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/irq.h>
25#include <linux/init.h>
26#include <linux/types.h>
27#include <linux/list.h>
28
29#include <asm/io.h>
30#include <asm/xen/hypervisor.h>
31
32#include <xen/xen.h>
33#include <xen/interface/xen.h>
34#include <xen/hvm.h>
35#include <xen/grant_table.h>
36#include <xen/page.h>
37#include <xen/events.h>
38#include <xen/interface/io/console.h>
39#include <xen/interface/sched.h>
40#include <xen/hvc-console.h>
41#include <xen/xenbus.h>
42
43#include "hvc_console.h"
44
45#define HVC_COOKIE   0x58656e /* "Xen" in hex */
46
47struct xencons_info {
48	struct list_head list;
49	struct xenbus_device *xbdev;
50	struct xencons_interface *intf;
51	unsigned int evtchn;
52	struct hvc_struct *hvc;
53	int irq;
54	int vtermno;
55	grant_ref_t gntref;
56};
57
58static LIST_HEAD(xenconsoles);
59static DEFINE_SPINLOCK(xencons_lock);
60
61/* ------------------------------------------------------------------ */
62
63static struct xencons_info *vtermno_to_xencons(int vtermno)
64{
65	struct xencons_info *entry, *n, *ret = NULL;
66
67	if (list_empty(&xenconsoles))
68			return NULL;
69
70	list_for_each_entry_safe(entry, n, &xenconsoles, list) {
71		if (entry->vtermno == vtermno) {
72			ret  = entry;
73			break;
74		}
75	}
76
77	return ret;
78}
79
80static inline int xenbus_devid_to_vtermno(int devid)
81{
82	return devid + HVC_COOKIE;
83}
84
85static inline void notify_daemon(struct xencons_info *cons)
86{
87	/* Use evtchn: this is called early, before irq is set up. */
88	notify_remote_via_evtchn(cons->evtchn);
89}
90
91static int __write_console(struct xencons_info *xencons,
92		const char *data, int len)
93{
94	XENCONS_RING_IDX cons, prod;
95	struct xencons_interface *intf = xencons->intf;
96	int sent = 0;
97
98	cons = intf->out_cons;
99	prod = intf->out_prod;
100	mb();			/* update queue values before going on */
101	BUG_ON((prod - cons) > sizeof(intf->out));
102
103	while ((sent < len) && ((prod - cons) < sizeof(intf->out)))
104		intf->out[MASK_XENCONS_IDX(prod++, intf->out)] = data[sent++];
105
106	wmb();			/* write ring before updating pointer */
107	intf->out_prod = prod;
108
109	if (sent)
110		notify_daemon(xencons);
111	return sent;
112}
113
114static int domU_write_console(uint32_t vtermno, const char *data, int len)
115{
116	int ret = len;
117	struct xencons_info *cons = vtermno_to_xencons(vtermno);
118	if (cons == NULL)
119		return -EINVAL;
120
121	/*
122	 * Make sure the whole buffer is emitted, polling if
123	 * necessary.  We don't ever want to rely on the hvc daemon
124	 * because the most interesting console output is when the
125	 * kernel is crippled.
