summaryrefslogtreecommitdiffstats
path: root/drivers/tty/hvc/hvc_xen.c
blob: 388a71afd6efe76db5ef1d54c0fc8c575f6d7243 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
// SPDX-License-Identifier: GPL-2.0+
/*
 * xen console driver interface to hvc_console.c
 *
 * (c) 2007 Gerd Hoffmann <kraxel@suse.de>
 */

#include <linux/console.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/irq.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/list.h>
#include <linux/serial_core.h>

#include <asm/io.h>
#include <asm/xen/hypervisor.h>

#include <xen/xen.h>
#include <xen/interface/xen.h>
#include <xen/hvm.h>
#include <xen/grant_table.h>
#include <xen/page.h>
#include <xen/events.h>
#include <xen/interface/io/console.h>
#include <xen/interface/sched.h>
#include <xen/hvc-console.h>
#include <xen/xenbus.h>

#include "hvc_console.h"

#define HVC_COOKIE   0x58656e /* "Xen" in hex */

struct xencons_info {
	struct list_head list;
	struct xenbus_device *xbdev;
	struct xencons_interface *intf;
	unsigned int evtchn;
	XENCONS_RING_IDX out_cons;
	unsigned int out_cons_same;
	struct hvc_struct *hvc;
	int irq;
	int vtermno;
	grant_ref_t gntref;
	spinlock_t ring_lock;
};

static LIST_HEAD(xenconsoles);
static DEFINE_SPINLOCK(xencons_lock);

/* ------------------------------------------------------------------ */

static struct xencons_info *vtermno_to_xencons(int vtermno)
{
	struct xencons_info *entry, *ret = NULL;
	unsigned long flags;

	spin_lock_irqsave(&xencons_lock, flags);
	if (list_empty(&xenconsoles)) {
		spin_unlock_irqrestore(&xencons_lock, flags);
		return NULL;
	}

	list_for_each_entry(entry, &xenconsoles, list) {
		if (entry->vtermno == vtermno) {
			ret  = entry;
			break;
		}
	}
	spin_unlock_irqrestore(&xencons_lock, flags);

	return ret;
}

static inline int xenbus_devid_to_vtermno(int devid)
{
	return devid + HVC_COOKIE;
}

static inline void notify_daemon(struct xencons_info *cons)
{
	/* Use evtchn: this is called early, before irq is set up. */
	notify_remote_via_evtchn(cons->evtchn);
}

static ssize_t __write_console(struct xencons_info *xencons,
			       const u8 *data, size_t len)
{
	XENCONS_RING_IDX cons, prod;
	struct xencons_interface *intf = xencons->intf;
	unsigned long flags;
	size_t sent = 0;

	spin_lock_irqsave(&xencons->ring_lock, flags);
	cons = intf->out_cons;
	prod = intf->out_prod;
	mb();			/* update queue values before going on */

	if ((prod - cons) > sizeof(intf->out)) {
		spin_unlock_irqrestore(&xencons->ring_lock, flags);
		pr_err_once("xencons: Illegal ring page indices");
		return -EINVAL;
	}

	while ((sent < len) && ((prod - cons) < sizeof(intf->out)))
		intf->out[MASK_XENCONS_IDX(prod++, intf->out)] = data[sent++];

	wmb();			/* write ring before updating pointer */
	intf->out_prod = prod;
	spin_unlock_irqrestore(&xencons->ring_lock, flags);

	if (sent)
		notify_daemon(xencons);
	return sent;
}

static ssize_t domU_write_console(uint32_t vtermno, const u8 *data, size_t len)
{
	struct xencons_info *cons = vtermno_to_xencons(vtermno);
	size_t ret = len;

	if (cons == NULL)
		return -EINVAL;

	/*
	 * Make sure the whole buffer is emitted, polling if
	 * necessary.  We don't ever want to rely on the hvc daemon
	 * because the most interesting console output is when the
	 * kernel is crippled.
	 */
	while (len) {
		ssize_t sent = __write_console(cons, data, len);

		if (sent < 0)
			return sent;

		data += sent;
		len -= sent;

		if (unlikely(len))
			HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
	}

	return ret;
}

static ssize_t domU_read_console(uint32_t vtermno, u8 *buf, size_t len)
{
	struct xencons_interface *intf;
	XENCONS_RING_IDX cons, prod;
	struct xencons_info *xencons = vtermno_to_xencons(vtermno);
	unsigned int eoiflag = 0;
	unsigned long flags;
	size_t recv = 0;

