hvc_xen.c revision 2da19ffd395d0fdba4ccbc4a3c751554059d4aa3 
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	 * If the toolstack (or the hypervisor) hasn't set these values, the
219	 * default value is 0. Even though mfn = 0 and evtchn = 0 are
220	 * theoretically correct values, in practice they never are and they
221	 * mean that a legacy toolstack hasn't initialized the pv console correctly.
222	 */
223	r = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v);
224	if (r < 0 || v == 0)
225		goto err;
226	info->evtchn = v;
227	v = 0;
228	r = hvm_get_parameter(HVM_PARAM_CONSOLE_PFN, &v);
229	if (r < 0 || v == 0)
230		goto err;
231	mfn = v;
232	info->intf = ioremap(mfn << PAGE_SHIFT, PAGE_SIZE);
233	if (info->intf == NULL)
234		goto err;
235	info->vtermno = HVC_COOKIE;
236
237	spin_lock(&xencons_lock);
238	list_add_tail(&info->list, &xenconsoles);
239	spin_unlock(&xencons_lock);
240
241	return 0;
242err:
243	kfree(info);
244	return -ENODEV;
245}
246
247static int xen_pv_console_init(void)
248{
249	struct xencons_info *info;
250
251	if (!xen_pv_domain())
252		return -ENODEV;
253
254	if (!xen_start_info->console.domU.evtchn)
255		return -ENODEV;
256
257	info = vtermno_to_xencons(HVC_COOKIE);
258	if (!info) {
259		info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL | __GFP_ZERO);
260		if (!info)
261			return -ENOMEM;
262	}
263
264	/* already configured */
265	if (info->intf != NULL)
266		return 0;
267
268	info->evtchn = xen_start_info->console.domU.evtchn;
269	info->intf = mfn_to_virt(xen_start_info->console.domU.mfn);
270	info->vtermno = HVC_COOKIE;
271
272	spin_lock(&xencons_lock);
273	list_add_tail(&info->list, &xenconsoles);
274	spin_unlock(&xencons_lock);
275
276	return 0;
277}
278
279static int xen_initial_domain_console_init(void)
280{
281	struct xencons_info *info;
282
283	if (!xen_initial_domain())
284		return -ENODEV;
285
286	info = vtermno_to_xencons(HVC_COOKIE);
287	if (!info) {
288		info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL | __GFP_ZERO);
289		if (!info)
290			return -ENOMEM;
291	}
292
293	info->irq = bind_virq_to_irq(VIRQ_CONSOLE, 0);
294	info->vtermno = HVC_COOKIE;
295
296	spin_lock(&xencons_lock);
297	list_add_tail(&info->list, &xenconsoles);
298	spin_unlock(&xencons_lock);
299
300	return 0;
301}
302
303void xen_console_resume(void)
304{
305	struct xencons_info *info = vtermno_to_xencons(HVC_COOKIE);
306	if (info != NULL && info->irq)
307		rebind_evtchn_irq(info->evtchn, info->irq);
308}
309
310static void xencons_disconnect_backend(struct xencons_info *info)
311{
312	if (info->irq > 0)
313		unbind_from_irqhandler(info->irq, NULL);
314	info->irq = 0;
315	if (info->evtchn > 0)
316		xenbus_free_evtchn(info->xbdev, info->evtchn);
317	info->evtchn = 0;
318	if (info->gntref > 0)
319		gnttab_free_grant_references(info->gntref);
320	info->gntref = 0;
321	if (info->hvc != NULL)
322		hvc_remove(info->hvc);
323	info->hvc = NULL;
324}
325
326static void xencons_free(struct xencons_info *info)
327{
328	free_page((unsigned long)info->intf);
329	info->intf = NULL;
330	info->vtermno = 0;
331	kfree(info);
332}
333
334static int xen_console_remove(struct xencons_info *info)
335{
336	xencons_disconnect_backend(info);
337	spin_lock(&xencons_lock);
338	list_del(&info->list);
339	spin_unlock(&xencons_lock);
340	if (info->xbdev != NULL)
341		xencons_free(info);
342	else {
343		if (xen_hvm_domain())
344			iounmap(info->intf);
345		kfree(info);
346	}
347	return 0;
348}
349
350#ifdef CONFIG_HVC_XEN_FRONTEND
351static struct xenbus_driver xencons_driver;
352
353static int xencons_remove(struct xenbus_device *dev)
354{
355	return xen_console_remove(dev_get_drvdata(&dev->dev));
