info->vtermno = HVC_COOKIE;
230
231	spin_lock(&xencons_lock);
232	list_add_tail(&info->list, &xenconsoles);
233	spin_unlock(&xencons_lock);
234
235	return 0;
236err:
237	kfree(info);
238	return -ENODEV;
239}
240
241static int xen_pv_console_init(void)
242{
243	struct xencons_info *info;
244
245	if (!xen_pv_domain())
246		return -ENODEV;
247
248	if (!xen_start_info->console.domU.evtchn)
249		return -ENODEV;
250
251	info = vtermno_to_xencons(HVC_COOKIE);
252	if (!info) {
253		info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL | __GFP_ZERO);
254		if (!info)
255			return -ENOMEM;
256	}
257
258	/* already configured */
259	if (info->intf != NULL)
260		return 0;
261
262	info->evtchn = xen_start_info->console.domU.evtchn;
263	info->intf = mfn_to_virt(xen_start_info->console.domU.mfn);
264	info->vtermno = HVC_COOKIE;
265
266	spin_lock(&xencons_lock);
267	list_add_tail(&info->list, &xenconsoles);
268	spin_unlock(&xencons_lock);
269
270	return 0;
271}
272
273static int xen_initial_domain_console_init(void)
274{
275	struct xencons_info *info;
276
277	if (!xen_initial_domain())
278		return -ENODEV;
279
280	info = vtermno_to_xencons(HVC_COOKIE);
281	if (!info) {
282		info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL | __GFP_ZERO);
283		if (!info)
284			return -ENOMEM;
285	}
286
287	info->irq = bind_virq_to_irq(VIRQ_CONSOLE, 0);
288	info->vtermno = HVC_COOKIE;
289
290	spin_lock(&xencons_lock);
291	list_add_tail(&info->list, &xenconsoles);
292	spin_unlock(&xencons_lock);
293
294	return 0;
295}
296
297void xen_console_resume(void)
298{
299	struct xencons_info *info = vtermno_to_xencons(HVC_COOKIE);
300	if (info != NULL && info->irq)
301		rebind_evtchn_irq(info->evtchn, info->irq);
302}
303
304static void xencons_disconnect_backend(struct xencons_info *info)
305{
306	if (info->irq > 0)
307		unbind_from_irqhandler(info->irq, NULL);
308	info->irq = 0;
309	if (info->evtchn > 0)
310		xenbus_free_evtchn(info->xbdev, info->evtchn);
311	info->evtchn = 0;
312	if (info->gntref > 0)
313		gnttab_free_grant_references(info->gntref);
314	info->gntref = 0;
315	if (info->hvc != NULL)
316		hvc_remove(info->hvc);
317	info->hvc = NULL;
318}
319
320static void xencons_free(struct xencons_info *info)
321{
322	free_page((unsigned long)info->intf);
323	info->intf = NULL;
324	info->vtermno = 0;
325	kfree(info);
326}
327
328static int xen_console_remove(struct xencons_info *info)
329{
330	xencons_disconnect_backend(info);
331	spin_lock(&xencons_lock);
332	list_del(&info->list);
333	spin_unlock(&xencons_lock);
334	if (info->xbdev != NULL)
335		xencons_free(info);
336	else {
337		if (xen_hvm_domain())
338			iounmap(info->intf);
339		kfree(info);
340	}
341	return 0;
342}
343
344#ifdef CONFIG_HVC_XEN_FRONTEND
345static struct xenbus_driver xencons_driver;
346
347static int xencons_remove(struct xenbus_device *dev)
348{
349	return xen_console_remove(dev_get_drvdata(&dev->dev));
350}
351
352static int xencons_connect_backend(struct xenbus_device *dev,
353				  struct xencons_info *info)
354{
355	int ret, evtchn, devid, ref, irq;
356	struct xenbus_transaction xbt;
357	grant_ref_t gref_head;
358	unsigned long mfn;
359
360	ret = xenbus_alloc_evtchn(dev, &evtchn);
361	if (ret)
362		return ret;
363	info->evtchn = evtchn;
364	irq = bind_evtchn_to_irq(evtchn);
365	if (irq < 0)
366		return irq;
367	info->irq = irq;
368	devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
