xref: /openbmc/linux/drivers/tty/hvc/hvc_xen.c (revision 9cfc5c90) 
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 rc;
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 gfn;
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 gfn = 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 	gfn = v;
233 	info->intf = xen_remap(gfn << XEN_PAGE_SHIFT, XEN_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 	/* GFN == MFN for PV guest */
269 	info->intf = gfn_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 
279 static 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);
289 		if (!info)
290 			return -ENOMEM;
291 	}
292 
293 	info->irq = bind_virq_to_irq(VIRQ_CONSOLE, 0, false);
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 
303 static void xen_console_update_evtchn(struct xencons_info *info)
304 {
305 	if (xen_hvm_domain()) {
306 		uint64_t v = 0;
307 		int err;
308 
309 		err = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v);
310 		if (!err && v)
311 			info->evtchn = v;
312 	} else
313 		info->evtchn = xen_start_info->console.domU.evtchn;
314 }
315 
316 void xen_console_resume(void)
317 {
318 	struct xencons_info *info = vtermno_to_xencons(HVC_COOKIE);
319 	if (info != NULL && info->irq) {
320 		if (!xen_initial_domain())
321 			xen_console_update_evtchn(info);
322 		rebind_evtchn_irq(info->evtchn, info->irq);
323 	}
324 }
325 
326 static void xencons_disconnect_backend(struct xencons_info *info)
327 {
328 	if (info->irq > 0)
329 		unbind_from_irqhandler(info->irq, NULL);
330 	info->irq = 0;
331 	if (info->evtchn > 0)
332 		xenbus_free_evtchn(info->xbdev, info->evtchn);
333 	info->evtchn = 0;
334 	if (info->gntref > 0)
335 		gnttab_free_grant_references(info->gntref);
336 	info->gntref = 0;
337 	if (info->hvc != NULL)
338 		hvc_remove(info->hvc);
339 	info->hvc = NULL;
340 }
341 
342 static void xencons_free(struct xencons_info *info)
343 {
344 	free_page((unsigned long)info->intf);
345 	info->intf = NULL;
346 	info->vtermno = 0;
347 	kfree(info);
348 }
349 
350 static int xen_console_remove(struct xencons_info *info)
351 {
352 	xencons_disconnect_backend(info);
353 	spin_lock(&xencons_lock);
354 	list_del(&info->list);
355 	spin_unlock(&xencons_lock);
356 	if (info->xbdev != NULL)
357 		xencons_free(info);
358 	else {
359 		if (xen_hvm_domain())
360 			iounmap(info->intf);
361 		kfree(info);
362 	}
363 	return 0;
364 }
365 
366 #ifdef CONFIG_HVC_XEN_FRONTEND
367 static int xencons_remove(struct xenbus_device *dev)
368 {
369 	return xen_console_remove(dev_get_drvdata(&dev->dev));
370 }
371 
372 static int xencons_connect_backend(struct xenbus_device *dev,
373 				  struct xencons_info *info)
374 {
375 	int ret, evtchn, devid, ref, irq;
376 	struct xenbus_transaction xbt;
377 	grant_ref_t gref_head;
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 	ret = gnttab_alloc_grant_references(1, &gref_head);
393 	if (ret < 0)
394 		return ret;
395 	info->gntref = gref_head;
396 	ref = gnttab_claim_grant_reference(&gref_head);
397 	if (ref < 0)
398 		return ref;
399 	gnttab_grant_foreign_access_ref(ref, info->xbdev->otherend_id,
400 					virt_to_gfn(info->intf), 0);
401 
402  again:
403 	ret = xenbus_transaction_start(&xbt);
404 	if (ret) {
405 		xenbus_dev_fatal(dev, ret, "starting transaction");