126	 */
127	while (len) {
128		int sent = __write_console(cons, data, len);
129
130		data += sent;
131		len -= sent;
132
133		if (unlikely(len))
134			HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
135	}
136
137	return ret;
138}
139
140static int domU_read_console(uint32_t vtermno, char *buf, int len)
141{
142	struct xencons_interface *intf;
143	XENCONS_RING_IDX cons, prod;
144	int recv = 0;
145	struct xencons_info *xencons = vtermno_to_xencons(vtermno);
146	if (xencons == NULL)
147		return -EINVAL;
148	intf = xencons->intf;
149
150	cons = intf->in_cons;
151	prod = intf->in_prod;
152	mb();			/* get pointers before reading ring */
153	BUG_ON((prod - cons) > sizeof(intf->in));
154
155	while (cons != prod && recv < len)
156		buf[recv++] = intf->in[MASK_XENCONS_IDX(cons++, intf->in)];
157
158	mb();			/* read ring before consuming */
159	intf->in_cons = cons;
160
161	notify_daemon(xencons);
162	return recv;
163}
164
165static struct hv_ops domU_hvc_ops = {
166	.get_chars = domU_read_console,
167	.put_chars = domU_write_console,
168	.notifier_add = notifier_add_irq,
169	.notifier_del = notifier_del_irq,
170	.notifier_hangup = notifier_hangup_irq,
171};
172
173static int dom0_read_console(uint32_t vtermno, char *buf, int len)
174{
175	return HYPERVISOR_console_io(CONSOLEIO_read, len, buf);
176}
177
178/*
179 * Either for a dom0 to write to the system console, or a domU with a
180 * debug version of Xen
181 */
182static int dom0_write_console(uint32_t vtermno, const char *str, int len)
183{
184	int rc = HYPERVISOR_console_io(CONSOLEIO_write, len, (char *)str);
185	if (rc < 0)
186		return rc;
187
188	return len;
189}
190
191static struct hv_ops dom0_hvc_ops = {
192	.get_chars = dom0_read_console,
193	.put_chars = dom0_write_console,
194	.notifier_add = notifier_add_irq,
195	.notifier_del = notifier_del_irq,
196	.notifier_hangup = notifier_hangup_irq,
197};
198
199static int xen_hvm_console_init(void)
200{
201	int r;
202	uint64_t v = 0;
203	unsigned long mfn;
204	struct xencons_info *info;
205
206	if (!xen_hvm_domain())
207		return -ENODEV;
208
209	info = vtermno_to_xencons(HVC_COOKIE);
210	if (!info) {
211		info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
212		if (!info)
213			return -ENOMEM;
214	} else if (info->intf != NULL) {
215		/* already configured */
216		return 0;
217	}
218	/*
219	 * If the toolstack (or the hypervisor) hasn't set these values, the
220	 * default value is 0. Even though mfn = 0 and evtchn = 0 are
221	 * theoretically correct values, in practice they never are and they
222	 * mean that a legacy toolstack hasn't initialized the pv console correctly.
223	 */
224	r = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v);
225	if (r < 0 || v == 0)
226		goto err;
227	info->evtchn = v;
228	v = 0;
229	r = hvm_get_parameter(HVM_PARAM_CONSOLE_PFN, &v);
230	if (r < 0 || v == 0)
231		goto err;
232	mfn = v;
233	info->intf = xen_remap(mfn << PAGE_SHIFT, PAGE_SIZE);
234	if (info->intf == NULL)
235		goto err;
236	info->vtermno = HVC_COOKIE;
237
238	spin_lock(&xencons_lock);
239	list_add_tail(&info->list, &xenconsoles);
240	spin_unlock(&xencons_lock);
241
242	return 0;
243err:
244	kfree(info);
245	return -ENODEV;
246}
247
248static int xen_pv_console_init(void)
249{
250	struct xencons_info *info;
251
252	if (!xen_pv_domain())
253		return -ENODEV;
254
255	if (!xen_start_info->console.domU.evtchn)
256		return -ENODEV;
257