369	info->hvc = hvc_alloc(xenbus_devid_to_vtermno(devid),
370			irq, &domU_hvc_ops, 256);
371	if (IS_ERR(info->hvc))
372		return PTR_ERR(info->hvc);
373	if (xen_pv_domain())
374		mfn = virt_to_mfn(info->intf);
375	else
376		mfn = __pa(info->intf) >> PAGE_SHIFT;
377	ret = gnttab_alloc_grant_references(1, &gref_head);
378	if (ret < 0)
379		return ret;
380	info->gntref = gref_head;
381	ref = gnttab_claim_grant_reference(&gref_head);
382	if (ref < 0)
383		return ref;
384	gnttab_grant_foreign_access_ref(ref, info->xbdev->otherend_id,
385			mfn, 0);
386
387 again:
388	ret = xenbus_transaction_start(&xbt);
389	if (ret) {
390		xenbus_dev_fatal(dev, ret, "starting transaction");
391		return ret;
392	}
393	ret = xenbus_printf(xbt, dev->nodename, "ring-ref", "%d", ref);
394	if (ret)
395		goto error_xenbus;
396	ret = xenbus_printf(xbt, dev->nodename, "port", "%u",
397			    evtchn);
398	if (ret)
399		goto error_xenbus;
400	ret = xenbus_printf(xbt, dev->nodename, "type", "ioemu");
401	if (ret)
402		goto error_xenbus;
403	ret = xenbus_transaction_end(xbt, 0);
404	if (ret) {
405		if (ret == -EAGAIN)
406			goto again;
407		xenbus_dev_fatal(dev, ret, "completing transaction");
408		return ret;
409	}
410
411	xenbus_switch_state(dev, XenbusStateInitialised);
412	return 0;
413
414 error_xenbus:
415	xenbus_transaction_end(xbt, 1);
416	xenbus_dev_fatal(dev, ret, "writing xenstore");
417	return ret;
418}
419
420static int __devinit xencons_probe(struct xenbus_device *dev,
421				  const struct xenbus_device_id *id)
422{
423	int ret, devid;
424	struct xencons_info *info;
425
426	devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
427	if (devid == 0)
428		return -ENODEV;
429
430	info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
431	if (!info)
432		return -ENOMEM;
433	dev_set_drvdata(&dev->dev, info);
434	info->xbdev = dev;
435	info->vtermno = xenbus_devid_to_vtermno(devid);
436	info->intf = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
437	if (!info->intf)
438		goto error_nomem;
439
440	ret = xencons_connect_backend(dev, info);
441	if (ret < 0)
442		goto error;
443	spin_lock(&xencons_lock);
444	list_add_tail(&info->list, &xenconsoles);
445	spin_unlock(&xencons_lock);
446
447	return 0;
448
449 error_nomem:
450	ret = -ENOMEM;
451	xenbus_dev_fatal(dev, ret, "allocating device memory");
452 error:
453	xencons_disconnect_backend(info);
454	xencons_free(info);
455	return ret;
456}
457
458static int xencons_resume(struct xenbus_device *dev)
459{
460	struct xencons_info *info = dev_get_drvdata(&dev->dev);
461
462	xencons_disconnect_backend(info);
463	memset(info->intf, 0, PAGE_SIZE);
464	return xencons_connect_backend(dev, info);
465}
466
467static void xencons_backend_changed(struct xenbus_device *dev,
468				   enum xenbus_state backend_state)
469{
470	switch (backend_state) {
471	case XenbusStateReconfiguring:
472	case XenbusStateReconfigured:
473	case XenbusStateInitialising:
474	case XenbusStateInitialised:
475	case XenbusStateUnknown:
476	case XenbusStateClosed:
477		break;
478
479	case XenbusStateInitWait:
480		break;
481
482	case XenbusStateConnected:
483		xenbus_switch_state(dev, XenbusStateConnected);
484		break;
485
486	case XenbusStateClosing:
487		xenbus_frontend_closed(dev);
488		break;
489	}
490}
491
492static const struct xenbus_device_id xencons_ids[] = {
493	{ "console" },
494	{ "" }
495};
496
497
498static DEFINE_XENBUS_DRIVER(xencons, "xenconsole",
