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/init.h>
  25 #include <linux/types.h>
  26 #include <linux/list.h>
  27
  28 #include <asm/io.h>
  29 #include <asm/xen/hypervisor.h>
  30
  31 #include <xen/xen.h>
  32 #include <xen/interface/xen.h>
  33 #include <xen/hvm.h>
  34 #include <xen/grant_table.h>
  35 #include <xen/page.h>
  36 #include <xen/events.h>
  37 #include <xen/interface/io/console.h>
  38 #include <xen/hvc-console.h>
  39 #include <xen/xenbus.h>
  40
  41 #include "hvc_console.h"
  42
  43 #define HVC_COOKIE   0x58656e /* "Xen" in hex */
  44
  45 struct xencons_info {
  46         struct list_head list;
  47         struct xenbus_device *xbdev;
  48         struct xencons_interface *intf;
  49         unsigned int evtchn;
  50         struct hvc_struct *hvc;
  51         int irq;
  52         int vtermno;
  53         grant_ref_t gntref;
  54 };
  55
  56 static LIST_HEAD(xenconsoles);
  57 static DEFINE_SPINLOCK(xencons_lock);
  58
  59 /* ------------------------------------------------------------------ */
  60
  61 static struct xencons_info *vtermno_to_xencons(int vtermno)
  62 {
  63         struct xencons_info *entry, *n, *ret = NULL;
  64
  65         if (list_empty(&xenconsoles))
  66                         return NULL;
  67
  68         list_for_each_entry_safe(entry, n, &xenconsoles, list) {
  69                 if (entry->vtermno == vtermno) {
  70                         ret  = entry;
  71                         break;
  72                 }
  73         }
  74
  75         return ret;
  76 }
  77
  78 static inline int xenbus_devid_to_vtermno(int devid)
  79 {
  80         return devid + HVC_COOKIE;
  81 }
  82
  83 static inline void notify_daemon(struct xencons_info *cons)
  84 {
  85         /* Use evtchn: this is called early, before irq is set up. */
  86         notify_remote_via_evtchn(cons->evtchn);
  87 }
  88
  89 static int __write_console(struct xencons_info *xencons,
  90                 const char *data, int len)
  91 {
  92         XENCONS_RING_IDX cons, prod;
  93         struct xencons_interface *intf = xencons->intf;
  94         int sent = 0;
  95
  96         cons = intf->out_cons;
  97         prod = intf->out_prod;
  98         mb();                   /* update queue values before going on */
  99         BUG_ON((prod - cons) > sizeof(intf->out));
 100
 101         while ((sent < len) && ((prod - cons) < sizeof(intf->out)))
 102                 intf->out[MASK_XENCONS_IDX(prod++, intf->out)] = data[sent++];
 103
 104         wmb();                  /* write ring before updating pointer */
 105         intf->out_prod = prod;
 106
 107         if (sent)
 108                 notify_daemon(xencons);
 109         return sent;
 110 }
 111
 112 static int domU_write_console(uint32_t vtermno, const char *data, int len)
 113 {
 114         int ret = len;
 115         struct xencons_info *cons = vtermno_to_xencons(vtermno);
 116         if (cons == NULL)
 117                 return -EINVAL;
 118
 119         /*
 120          * Make sure the whole buffer is emitted, polling if
 121          * necessary.  We don't ever want to rely on the hvc daemon
 122          * because the most interesting console output is when the
 123          * kernel is crippled.
