1 // SPDX-License-Identifier: GPL-2.0+
3 * xen console driver interface to hvc_console.c
5 * (c) 2007 Gerd Hoffmann <kraxel@suse.de>
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>
18 #include <asm/xen/hypervisor.h>
21 #include <xen/interface/xen.h>
23 #include <xen/grant_table.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>
31 #include "hvc_console.h"
33 #define HVC_COOKIE 0x58656e /* "Xen" in hex */
36 struct list_head list;
37 struct xenbus_device *xbdev;
38 struct xencons_interface *intf;
40 struct hvc_struct *hvc;
46 static LIST_HEAD(xenconsoles);
47 static DEFINE_SPINLOCK(xencons_lock);
49 /* ------------------------------------------------------------------ */
51 static struct xencons_info *vtermno_to_xencons(int vtermno)
53 struct xencons_info *entry, *n, *ret = NULL;
55 if (list_empty(&xenconsoles))
58 list_for_each_entry_safe(entry, n, &xenconsoles, list) {
59 if (entry->vtermno == vtermno) {
68 static inline int xenbus_devid_to_vtermno(int devid)
70 return devid + HVC_COOKIE;
73 static inline void notify_daemon(struct xencons_info *cons)
75 /* Use evtchn: this is called early, before irq is set up. */
76 notify_remote_via_evtchn(cons->evtchn);
79 static int __write_console(struct xencons_info *xencons,
80 const char *data, int len)
82 XENCONS_RING_IDX cons, prod;
83 struct xencons_interface *intf = xencons->intf;
86 cons = intf->out_cons;
87 prod = intf->out_prod;
88 mb(); /* update queue values before going on */
90 if ((prod - cons) > sizeof(intf->out)) {
91 pr_err_once("xencons: Illegal ring page indices");
95 while ((sent < len) && ((prod - cons) < sizeof(intf->out)))
96 intf->out[MASK_XENCONS_IDX(prod++, intf->out)] = data[sent++];
98 wmb(); /* write ring before updating pointer */
99 intf->out_prod = prod;
102 notify_daemon(xencons);
106 static int domU_write_console(uint32_t vtermno, const char *data, int len)
109 struct xencons_info *cons = vtermno_to_xencons(vtermno);
114 * Make sure the whole buffer is emitted, polling if
115 * necessary. We don't ever want to rely on the hvc daemon
116 * because the most interesting console output is when the
117 * kernel is crippled.
120 int sent = __write_console(cons, data, len);
129 HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
135 static int domU_read_console(uint32_t vtermno, char *buf, int len)
137 struct xencons_interface *intf;
138 XENCONS_RING_IDX cons, prod;
140 struct xencons_info *xencons = vtermno_to_xencons(vtermno);
143 intf = xencons->intf;
145 cons = intf->in_cons;
146 prod = intf->in_prod;
147 mb(); /* get pointers before reading ring */
149 if ((prod - cons) > sizeof(intf->in)) {
150 pr_err_once("xencons: Illegal ring page indices");
154 while (cons != prod && recv < len)
155 buf[recv++] = intf->in[MASK_XENCONS_IDX(cons++, intf->in)];
157 mb(); /* read ring before consuming */
158 intf->in_cons = cons;
160 notify_daemon(xencons);
164 static const struct hv_ops domU_hvc_ops = {
165 .get_chars = domU_read_console,
166 .put_chars = domU_write_console,
167 .notifier_add = notifier_add_irq,
168 .notifier_del = notifier_del_irq,
169 .notifier_hangup = notifier_hangup_irq,
172 static int dom0_read_console(uint32_t vtermno, char *buf, int len)
174 return HYPERVISOR_console_io(CONSOLEIO_read, len, buf);
178 * Either for a dom0 to write to the system console, or a domU with a
179 * debug version of Xen
181 static int dom0_write_console(uint32_t vtermno, const char *str, int len)
183 int rc = HYPERVISOR_console_io(CONSOLEIO_write, len, (char *)str);
190 static const struct hv_ops dom0_hvc_ops = {
191 .get_chars = dom0_read_console,
192 .put_chars = dom0_write_console,
193 .notifier_add = notifier_add_irq,
194 .notifier_del = notifier_del_irq,
195 .notifier_hangup = notifier_hangup_irq,
198 static int xen_hvm_console_init(void)
203 struct xencons_info *info;
205 if (!xen_hvm_domain())
208 info = vtermno_to_xencons(HVC_COOKIE);
210 info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
213 } else if (info->intf != NULL) {
214 /* already configured */
218 * If the toolstack (or the hypervisor) hasn't set these values, the
219 * default value is 0. Even though gfn = 0 and evtchn = 0 are
220 * theoretically correct values, in practice they never are and they
221 * mean that a legacy toolstack hasn't initialized the pv console correctly.