406 		return ret;
407 	}
408 	ret = xenbus_printf(xbt, dev->nodename, "ring-ref", "%d", ref);
409 	if (ret)
410 		goto error_xenbus;
411 	ret = xenbus_printf(xbt, dev->nodename, "port", "%u",
412 			    evtchn);
413 	if (ret)
414 		goto error_xenbus;
415 	ret = xenbus_transaction_end(xbt, 0);
416 	if (ret) {
417 		if (ret == -EAGAIN)
418 			goto again;
419 		xenbus_dev_fatal(dev, ret, "completing transaction");
420 		return ret;
421 	}
422 
423 	xenbus_switch_state(dev, XenbusStateInitialised);
424 	return 0;
425 
426  error_xenbus:
427 	xenbus_transaction_end(xbt, 1);
428 	xenbus_dev_fatal(dev, ret, "writing xenstore");
429 	return ret;
430 }
431 
432 static int xencons_probe(struct xenbus_device *dev,
433 				  const struct xenbus_device_id *id)
434 {
435 	int ret, devid;
436 	struct xencons_info *info;
437 
438 	devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
439 	if (devid == 0)
440 		return -ENODEV;
441 
442 	info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
443 	if (!info)
444 		return -ENOMEM;
445 	dev_set_drvdata(&dev->dev, info);
446 	info->xbdev = dev;
447 	info->vtermno = xenbus_devid_to_vtermno(devid);
448 	info->intf = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
449 	if (!info->intf)
450 		goto error_nomem;
451 
452 	ret = xencons_connect_backend(dev, info);
453 	if (ret < 0)
454 		goto error;
455 	spin_lock(&xencons_lock);
456 	list_add_tail(&info->list, &xenconsoles);
457 	spin_unlock(&xencons_lock);
458 
459 	return 0;
460 
461  error_nomem:
462 	ret = -ENOMEM;
463 	xenbus_dev_fatal(dev, ret, "allocating device memory");
464  error:
465 	xencons_disconnect_backend(info);
466 	xencons_free(info);
467 	return ret;
468 }
469 
470 static int xencons_resume(struct xenbus_device *dev)
471 {
472 	struct xencons_info *info = dev_get_drvdata(&dev->dev);
473 
474 	xencons_disconnect_backend(info);
475 	memset(info->intf, 0, XEN_PAGE_SIZE);
476 	return xencons_connect_backend(dev, info);
477 }
478 
479 static void xencons_backend_changed(struct xenbus_device *dev,
480 				   enum xenbus_state backend_state)
481 {
482 	switch (backend_state) {
483 	case XenbusStateReconfiguring:
484 	case XenbusStateReconfigured:
485 	case XenbusStateInitialising:
486 	case XenbusStateInitialised:
487 	case XenbusStateUnknown:
488 		break;
489 
490 	case XenbusStateInitWait:
491 		break;
492 
493 	case XenbusStateConnected:
494 		xenbus_switch_state(dev, XenbusStateConnected);
495 		break;
496 
497 	case XenbusStateClosed:
498 		if (dev->state == XenbusStateClosed)
499 			break;
500 		/* Missed the backend's CLOSING state -- fallthrough */
501 	case XenbusStateClosing:
502 		xenbus_frontend_closed(dev);
503 		break;
504 	}
505 }
506 
507 static const struct xenbus_device_id xencons_ids[] = {
508 	{ "console" },
509 	{ "" }
510 };
511 
512 static struct xenbus_driver xencons_driver = {
513 	.name = "xenconsole",
514 	.ids = xencons_ids,
515 	.probe = xencons_probe,
516 	.remove = xencons_remove,
517 	.resume = xencons_resume,
518 	.otherend_changed = xencons_backend_changed,
519 };
520 #endif /* CONFIG_HVC_XEN_FRONTEND */
521 
522 static int __init xen_hvc_init(void)
523 {
524 	int r;
525 	struct xencons_info *info;
526 	const struct hv_ops *ops;
527 
528 	if (!xen_domain())