 124          */
 125         while (len) {
 126                 int sent = __write_console(cons, data, len);
 127
 128                 data += sent;
 129                 len -= sent;
 130
 131                 if (unlikely(len))
 132                         HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
 133         }
 134
 135         return ret;
 136 }
 137
 138 static int domU_read_console(uint32_t vtermno, char *buf, int len)
 139 {
 140         struct xencons_interface *intf;
 141         XENCONS_RING_IDX cons, prod;
 142         int recv = 0;
 143         struct xencons_info *xencons = vtermno_to_xencons(vtermno);
 144         if (xencons == NULL)
 145                 return -EINVAL;
 146         intf = xencons->intf;
 147
 148         cons = intf->in_cons;
 149         prod = intf->in_prod;
 150         mb();                   /* get pointers before reading ring */
 151         BUG_ON((prod - cons) > sizeof(intf->in));
 152
 153         while (cons != prod && recv < len)
 154                 buf[recv++] = intf->in[MASK_XENCONS_IDX(cons++, intf->in)];
 155
 156         mb();                   /* read ring before consuming */
 157         intf->in_cons = cons;
 158
 159         notify_daemon(xencons);
 160         return recv;
 161 }
 162
 163 static struct hv_ops domU_hvc_ops = {
 164         .get_chars = domU_read_console,
 165         .put_chars = domU_write_console,
 166         .notifier_add = notifier_add_irq,
 167         .notifier_del = notifier_del_irq,
 168         .notifier_hangup = notifier_hangup_irq,
 169 };
 170
 171 static int dom0_read_console(uint32_t vtermno, char *buf, int len)
 172 {
 173         return HYPERVISOR_console_io(CONSOLEIO_read, len, buf);
 174 }
 175
 176 /*
 177  * Either for a dom0 to write to the system console, or a domU with a
 178  * debug version of Xen
 179  */
 180 static int dom0_write_console(uint32_t vtermno, const char *str, int len)
 181 {
 182         int rc = HYPERVISOR_console_io(CONSOLEIO_write, len, (char *)str);
 183         if (rc < 0)
 184                 return 0;
 185
 186         return len;
 187 }
 188
 189 static struct hv_ops dom0_hvc_ops = {
 190         .get_chars = dom0_read_console,
 191         .put_chars = dom0_write_console,
 192         .notifier_add = notifier_add_irq,
 193         .notifier_del = notifier_del_irq,
 194         .notifier_hangup = notifier_hangup_irq,
 195 };
 196
 197 static int xen_hvm_console_init(void)
 198 {
 199         int r;
 200         uint64_t v = 0;
 201         unsigned long mfn;
 202         struct xencons_info *info;
 203
 204         if (!xen_hvm_domain())
 205                 return -ENODEV;
 206
 207         info = vtermno_to_xencons(HVC_COOKIE);
 208         if (!info) {
 209                 info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL | __GFP_ZERO);
 210                 if (!info)
 211                         return -ENOMEM;
 212         }
 213
 214         /* already configured */
 215         if (info->intf != NULL)
 216                 return 0;
 217         /*
 218          * If the toolstack (or the hypervisor) hasn't set these values, the
 219          * default value is 0. Even though mfn = 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.
 222          */
 223         r = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v);
 224         if (r < 0 || v == 0)
 225                 goto err;
 226         info->evtchn = v;
 227         v = 0;
 228         r = hvm_get_parameter(HVM_PARAM_CONSOLE_PFN, &v);
 229         if (r < 0 || v == 0)
 230                 goto err;
 231         mfn = v;
 232         info->intf = ioremap(mfn << PAGE_SHIFT, PAGE_SIZE);
 233         if (info->intf == NULL)
 234                 goto err;
 235         info->vtermno = HVC_COOKIE;
 236
 237         spin_lock(&xencons_lock);
 238         list_add_tail(&info->list, &xenconsoles);
 239         spin_unlock(&xencons_lock);
 240
 241         return 0;
 242 err:
 243         kfree(info);
 244         return -ENODEV;
 245 }
 246
 247 static int xen_pv_console_init(void)
 248 {
 249         struct xencons_info *info;
 250
 251         if (!xen_pv_domain())
 252                 return -ENODEV;
 253
