1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * xen console driver interface to hvc_console.c
4 *
5 * (c) 2007 Gerd Hoffmann <kraxel@suse.de>
6 */
7
8 #include <linux/console.h>
9 #include <linux/delay.h>
10 #include <linux/err.h>
11 #include <linux/irq.h>
12 #include <linux/init.h>
13 #include <linux/types.h>
14 #include <linux/list.h>
15 #include <linux/serial_core.h>
16
17 #include <asm/io.h>
18 #include <asm/xen/hypervisor.h>
19
20 #include <xen/xen.h>
21 #include <xen/interface/xen.h>
22 #include <xen/hvm.h>
23 #include <xen/grant_table.h>
24 #include <xen/page.h>
25 #include <xen/events.h>
26 #include <xen/interface/io/console.h>
27 #include <xen/interface/sched.h>
28 #include <xen/hvc-console.h>
29 #include <xen/xenbus.h>
30
31 #include "hvc_console.h"
32
33 #define HVC_COOKIE 0x58656e /* "Xen" in hex */
34
35 struct xencons_info {
36 struct list_head list;
37 struct xenbus_device *xbdev;
38 struct xencons_interface *intf;
39 unsigned int evtchn;
40 struct hvc_struct *hvc;
41 int irq;
42 int vtermno;
43 grant_ref_t gntref;
44 };
45
46 static LIST_HEAD(xenconsoles);
47 static DEFINE_SPINLOCK(xencons_lock);
48
49 /* ------------------------------------------------------------------ */
50
vtermno_to_xencons(int vtermno)51 static struct xencons_info *vtermno_to_xencons(int vtermno)
52 {
53 struct xencons_info *entry, *n, *ret = NULL;
54
55 if (list_empty(&xenconsoles))
56 return NULL;
57
58 list_for_each_entry_safe(entry, n, &xenconsoles, list) {
59 if (entry->vtermno == vtermno) {
60 ret = entry;
61 break;
62 }
63 }
64
65 return ret;
66 }
67
xenbus_devid_to_vtermno(int devid)68 static inline int xenbus_devid_to_vtermno(int devid)
69 {
70 return devid + HVC_COOKIE;
71 }
72
notify_daemon(struct xencons_info * cons)73 static inline void notify_daemon(struct xencons_info *cons)
74 {
75 /* Use evtchn: this is called early, before irq is set up. */
76 notify_remote_via_evtchn(cons->evtchn);
77 }
78
__write_console(struct xencons_info * xencons,const char * data,int len)79 static int __write_console(struct xencons_info *xencons,
80 const char *data, int len)
81 {
82 XENCONS_RING_IDX cons, prod;
83 struct xencons_interface *intf = xencons->intf;
84 int sent = 0;
85
86 cons = intf->out_cons;
87 prod = intf->out_prod;
88 mb(); /* update queue values before going on */
89 BUG_ON((prod - cons) > sizeof(intf->out));
90
91 while ((sent < len) && ((prod - cons) < sizeof(intf->out)))
92 intf->out[MASK_XENCONS_IDX(prod++, intf->out)] = data[sent++];
93
94 wmb(); /* write ring before updating pointer */
95 intf->out_prod = prod;
96
97 if (sent)
98 notify_daemon(xencons);
99 return sent;
100 }
101
domU_write_console(uint32_t vtermno,const char * data,int len)102 static int domU_write_console(uint32_t vtermno, const char *data, int len)
103 {
104 int ret = len;
105 struct xencons_info *cons = vtermno_to_xencons(vtermno);
106 if (cons == NULL)
107 return -EINVAL;
108
109 /*
110 * Make sure the whole buffer is emitted, polling if
111 * necessary. We don't ever want to rely on the hvc daemon
112 * because the most interesting console output is when the
113 * kernel is crippled.