	if (xencons == NULL)
		return -EINVAL;
	intf = xencons->intf;

	spin_lock_irqsave(&xencons->ring_lock, flags);
	cons = intf->in_cons;
	prod = intf->in_prod;
	mb();			/* get pointers before reading ring */

	if ((prod - cons) > sizeof(intf->in)) {
		spin_unlock_irqrestore(&xencons->ring_lock, flags);
		pr_err_once("xencons: Illegal ring page indices");
		return -EINVAL;
	}

	while (cons != prod && recv < len)
		buf[recv++] = intf->in[MASK_XENCONS_IDX(cons++, intf->in)];

	mb();			/* read ring before consuming */
	intf->in_cons = cons;

	/*
	 * When to mark interrupt having been spurious:
	 * - there was no new data to be read, and
	 * - the backend did not consume some output bytes, and
	 * - the previous round with no read data didn't see consumed bytes
	 *   (we might have a race with an interrupt being in flight while
	 *   updating xencons->out_cons, so account for that by allowing one
	 *   round without any visible reason)
	 */
	if (intf->out_cons != xencons->out_cons) {
		xencons->out_cons = intf->out_cons;
		xencons->out_cons_same = 0;
	}
	if (!recv && xencons->out_cons_same++ > 1) {
		eoiflag = XEN_EOI_FLAG_SPURIOUS;
	}
	spin_unlock_irqrestore(&xencons->ring_lock, flags);

	if (recv) {
		notify_daemon(xencons);
	}

	xen_irq_lateeoi(xencons->irq, eoiflag);

	return recv;
}

static const struct hv_ops domU_hvc_ops = {
	.get_chars = domU_read_console,
	.put_chars = domU_write_console,
	.notifier_add = notifier_add_irq,
	.notifier_del = notifier_del_irq,
	.notifier_hangup = notifier_hangup_irq,
};

static ssize_t dom0_read_console(uint32_t vtermno, u8 *buf, size_t len)
{
	return HYPERVISOR_console_io(CONSOLEIO_read, len, buf);
}

/*
 * Either for a dom0 to write to the system console, or a domU with a
 * debug version of Xen
 */
static ssize_t dom0_write_console(uint32_t vtermno, const u8 *str, size_t len)
{
	int rc = HYPERVISOR_console_io(CONSOLEIO_write, len, (u8 *)str);
	if (rc < 0)
		return rc;

	return len;
}

static const struct hv_ops dom0_hvc_ops = {
	.get_chars = dom0_read_console,
	.put_chars = dom0_write_console,
	.notifier_add = notifier_add_irq,
	.notifier_del = notifier_del_irq,
	.notifier_hangup = notifier_hangup_irq,
};

static int xen_hvm_console_init(void)
{
	int r;
	uint64_t v = 0;
	unsigned long gfn, flags;
	struct xencons_info *info;

	if (!xen_hvm_domain())
		return -ENODEV;

	info = vtermno_to_xencons(HVC_COOKIE);
	if (!info) {
		info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
		if (!info)
			return -ENOMEM;
		spin_lock_init(&info->ring_lock);
	} else if (info->intf != NULL) {
		/* already configured */
		return 0;
	}
	/*
	 * If the toolstack (or the hypervisor) hasn't set these values, the
	 * default value is 0. Even though gfn = 0 and evtchn = 0 are
	 * theoretically correct values, in practice they never are and they
	 * mean that a legacy toolstack hasn't initialized the pv console correctly.
	 */
	r = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v);
	if (r < 0 || v == 0)
		goto err;
	info->evtchn = v;
	v = 0;
	r = hvm_get_parameter(HVM_PARAM_CONSOLE_PFN, &v);
	if (r < 0 || v == 0)
		goto err;
	gfn = v;
	info->intf = memremap(gfn << XEN_PAGE_SHIFT, XEN_PAGE_SIZE, MEMREMAP_WB);
	if (info->intf == NULL)
		goto err;
	info->vtermno = HVC_COOKIE;

	spin_lock_irqsave(&xencons_lock, flags);
	list_add_tail(&info->list, &xenconsoles);
	spin_unlock_irqrestore(&xencons_lock, flags);

	return 0;
err:
	kfree(info);
	return -ENODEV;
}

static int xencons_info_pv_init(struct xencons_info *info, int vtermno)
{
	spin_lock_init(&info->ring_lock);
	info->evtchn = xen_start_info->console.domU.evtchn;
	/* GFN == MFN for PV guest */
	info->intf = gfn_to_virt(xen_start_info->console.domU.mfn);
	info->vtermno = vtermno;