 254         if (!xen_start_info->console.domU.evtchn)
 255                 return -ENODEV;
 256
 257         info = vtermno_to_xencons(HVC_COOKIE);
 258         if (!info) {
 259                 info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL | __GFP_ZERO);
 260                 if (!info)
 261                         return -ENOMEM;
 262         }
 263
 264         /* already configured */
 265         if (info->intf != NULL)
 266                 return 0;
 267
 268         info->evtchn = xen_start_info->console.domU.evtchn;
 269         info->intf = mfn_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 | __GFP_ZERO);
 289                 if (!info)
 290                         return -ENOMEM;
 291         }
 292
 293         info->irq = bind_virq_to_irq(VIRQ_CONSOLE, 0);
 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 void xen_console_resume(void)
 304 {
 305         struct xencons_info *info = vtermno_to_xencons(HVC_COOKIE);
 306         if (info != NULL && info->irq)
 307                 rebind_evtchn_irq(info->evtchn, info->irq);
 308 }
 309
 310 static void xencons_disconnect_backend(struct xencons_info *info)
 311 {
 312         if (info->irq > 0)
 313                 unbind_from_irqhandler(info->irq, NULL);
 314         info->irq = 0;
 315         if (info->evtchn > 0)
 316                 xenbus_free_evtchn(info->xbdev, info->evtchn);
 317         info->evtchn = 0;
 318         if (info->gntref > 0)
 319                 gnttab_free_grant_references(info->gntref);
 320         info->gntref = 0;
 321         if (info->hvc != NULL)
 322                 hvc_remove(info->hvc);
 323         info->hvc = NULL;
 324 }
 325
 326 static void xencons_free(struct xencons_info *info)
 327 {
 328         free_page((unsigned long)info->intf);
 329         info->intf = NULL;
 330         info->vtermno = 0;
 331         kfree(info);
 332 }
 333
 334 static int xen_console_remove(struct xencons_info *info)
 335 {
 336         xencons_disconnect_backend(info);
 337         spin_lock(&xencons_lock);
 338         list_del(&info->list);
 339         spin_unlock(&xencons_lock);
 340         if (info->xbdev != NULL)
 341                 xencons_free(info);
 342         else {
 343                 if (xen_hvm_domain())
 344                         iounmap(info->intf);
 345                 kfree(info);
 346         }
 347         return 0;
 348 }
 349
 350 #ifdef CONFIG_HVC_XEN_FRONTEND
 351 static struct xenbus_driver xencons_driver;
 352
 353 static int xencons_remove(struct xenbus_device *dev)
 354 {
 355         return xen_console_remove(dev_get_drvdata(&dev->dev));
 356 }
 357
 358 static int xencons_connect_backend(struct xenbus_device *dev,
 359                                   struct xencons_info *info)
 360 {
 361         int ret, evtchn, devid, ref, irq;
 362         struct xenbus_transaction xbt;
 363         grant_ref_t gref_head;
 364         unsigned long mfn;
 365
 366         ret = xenbus_alloc_evtchn(dev, &evtchn);
 367         if (ret)
 368                 return ret;
 369         info->evtchn = evtchn;
 370         irq = bind_evtchn_to_irq(evtchn);
 371         if (irq < 0)
 372                 return irq;
 373         info->irq = irq;
 374         devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
 375         info->hvc = hvc_alloc(xenbus_devid_to_vtermno(devid),
 376                         irq, &domU_hvc_ops, 256);
 377         if (IS_ERR(info->hvc))
 378                 return PTR_ERR(info->hvc);
 379         if (xen_pv_domain())
 380                 mfn = virt_to_mfn(info->intf);
 381         else
 382                 mfn = __pa(info->intf) >> PAGE_SHIFT;
 383         ret = gnttab_alloc_grant_references(1, &gref_head);
 384         if (ret < 0)
 385                 return ret;
 386         info->gntref = gref_head;
 387         ref = gnttab_claim_grant_reference(&gref_head);
 388         if (ref < 0)
 389                 return ref;
 390         gnttab_grant_foreign_access_ref(ref, info->xbdev->otherend_id,
 391                         mfn, 0);
 392
 393  again:
 394         ret = xenbus_transaction_start(&xbt);
 395         if (ret) {
 396                 xenbus_dev_fatal(dev, ret, "starting transaction");
 397                 return ret;