114 */
115 while (len) {
116 int sent = __write_console(cons, data, len);
117
118 data += sent;
119 len -= sent;
120
121 if (unlikely(len))
122 HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
123 }
124
125 return ret;
126 }
127
domU_read_console(uint32_t vtermno,char * buf,int len)128 static int domU_read_console(uint32_t vtermno, char *buf, int len)
129 {
130 struct xencons_interface *intf;
131 XENCONS_RING_IDX cons, prod;
132 int recv = 0;
133 struct xencons_info *xencons = vtermno_to_xencons(vtermno);
134 if (xencons == NULL)
135 return -EINVAL;
136 intf = xencons->intf;
137
138 cons = intf->in_cons;
139 prod = intf->in_prod;
140 mb(); /* get pointers before reading ring */
141 BUG_ON((prod - cons) > sizeof(intf->in));
142
143 while (cons != prod && recv < len)
144 buf[recv++] = intf->in[MASK_XENCONS_IDX(cons++, intf->in)];
145
146 mb(); /* read ring before consuming */
147 intf->in_cons = cons;
148
149 notify_daemon(xencons);
150 return recv;
151 }
152
153 static const struct hv_ops domU_hvc_ops = {
154 .get_chars = domU_read_console,
155 .put_chars = domU_write_console,
156 .notifier_add = notifier_add_irq,
157 .notifier_del = notifier_del_irq,
158 .notifier_hangup = notifier_hangup_irq,
159 };
160
dom0_read_console(uint32_t vtermno,char * buf,int len)161 static int dom0_read_console(uint32_t vtermno, char *buf, int len)
162 {
163 return HYPERVISOR_console_io(CONSOLEIO_read, len, buf);
164 }
165
166 /*
167 * Either for a dom0 to write to the system console, or a domU with a
168 * debug version of Xen
169 */
dom0_write_console(uint32_t vtermno,const char * str,int len)170 static int dom0_write_console(uint32_t vtermno, const char *str, int len)
171 {
172 int rc = HYPERVISOR_console_io(CONSOLEIO_write, len, (char *)str);
173 if (rc < 0)
174 return rc;
175
176 return len;
177 }
178
179 static const struct hv_ops dom0_hvc_ops = {
180 .get_chars = dom0_read_console,
181 .put_chars = dom0_write_console,
182 .notifier_add = notifier_add_irq,
183 .notifier_del = notifier_del_irq,
184 .notifier_hangup = notifier_hangup_irq,
185 };
186
xen_hvm_console_init(void)187 static int xen_hvm_console_init(void)
188 {
189 int r;
190 uint64_t v = 0;
191 unsigned long gfn;
192 struct xencons_info *info;
193
194 if (!xen_hvm_domain())
195 return -ENODEV;
196
197 info = vtermno_to_xencons(HVC_COOKIE);
198 if (!info) {
199 info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
200 if (!info)
201 return -ENOMEM;
202 } else if (info->intf != NULL) {
203 /* already configured */
204 return 0;
205 }
206 /*
207 * If the toolstack (or the hypervisor) hasn't set these values, the
208 * default value is 0. Even though gfn = 0 and evtchn = 0 are
209 * theoretically correct values, in practice they never are and they
210 * mean that a legacy toolstack hasn't initialized the pv console correctly.
211 */
212 r = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v);
213 if (r < 0 || v == 0)
214 goto err;
215 info->evtchn = v;
216 v = 0;
217 r = hvm_get_parameter(HVM_PARAM_CONSOLE_PFN, &v);
218 if (r < 0 || v == 0)
219 goto err;
220 gfn = v;
221 info->intf = xen_remap(gfn << XEN_PAGE_SHIFT, XEN_PAGE_SIZE);
222 if (info->intf == NULL)
223 goto err;
224 info->vtermno = HVC_COOKIE;
225
226 spin_lock(&xencons_lock);
227 list_add_tail(&info->list, &xenconsoles);
228 spin_unlock(&xencons_lock);
229
230 return 0;
231 err:
232 kfree(info);
233 return -ENODEV;
234 }
235
xencons_info_pv_init(struct xencons_info * info,int vtermno)236 static int xencons_info_pv_init(struct xencons_info *info, int vtermno)
237 {
238 info->evtchn = xen_start_info->console.domU.evtchn;
239 /* GFN == MFN for PV guest */
240 info->intf = gfn_to_virt(xen_start_info->console.domU.mfn);
241 info->vtermno = vtermno;
242
243 list_add_tail(&info->list, &xenconsoles);
244
245 return 0;
246 }
247
xen_pv_console_init(void)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 spin_lock(&xencons_lock);