258	info = vtermno_to_xencons(HVC_COOKIE);
259	if (!info) {
260		info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
261		if (!info)
262			return -ENOMEM;
263	} else if (info->intf != NULL) {
264		/* already configured */
265		return 0;
266	}
267	info->evtchn = xen_start_info->console.domU.evtchn;
268	info->intf = mfn_to_virt(xen_start_info->console.domU.mfn);
269	info->vtermno = HVC_COOKIE;
270
271	spin_lock(&xencons_lock);
272	list_add_tail(&info->list, &xenconsoles);
273	spin_unlock(&xencons_lock);
274
275	return 0;
276}
277
278static int xen_initial_domain_console_init(void)
279{
280	struct xencons_info *info;
281
282	if (!xen_initial_domain())
283		return -ENODEV;
284
285	info = vtermno_to_xencons(HVC_COOKIE);
286	if (!info) {
287		info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
288		if (!info)
289			return -ENOMEM;
290	}
291
292	info->irq = bind_virq_to_irq(VIRQ_CONSOLE, 0, false);
293	info->vtermno = HVC_COOKIE;
294
295	spin_lock(&xencons_lock);
296	list_add_tail(&info->list, &xenconsoles);
297	spin_unlock(&xencons_lock);
298
299	return 0;
300}
301
302static void xen_console_update_evtchn(struct xencons_info *info)
303{
304	if (xen_hvm_domain()) {
305		uint64_t v;
306		int err;
307
308		err = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v);
309		if (!err && v)
310			info->evtchn = v;
311	} else
312		info->evtchn = xen_start_info->console.domU.evtchn;
313}
314
315void xen_console_resume(void)
316{
317	struct xencons_info *info = vtermno_to_xencons(HVC_COOKIE);
318	if (info != NULL && info->irq) {
319		if (!xen_initial_domain())
320			xen_console_update_evtchn(info);
321		rebind_evtchn_irq(info->evtchn, info->irq);
322	}
323}
324
325static void xencons_disconnect_backend(struct xencons_info *info)
326{
327	if (info->irq > 0)
328		unbind_from_irqhandler(info->irq, NULL);
329	info->irq = 0;
330	if (info->evtchn > 0)
331		xenbus_free_evtchn(info->xbdev, info->evtchn);
332	info->evtchn = 0;
333	if (info->gntref > 0)
334		gnttab_free_grant_references(info->gntref);
335	info->gntref = 0;
336	if (info->hvc != NULL)
337		hvc_remove(info->hvc);
338	info->hvc = NULL;
339}
340
341static void xencons_free(struct xencons_info *info)
342{
343	free_page((unsigned long)info->intf);
344	info->intf = NULL;
345	info->vtermno = 0;
346	kfree(info);
347}
348
349static int xen_console_remove(struct xencons_info *info)
350{
351	xencons_disconnect_backend(info);
352	spin_lock(&xencons_lock);
353	list_del(&info->list);
354	spin_unlock(&xencons_lock);
355	if (info->xbdev != NULL)
356		xencons_free(info);
357	else {
358		if (xen_hvm_domain())
359			iounmap(info->intf);
360		kfree(info);
361	}
362	return 0;
363}
364
365#ifdef CONFIG_HVC_XEN_FRONTEND
366static int xencons_remove(struct xenbus_device *dev)
367{
368	return xen_console_remove(dev_get_drvdata(&dev->dev));
369}
370
371static int xencons_connect_backend(struct xenbus_device *dev,
372				  struct xencons_info *info)
373{
374	int ret, evtchn, devid, ref, irq;
375	struct xenbus_transaction xbt;
376	grant_ref_t gref_head;
377	unsigned long mfn;
378
379	ret = xenbus_alloc_evtchn(dev, &evtchn);
380	if (ret)
381		return ret;
382	info->evtchn = evtchn;
383	irq = bind_evtchn_to_irq(evtchn);
384	if (irq < 0)
385		return irq;
386	info->irq = irq;
387	devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
388	info->hvc = hvc_alloc(xenbus_devid_to_vtermno(devid),
389			irq, &domU_hvc_ops, 256);