 398         }
 399         ret = xenbus_printf(xbt, dev->nodename, "ring-ref", "%d", ref);
 400         if (ret)
 401                 goto error_xenbus;
 402         ret = xenbus_printf(xbt, dev->nodename, "port", "%u",
 403                             evtchn);
 404         if (ret)
 405                 goto error_xenbus;
 406         ret = xenbus_printf(xbt, dev->nodename, "type", "ioemu");
 407         if (ret)
 408                 goto error_xenbus;
 409         ret = xenbus_transaction_end(xbt, 0);
 410         if (ret) {
 411                 if (ret == -EAGAIN)
 412                         goto again;
 413                 xenbus_dev_fatal(dev, ret, "completing transaction");
 414                 return ret;
 415         }
 416
 417         xenbus_switch_state(dev, XenbusStateInitialised);
 418         return 0;
 419
 420  error_xenbus:
 421         xenbus_transaction_end(xbt, 1);
 422         xenbus_dev_fatal(dev, ret, "writing xenstore");
 423         return ret;
 424 }
 425
 426 static int __devinit xencons_probe(struct xenbus_device *dev,
 427                                   const struct xenbus_device_id *id)
 428 {
 429         int ret, devid;
 430         struct xencons_info *info;
 431
 432         devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
 433         if (devid == 0)
 434                 return -ENODEV;
 435
 436         info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
 437         if (!info)
 438                 return -ENOMEM;
 439         dev_set_drvdata(&dev->dev, info);
 440         info->xbdev = dev;
 441         info->vtermno = xenbus_devid_to_vtermno(devid);
 442         info->intf = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
 443         if (!info->intf)
 444                 goto error_nomem;
 445
 446         ret = xencons_connect_backend(dev, info);
 447         if (ret < 0)
 448                 goto error;
 449         spin_lock(&xencons_lock);
 450         list_add_tail(&info->list, &xenconsoles);
 451         spin_unlock(&xencons_lock);
 452
 453         return 0;
 454
 455  error_nomem:
 456         ret = -ENOMEM;
 457         xenbus_dev_fatal(dev, ret, "allocating device memory");
 458  error:
 459         xencons_disconnect_backend(info);
 460         xencons_free(info);
 461         return ret;
 462 }
 463
 464 static int xencons_resume(struct xenbus_device *dev)
 465 {
 466         struct xencons_info *info = dev_get_drvdata(&dev->dev);
 467
 468         xencons_disconnect_backend(info);
 469         memset(info->intf, 0, PAGE_SIZE);
 470         return xencons_connect_backend(dev, info);
 471 }
 472
 473 static void xencons_backend_changed(struct xenbus_device *dev,
 474                                    enum xenbus_state backend_state)
 475 {
 476         switch (backend_state) {
 477         case XenbusStateReconfiguring:
 478         case XenbusStateReconfigured:
 479         case XenbusStateInitialising:
 480         case XenbusStateInitialised:
 481         case XenbusStateUnknown:
 482         case XenbusStateClosed:
 483                 break;
 484
 485         case XenbusStateInitWait:
 486                 break;
 487
 488         case XenbusStateConnected:
 489                 xenbus_switch_state(dev, XenbusStateConnected);
 490                 break;
 491
 492         case XenbusStateClosing:
 493                 xenbus_frontend_closed(dev);
 494                 break;
 495         }
 496 }
 497
 498 static const struct xenbus_device_id xencons_ids[] = {
 499         { "console" },
 500         { "" }
 501 };
 502
 503
 504 static DEFINE_XENBUS_DRIVER(xencons, "xenconsole",
 505         .probe = xencons_probe,
 506         .remove = xencons_remove,
 507         .resume = xencons_resume,
 508         .otherend_changed = xencons_backend_changed,
 509 );
 510 #endif /* CONFIG_HVC_XEN_FRONTEND */
 511
 512 static int __init xen_hvc_init(void)
 513 {
 514         int r;
 515         struct xencons_info *info;
 516         const struct hv_ops *ops;
 517
 518         if (!xen_domain())
 519                 return -ENODEV;
 520
 521         if (xen_initial_domain()) {
 522                 ops = &dom0_hvc_ops;
 523                 r = xen_initial_domain_console_init();
