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 0;
 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 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 = ioremap(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;
 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 | __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
 278 static 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
 302 void 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
 309 static 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
 325 static 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
 333 static 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
 350 static struct xenbus_driver xencons_driver;
 351
 352 static int xencons_remove(struct xenbus_device *dev)
 353 {
 354         return xen_console_remove(dev_get_drvdata(&dev->dev));
 355 }
 356
 357 static 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
 425 static 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
 463 static 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
 472 static 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
 500 static const struct xenbus_device_id xencons_ids[] = {
 501         { "console" },
 502         { "" }
 503 };
 504
 505
 506 static 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
 514 static 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
 565 static 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
 577 static 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
 603 module_init(xen_hvc_init);
 604 module_exit(xen_hvc_fini);
 605 console_initcall(xen_cons_init);
 606
 607 #ifdef CONFIG_EARLY_PRINTK
 608 static 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
 635 struct 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
 642 void xen_raw_console_write(const char *str)
 643 {
 644         dom0_write_console(0, str, strlen(str));
 645 }
 646
 647 void 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 }