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
  47 struct 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
  58 static LIST_HEAD(xenconsoles);
  59 static DEFINE_SPINLOCK(xencons_lock);
  60
  61 /* ------------------------------------------------------------------ */
  62
  63 static 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
  80 static inline int xenbus_devid_to_vtermno(int devid)
  81 {
  82         return devid + HVC_COOKIE;
  83 }
  84
  85 static 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
  91 static 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
 114 static 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
 140 static 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
 165 static 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
 173 static 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  */
 182 static 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 rc;
 187
 188         return len;
 189 }
 190
 191 static 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
 199 static int xen_hvm_console_init(void)
 200 {
 201         int r;
 202         uint64_t v = 0;
 203         unsigned long gfn;
 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);
 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 gfn = 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         gfn = v;
 233         info->intf = xen_remap(gfn << XEN_PAGE_SHIFT, XEN_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;
 243 err:
 244         kfree(info);
 245         return -ENODEV;
 246 }
 247
 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         info->evtchn = xen_start_info->console.domU.evtchn;
 268         /* GFN == MFN for PV guest */
 269         info->intf = gfn_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);
 289                 if (!info)
 290                         return -ENOMEM;
 291         }
 292
 293         info->irq = bind_virq_to_irq(VIRQ_CONSOLE, 0, false);
 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 static void xen_console_update_evtchn(struct xencons_info *info)
 304 {
 305         if (xen_hvm_domain()) {
 306                 uint64_t v = 0;
 307                 int err;
 308
 309                 err = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v);
 310                 if (!err && v)
 311                         info->evtchn = v;
 312         } else
 313                 info->evtchn = xen_start_info->console.domU.evtchn;
 314 }
 315
 316 void xen_console_resume(void)
 317 {
 318         struct xencons_info *info = vtermno_to_xencons(HVC_COOKIE);
 319         if (info != NULL && info->irq) {
 320                 if (!xen_initial_domain())
 321                         xen_console_update_evtchn(info);
 322                 rebind_evtchn_irq(info->evtchn, info->irq);
 323         }
 324 }
 325
 326 static void xencons_disconnect_backend(struct xencons_info *info)
 327 {
 328         if (info->irq > 0)
 329                 unbind_from_irqhandler(info->irq, NULL);
 330         info->irq = 0;
 331         if (info->evtchn > 0)
 332                 xenbus_free_evtchn(info->xbdev, info->evtchn);
 333         info->evtchn = 0;
 334         if (info->gntref > 0)
 335                 gnttab_free_grant_references(info->gntref);
 336         info->gntref = 0;
 337         if (info->hvc != NULL)
 338                 hvc_remove(info->hvc);
 339         info->hvc = NULL;
 340 }
 341
 342 static void xencons_free(struct xencons_info *info)
 343 {
 344         free_page((unsigned long)info->intf);
 345         info->intf = NULL;
 346         info->vtermno = 0;
 347         kfree(info);
 348 }
 349
 350 static int xen_console_remove(struct xencons_info *info)
 351 {
 352         xencons_disconnect_backend(info);
 353         spin_lock(&xencons_lock);
 354         list_del(&info->list);
 355         spin_unlock(&xencons_lock);
 356         if (info->xbdev != NULL)
 357                 xencons_free(info);
 358         else {
 359                 if (xen_hvm_domain())
 360                         iounmap(info->intf);
 361                 kfree(info);
 362         }
 363         return 0;
 364 }
 365
 366 #ifdef CONFIG_HVC_XEN_FRONTEND
 367 static int xencons_remove(struct xenbus_device *dev)
 368 {
 369         return xen_console_remove(dev_get_drvdata(&dev->dev));
 370 }
 371
 372 static int xencons_connect_backend(struct xenbus_device *dev,
 373                                   struct xencons_info *info)
 374 {
 375         int ret, evtchn, devid, ref, irq;
 376         struct xenbus_transaction xbt;
 377         grant_ref_t gref_head;
 378
 379         ret = xenbus_alloc_evtchn(dev, &evtchn);
 380         if (ret)
 381                 return ret;
 382         info->evtchn = evtchn;
 383         irq = bind_evtchn_to_irq(evtchn);