356}
357
358static int xencons_connect_backend(struct xenbus_device *dev,
359				  struct xencons_info *info)
360{
361	int ret, evtchn, devid, ref, irq;
362	struct xenbus_transaction xbt;
363	grant_ref_t gref_head;
364	unsigned long mfn;
365
366	ret = xenbus_alloc_evtchn(dev, &evtchn);
367	if (ret)
368		return ret;
369	info->evtchn = evtchn;
370	irq = bind_evtchn_to_irq(evtchn);
371	if (irq < 0)
372		return irq;
373	info->irq = irq;
374	devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
375	info->hvc = hvc_alloc(xenbus_devid_to_vtermno(devid),
376			irq, &domU_hvc_ops, 256);
377	if (IS_ERR(info->hvc))
378		return PTR_ERR(info->hvc);
379	if (xen_pv_domain())
380		mfn = virt_to_mfn(info->intf);
381	else
382		mfn = __pa(info->intf) >> PAGE_SHIFT;
383	ret = gnttab_alloc_grant_references(1, &gref_head);
384	if (ret < 0)
385		return ret;
386	info->gntref = gref_head;
387	ref = gnttab_claim_grant_reference(&gref_head);
388	if (ref < 0)
389		return ref;
390	gnttab_grant_foreign_access_ref(ref, info->xbdev->otherend_id,
391			mfn, 0);
392
393 again:
394	ret = xenbus_transaction_start(&xbt);
395	if (ret) {
396		xenbus_dev_fatal(dev, ret, "starting transaction");
397		return ret;
398	}
399	ret = xenbus_printf(xbt, dev->nodename, "ring-ref", "%d", ref);
400	if (ret)
401		goto error_xenbus;
402	ret = xenbus_printf(xbt, dev->nodename, "port", "%u",
403			    evtchn);
404	if (ret)
405		goto error_xenbus;
406	ret = xenbus_printf(xbt, dev->nodename, "type", "ioemu");
407	if (ret)
408		goto error_xenbus;
409	ret = xenbus_transaction_end(xbt, 0);
410	if (ret) {
411		if (ret == -EAGAIN)
412			goto again;
413		xenbus_dev_fatal(dev, ret, "completing transaction");
414		return ret;
415	}
416
417	xenbus_switch_state(dev, XenbusStateInitialised);
418	return 0;
419
420 error_xenbus:
421	xenbus_transaction_end(xbt, 1);
422	xenbus_dev_fatal(dev, ret, "writing xenstore");
423	return ret;
424}
425
426static int __devinit xencons_probe(struct xenbus_device *dev,
427				  const struct xenbus_device_id *id)
428{
429	int ret, devid;
430	struct xencons_info *info;
431
432	devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
433	if (devid == 0)
434		return -ENODEV;
435
436	info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
437	if (!info)
438		return -ENOMEM;
439	dev_set_drvdata(&dev->dev, info);
440	info->xbdev = dev;
441	info->vtermno = xenbus_devid_to_vtermno(devid);
442	info->intf = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
443	if (!info->intf)
444		goto error_nomem;
445
446	ret = xencons_connect_backend(dev, info);
447	if (ret < 0)
448		goto error;
449	spin_lock(&xencons_lock);
450	list_add_tail(&info->list, &xenconsoles);
451	spin_unlock(&xencons_lock);
452
453	return 0;
454
455 error_nomem:
456	ret = -ENOMEM;
457	xenbus_dev_fatal(dev, ret, "allocating device memory");
458 error:
459	xencons_disconnect_backend(info);
460	xencons_free(info);
461	return ret;
462}
463
464static int xencons_resume(struct xenbus_device *dev)
465{
466	struct xencons_info *info = dev_get_drvdata(&dev->dev);
467
468	xencons_disconnect_backend(info);
469	memset(info->intf, 0, PAGE_SIZE);
470	return xencons_connect_backend(dev, info);
471}
472
473static void xencons_backend_changed(struct xenbus_device *dev,
474				   enum xenbus_state backend_state)
475{
476	switch (backend_state) {
477	case XenbusStateReconfiguring:
478	case XenbusStateReconfigured:
479	case XenbusStateInitialising:
480	case XenbusStateInitialised:
481	case XenbusStateUnknown:
482	case XenbusStateClosed:
483		break;
484
485	case XenbusStateInitWait:
486		break;
487
488	case XenbusStateConnected:
489		xenbus_switch_state(dev, XenbusStateConnected);
490		break;