390	if (IS_ERR(info->hvc))
391		return PTR_ERR(info->hvc);
392	if (xen_pv_domain())
393		mfn = virt_to_mfn(info->intf);
394	else
395		mfn = __pa(info->intf) >> PAGE_SHIFT;
396	ret = gnttab_alloc_grant_references(1, &gref_head);
397	if (ret < 0)
398		return ret;
399	info->gntref = gref_head;
400	ref = gnttab_claim_grant_reference(&gref_head);
401	if (ref < 0)
402		return ref;
403	gnttab_grant_foreign_access_ref(ref, info->xbdev->otherend_id,
404			mfn, 0);
405
406 again:
407	ret = xenbus_transaction_start(&xbt);
408	if (ret) {
409		xenbus_dev_fatal(dev, ret, "starting transaction");
410		return ret;
411	}
412	ret = xenbus_printf(xbt, dev->nodename, "ring-ref", "%d", ref);
413	if (ret)
414		goto error_xenbus;
415	ret = xenbus_printf(xbt, dev->nodename, "port", "%u",
416			    evtchn);
417	if (ret)
418		goto error_xenbus;
419	ret = xenbus_transaction_end(xbt, 0);
420	if (ret) {
421		if (ret == -EAGAIN)
422			goto again;
423		xenbus_dev_fatal(dev, ret, "completing transaction");
424		return ret;
425	}
426
427	xenbus_switch_state(dev, XenbusStateInitialised);
428	return 0;
429
430 error_xenbus:
431	xenbus_transaction_end(xbt, 1);
432	xenbus_dev_fatal(dev, ret, "writing xenstore");
433	return ret;
434}
435
436static int xencons_probe(struct xenbus_device *dev,
437				  const struct xenbus_device_id *id)
438{
439	int ret, devid;
440	struct xencons_info *info;
441
442	devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
443	if (devid == 0)
444		return -ENODEV;
445
446	info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
447	if (!info)
448		return -ENOMEM;
449	dev_set_drvdata(&dev->dev, info);
450	info->xbdev = dev;
451	info->vtermno = xenbus_devid_to_vtermno(devid);
452	info->intf = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
453	if (!info->intf)
454		goto error_nomem;
455
456	ret = xencons_connect_backend(dev, info);
457	if (ret < 0)
458		goto error;
459	spin_lock(&xencons_lock);
460	list_add_tail(&info->list, &xenconsoles);
461	spin_unlock(&xencons_lock);
462
463	return 0;
464
465 error_nomem:
466	ret = -ENOMEM;
467	xenbus_dev_fatal(dev, ret, "allocating device memory");
468 error:
469	xencons_disconnect_backend(info);
470	xencons_free(info);
471	return ret;
472}
473
474static int xencons_resume(struct xenbus_device *dev)
475{
476	struct xencons_info *info = dev_get_drvdata(&dev->dev);
477
478	xencons_disconnect_backend(info);
479	memset(info->intf, 0, PAGE_SIZE);
480	return xencons_connect_backend(dev, info);
481}
482
483static void xencons_backend_changed(struct xenbus_device *dev,
484				   enum xenbus_state backend_state)
485{
486	switch (backend_state) {
487	case XenbusStateReconfiguring:
488	case XenbusStateReconfigured:
489	case XenbusStateInitialising:
490	case XenbusStateInitialised:
491	case XenbusStateUnknown:
492		break;
493
494	case XenbusStateInitWait:
495		break;
496
497	case XenbusStateConnected:
498		xenbus_switch_state(dev, XenbusStateConnected);
499		break;
500
501	case XenbusStateClosed:
502		if (dev->state == XenbusStateClosed)
503			break;
504		/* Missed the backend's CLOSING state -- fallthrough */
505	case XenbusStateClosing:
506		xenbus_frontend_closed(dev);
507		break;
508	}
509}
510
511static const struct xenbus_device_id xencons_ids[] = {
512	{ "console" },
513	{ "" }
514};
515
516static struct xenbus_driver xencons_driver = {
517	.name = "xenconsole",
518	.ids = xencons_ids,
519	.probe = xencons_probe,