 384         if (irq < 0)
 385                 return irq;
 386         info->irq = irq;
 387         devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
 388         info->hvc = hvc_alloc(xenbus_devid_to_vtermno(devid),
 389                         irq, &domU_hvc_ops, 256);
 390         if (IS_ERR(info->hvc))
 391                 return PTR_ERR(info->hvc);
 392         ret = gnttab_alloc_grant_references(1, &gref_head);
 393         if (ret < 0)
 394                 return ret;
 395         info->gntref = gref_head;
 396         ref = gnttab_claim_grant_reference(&gref_head);
 397         if (ref < 0)
 398                 return ref;
 399         gnttab_grant_foreign_access_ref(ref, info->xbdev->otherend_id,
 400                                         virt_to_gfn(info->intf), 0);
 401
 402  again:
 403         ret = xenbus_transaction_start(&xbt);
 404         if (ret) {
 405                 xenbus_dev_fatal(dev, ret, "starting transaction");
 406                 return ret;
 407         }
 408         ret = xenbus_printf(xbt, dev->nodename, "ring-ref", "%d", ref);
 409         if (ret)
 410                 goto error_xenbus;
 411         ret = xenbus_printf(xbt, dev->nodename, "port", "%u",
 412                             evtchn);
 413         if (ret)
 414                 goto error_xenbus;
 415         ret = xenbus_transaction_end(xbt, 0);
 416         if (ret) {
 417                 if (ret == -EAGAIN)
 418                         goto again;
 419                 xenbus_dev_fatal(dev, ret, "completing transaction");
 420                 return ret;
 421         }
 422
 423         xenbus_switch_state(dev, XenbusStateInitialised);
 424         return 0;
 425
 426  error_xenbus:
 427         xenbus_transaction_end(xbt, 1);
 428         xenbus_dev_fatal(dev, ret, "writing xenstore");
 429         return ret;
 430 }
 431
 432 static int xencons_probe(struct xenbus_device *dev,
 433                                   const struct xenbus_device_id *id)
 434 {
 435         int ret, devid;
 436         struct xencons_info *info;
 437
 438         devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
 439         if (devid == 0)
 440                 return -ENODEV;
 441
 442         info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
 443         if (!info)
 444                 return -ENOMEM;
 445         dev_set_drvdata(&dev->dev, info);
 446         info->xbdev = dev;
 447         info->vtermno = xenbus_devid_to_vtermno(devid);
 448         info->intf = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
 449         if (!info->intf)
 450                 goto error_nomem;
 451
 452         ret = xencons_connect_backend(dev, info);
 453         if (ret < 0)
 454                 goto error;
 455         spin_lock(&xencons_lock);
 456         list_add_tail(&info->list, &xenconsoles);
 457         spin_unlock(&xencons_lock);
 458
 459         return 0;
 460
 461  error_nomem:
 462         ret = -ENOMEM;
 463         xenbus_dev_fatal(dev, ret, "allocating device memory");
 464  error:
 465         xencons_disconnect_backend(info);
 466         xencons_free(info);
 467         return ret;
 468 }
 469
 470 static int xencons_resume(struct xenbus_device *dev)
 471 {
 472         struct xencons_info *info = dev_get_drvdata(&dev->dev);
 473
 474         xencons_disconnect_backend(info);
 475         memset(info->intf, 0, XEN_PAGE_SIZE);
 476         return xencons_connect_backend(dev, info);
 477 }
 478
 479 static void xencons_backend_changed(struct xenbus_device *dev,
 480                                    enum xenbus_state backend_state)
 481 {
 482         switch (backend_state) {
 483         case XenbusStateReconfiguring:
 484         case XenbusStateReconfigured:
 485         case XenbusStateInitialising:
 486         case XenbusStateInitialised:
 487         case XenbusStateUnknown:
 488                 break;
 489
 490         case XenbusStateInitWait:
 491                 break;
 492
 493         case XenbusStateConnected:
 494                 xenbus_switch_state(dev, XenbusStateConnected);
 495                 break;
 496
 497         case XenbusStateClosed:
 498                 if (dev->state == XenbusStateClosed)
 499                         break;
 500                 /* Missed the backend's CLOSING state -- fallthrough */
 501         case XenbusStateClosing:
 502                 xenbus_frontend_closed(dev);
 503                 break;
 504         }
 505 }
 506
 507 static const struct xenbus_device_id xencons_ids[] = {
 508         { "console" },
 509         { "" }
 510 };
 511
 512 static struct xenbus_driver xencons_driver = {
 513         .name = "xenconsole",
 514         .ids = xencons_ids,
 515         .probe = xencons_probe,
 516         .remove = xencons_remove,
 517         .resume = xencons_resume,