529 		return -ENODEV;
530 
531 	if (xen_initial_domain()) {
532 		ops = &dom0_hvc_ops;
533 		r = xen_initial_domain_console_init();
534 		if (r < 0)
535 			return r;
536 		info = vtermno_to_xencons(HVC_COOKIE);
537 	} else {
538 		ops = &domU_hvc_ops;
539 		if (xen_hvm_domain())
540 			r = xen_hvm_console_init();
541 		else
542 			r = xen_pv_console_init();
543 		if (r < 0)
544 			return r;
545 
546 		info = vtermno_to_xencons(HVC_COOKIE);
547 		info->irq = bind_evtchn_to_irq(info->evtchn);
548 	}
549 	if (info->irq < 0)
550 		info->irq = 0; /* NO_IRQ */
551 	else
552 		irq_set_noprobe(info->irq);
553 
554 	info->hvc = hvc_alloc(HVC_COOKIE, info->irq, ops, 256);
555 	if (IS_ERR(info->hvc)) {
556 		r = PTR_ERR(info->hvc);
557 		spin_lock(&xencons_lock);
558 		list_del(&info->list);
559 		spin_unlock(&xencons_lock);
560 		if (info->irq)
561 			unbind_from_irqhandler(info->irq, NULL);
562 		kfree(info);
563 		return r;
564 	}
565 
566 	r = 0;
567 #ifdef CONFIG_HVC_XEN_FRONTEND
568 	r = xenbus_register_frontend(&xencons_driver);
569 #endif
570 	return r;
571 }
572 device_initcall(xen_hvc_init);
573 
574 static int xen_cons_init(void)
575 {
576 	const struct hv_ops *ops;
577 
578 	if (!xen_domain())
579 		return 0;
580 
581 	if (xen_initial_domain())
582 		ops = &dom0_hvc_ops;
583 	else {
584 		int r;
585 		ops = &domU_hvc_ops;
586 
587 		if (xen_hvm_domain())
588 			r = xen_hvm_console_init();
589 		else
590 			r = xen_pv_console_init();
591 		if (r < 0)
592 			return r;
593 	}
594 
595 	hvc_instantiate(HVC_COOKIE, 0, ops);
596 	return 0;
597 }
598 console_initcall(xen_cons_init);
599 
600 #ifdef CONFIG_EARLY_PRINTK
601 static void xenboot_write_console(struct console *console, const char *string,
602 				  unsigned len)
603 {
604 	unsigned int linelen, off = 0;
605 	const char *pos;
606 
607 	if (!xen_pv_domain())
608 		return;
609 
610 	dom0_write_console(0, string, len);
611 
612 	if (xen_initial_domain())
613 		return;
614 
615 	domU_write_console(0, "(early) ", 8);
616 	while (off < len && NULL != (pos = strchr(string+off, '\n'))) {
617 		linelen = pos-string+off;
618 		if (off + linelen > len)
619 			break;
620 		domU_write_console(0, string+off, linelen);
621 		domU_write_console(0, "\r\n", 2);
622 		off += linelen + 1;
623 	}
624 	if (off < len)
625 		domU_write_console(0, string+off, len-off);
626 }
627 
628 struct console xenboot_console = {
629 	.name		= "xenboot",
630 	.write		= xenboot_write_console,
631 	.flags		= CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
632 	.index		= -1,
633 };
634 #endif	/* CONFIG_EARLY_PRINTK */
635 
636 void xen_raw_console_write(const char *str)
637 {
638 	ssize_t len = strlen(str);
639 	int rc = 0;
640 
641 	if (xen_domain()) {
642 		rc = dom0_write_console(0, str, len);
643 #ifdef CONFIG_X86
644 		if (rc == -ENOSYS && xen_hvm_domain())
645 			goto outb_print;
646 
647 	} else if (xen_cpuid_base()) {
648 		int i;
649 outb_print:
650 		for (i = 0; i < len; i++)
651 			outb(str[i], 0xe9);
652 #endif
653 	}
654 }
655 
656 void xen_raw_printk(const char *fmt, ...)
657 {
658 	static char buf[512];
659 	va_list ap;
660 
661 	va_start(ap, fmt);
662 	vsnprintf(buf, sizeof(buf), fmt, ap);
663 	va_end(ap);
664 
665 	xen_raw_console_write(buf);
666 }
667