499	.probe = xencons_probe,
500	.remove = xencons_remove,
501	.resume = xencons_resume,
502	.otherend_changed = xencons_backend_changed,
503);
504#endif /* CONFIG_HVC_XEN_FRONTEND */
505
506static int __init xen_hvc_init(void)
507{
508	int r;
509	struct xencons_info *info;
510	const struct hv_ops *ops;
511
512	if (!xen_domain())
513		return -ENODEV;
514
515	if (xen_initial_domain()) {
516		ops = &dom0_hvc_ops;
517		r = xen_initial_domain_console_init();
518		if (r < 0)
519			return r;
520		info = vtermno_to_xencons(HVC_COOKIE);
521	} else {
522		ops = &domU_hvc_ops;
523		if (xen_hvm_domain())
524			r = xen_hvm_console_init();
525		else
526			r = xen_pv_console_init();
527		if (r < 0)
528			return r;
529
530		info = vtermno_to_xencons(HVC_COOKIE);
531		info->irq = bind_evtchn_to_irq(info->evtchn);
532	}
533	if (info->irq < 0)
534		info->irq = 0; /* NO_IRQ */
535	else
536		irq_set_noprobe(info->irq);
537
538	info->hvc = hvc_alloc(HVC_COOKIE, info->irq, ops, 256);
539	if (IS_ERR(info->hvc)) {
540		r = PTR_ERR(info->hvc);
541		spin_lock(&xencons_lock);
542		list_del(&info->list);
543		spin_unlock(&xencons_lock);
544		if (info->irq)
545			unbind_from_irqhandler(info->irq, NULL);
546		kfree(info);
547		return r;
548	}
549
550	r = 0;
551#ifdef CONFIG_HVC_XEN_FRONTEND
552	r = xenbus_register_frontend(&xencons_driver);
553#endif
554	return r;
555}
556
557static void __exit xen_hvc_fini(void)
558{
559	struct xencons_info *entry, *next;
560
561	if (list_empty(&xenconsoles))
562			return;
563
564	list_for_each_entry_safe(entry, next, &xenconsoles, list) {
565		xen_console_remove(entry);
566	}
567}
568
569static int xen_cons_init(void)
570{
571	const struct hv_ops *ops;
572
573	if (!xen_domain())
574		return 0;
575
576	if (xen_initial_domain())
577		ops = &dom0_hvc_ops;
578	else {
579		int r;
580		ops = &domU_hvc_ops;
581
582		if (xen_hvm_domain())
583			r = xen_hvm_console_init();
584		else
585			r = xen_pv_console_init();
586		if (r < 0)
587			return r;
588	}
589
590	hvc_instantiate(HVC_COOKIE, 0, ops);
591	return 0;
592}
593
594
595module_init(xen_hvc_init);
596module_exit(xen_hvc_fini);
597console_initcall(xen_cons_init);
598
599#ifdef CONFIG_EARLY_PRINTK
600static void xenboot_write_console(struct console *console, const char *string,
601				  unsigned len)
602{
603	unsigned int linelen, off = 0;
604	const char *pos;
605
606	if (!xen_pv_domain())
607		return;
608
609	dom0_write_console(0, string, len);
610
611	if (xen_initial_domain())
612		return;
613
614	domU_write_console(0, "(early) ", 8);
615	while (off < len && NULL != (pos = strchr(string+off, '\n'))) {
616		linelen = pos-string+off;
617		if (off + linelen > len)
618			break;
619		domU_write_console(0, string+off, linelen);
620		domU_write_console(0, "\r\n", 2);
621		off += linelen + 1;
622	}
623	if (off < len)
624		domU_write_console(0, string+off, len-off);
625}
626
627struct console xenboot_console = {
628	.name		= "xenboot",
629	.write		= xenboot_write_console,
630	.flags		= CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
631};
632#endif	/* CONFIG_EARLY_PRINTK */
633
634void xen_raw_console_write(const char *str)
635{
636	dom0_write_console(0, str, strlen(str));
637}
638
639void xen_raw_printk(const char *fmt, ...)
640{
641	static char buf[512];
642	va_list ap;
643
644	va_start(ap, fmt);
645	vsnprintf(buf, sizeof(buf), fmt, ap);
646	va_end(ap);
647
648	xen_raw_console_write(buf);
649}
650