Root/drivers/tty/hvc/hvc_xen.c

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
47struct 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
58static LIST_HEAD(xenconsoles);
59static DEFINE_SPINLOCK(xencons_lock);
60
61/* ------------------------------------------------------------------ */
62
63static 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
80static inline int xenbus_devid_to_vtermno(int devid)
81{
82    return devid + HVC_COOKIE;
83}
84
85static 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
91static 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
114static 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
140static 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
165static 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
173static 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 */
182static 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
191static 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
199static 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 | __GFP_ZERO);
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;
243err:
244    kfree(info);
245    return -ENODEV;
246}
247
248static 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 | __GFP_ZERO);
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
278static 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 | __GFP_ZERO);
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
302void 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
309static 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
325static 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
333static 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
350static struct xenbus_driver xencons_driver;
351
352static int xencons_remove(struct xenbus_device *dev)
353{
354    return xen_console_remove(dev_get_drvdata(&dev->dev));
355}
356
357static 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
425static 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
463static 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
472static 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
500static const struct xenbus_device_id xencons_ids[] = {
501    { "console" },
502    { "" }
503};
504
505
506static 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
514static 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
565static 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
577static 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
603module_init(xen_hvc_init);
604module_exit(xen_hvc_fini);
605console_initcall(xen_cons_init);
606
607#ifdef CONFIG_EARLY_PRINTK
608static 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
635struct console xenboot_console = {
636    .name = "xenboot",
637    .write = xenboot_write_console,
638    .flags = CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
639};
640#endif /* CONFIG_EARLY_PRINTK */
641
642void xen_raw_console_write(const char *str)
643{
644    dom0_write_console(0, str, strlen(str));
645}
646
647void xen_raw_printk(const char *fmt, ...)
648{
649    static char buf[512];
650    va_list ap;
651
652    va_start(ap, fmt);
653    vsnprintf(buf, sizeof(buf), fmt, ap);
654    va_end(ap);
655
656    xen_raw_console_write(buf);
657}
658

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