	list_add_tail(&info->list, &xenconsoles);

	return 0;
}

static int xen_pv_console_init(void)
{
	struct xencons_info *info;
	unsigned long flags;

	if (!xen_pv_domain())
		return -ENODEV;

	if (!xen_start_info->console.domU.evtchn)
		return -ENODEV;

	info = vtermno_to_xencons(HVC_COOKIE);
	if (!info) {
		info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
		if (!info)
			return -ENOMEM;
	} else if (info->intf != NULL) {
		/* already configured */
		return 0;
	}
	spin_lock_irqsave(&xencons_lock, flags);
	xencons_info_pv_init(info, HVC_COOKIE);
	spin_unlock_irqrestore(&xencons_lock, flags);

	return 0;
}

static int xen_initial_domain_console_init(void)
{
	struct xencons_info *info;
	unsigned long flags;

	if (!xen_initial_domain())
		return -ENODEV;

	info = vtermno_to_xencons(HVC_COOKIE);
	if (!info) {
		info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
		if (!info)
			return -ENOMEM;
		spin_lock_init(&info->ring_lock);
	}

	info->irq = bind_virq_to_irq(VIRQ_CONSOLE, 0, false);
	info->vtermno = HVC_COOKIE;

	spin_lock_irqsave(&xencons_lock, flags);
	list_add_tail(&info->list, &xenconsoles);
	spin_unlock_irqrestore(&xencons_lock, flags);

	return 0;
}

static void xen_console_update_evtchn(struct xencons_info *info)
{
	if (xen_hvm_domain()) {
		uint64_t v = 0;
		int err;

		err = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v);
		if (!err && v)
			info->evtchn = v;
	} else
		info->evtchn = xen_start_info->console.domU.evtchn;
}

void xen_console_resume(void)
{
	struct xencons_info *info = vtermno_to_xencons(HVC_COOKIE);
	if (info != NULL && info->irq) {
		if (!xen_initial_domain())
			xen_console_update_evtchn(info);
		rebind_evtchn_irq(info->evtchn, info->irq);
	}
}

#ifdef CONFIG_HVC_XEN_FRONTEND
static void xencons_disconnect_backend(struct xencons_info *info)
{
	if (info->hvc != NULL)
		hvc_remove(info->hvc);
	info->hvc = NULL;
	if (info->irq > 0) {
		evtchn_put(info->evtchn);
		info->irq = 0;
		info->evtchn = 0;
	}
	/* evtchn_put() will also close it so this is only an error path */
	if (info->evtchn > 0)
		xenbus_free_evtchn(info->xbdev, info->evtchn);
	info->evtchn = 0;
	if (info->gntref > 0)
		gnttab_free_grant_references(info->gntref);
	info->gntref = 0;
}

static void xencons_free(struct xencons_info *info)
{
	free_page((unsigned long)info->intf);
	info->intf = NULL;
	info->vtermno = 0;
	kfree(info);
}

static int xen_console_remove(struct xencons_info *info)
{
	unsigned long flags;

	xencons_disconnect_backend(info);
	spin_lock_irqsave(&xencons_lock, flags);
	list_del(&info->list);
	spin_unlock_irqrestore(&xencons_lock, flags);
	if (info->xbdev != NULL)
		xencons_free(info);
	else {
		if (xen_hvm_domain())
			iounmap(info->intf);
		kfree(info);
	}
	return 0;
}

static void xencons_remove(struct xenbus_device *dev)
{
	xen_console_remove(dev_get_drvdata(&dev->dev));
}

static int xencons_connect_backend(struct xenbus_device *dev,
				  struct xencons_info *info)
{
	int ret, evtchn, devid, ref, irq;
	struct xenbus_transaction xbt;
	grant_ref_t gref_head;

	ret = xenbus_alloc_evtchn(dev, &evtchn);
	if (ret)
		return ret;
	info->evtchn = evtchn;
	irq = bind_evtchn_to_irq_lateeoi(evtchn);
	if (irq < 0)
		return irq;
	info->irq = irq;
	devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
	info->hvc = hvc_alloc(xenbus_devid_to_vtermno(devid),
			irq, &domU_hvc_ops, 256);
	if (IS_ERR(info->hvc))
		return PTR_ERR(info->hvc);
	ret = gnttab_alloc_grant_references(1, &gref_head);
	if (ret < 0)
		return ret;
	info->gntref = gref_head;
	ref = gnttab_claim_grant_reference(&gref_head);
	if (ref < 0)
		return ref;
	gnttab_grant_foreign_access_ref(ref, info->xbdev->otherend_id,
					virt_to_gfn(info->intf), 0);