223 r = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v);
228 r = hvm_get_parameter(HVM_PARAM_CONSOLE_PFN, &v);
232 info->intf = xen_remap(gfn << XEN_PAGE_SHIFT, XEN_PAGE_SIZE);
233 if (info->intf == NULL)
235 info->vtermno = HVC_COOKIE;
237 spin_lock(&xencons_lock);
238 list_add_tail(&info->list, &xenconsoles);
239 spin_unlock(&xencons_lock);
247 static int xencons_info_pv_init(struct xencons_info *info, int vtermno)
249 info->evtchn = xen_start_info->console.domU.evtchn;
250 /* GFN == MFN for PV guest */
251 info->intf = gfn_to_virt(xen_start_info->console.domU.mfn);
252 info->vtermno = vtermno;
254 list_add_tail(&info->list, &xenconsoles);
259 static int xen_pv_console_init(void)
261 struct xencons_info *info;
263 if (!xen_pv_domain())
266 if (!xen_start_info->console.domU.evtchn)
269 info = vtermno_to_xencons(HVC_COOKIE);
271 info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
274 } else if (info->intf != NULL) {
275 /* already configured */
278 spin_lock(&xencons_lock);
279 xencons_info_pv_init(info, HVC_COOKIE);
280 spin_unlock(&xencons_lock);
285 static int xen_initial_domain_console_init(void)
287 struct xencons_info *info;
289 if (!xen_initial_domain())
292 info = vtermno_to_xencons(HVC_COOKIE);
294 info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
299 info->irq = bind_virq_to_irq(VIRQ_CONSOLE, 0, false);
300 info->vtermno = HVC_COOKIE;
302 spin_lock(&xencons_lock);
303 list_add_tail(&info->list, &xenconsoles);
304 spin_unlock(&xencons_lock);
309 static void xen_console_update_evtchn(struct xencons_info *info)
311 if (xen_hvm_domain()) {
315 err = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v);
319 info->evtchn = xen_start_info->console.domU.evtchn;
322 void xen_console_resume(void)
324 struct xencons_info *info = vtermno_to_xencons(HVC_COOKIE);
325 if (info != NULL && info->irq) {
326 if (!xen_initial_domain())
327 xen_console_update_evtchn(info);
328 rebind_evtchn_irq(info->evtchn, info->irq);
332 #ifdef CONFIG_HVC_XEN_FRONTEND
333 static void xencons_disconnect_backend(struct xencons_info *info)
336 unbind_from_irqhandler(info->irq, NULL);
338 if (info->evtchn > 0)
339 xenbus_free_evtchn(info->xbdev, info->evtchn);
341 if (info->gntref > 0)
342 gnttab_free_grant_references(info->gntref);
344 if (info->hvc != NULL)
345 hvc_remove(info->hvc);
349 static void xencons_free(struct xencons_info *info)
351 free_page((unsigned long)info->intf);
357 static int xen_console_remove(struct xencons_info *info)
359 xencons_disconnect_backend(info);
360 spin_lock(&xencons_lock);
361 list_del(&info->list);
362 spin_unlock(&xencons_lock);
363 if (info->xbdev != NULL)
366 if (xen_hvm_domain())
373 static int xencons_remove(struct xenbus_device *dev)
375 return xen_console_remove(dev_get_drvdata(&dev->dev));
378 static int xencons_connect_backend(struct xenbus_device *dev,
379 struct xencons_info *info)
381 int ret, evtchn, devid, ref, irq;
382 struct xenbus_transaction xbt;
383 grant_ref_t gref_head;
385 ret = xenbus_alloc_evtchn(dev, &evtchn);
388 info->evtchn = evtchn;
389 irq = bind_evtchn_to_irq(evtchn);
393 devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
394 info->hvc = hvc_alloc(xenbus_devid_to_vtermno(devid),
395 irq, &domU_hvc_ops, 256);
396 if (IS_ERR(info->hvc))
397 return PTR_ERR(info->hvc);
398 ret = gnttab_alloc_grant_references(1, &gref_head);
401 info->gntref = gref_head;
402 ref = gnttab_claim_grant_reference(&gref_head);
405 gnttab_grant_foreign_access_ref(ref, info->xbdev->otherend_id,
406 virt_to_gfn(info->intf), 0);
409 ret = xenbus_transaction_start(&xbt);
411 xenbus_dev_fatal(dev, ret, "starting transaction");
414 ret = xenbus_printf(xbt, dev->nodename, "ring-ref", "%d", ref);
417 ret = xenbus_printf(xbt, dev->nodename, "port", "%u",
421 ret = xenbus_transaction_end(xbt, 0);
425 xenbus_dev_fatal(dev, ret, "completing transaction");
429 xenbus_switch_state(dev, XenbusStateInitialised);
433 xenbus_transaction_end(xbt, 1);
434 xenbus_dev_fatal(dev, ret, "writing xenstore");
438 static int xencons_probe(struct xenbus_device *dev,
439 const struct xenbus_device_id *id)
442 struct xencons_info *info;
444 devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
448 info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
451 dev_set_drvdata(&dev->dev, info);
453 info->vtermno = xenbus_devid_to_vtermno(devid);
454 info->intf = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
