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         } else if (info->intf != NULL) {
 213                 /* already configured */
 214                 return 0;
 215         }
 216         /*
 217          * If the toolstack (or the hypervisor) hasn't set these values, the
 218          * default value is 0. Even though mfn = 0 and evtchn = 0 are
 219          * theoretically correct values, in practice they never are and they
 220          * mean that a legacy toolstack hasn't initialized the pv console correctly.
 221          */
 222         r = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v);
 223         if (r < 0 || v == 0)
 224                 goto err;
 225         info->evtchn = v;
 226         v = 0;
 227         r = hvm_get_parameter(HVM_PARAM_CONSOLE_PFN, &v);
 228         if (r < 0 || v == 0)
 229                 goto err;
 230         mfn = v;
 231         info->intf = ioremap(mfn << PAGE_SHIFT, PAGE_SIZE);
 232         if (info->intf == NULL)
 233                 goto err;
 234         info->vtermno = HVC_COOKIE;
 235
 236         spin_lock(&xencons_lock);
 237         list_add_tail(&info->list, &xenconsoles);
 238         spin_unlock(&xencons_lock);
 239
 240         return 0;
 241 err:
 242         kfree(info);
 243         return -ENODEV;
 244 }
 245
 246 static int xen_pv_console_init(void)
 247 {
 248         struct xencons_info *info;
 249
 250         if (!xen_pv_domain())
 251                 return -ENODEV;
 252
 253         if (!xen_start_info->console.domU.evtchn)
 254                 return -ENODEV;
 255
 256         info = vtermno_to_xencons(HVC_COOKIE);
 257         if (!info) {
 258                 info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL | __GFP_ZERO);
 259                 if (!info)
 260                         return -ENOMEM;
 261         } else if (info->intf != NULL) {
 262                 /* already configured */
 263                 return 0;
 264         }
 265         info->evtchn = xen_start_info->console.domU.evtchn;
 266         info->intf = mfn_to_virt(xen_start_info->console.domU.mfn);
 267         info->vtermno = HVC_COOKIE;
 268
 269         spin_lock(&xencons_lock);
 270         list_add_tail(&info->list, &xenconsoles);
 271         spin_unlock(&xencons_lock);
 272
 273         return 0;
 274 }
 275
 276 static int xen_initial_domain_console_init(void)
 277 {
 278         struct xencons_info *info;
 279
 280         if (!xen_initial_domain())
 281                 return -ENODEV;
 282
 283         info = vtermno_to_xencons(HVC_COOKIE);
 284         if (!info) {
 285                 info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL | __GFP_ZERO);
 286                 if (!info)
 287                         return -ENOMEM;
 288         }
 289
 290         info->irq = bind_virq_to_irq(VIRQ_CONSOLE, 0);
 291         info->vtermno = HVC_COOKIE;
 292
 293         spin_lock(&xencons_lock);
 294         list_add_tail(&info->list, &xenconsoles);
 295         spin_unlock(&xencons_lock);
 296
 297         return 0;
 298 }
 299
 300 void xen_console_resume(void)
 301 {
 302         struct xencons_info *info = vtermno_to_xencons(HVC_COOKIE);
 303         if (info != NULL && info->irq)
 304                 rebind_evtchn_irq(info->evtchn, info->irq);
 305 }
 306
 307 static void xencons_disconnect_backend(struct xencons_info *info)
 308 {
 309         if (info->irq > 0)
 310                 unbind_from_irqhandler(info->irq, NULL);
 311         info->irq = 0;
 312         if (info->evtchn > 0)
 313                 xenbus_free_evtchn(info->xbdev, info->evtchn);
 314         info->evtchn = 0;
 315         if (info->gntref > 0)
 316                 gnttab_free_grant_references(info->gntref);
 317         info->gntref = 0;
 318         if (info->hvc != NULL)
 319                 hvc_remove(info->hvc);
 320         info->hvc = NULL;
 321 }
 322
 323 static void xencons_free(struct xencons_info *info)
 324 {
 325         free_page((unsigned long)info->intf);
 326         info->intf = NULL;
 327         info->vtermno = 0;
 328         kfree(info);
 329 }
 330
 331 static int xen_console_remove(struct xencons_info *info)
 332 {
 333         xencons_disconnect_backend(info);
 334         spin_lock(&xencons_lock);
 335         list_del(&info->list);
 336         spin_unlock(&xencons_lock);
 337         if (info->xbdev != NULL)
 338                 xencons_free(info);
 339         else {
 340                 if (xen_hvm_domain())
 341                         iounmap(info->intf);
 342                 kfree(info);
 343         }
 344         return 0;
 345 }
 346
 347 #ifdef CONFIG_HVC_XEN_FRONTEND
 348 static struct xenbus_driver xencons_driver;
 349
 350 static int xencons_remove(struct xenbus_device *dev)
 351 {
 352         return xen_console_remove(dev_get_drvdata(&dev->dev));
 353 }
 354
 355 static int xencons_connect_backend(struct xenbus_device *dev,
 356                                   struct xencons_info *info)
