xref: /openbmc/linux/drivers/tty/hvc/hvc_xen.c (revision cd5d5810) 
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 
47 struct 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 
58 static LIST_HEAD(xenconsoles);
59 static DEFINE_SPINLOCK(xencons_lock);
60 
61 /* ------------------------------------------------------------------ */
62 
63 static 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 
80 static inline int xenbus_devid_to_vtermno(int devid)
81 {
82 	return devid + HVC_COOKIE;
83 }
84 
85 static 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 
91 static 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 
114 static 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 
140 static 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 
165 static 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 
173 static 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  */
182 static 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 0;
187 
188 	return len;
189 }
190 
191 static 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 
199 static 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;
243 err:
244 	kfree(info);
245 	return -ENODEV;
246 }
247 
248 static 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 
278 static 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);
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 
302 void xen_console_resume(void)
303 {
304 	struct xencons_info *info = vtermno_to_xencons(HVC_COOKIE);
305 	if (info != NULL && info->irq)
306 		rebind_evtchn_irq(info->evtchn, info->irq);
307 }
308 
309 static void xencons_disconnect_backend(struct xencons_info *info)
310 {
311 	if (info->irq > 0)
312 		unbind_from_irqhandler(info->irq, NULL);
313 	info->irq = 0;
314 	if (info->evtchn > 0)
315 		xenbus_free_evtchn(info->xbdev, info->evtchn);
316 	info->evtchn = 0;
317 	if (info->gntref > 0)
318 		gnttab_free_grant_references(info->gntref);
319 	info->gntref = 0;
320 	if (info->hvc != NULL)
321 		hvc_remove(info->hvc);
322 	info->hvc = NULL;
323 }
324 
325 static void xencons_free(struct xencons_info *info)
326 {
327 	free_page((unsigned long)info->intf);
328 	info->intf = NULL;
329 	info->vtermno = 0;
330 	kfree(info);
331 }
332 
333 static int xen_console_remove(struct xencons_info *info)
334 {
335 	xencons_disconnect_backend(info);
336 	spin_lock(&xencons_lock);
337 	list_del(&info->list);
338 	spin_unlock(&xencons_lock);
339 	if (info->xbdev != NULL)
340 		xencons_free(info);
341 	else {
342 		if (xen_hvm_domain())
343 			iounmap(info->intf);
344 		kfree(info);
345 	}
346 	return 0;
347 }
348 
349 #ifdef CONFIG_HVC_XEN_FRONTEND
350 static struct xenbus_driver xencons_driver;
351 
352 static int xencons_remove(struct xenbus_device *dev)
353 {
354 	return xen_console_remove(dev_get_drvdata(&dev->dev));
355 }
356 
357 static int xencons_connect_backend(struct xenbus_device *dev,
358 				  struct xencons_info *info)
359 {
360 	int ret, evtchn, devid, ref, irq;
361 	struct xenbus_transaction xbt;
362 	grant_ref_t gref_head;
363 	unsigned long mfn;
364 
365 	ret = xenbus_alloc_evtchn(dev, &evtchn);
366 	if (ret)
367 		return ret;
368 	info->evtchn = evtchn;
369 	irq = bind_evtchn_to_irq(evtchn);
370 	if (irq < 0)
371 		return irq;
372 	info->irq = irq;
373 	devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
374 	info->hvc = hvc_alloc(xenbus_devid_to_vtermno(devid),
375 			irq, &domU_hvc_ops, 256);
376 	if (IS_ERR(info->hvc))
377 		return PTR_ERR(info->hvc);
378 	if (xen_pv_domain())