458 ret = xencons_connect_backend(dev, info);
461 spin_lock(&xencons_lock);
462 list_add_tail(&info->list, &xenconsoles);
463 spin_unlock(&xencons_lock);
469 xenbus_dev_fatal(dev, ret, "allocating device memory");
471 xencons_disconnect_backend(info);
476 static int xencons_resume(struct xenbus_device *dev)
478 struct xencons_info *info = dev_get_drvdata(&dev->dev);
480 xencons_disconnect_backend(info);
481 memset(info->intf, 0, XEN_PAGE_SIZE);
482 return xencons_connect_backend(dev, info);
485 static void xencons_backend_changed(struct xenbus_device *dev,
486 enum xenbus_state backend_state)
488 switch (backend_state) {
489 case XenbusStateReconfiguring:
490 case XenbusStateReconfigured:
491 case XenbusStateInitialising:
492 case XenbusStateInitialised:
493 case XenbusStateUnknown:
496 case XenbusStateInitWait:
499 case XenbusStateConnected:
500 xenbus_switch_state(dev, XenbusStateConnected);
503 case XenbusStateClosed:
504 if (dev->state == XenbusStateClosed)
506 fallthrough; /* Missed the backend's CLOSING state */
507 case XenbusStateClosing:
508 xenbus_frontend_closed(dev);
513 static const struct xenbus_device_id xencons_ids[] = {
518 static struct xenbus_driver xencons_driver = {
519 .name = "xenconsole",
521 .probe = xencons_probe,
522 .remove = xencons_remove,
523 .resume = xencons_resume,
524 .otherend_changed = xencons_backend_changed,
526 #endif /* CONFIG_HVC_XEN_FRONTEND */
528 static int __init xen_hvc_init(void)
531 struct xencons_info *info;
532 const struct hv_ops *ops;
537 if (xen_initial_domain()) {
539 r = xen_initial_domain_console_init();
542 info = vtermno_to_xencons(HVC_COOKIE);
545 if (xen_hvm_domain())
546 r = xen_hvm_console_init();
548 r = xen_pv_console_init();
552 info = vtermno_to_xencons(HVC_COOKIE);
553 info->irq = bind_evtchn_to_irq(info->evtchn);
556 info->irq = 0; /* NO_IRQ */
558 irq_set_noprobe(info->irq);
560 info->hvc = hvc_alloc(HVC_COOKIE, info->irq, ops, 256);
561 if (IS_ERR(info->hvc)) {
562 r = PTR_ERR(info->hvc);
563 spin_lock(&xencons_lock);
564 list_del(&info->list);
565 spin_unlock(&xencons_lock);
567 unbind_from_irqhandler(info->irq, NULL);
573 #ifdef CONFIG_HVC_XEN_FRONTEND
574 r = xenbus_register_frontend(&xencons_driver);
578 device_initcall(xen_hvc_init);
580 static int xen_cons_init(void)
582 const struct hv_ops *ops;
587 if (xen_initial_domain())
593 if (xen_hvm_domain())
594 r = xen_hvm_console_init();
596 r = xen_pv_console_init();
601 hvc_instantiate(HVC_COOKIE, 0, ops);
604 console_initcall(xen_cons_init);
607 static void xen_hvm_early_write(uint32_t vtermno, const char *str, int len)
609 if (xen_cpuid_base())
610 outsb(0xe9, str, len);
613 static void xen_hvm_early_write(uint32_t vtermno, const char *str, int len) { }
616 #ifdef CONFIG_EARLY_PRINTK
617 static int __init xenboot_console_setup(struct console *console, char *string)
619 static struct xencons_info xenboot;
621 if (xen_initial_domain() || !xen_pv_domain())
624 return xencons_info_pv_init(&xenboot, 0);
627 static void xenboot_write_console(struct console *console, const char *string,
630 unsigned int linelen, off = 0;
633 if (dom0_write_console(0, string, len) >= 0)
636 if (!xen_pv_domain()) {
637 xen_hvm_early_write(0, string, len);
641 if (domU_write_console(0, "(early) ", 8) < 0)
643 while (off < len && NULL != (pos = strchr(string+off, '\n'))) {
644 linelen = pos-string+off;
645 if (off + linelen > len)
647 domU_write_console(0, string+off, linelen);
648 domU_write_console(0, "\r\n", 2);
652 domU_write_console(0, string+off, len-off);
655 struct console xenboot_console = {
657 .write = xenboot_write_console,
658 .setup = xenboot_console_setup,
659 .flags = CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
662 #endif /* CONFIG_EARLY_PRINTK */
664 void xen_raw_console_write(const char *str)
666 ssize_t len = strlen(str);
670 rc = dom0_write_console(0, str, len);
671 if (rc != -ENOSYS || !xen_hvm_domain())
674 xen_hvm_early_write(0, str, len);
677 void xen_raw_printk(const char *fmt, ...)
679 static char buf[512];
683 vsnprintf(buf, sizeof(buf), fmt, ap);
686 xen_raw_console_write(buf);
689 static void xenboot_earlycon_write(struct console *console,
693 dom0_write_console(0, string, len);
696 static int __init xenboot_earlycon_setup(struct earlycon_device *device,
699 device->con->write = xenboot_earlycon_write;
702 EARLYCON_DECLARE(xenboot, xenboot_earlycon_setup);