 again:
	ret = xenbus_transaction_start(&xbt);
	if (ret) {
		xenbus_dev_fatal(dev, ret, "starting transaction");
		return ret;
	}
	ret = xenbus_printf(xbt, dev->nodename, "ring-ref", "%d", ref);
	if (ret)
		goto error_xenbus;
	ret = xenbus_printf(xbt, dev->nodename, "port", "%u",
			    evtchn);
	if (ret)
		goto error_xenbus;
	ret = xenbus_transaction_end(xbt, 0);
	if (ret) {
		if (ret == -EAGAIN)
			goto again;
		xenbus_dev_fatal(dev, ret, "completing transaction");
		return ret;
	}

	xenbus_switch_state(dev, XenbusStateInitialised);
	return 0;

 error_xenbus:
	xenbus_transaction_end(xbt, 1);
	xenbus_dev_fatal(dev, ret, "writing xenstore");
	return ret;
}

static int xencons_probe(struct xenbus_device *dev,
				  const struct xenbus_device_id *id)
{
	int ret, devid;
	struct xencons_info *info;
	unsigned long flags;

	devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
	if (devid == 0)
		return -ENODEV;

	info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
	if (!info)
		return -ENOMEM;
	spin_lock_init(&info->ring_lock);
	dev_set_drvdata(&dev->dev, info);
	info->xbdev = dev;
	info->vtermno = xenbus_devid_to_vtermno(devid);
	info->intf = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
	if (!info->intf)
		goto error_nomem;

	ret = xencons_connect_backend(dev, info);
	if (ret < 0)
		goto error;
	spin_lock_irqsave(&xencons_lock, flags);
	list_add_tail(&info->list, &xenconsoles);
	spin_unlock_irqrestore(&xencons_lock, flags);

	return 0;

 error_nomem:
	ret = -ENOMEM;
	xenbus_dev_fatal(dev, ret, "allocating device memory");
 error:
	xencons_disconnect_backend(info);
	xencons_free(info);
	return ret;
}

static int xencons_resume(struct xenbus_device *dev)
{
	struct xencons_info *info = dev_get_drvdata(&dev->dev);

	xencons_disconnect_backend(info);
	memset(info->intf, 0, XEN_PAGE_SIZE);
	return xencons_connect_backend(dev, info);
}

static void xencons_backend_changed(struct xenbus_device *dev,
				   enum xenbus_state backend_state)
{
	switch (backend_state) {
	case XenbusStateReconfiguring:
	case XenbusStateReconfigured:
	case XenbusStateInitialising:
	case XenbusStateInitialised:
	case XenbusStateUnknown:
		break;

	case XenbusStateInitWait:
		break;

	case XenbusStateConnected:
		xenbus_switch_state(dev, XenbusStateConnected);
		break;

	case XenbusStateClosed:
		if (dev->state == XenbusStateClosed)
			break;
		fallthrough;	/* Missed the backend's CLOSING state */
	case XenbusStateClosing: {
		struct xencons_info *info = dev_get_drvdata(&dev->dev);

		/*
		 * Don't tear down the evtchn and grant ref before the other
		 * end has disconnected, but do stop userspace from trying
		 * to use the device before we allow the backend to close.
		 */
		if (info->hvc) {
			hvc_remove(info->hvc);
			info->hvc = NULL;
		}

		xenbus_frontend_closed(dev);
		break;
	}
	}
}

static const struct xenbus_device_id xencons_ids[] = {
	{ "console" },
	{ "" }
};

static struct xenbus_driver xencons_driver = {
	.name = "xenconsole",
	.ids = xencons_ids,
	.probe = xencons_probe,
	.remove = xencons_remove,
	.resume = xencons_resume,
	.otherend_changed = xencons_backend_changed,
	.not_essential = true,
};
#endif /* CONFIG_HVC_XEN_FRONTEND */

static int __init xen_hvc_init(void)
{
	int r;
	struct xencons_info *info;
	const struct hv_ops *ops;

	if (!xen_domain())
		return -ENODEV;