379 		mfn = virt_to_mfn(info->intf);
380 	else
381 		mfn = __pa(info->intf) >> PAGE_SHIFT;
382 	ret = gnttab_alloc_grant_references(1, &gref_head);
383 	if (ret < 0)
384 		return ret;
385 	info->gntref = gref_head;
386 	ref = gnttab_claim_grant_reference(&gref_head);
387 	if (ref < 0)
388 		return ref;
389 	gnttab_grant_foreign_access_ref(ref, info->xbdev->otherend_id,
390 			mfn, 0);
391 
392  again:
393 	ret = xenbus_transaction_start(&xbt);
394 	if (ret) {
395 		xenbus_dev_fatal(dev, ret, "starting transaction");
396 		return ret;
397 	}
398 	ret = xenbus_printf(xbt, dev->nodename, "ring-ref", "%d", ref);
399 	if (ret)
400 		goto error_xenbus;
401 	ret = xenbus_printf(xbt, dev->nodename, "port", "%u",
402 			    evtchn);
403 	if (ret)
404 		goto error_xenbus;
405 	ret = xenbus_printf(xbt, dev->nodename, "type", "ioemu");
406 	if (ret)
407 		goto error_xenbus;
408 	ret = xenbus_transaction_end(xbt, 0);
409 	if (ret) {
410 		if (ret == -EAGAIN)
411 			goto again;
412 		xenbus_dev_fatal(dev, ret, "completing transaction");
413 		return ret;
414 	}
415 
416 	xenbus_switch_state(dev, XenbusStateInitialised);
417 	return 0;
418 
419  error_xenbus:
420 	xenbus_transaction_end(xbt, 1);
421 	xenbus_dev_fatal(dev, ret, "writing xenstore");
422 	return ret;
423 }
424 
425 static int xencons_probe(struct xenbus_device *dev,
426 				  const struct xenbus_device_id *id)
427 {
428 	int ret, devid;
429 	struct xencons_info *info;
430 
431 	devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
432 	if (devid == 0)
433 		return -ENODEV;
434 
435 	info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
436 	if (!info)
437 		return -ENOMEM;
438 	dev_set_drvdata(&dev->dev, info);
439 	info->xbdev = dev;
440 	info->vtermno = xenbus_devid_to_vtermno(devid);
441 	info->intf = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
442 	if (!info->intf)
443 		goto error_nomem;
444 
445 	ret = xencons_connect_backend(dev, info);
446 	if (ret < 0)
447 		goto error;
448 	spin_lock(&xencons_lock);
449 	list_add_tail(&info->list, &xenconsoles);
450 	spin_unlock(&xencons_lock);
451 
452 	return 0;
453 
454  error_nomem:
455 	ret = -ENOMEM;
456 	xenbus_dev_fatal(dev, ret, "allocating device memory");
457  error:
458 	xencons_disconnect_backend(info);
459 	xencons_free(info);
460 	return ret;
461 }
462 
463 static int xencons_resume(struct xenbus_device *dev)
464 {
465 	struct xencons_info *info = dev_get_drvdata(&dev->dev);
466 
467 	xencons_disconnect_backend(info);
468 	memset(info->intf, 0, PAGE_SIZE);
469 	return xencons_connect_backend(dev, info);
470 }
471 
472 static void xencons_backend_changed(struct xenbus_device *dev,
473 				   enum xenbus_state backend_state)
474 {
475 	switch (backend_state) {
476 	case XenbusStateReconfiguring:
477 	case XenbusStateReconfigured:
478 	case XenbusStateInitialising:
479 	case XenbusStateInitialised:
480 	case XenbusStateUnknown:
481 		break;
482 
483 	case XenbusStateInitWait:
484 		break;
485 
486 	case XenbusStateConnected:
487 		xenbus_switch_state(dev, XenbusStateConnected);
488 		break;
489 
490 	case XenbusStateClosed:
491 		if (dev->state == XenbusStateClosed)
492 			break;
493 		/* Missed the backend's CLOSING state -- fallthrough */
494 	case XenbusStateClosing:
495 		xenbus_frontend_closed(dev);
496 		break;
497 	}
498 }
499 
500 static const struct xenbus_device_id xencons_ids[] = {
501 	{ "console" },
502 	{ "" }
503 };
504 
505 
506 static DEFINE_XENBUS_DRIVER(xencons, "xenconsole",
507 	.probe = xencons_probe,
508 	.remove = xencons_remove,