 524                 if (r < 0)
 525                         return r;
 526                 info = vtermno_to_xencons(HVC_COOKIE);
 527         } else {
 528                 ops = &domU_hvc_ops;
 529                 if (xen_hvm_domain())
 530                         r = xen_hvm_console_init();
 531                 else
 532                         r = xen_pv_console_init();
 533                 if (r < 0)
 534                         return r;
 535
 536                 info = vtermno_to_xencons(HVC_COOKIE);
 537                 info->irq = bind_evtchn_to_irq(info->evtchn);
 538         }
 539         if (info->irq < 0)
 540                 info->irq = 0; /* NO_IRQ */
 541         else
 542                 irq_set_noprobe(info->irq);
 543
 544         info->hvc = hvc_alloc(HVC_COOKIE, info->irq, ops, 256);
 545         if (IS_ERR(info->hvc)) {
 546                 r = PTR_ERR(info->hvc);
 547                 spin_lock(&xencons_lock);
 548                 list_del(&info->list);
 549                 spin_unlock(&xencons_lock);
 550                 if (info->irq)
 551                         unbind_from_irqhandler(info->irq, NULL);
 552                 kfree(info);
 553                 return r;
 554         }
 555
 556         r = 0;
 557 #ifdef CONFIG_HVC_XEN_FRONTEND
 558         r = xenbus_register_frontend(&xencons_driver);
 559 #endif
 560         return r;
 561 }
 562
 563 static void __exit xen_hvc_fini(void)
 564 {
 565         struct xencons_info *entry, *next;
 566
 567         if (list_empty(&xenconsoles))
 568                         return;
 569
 570         list_for_each_entry_safe(entry, next, &xenconsoles, list) {
 571                 xen_console_remove(entry);
 572         }
 573 }
 574
 575 static int xen_cons_init(void)
 576 {
 577         const struct hv_ops *ops;
 578
 579         if (!xen_domain())
 580                 return 0;
 581
 582         if (xen_initial_domain())
 583                 ops = &dom0_hvc_ops;
 584         else {
 585                 int r;
 586                 ops = &domU_hvc_ops;
 587
 588                 if (xen_hvm_domain())
 589                         r = xen_hvm_console_init();
 590                 else
 591                         r = xen_pv_console_init();
 592                 if (r < 0)
 593                         return r;
 594         }
 595
 596         hvc_instantiate(HVC_COOKIE, 0, ops);
 597         return 0;
 598 }
 599
 600
 601 module_init(xen_hvc_init);
 602 module_exit(xen_hvc_fini);
 603 console_initcall(xen_cons_init);
 604
 605 #ifdef CONFIG_EARLY_PRINTK
 606 static void xenboot_write_console(struct console *console, const char *string,
 607                                   unsigned len)
 608 {
 609         unsigned int linelen, off = 0;
 610         const char *pos;
 611
 612         if (!xen_pv_domain())
 613                 return;
 614
 615         dom0_write_console(0, string, len);
 616
 617         if (xen_initial_domain())
 618                 return;
 619
 620         domU_write_console(0, "(early) ", 8);
 621         while (off < len && NULL != (pos = strchr(string+off, '\n'))) {
 622                 linelen = pos-string+off;
 623                 if (off + linelen > len)
 624                         break;
 625                 domU_write_console(0, string+off, linelen);
 626                 domU_write_console(0, "\r\n", 2);
 627                 off += linelen + 1;
 628         }
 629         if (off < len)
 630                 domU_write_console(0, string+off, len-off);
 631 }
 632
 633 struct console xenboot_console = {
 634         .name           = "xenboot",
 635         .write          = xenboot_write_console,
 636         .flags          = CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
 637 };
 638 #endif  /* CONFIG_EARLY_PRINTK */
 639
 640 void xen_raw_console_write(const char *str)
 641 {
 642         dom0_write_console(0, str, strlen(str));
 643 }
 644
 645 void xen_raw_printk(const char *fmt, ...)
 646 {
 647         static char buf[512];
 648         va_list ap;
 649
 650         va_start(ap, fmt);
 651         vsnprintf(buf, sizeof(buf), fmt, ap);
 652         va_end(ap);
 653
 654         xen_raw_console_write(buf);
 655 }