	if (xen_initial_domain()) {
		ops = &dom0_hvc_ops;
		r = xen_initial_domain_console_init();
		if (r < 0)
			goto register_fe;
		info = vtermno_to_xencons(HVC_COOKIE);
	} else {
		ops = &domU_hvc_ops;
		if (xen_hvm_domain())
			r = xen_hvm_console_init();
		else
			r = xen_pv_console_init();
		if (r < 0)
			goto register_fe;

		info = vtermno_to_xencons(HVC_COOKIE);
		info->irq = bind_evtchn_to_irq_lateeoi(info->evtchn);
	}
	if (info->irq < 0)
		info->irq = 0; /* NO_IRQ */
	else
		irq_set_noprobe(info->irq);

	info->hvc = hvc_alloc(HVC_COOKIE, info->irq, ops, 256);
	if (IS_ERR(info->hvc)) {
		unsigned long flags;

		r = PTR_ERR(info->hvc);
		spin_lock_irqsave(&xencons_lock, flags);
		list_del(&info->list);
		spin_unlock_irqrestore(&xencons_lock, flags);
		if (info->irq)
			evtchn_put(info->evtchn);
		kfree(info);
		return r;
	}

	r = 0;
 register_fe:
#ifdef CONFIG_HVC_XEN_FRONTEND
	r = xenbus_register_frontend(&xencons_driver);
#endif
	return r;
}
device_initcall(xen_hvc_init);

static int xen_cons_init(void)
{
	const struct hv_ops *ops;

	if (!xen_domain())
		return 0;

	if (xen_initial_domain())
		ops = &dom0_hvc_ops;
	else {
		int r;
		ops = &domU_hvc_ops;

		if (xen_hvm_domain())
			r = xen_hvm_console_init();
		else
			r = xen_pv_console_init();
		if (r < 0)
			return r;
	}

	hvc_instantiate(HVC_COOKIE, 0, ops);
	return 0;
}
console_initcall(xen_cons_init);

#ifdef CONFIG_X86
static void xen_hvm_early_write(uint32_t vtermno, const char *str, int len)
{
	if (xen_cpuid_base())
		outsb(0xe9, str, len);
}
#else
static void xen_hvm_early_write(uint32_t vtermno, const char *str, int len) { }
#endif

#ifdef CONFIG_EARLY_PRINTK
static int __init xenboot_console_setup(struct console *console, char *string)
{
	static struct xencons_info xenboot;

	if (xen_initial_domain() || !xen_pv_domain())
		return 0;

	return xencons_info_pv_init(&xenboot, 0);
}

static void xenboot_write_console(struct console *console, const char *string,
				  unsigned len)
{
	unsigned int linelen, off = 0;
	const char *pos;

	if (dom0_write_console(0, string, len) >= 0)
		return;

	if (!xen_pv_domain()) {
		xen_hvm_early_write(0, string, len);
		return;
	}

	if (domU_write_console(0, "(early) ", 8) < 0)
		return;
	while (off < len && NULL != (pos = strchr(string+off, '\n'))) {
		linelen = pos-string+off;
		if (off + linelen > len)
			break;
		domU_write_console(0, string+off, linelen);
		domU_write_console(0, "\r\n", 2);
		off += linelen + 1;
	}
	if (off < len)
		domU_write_console(0, string+off, len-off);
}

struct console xenboot_console = {
	.name		= "xenboot",
	.write		= xenboot_write_console,
	.setup		= xenboot_console_setup,
	.flags		= CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
	.index		= -1,
};
#endif	/* CONFIG_EARLY_PRINTK */

void xen_raw_console_write(const char *str)
{
	ssize_t len = strlen(str);
	int rc = 0;

	if (xen_domain()) {
		rc = dom0_write_console(0, str, len);
		if (rc != -ENOSYS || !xen_hvm_domain())
			return;
	}
	xen_hvm_early_write(0, str, len);
}

void xen_raw_printk(const char *fmt, ...)
{
	static char buf[512];
	va_list ap;

	va_start(ap, fmt);
	vsnprintf(buf, sizeof(buf), fmt, ap);
	va_end(ap);

	xen_raw_console_write(buf);
}

static void xenboot_earlycon_write(struct console *console,
				  const char *string,
				  unsigned len)
{
	dom0_write_console(0, string, len);
}

static int __init xenboot_earlycon_setup(struct earlycon_device *device,
					    const char *opt)
{
	device->con->write = xenboot_earlycon_write;
	return 0;
}
EARLYCON_DECLARE(xenboot, xenboot_earlycon_setup);