520	.remove = xencons_remove,
521	.resume = xencons_resume,
522	.otherend_changed = xencons_backend_changed,
523};
524#endif /* CONFIG_HVC_XEN_FRONTEND */
525
526static int __init xen_hvc_init(void)
527{
528	int r;
529	struct xencons_info *info;
530	const struct hv_ops *ops;
531
532	if (!xen_domain())
533		return -ENODEV;
534
535	if (xen_initial_domain()) {
536		ops = &dom0_hvc_ops;
537		r = xen_initial_domain_console_init();
538		if (r < 0)
539			return r;
540		info = vtermno_to_xencons(HVC_COOKIE);
541	} else {
542		ops = &domU_hvc_ops;
543		if (xen_hvm_domain())
544			r = xen_hvm_console_init();
545		else
546			r = xen_pv_console_init();
547		if (r < 0)
548			return r;
549
550		info = vtermno_to_xencons(HVC_COOKIE);
551		info->irq = bind_evtchn_to_irq(info->evtchn);
552	}
553	if (info->irq < 0)
554		info->irq = 0; /* NO_IRQ */
555	else
556		irq_set_noprobe(info->irq);
557
558	info->hvc = hvc_alloc(HVC_COOKIE, info->irq, ops, 256);
559	if (IS_ERR(info->hvc)) {
560		r = PTR_ERR(info->hvc);
561		spin_lock(&xencons_lock);
562		list_del(&info->list);
563		spin_unlock(&xencons_lock);
564		if (info->irq)
565			unbind_from_irqhandler(info->irq, NULL);
566		kfree(info);
567		return r;
568	}
569
570	r = 0;
571#ifdef CONFIG_HVC_XEN_FRONTEND
572	r = xenbus_register_frontend(&xencons_driver);
573#endif
574	return r;
575}
576device_initcall(xen_hvc_init);
577
578static int xen_cons_init(void)
579{
580	const struct hv_ops *ops;
581
582	if (!xen_domain())
583		return 0;
584
585	if (xen_initial_domain())
586		ops = &dom0_hvc_ops;
587	else {
588		int r;
589		ops = &domU_hvc_ops;
590
591		if (xen_hvm_domain())
592			r = xen_hvm_console_init();
593		else
594			r = xen_pv_console_init();
595		if (r < 0)
596			return r;
597	}
598
599	hvc_instantiate(HVC_COOKIE, 0, ops);
600	return 0;
601}
602console_initcall(xen_cons_init);
603
604#ifdef CONFIG_EARLY_PRINTK
605static void xenboot_write_console(struct console *console, const char *string,
606				  unsigned len)
607{
608	unsigned int linelen, off = 0;
609	const char *pos;
610
611	if (!xen_pv_domain())
612		return;
613
614	dom0_write_console(0, string, len);
615
616	if (xen_initial_domain())
617		return;
618
619	domU_write_console(0, "(early) ", 8);
620	while (off < len && NULL != (pos = strchr(string+off, '\n'))) {
621		linelen = pos-string+off;
622		if (off + linelen > len)
623			break;
624		domU_write_console(0, string+off, linelen);
625		domU_write_console(0, "\r\n", 2);
626		off += linelen + 1;
627	}
628	if (off < len)
629		domU_write_console(0, string+off, len-off);
630}
631
632struct console xenboot_console = {
633	.name		= "xenboot",
634	.write		= xenboot_write_console,
635	.flags		= CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
636	.index		= -1,
637};
638#endif	/* CONFIG_EARLY_PRINTK */
639
640void xen_raw_console_write(const char *str)
641{
642	ssize_t len = strlen(str);
643	int rc = 0;
644
645	if (xen_domain()) {
646		rc = dom0_write_console(0, str, len);
647#ifdef CONFIG_X86
648		if (rc == -ENOSYS && xen_hvm_domain())
649			goto outb_print;
650
651	} else if (xen_cpuid_base()) {
652		int i;
653outb_print:
654		for (i = 0; i < len; i++)
655			outb(str[i], 0xe9);
656#endif
657	}
658}
659
660void xen_raw_printk(const char *fmt, ...)
661{
662	static char buf[512];
663	va_list ap;
664
665	va_start(ap, fmt);
666	vsnprintf(buf, sizeof(buf), fmt, ap);
667	va_end(ap);
668
669	xen_raw_console_write(buf);
670}
671