509 	.resume = xencons_resume,
510 	.otherend_changed = xencons_backend_changed,
511 );
512 #endif /* CONFIG_HVC_XEN_FRONTEND */
513 
514 static int __init xen_hvc_init(void)
515 {
516 	int r;
517 	struct xencons_info *info;
518 	const struct hv_ops *ops;
519 
520 	if (!xen_domain())
521 		return -ENODEV;
522 
523 	if (xen_initial_domain()) {
524 		ops = &dom0_hvc_ops;
525 		r = xen_initial_domain_console_init();
526 		if (r < 0)
527 			return r;
528 		info = vtermno_to_xencons(HVC_COOKIE);
529 	} else {
530 		ops = &domU_hvc_ops;
531 		if (xen_hvm_domain())
532 			r = xen_hvm_console_init();
533 		else
534 			r = xen_pv_console_init();
535 		if (r < 0)
536 			return r;
537 
538 		info = vtermno_to_xencons(HVC_COOKIE);
539 		info->irq = bind_evtchn_to_irq(info->evtchn);
540 	}
541 	if (info->irq < 0)
542 		info->irq = 0; /* NO_IRQ */
543 	else
544 		irq_set_noprobe(info->irq);
545 
546 	info->hvc = hvc_alloc(HVC_COOKIE, info->irq, ops, 256);
547 	if (IS_ERR(info->hvc)) {
548 		r = PTR_ERR(info->hvc);
549 		spin_lock(&xencons_lock);
550 		list_del(&info->list);
551 		spin_unlock(&xencons_lock);
552 		if (info->irq)
553 			unbind_from_irqhandler(info->irq, NULL);
554 		kfree(info);
555 		return r;
556 	}
557 
558 	r = 0;
559 #ifdef CONFIG_HVC_XEN_FRONTEND
560 	r = xenbus_register_frontend(&xencons_driver);
561 #endif
562 	return r;
563 }
564 
565 static void __exit xen_hvc_fini(void)
566 {
567 	struct xencons_info *entry, *next;
568 
569 	if (list_empty(&xenconsoles))
570 			return;
571 
572 	list_for_each_entry_safe(entry, next, &xenconsoles, list) {
573 		xen_console_remove(entry);
574 	}
575 }
576 
577 static int xen_cons_init(void)
578 {
579 	const struct hv_ops *ops;
580 
581 	if (!xen_domain())
582 		return 0;
583 
584 	if (xen_initial_domain())
585 		ops = &dom0_hvc_ops;
586 	else {
587 		int r;
588 		ops = &domU_hvc_ops;
589 
590 		if (xen_hvm_domain())
591 			r = xen_hvm_console_init();
592 		else
593 			r = xen_pv_console_init();
594 		if (r < 0)
595 			return r;
596 	}
597 
598 	hvc_instantiate(HVC_COOKIE, 0, ops);
599 	return 0;
600 }
601 
602 
603 module_init(xen_hvc_init);
604 module_exit(xen_hvc_fini);
605 console_initcall(xen_cons_init);
606 
607 #ifdef CONFIG_EARLY_PRINTK
608 static void xenboot_write_console(struct console *console, const char *string,
609 				  unsigned len)
610 {
611 	unsigned int linelen, off = 0;
612 	const char *pos;
613 
614 	if (!xen_pv_domain())
615 		return;
616 
617 	dom0_write_console(0, string, len);
618 
619 	if (xen_initial_domain())
620 		return;
621 
622 	domU_write_console(0, "(early) ", 8);
623 	while (off < len && NULL != (pos = strchr(string+off, '\n'))) {
624 		linelen = pos-string+off;
625 		if (off + linelen > len)
626 			break;
627 		domU_write_console(0, string+off, linelen);
628 		domU_write_console(0, "\r\n", 2);
629 		off += linelen + 1;
630 	}
631 	if (off < len)
632 		domU_write_console(0, string+off, len-off);
633 }
634 
635 struct console xenboot_console = {
636 	.name		= "xenboot",
637 	.write		= xenboot_write_console,
638 	.flags		= CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
639 	.index		= -1,
640 };
641 #endif	/* CONFIG_EARLY_PRINTK */
642 
643 void xen_raw_console_write(const char *str)
644 {
645 	dom0_write_console(0, str, strlen(str));
646 }
647 
648 void xen_raw_printk(const char *fmt, ...)
649 {
650 	static char buf[512];
651 	va_list ap;
652 
653 	va_start(ap, fmt);
654 	vsnprintf(buf, sizeof(buf), fmt, ap);
655 	va_end(ap);
656 
657 	xen_raw_console_write(buf);
658 }
659