491
492	case XenbusStateClosing:
493		xenbus_frontend_closed(dev);
494		break;
495	}
496}
497
498static const struct xenbus_device_id xencons_ids[] = {
499	{ "console" },
500	{ "" }
501};
502
503
504static DEFINE_XENBUS_DRIVER(xencons, "xenconsole",
505	.probe = xencons_probe,
506	.remove = xencons_remove,
507	.resume = xencons_resume,
508	.otherend_changed = xencons_backend_changed,
509);
510#endif /* CONFIG_HVC_XEN_FRONTEND */
511
512static int __init xen_hvc_init(void)
513{
514	int r;
515	struct xencons_info *info;
516	const struct hv_ops *ops;
517
518	if (!xen_domain())
519		return -ENODEV;
520
521	if (xen_initial_domain()) {
522		ops = &dom0_hvc_ops;
523		r = xen_initial_domain_console_init();
524		if (r < 0)
525			return r;
526		info = vtermno_to_xencons(HVC_COOKIE);
527	} else {
528		ops = &domU_hvc_ops;
529		if (xen_hvm_domain())
530			r = xen_hvm_console_init();
531		else
532			r = xen_pv_console_init();
533		if (r < 0)
534			return r;
535
536		info = vtermno_to_xencons(HVC_COOKIE);
537		info->irq = bind_evtchn_to_irq(info->evtchn);
538	}
539	if (info->irq < 0)
540		info->irq = 0; /* NO_IRQ */
541	else
542		irq_set_noprobe(info->irq);
543
544	info->hvc = hvc_alloc(HVC_COOKIE, info->irq, ops, 256);
545	if (IS_ERR(info->hvc)) {
546		r = PTR_ERR(info->hvc);
547		spin_lock(&xencons_lock);
548		list_del(&info->list);
549		spin_unlock(&xencons_lock);
550		if (info->irq)
551			unbind_from_irqhandler(info->irq, NULL);
552		kfree(info);
553		return r;
554	}
555
556	r = 0;
557#ifdef CONFIG_HVC_XEN_FRONTEND
558	r = xenbus_register_frontend(&xencons_driver);
559#endif
560	return r;
561}
562
563static void __exit xen_hvc_fini(void)
564{
565	struct xencons_info *entry, *next;
566
567	if (list_empty(&xenconsoles))
568			return;
569
570	list_for_each_entry_safe(entry, next, &xenconsoles, list) {
571		xen_console_remove(entry);
572	}
573}
574
575static int xen_cons_init(void)
576{
577	const struct hv_ops *ops;
578
579	if (!xen_domain())
580		return 0;
581
582	if (xen_initial_domain())
583		ops = &dom0_hvc_ops;
584	else {
585		int r;
586		ops = &domU_hvc_ops;
587
588		if (xen_hvm_domain())
589			r = xen_hvm_console_init();
590		else
591			r = xen_pv_console_init();
592		if (r < 0)
593			return r;
594	}
595
596	hvc_instantiate(HVC_COOKIE, 0, ops);
597	return 0;
598}
599
600
601module_init(xen_hvc_init);
602module_exit(xen_hvc_fini);
603console_initcall(xen_cons_init);
604
605#ifdef CONFIG_EARLY_PRINTK
606static void xenboot_write_console(struct console *console, const char *string,
607				  unsigned len)
608{
609	unsigned int linelen, off = 0;
610	const char *pos;
611
612	if (!xen_pv_domain())
613		return;
614
615	dom0_write_console(0, string, len);
616
617	if (xen_initial_domain())
618		return;
619
620	domU_write_console(0, "(early) ", 8);
621	while (off < len && NULL != (pos = strchr(string+off, '\n'))) {
622		linelen = pos-string+off;
623		if (off + linelen > len)
624			break;
625		domU_write_console(0, string+off, linelen);
626		domU_write_console(0, "\r\n", 2);
627		off += linelen + 1;
628	}
629	if (off < len)
630		domU_write_console(0, string+off, len-off);
631}
632
633struct console xenboot_console = {
634	.name		= "xenboot",
635	.write		= xenboot_write_console,
636	.flags		= CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
637};
638#endif	/* CONFIG_EARLY_PRINTK */
639
640void xen_raw_console_write(const char *str)
641{
642	dom0_write_console(0, str, strlen(str));
643}
644
645void xen_raw_printk(const char *fmt, ...)
646{
647	static char buf[512];
648	va_list ap;
649
650	va_start(ap, fmt);
651	vsnprintf(buf, sizeof(buf), fmt, ap);
652	va_end(ap);
653
654	xen_raw_console_write(buf);
655}
656