 518         .otherend_changed = xencons_backend_changed,
 519 };
 520 #endif /* CONFIG_HVC_XEN_FRONTEND */
 521
 522 static int __init xen_hvc_init(void)
 523 {
 524         int r;
 525         struct xencons_info *info;
 526         const struct hv_ops *ops;
 527
 528         if (!xen_domain())
 529                 return -ENODEV;
 530
 531         if (xen_initial_domain()) {
 532                 ops = &dom0_hvc_ops;
 533                 r = xen_initial_domain_console_init();
 534                 if (r < 0)
 535                         return r;
 536                 info = vtermno_to_xencons(HVC_COOKIE);
 537         } else {
 538                 ops = &domU_hvc_ops;
 539                 if (xen_hvm_domain())
 540                         r = xen_hvm_console_init();
 541                 else
 542                         r = xen_pv_console_init();
 543                 if (r < 0)
 544                         return r;
 545
 546                 info = vtermno_to_xencons(HVC_COOKIE);
 547                 info->irq = bind_evtchn_to_irq(info->evtchn);
 548         }
 549         if (info->irq < 0)
 550                 info->irq = 0; /* NO_IRQ */
 551         else
 552                 irq_set_noprobe(info->irq);
 553
 554         info->hvc = hvc_alloc(HVC_COOKIE, info->irq, ops, 256);
 555         if (IS_ERR(info->hvc)) {
 556                 r = PTR_ERR(info->hvc);
 557                 spin_lock(&xencons_lock);
 558                 list_del(&info->list);
 559                 spin_unlock(&xencons_lock);
 560                 if (info->irq)
 561                         unbind_from_irqhandler(info->irq, NULL);
 562                 kfree(info);
 563                 return r;
 564         }
 565
 566         r = 0;
 567 #ifdef CONFIG_HVC_XEN_FRONTEND
 568         r = xenbus_register_frontend(&xencons_driver);
 569 #endif
 570         return r;
 571 }
 572 device_initcall(xen_hvc_init);
 573
 574 static int xen_cons_init(void)
 575 {
 576         const struct hv_ops *ops;
 577
 578         if (!xen_domain())
 579                 return 0;
 580
 581         if (xen_initial_domain())
 582                 ops = &dom0_hvc_ops;
 583         else {
 584                 int r;
 585                 ops = &domU_hvc_ops;
 586
 587                 if (xen_hvm_domain())
 588                         r = xen_hvm_console_init();
 589                 else
 590                         r = xen_pv_console_init();
 591                 if (r < 0)
 592                         return r;
 593         }
 594
 595         hvc_instantiate(HVC_COOKIE, 0, ops);
 596         return 0;
 597 }
 598 console_initcall(xen_cons_init);
 599
 600 #ifdef CONFIG_EARLY_PRINTK
 601 static void xenboot_write_console(struct console *console, const char *string,
 602                                   unsigned len)
 603 {
 604         unsigned int linelen, off = 0;
 605         const char *pos;
 606
 607         if (!xen_pv_domain())
 608                 return;
 609
 610         dom0_write_console(0, string, len);
 611
 612         if (xen_initial_domain())
 613                 return;
 614
 615         domU_write_console(0, "(early) ", 8);
 616         while (off < len && NULL != (pos = strchr(string+off, '\n'))) {
 617                 linelen = pos-string+off;
 618                 if (off + linelen > len)
 619                         break;
 620                 domU_write_console(0, string+off, linelen);
 621                 domU_write_console(0, "\r\n", 2);
 622                 off += linelen + 1;
 623         }
 624         if (off < len)
 625                 domU_write_console(0, string+off, len-off);
 626 }
 627
 628 struct console xenboot_console = {
 629         .name           = "xenboot",
 630         .write          = xenboot_write_console,
 631         .flags          = CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
 632         .index          = -1,
 633 };
 634 #endif  /* CONFIG_EARLY_PRINTK */
 635
 636 void xen_raw_console_write(const char *str)
 637 {
 638         ssize_t len = strlen(str);
 639         int rc = 0;
 640
 641         if (xen_domain()) {
 642                 rc = dom0_write_console(0, str, len);
 643 #ifdef CONFIG_X86
 644                 if (rc == -ENOSYS && xen_hvm_domain())
 645                         goto outb_print;
 646
 647         } else if (xen_cpuid_base()) {
 648                 int i;
 649 outb_print:
 650                 for (i = 0; i < len; i++)
 651                         outb(str[i], 0xe9);
 652 #endif
 653         }
 654 }
 655
 656 void xen_raw_printk(const char *fmt, ...)
 657 {
 658         static char buf[512];
 659         va_list ap;
 660
 661         va_start(ap, fmt);
 662         vsnprintf(buf, sizeof(buf), fmt, ap);
 663         va_end(ap);
 664
 665         xen_raw_console_write(buf);
 666 }