 357 {
 358         int ret, evtchn, devid, ref, irq;
 359         struct xenbus_transaction xbt;
 360         grant_ref_t gref_head;
 361         unsigned long mfn;
 362
 363         ret = xenbus_alloc_evtchn(dev, &evtchn);
 364         if (ret)
 365                 return ret;
 366         info->evtchn = evtchn;
 367         irq = bind_evtchn_to_irq(evtchn);
 368         if (irq < 0)
 369                 return irq;
 370         info->irq = irq;
 371         devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
 372         info->hvc = hvc_alloc(xenbus_devid_to_vtermno(devid),
 373                         irq, &domU_hvc_ops, 256);
 374         if (IS_ERR(info->hvc))
 375                 return PTR_ERR(info->hvc);
 376         if (xen_pv_domain())
 377                 mfn = virt_to_mfn(info->intf);
 378         else
 379                 mfn = __pa(info->intf) >> PAGE_SHIFT;
 380         ret = gnttab_alloc_grant_references(1, &gref_head);
 381         if (ret < 0)
 382                 return ret;
 383         info->gntref = gref_head;
 384         ref = gnttab_claim_grant_reference(&gref_head);
 385         if (ref < 0)
 386                 return ref;
 387         gnttab_grant_foreign_access_ref(ref, info->xbdev->otherend_id,
 388                         mfn, 0);
 389
 390  again:
 391         ret = xenbus_transaction_start(&xbt);
 392         if (ret) {
 393                 xenbus_dev_fatal(dev, ret, "starting transaction");
 394                 return ret;
 395         }
 396         ret = xenbus_printf(xbt, dev->nodename, "ring-ref", "%d", ref);
 397         if (ret)
 398                 goto error_xenbus;
 399         ret = xenbus_printf(xbt, dev->nodename, "port", "%u",
 400                             evtchn);
 401         if (ret)
 402                 goto error_xenbus;
 403         ret = xenbus_printf(xbt, dev->nodename, "type", "ioemu");
 404         if (ret)
 405                 goto error_xenbus;
 406         ret = xenbus_transaction_end(xbt, 0);
 407         if (ret) {
 408                 if (ret == -EAGAIN)
 409                         goto again;
 410                 xenbus_dev_fatal(dev, ret, "completing transaction");
 411                 return ret;
 412         }
 413
 414         xenbus_switch_state(dev, XenbusStateInitialised);
 415         return 0;
 416
 417  error_xenbus:
 418         xenbus_transaction_end(xbt, 1);
 419         xenbus_dev_fatal(dev, ret, "writing xenstore");
 420         return ret;
 421 }
 422
 423 static int __devinit xencons_probe(struct xenbus_device *dev,
 424                                   const struct xenbus_device_id *id)
 425 {
 426         int ret, devid;
 427         struct xencons_info *info;
 428
 429         devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
 430         if (devid == 0)
 431                 return -ENODEV;
 432
 433         info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
 434         if (!info)
 435                 return -ENOMEM;
 436         dev_set_drvdata(&dev->dev, info);
 437         info->xbdev = dev;
 438         info->vtermno = xenbus_devid_to_vtermno(devid);
 439         info->intf = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
 440         if (!info->intf)
 441                 goto error_nomem;
 442
 443         ret = xencons_connect_backend(dev, info);
 444         if (ret < 0)
 445                 goto error;
 446         spin_lock(&xencons_lock);
 447         list_add_tail(&info->list, &xenconsoles);
 448         spin_unlock(&xencons_lock);
 449
 450         return 0;
 451
 452  error_nomem:
 453         ret = -ENOMEM;
 454         xenbus_dev_fatal(dev, ret, "allocating device memory");
 455  error:
 456         xencons_disconnect_backend(info);
 457         xencons_free(info);
 458         return ret;
 459 }
 460
 461 static int xencons_resume(struct xenbus_device *dev)
 462 {
 463         struct xencons_info *info = dev_get_drvdata(&dev->dev);
 464
 465         xencons_disconnect_backend(info);
 466         memset(info->intf, 0, PAGE_SIZE);
 467         return xencons_connect_backend(dev, info);
 468 }
 469
 470 static void xencons_backend_changed(struct xenbus_device *dev,
 471                                    enum xenbus_state backend_state)
 472 {
 473         switch (backend_state) {
 474         case XenbusStateReconfiguring:
 475         case XenbusStateReconfigured:
 476         case XenbusStateInitialising:
 477         case XenbusStateInitialised:
 478         case XenbusStateUnknown:
 479         case XenbusStateClosed:
 480                 break;
 481
 482         case XenbusStateInitWait:
 483                 break;
 484
 485         case XenbusStateConnected:
 486                 xenbus_switch_state(dev, XenbusStateConnected);
 487                 break;
 488
 489         case XenbusStateClosing:
 490                 xenbus_frontend_closed(dev);
 491                 break;
 492         }
 493 }
 494