268 xencons_info_pv_init(info, HVC_COOKIE);
269 spin_unlock(&xencons_lock);
270
271 return 0;
272 }
273
xen_initial_domain_console_init(void)274 static int xen_initial_domain_console_init(void)
275 {
276 struct xencons_info *info;
277
278 if (!xen_initial_domain())
279 return -ENODEV;
280
281 info = vtermno_to_xencons(HVC_COOKIE);
282 if (!info) {
283 info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
284 if (!info)
285 return -ENOMEM;
286 }
287
288 info->irq = bind_virq_to_irq(VIRQ_CONSOLE, 0, false);
289 info->vtermno = HVC_COOKIE;
290
291 spin_lock(&xencons_lock);
292 list_add_tail(&info->list, &xenconsoles);
293 spin_unlock(&xencons_lock);
294
295 return 0;
296 }
297
xen_console_update_evtchn(struct xencons_info * info)298 static void xen_console_update_evtchn(struct xencons_info *info)
299 {
300 if (xen_hvm_domain()) {
301 uint64_t v = 0;
302 int err;
303
304 err = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v);
305 if (!err && v)
306 info->evtchn = v;
307 } else
308 info->evtchn = xen_start_info->console.domU.evtchn;
309 }
310
xen_console_resume(void)311 void xen_console_resume(void)
312 {
313 struct xencons_info *info = vtermno_to_xencons(HVC_COOKIE);
314 if (info != NULL && info->irq) {
315 if (!xen_initial_domain())
316 xen_console_update_evtchn(info);
317 rebind_evtchn_irq(info->evtchn, info->irq);
318 }
319 }
320
321 #ifdef CONFIG_HVC_XEN_FRONTEND
xencons_disconnect_backend(struct xencons_info * info)322 static void xencons_disconnect_backend(struct xencons_info *info)
323 {
324 if (info->irq > 0)
325 unbind_from_irqhandler(info->irq, NULL);
326 info->irq = 0;
327 if (info->evtchn > 0)
328 xenbus_free_evtchn(info->xbdev, info->evtchn);
329 info->evtchn = 0;
330 if (info->gntref > 0)
331 gnttab_free_grant_references(info->gntref);
332 info->gntref = 0;
333 if (info->hvc != NULL)
334 hvc_remove(info->hvc);
335 info->hvc = NULL;
336 }
337
xencons_free(struct xencons_info * info)338 static void xencons_free(struct xencons_info *info)
339 {
340 free_page((unsigned long)info->intf);
341 info->intf = NULL;
342 info->vtermno = 0;
343 kfree(info);
344 }
345
xen_console_remove(struct xencons_info * info)346 static int xen_console_remove(struct xencons_info *info)
347 {
348 xencons_disconnect_backend(info);
349 spin_lock(&xencons_lock);
350 list_del(&info->list);
351 spin_unlock(&xencons_lock);
352 if (info->xbdev != NULL)
353 xencons_free(info);
354 else {
355 if (xen_hvm_domain())
356 iounmap(info->intf);
357 kfree(info);
358 }
359 return 0;
360 }
361
xencons_remove(struct xenbus_device * dev)362 static int xencons_remove(struct xenbus_device *dev)
363 {
364 return xen_console_remove(dev_get_drvdata(&dev->dev));
365 }
366
xencons_connect_backend(struct xenbus_device * dev,struct xencons_info * info)367 static int xencons_connect_backend(struct xenbus_device *dev,
368 struct xencons_info *info)
369 {
370 int ret, evtchn, devid, ref, irq;
371 struct xenbus_transaction xbt;
372 grant_ref_t gref_head;
373
374 ret = xenbus_alloc_evtchn(dev, &evtchn);
375 if (ret)
376 return ret;
377 info->evtchn = evtchn;
378 irq = bind_evtchn_to_irq(evtchn);
379 if (irq < 0)
380 return irq;
381 info->irq = irq;
382 devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
383 info->hvc = hvc_alloc(xenbus_devid_to_vtermno(devid),
384 irq, &domU_hvc_ops, 256);
385 if (IS_ERR(info->hvc))
386 return PTR_ERR(info->hvc);
387 ret = gnttab_alloc_grant_references(1, &gref_head);
388 if (ret < 0)
389 return ret;
390 info->gntref = gref_head;
391 ref = gnttab_claim_grant_reference(&gref_head);
392 if (ref < 0)
393 return ref;
394 gnttab_grant_foreign_access_ref(ref, info->xbdev->otherend_id,
395 virt_to_gfn(info->intf), 0);
396
397 again:
398 ret = xenbus_transaction_start(&xbt);
399 if (ret) {
400 xenbus_dev_fatal(dev, ret, "starting transaction");
401 return ret;
402 }