 495 static const struct xenbus_device_id xencons_ids[] = {
 496         { "console" },
 497         { "" }
 498 };
 499
 500
 501 static DEFINE_XENBUS_DRIVER(xencons, "xenconsole",
 502         .probe = xencons_probe,
 503         .remove = xencons_remove,
 504         .resume = xencons_resume,
 505         .otherend_changed = xencons_backend_changed,
 506 );
 507 #endif /* CONFIG_HVC_XEN_FRONTEND */
 508
 509 static int __init xen_hvc_init(void)
 510 {
 511         int r;
 512         struct xencons_info *info;
 513         const struct hv_ops *ops;
 514
 515         if (!xen_domain())
 516                 return -ENODEV;
 517
 518         if (xen_initial_domain()) {
 519                 ops = &dom0_hvc_ops;
 520                 r = xen_initial_domain_console_init();
 521                 if (r < 0)
 522                         return r;
 523                 info = vtermno_to_xencons(HVC_COOKIE);
 524         } else {
 525                 ops = &domU_hvc_ops;
 526                 if (xen_hvm_domain())
 527                         r = xen_hvm_console_init();
 528                 else
 529                         r = xen_pv_console_init();
 530                 if (r < 0)
 531                         return r;
 532
 533                 info = vtermno_to_xencons(HVC_COOKIE);
 534                 info->irq = bind_evtchn_to_irq(info->evtchn);
 535         }
 536         if (info->irq < 0)
 537                 info->irq = 0; /* NO_IRQ */
 538         else
 539                 irq_set_noprobe(info->irq);
 540
 541         info->hvc = hvc_alloc(HVC_COOKIE, info->irq, ops, 256);
 542         if (IS_ERR(info->hvc)) {
 543                 r = PTR_ERR(info->hvc);
 544                 spin_lock(&xencons_lock);
 545                 list_del(&info->list);
 546                 spin_unlock(&xencons_lock);
 547                 if (info->irq)
 548                         unbind_from_irqhandler(info->irq, NULL);
 549                 kfree(info);
 550                 return r;
 551         }
 552
 553         r = 0;
 554 #ifdef CONFIG_HVC_XEN_FRONTEND
 555         r = xenbus_register_frontend(&xencons_driver);
 556 #endif
 557         return r;
 558 }
 559
 560 static void __exit xen_hvc_fini(void)
 561 {
 562         struct xencons_info *entry, *next;
 563
 564         if (list_empty(&xenconsoles))
 565                         return;
 566
 567         list_for_each_entry_safe(entry, next, &xenconsoles, list) {
 568                 xen_console_remove(entry);
 569         }
 570 }
 571
 572 static int xen_cons_init(void)
 573 {
 574         const struct hv_ops *ops;
 575
 576         if (!xen_domain())
 577                 return 0;
 578
 579         if (xen_initial_domain())
 580                 ops = &dom0_hvc_ops;
 581         else {
 582                 int r;
 583                 ops = &domU_hvc_ops;
 584
 585                 if (xen_hvm_domain())
 586                         r = xen_hvm_console_init();
 587                 else
 588                         r = xen_pv_console_init();
 589                 if (r < 0)
 590                         return r;
 591         }
 592
 593         hvc_instantiate(HVC_COOKIE, 0, ops);
 594         return 0;
 595 }
 596
 597
 598 module_init(xen_hvc_init);
 599 module_exit(xen_hvc_fini);
 600 console_initcall(xen_cons_init);
 601
 602 #ifdef CONFIG_EARLY_PRINTK
 603 static void xenboot_write_console(struct console *console, const char *string,
 604                                   unsigned len)
 605 {
 606         unsigned int linelen, off = 0;
 607         const char *pos;
 608
 609         if (!xen_pv_domain())
 610                 return;
 611
 612         dom0_write_console(0, string, len);
 613
 614         if (xen_initial_domain())
 615                 return;
 616
 617         domU_write_console(0, "(early) ", 8);
 618         while (off < len && NULL != (pos = strchr(string+off, '\n'))) {
 619                 linelen = pos-string+off;
 620                 if (off + linelen > len)
 621                         break;
 622                 domU_write_console(0, string+off, linelen);
 623                 domU_write_console(0, "\r\n", 2);
 624                 off += linelen + 1;
 625         }
 626         if (off < len)
 627                 domU_write_console(0, string+off, len-off);
 628 }
 629
 630 struct console xenboot_console = {
 631         .name           = "xenboot",
 632         .write          = xenboot_write_console,
 633         .flags          = CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
 634 };
 635 #endif  /* CONFIG_EARLY_PRINTK */
 636
 637 void xen_raw_console_write(const char *str)
 638 {
 639         dom0_write_console(0, str, strlen(str));
 640 }
 641
 642 void xen_raw_printk(const char *fmt, ...)
 643 {
 644         static char buf[512];
 645         va_list ap;
 646
 647         va_start(ap, fmt);
 648         vsnprintf(buf, sizeof(buf), fmt, ap);
 649         va_end(ap);
 650
 651         xen_raw_console_write(buf);
 652 }