403 ret = xenbus_printf(xbt, dev->nodename, "ring-ref", "%d", ref);
404 if (ret)
405 goto error_xenbus;
406 ret = xenbus_printf(xbt, dev->nodename, "port", "%u",
407 evtchn);
408 if (ret)
409 goto error_xenbus;
410 ret = xenbus_transaction_end(xbt, 0);
411 if (ret) {
412 if (ret == -EAGAIN)
413 goto again;
414 xenbus_dev_fatal(dev, ret, "completing transaction");
415 return ret;
416 }
417
418 xenbus_switch_state(dev, XenbusStateInitialised);
419 return 0;
420
421 error_xenbus:
422 xenbus_transaction_end(xbt, 1);
423 xenbus_dev_fatal(dev, ret, "writing xenstore");
424 return ret;
425 }
426
xencons_probe(struct xenbus_device * dev,const struct xenbus_device_id * id)427 static int xencons_probe(struct xenbus_device *dev,
428 const struct xenbus_device_id *id)
429 {
430 int ret, devid;
431 struct xencons_info *info;
432
433 devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
434 if (devid == 0)
435 return -ENODEV;
436
437 info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
438 if (!info)
439 return -ENOMEM;
440 dev_set_drvdata(&dev->dev, info);
441 info->xbdev = dev;
442 info->vtermno = xenbus_devid_to_vtermno(devid);
443 info->intf = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
444 if (!info->intf)
445 goto error_nomem;
446
447 ret = xencons_connect_backend(dev, info);
448 if (ret < 0)
449 goto error;
450 spin_lock(&xencons_lock);
451 list_add_tail(&info->list, &xenconsoles);
452 spin_unlock(&xencons_lock);
453
454 return 0;
455
456 error_nomem:
457 ret = -ENOMEM;
458 xenbus_dev_fatal(dev, ret, "allocating device memory");
459 error:
460 xencons_disconnect_backend(info);
461 xencons_free(info);
462 return ret;
463 }
464
xencons_resume(struct xenbus_device * dev)465 static int xencons_resume(struct xenbus_device *dev)
466 {
467 struct xencons_info *info = dev_get_drvdata(&dev->dev);
468
469 xencons_disconnect_backend(info);
470 memset(info->intf, 0, XEN_PAGE_SIZE);
471 return xencons_connect_backend(dev, info);
472 }
473
xencons_backend_changed(struct xenbus_device * dev,enum xenbus_state backend_state)474 static void xencons_backend_changed(struct xenbus_device *dev,
475 enum xenbus_state backend_state)
476 {
477 switch (backend_state) {
478 case XenbusStateReconfiguring:
479 case XenbusStateReconfigured:
480 case XenbusStateInitialising:
481 case XenbusStateInitialised:
482 case XenbusStateUnknown:
483 break;
484
485 case XenbusStateInitWait:
486 break;
487
488 case XenbusStateConnected:
489 xenbus_switch_state(dev, XenbusStateConnected);
490 break;
491
492 case XenbusStateClosed:
493 if (dev->state == XenbusStateClosed)
494 break;
495 fallthrough; /* Missed the backend's CLOSING state */
496 case XenbusStateClosing:
497 xenbus_frontend_closed(dev);
498 break;
499 }
500 }
501
502 static const struct xenbus_device_id xencons_ids[] = {
503 { "console" },
504 { "" }
505 };
506
507 static struct xenbus_driver xencons_driver = {
508 .name = "xenconsole",
509 .ids = xencons_ids,
510 .probe = xencons_probe,
511 .remove = xencons_remove,
512 .resume = xencons_resume,
513 .otherend_changed = xencons_backend_changed,
514 };
515 #endif /* CONFIG_HVC_XEN_FRONTEND */
516
xen_hvc_init(void)517 static int __init xen_hvc_init(void)
518 {
519 int r;
520 struct xencons_info *info;
521 const struct hv_ops *ops;
522
523 if (!xen_domain())
524 return -ENODEV;
525
526 if (xen_initial_domain()) {
527 ops = &dom0_hvc_ops;
528 r = xen_initial_domain_console_init();
529 if (r < 0)
530 return r;
531 info = vtermno_to_xencons(HVC_COOKIE);
532 } else {
533 ops = &domU_hvc_ops;
534 if (xen_hvm_domain())
535 r = xen_hvm_console_init();
536 else
537 r = xen_pv_console_init();
538 if (r < 0)
539 return r;
540
541 info = vtermno_to_xencons(HVC_COOKIE);
542 info->irq = bind_evtchn_to_irq(info->evtchn);
543 }
544 if (info->irq < 0)
545 info->irq = 0; /* NO_IRQ */
546 else
547 irq_set_noprobe(info->irq);
548
549 info->hvc = hvc_alloc(HVC_COOKIE, info->irq, ops, 256);
550 if (IS_ERR(info->hvc)) {
551 r = PTR_ERR(info->hvc);
552 spin_lock(&xencons_lock);
553 list_del(&info->list);
554 spin_unlock(&xencons_lock);
555 if (info->irq)
556 unbind_from_irqhandler(info->irq, NULL);
557 kfree(info);
558 return r;
559 }
560
561 r = 0;
562 #ifdef CONFIG_HVC_XEN_FRONTEND
563 r = xenbus_register_frontend(&xencons_driver);
564 #endif
565 return r;
566 }
567 device_initcall(xen_hvc_init);
568
xen_cons_init(void)569 static int xen_cons_init(void)
570 {
571 const struct hv_ops *ops;
572
573 if (!xen_domain())
574 return 0;
575
576 if (xen_initial_domain())
577 ops = &dom0_hvc_ops;
578 else {
579 int r;
580 ops = &domU_hvc_ops;
581
582 if (xen_hvm_domain())
583 r = xen_hvm_console_init();
584 else
585 r = xen_pv_console_init();
586 if (r < 0)
587 return r;
588 }
589
590 hvc_instantiate(HVC_COOKIE, 0, ops);
591 return 0;
592 }
593 console_initcall(xen_cons_init);
594
595 #ifdef CONFIG_X86
xen_hvm_early_write(uint32_t vtermno,const char * str,int len)596 static void xen_hvm_early_write(uint32_t vtermno, const char *str, int len)
597 {
598 if (xen_cpuid_base())
599 outsb(0xe9, str, len);
600 }
601 #else
xen_hvm_early_write(uint32_t vtermno,const char * str,int len)602 static void xen_hvm_early_write(uint32_t vtermno, const char *str, int len) { }
603 #endif
604
605 #ifdef CONFIG_EARLY_PRINTK
xenboot_console_setup(struct console * console,char * string)606 static int __init xenboot_console_setup(struct console *console, char *string)
607 {
608 static struct xencons_info xenboot;
609
610 if (xen_initial_domain())
611 return 0;
612 if (!xen_pv_domain())
613 return -ENODEV;
614
615 return xencons_info_pv_init(&xenboot, 0);
616 }
617
xenboot_write_console(struct console * console,const char * string,unsigned len)618 static void xenboot_write_console(struct console *console, const char *string,
619 unsigned len)
620 {
621 unsigned int linelen, off = 0;
622 const char *pos;
623
624 if (!xen_pv_domain()) {
625 xen_hvm_early_write(0, string, len);
626 return;
627 }
628
629 dom0_write_console(0, string, len);
630
631 if (xen_initial_domain())
632 return;
633
634 domU_write_console(0, "(early) ", 8);
635 while (off < len && NULL != (pos = strchr(string+off, '\n'))) {
636 linelen = pos-string+off;
637 if (off + linelen > len)
638 break;
639 domU_write_console(0, string+off, linelen);
640 domU_write_console(0, "\r\n", 2);
641 off += linelen + 1;
642 }
643 if (off < len)
644 domU_write_console(0, string+off, len-off);
645 }
646
647 struct console xenboot_console = {
648 .name = "xenboot",
649 .write = xenboot_write_console,
650 .setup = xenboot_console_setup,
651 .flags = CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
652 .index = -1,
653 };
654 #endif /* CONFIG_EARLY_PRINTK */
655
xen_raw_console_write(const char * str)656 void xen_raw_console_write(const char *str)
657 {
658 ssize_t len = strlen(str);
659 int rc = 0;
660
661 if (xen_domain()) {
662 rc = dom0_write_console(0, str, len);
663 if (rc != -ENOSYS || !xen_hvm_domain())
664 return;
665 }
666 xen_hvm_early_write(0, str, len);
667 }
668
xen_raw_printk(const char * fmt,...)669 void xen_raw_printk(const char *fmt, ...)
670 {
671 static char buf[512];
672 va_list ap;
673
674 va_start(ap, fmt);
675 vsnprintf(buf, sizeof(buf), fmt, ap);
676 va_end(ap);
677
678 xen_raw_console_write(buf);
679 }
680
xenboot_earlycon_write(struct console * console,const char * string,unsigned len)681 static void xenboot_earlycon_write(struct console *console,
682 const char *string,
683 unsigned len)
684 {
685 dom0_write_console(0, string, len);
686 }
687
xenboot_earlycon_setup(struct earlycon_device * device,const char * opt)688 static int __init xenboot_earlycon_setup(struct earlycon_device *device,
689 const char *opt)
690 {
691 device->con->write = xenboot_earlycon_write;
692 return 0;
693 }
694 EARLYCON_DECLARE(xenboot, xenboot_earlycon_setup);
695
