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 #include <linux/serial_core.h>
  29
  30 #include <asm/io.h>
  31 #include <asm/xen/hypervisor.h>
  32
  33 #include <xen/xen.h>
  34 #include <xen/interface/xen.h>
  35 #include <xen/hvm.h>
  36 #include <xen/grant_table.h>
  37 #include <xen/page.h>
  38 #include <xen/events.h>
  39 #include <xen/interface/io/console.h>
  40 #include <xen/interface/sched.h>
  41 #include <xen/hvc-console.h>
  42 #include <xen/xenbus.h>
  43
  44 #include "hvc_console.h"
  45
  46 #define HVC_COOKIE   0x58656e /* "Xen" in hex */
  47
  48 struct xencons_info {
  49         struct list_head list;
  50         struct xenbus_device *xbdev;
  51         struct xencons_interface *intf;
  52         unsigned int evtchn;
  53         struct hvc_struct *hvc;
  54         int irq;
  55         int vtermno;
  56         grant_ref_t gntref;
  57 };
  58
  59 static LIST_HEAD(xenconsoles);
  60 static DEFINE_SPINLOCK(xencons_lock);
  61
  62 /* ------------------------------------------------------------------ */
  63
  64 static struct xencons_info *vtermno_to_xencons(int vtermno)
  65 {
  66         struct xencons_info *entry, *n, *ret = NULL;
  67
  68         if (list_empty(&xenconsoles))
  69                         return NULL;
  70
  71         list_for_each_entry_safe(entry, n, &xenconsoles, list) {
  72                 if (entry->vtermno == vtermno) {
  73                         ret  = entry;
  74                         break;
  75                 }
  76         }
  77
  78         return ret;
  79 }
  80
  81 static inline int xenbus_devid_to_vtermno(int devid)
  82 {
  83         return devid + HVC_COOKIE;
  84 }
  85
  86 static inline void notify_daemon(struct xencons_info *cons)
  87 {
  88         /* Use evtchn: this is called early, before irq is set up. */
  89         notify_remote_via_evtchn(cons->evtchn);
  90 }
  91
  92 static int __write_console(struct xencons_info *xencons,
  93                 const char *data, int len)
  94 {
  95         XENCONS_RING_IDX cons, prod;
  96         struct xencons_interface *intf = xencons->intf;
  97         int sent = 0;
  98
  99         cons = intf->out_cons;
 100         prod = intf->out_prod;
 101         mb();                   /* update queue values before going on */
 102         BUG_ON((prod - cons) > sizeof(intf->out));
 103
 104         while ((sent < len) && ((prod - cons) < sizeof(intf->out)))
 105                 intf->out[MASK_XENCONS_IDX(prod++, intf->out)] = data[sent++];
 106
 107         wmb();                  /* write ring before updating pointer */
 108         intf->out_prod = prod;
 109
 110         if (sent)
 111                 notify_daemon(xencons);
 112         return sent;
 113 }
 114
 115 static int domU_write_console(uint32_t vtermno, const char *data, int len)
 116 {
 117         int ret = len;
 118         struct xencons_info *cons = vtermno_to_xencons(vtermno);
 119         if (cons == NULL)
 120                 return -EINVAL;
 121
 122         /*
 123          * Make sure the whole buffer is emitted, polling if
 124          * necessary.  We don't ever want to rely on the hvc daemon
 125          * because the most interesting console output is when the
 126          * kernel is crippled.
 127          */
 128         while (len) {
 129                 int sent = __write_console(cons, data, len);
 130
 131                 data += sent;
 132                 len -= sent;
 133
 134                 if (unlikely(len))
 135                         HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
 136         }
 137
 138         return ret;
 139 }
 140
 141 static int domU_read_console(uint32_t vtermno, char *buf, int len)
 142 {
 143         struct xencons_interface *intf;
 144         XENCONS_RING_IDX cons, prod;
 145         int recv = 0;
 146         struct xencons_info *xencons = vtermno_to_xencons(vtermno);
 147         if (xencons == NULL)
 148                 return -EINVAL;
 149         intf = xencons->intf;
 150
 151         cons = intf->in_cons;
 152         prod = intf->in_prod;
 153         mb();                   /* get pointers before reading ring */
 154         BUG_ON((prod - cons) > sizeof(intf->in));
 155
 156         while (cons != prod && recv < len)
 157                 buf[recv++] = intf->in[MASK_XENCONS_IDX(cons++, intf->in)];
 158
 159         mb();                   /* read ring before consuming */
 160         intf->in_cons = cons;
 161
 162         notify_daemon(xencons);
 163         return recv;
 164 }
 165
 166 static const struct hv_ops domU_hvc_ops = {
 167         .get_chars = domU_read_console,
 168         .put_chars = domU_write_console,
 169         .notifier_add = notifier_add_irq,
 170         .notifier_del = notifier_del_irq,
 171         .notifier_hangup = notifier_hangup_irq,
 172 };
 173
 174 static int dom0_read_console(uint32_t vtermno, char *buf, int len)
 175 {
 176         return HYPERVISOR_console_io(CONSOLEIO_read, len, buf);
 177 }
 178
 179 /*
 180  * Either for a dom0 to write to the system console, or a domU with a
 181  * debug version of Xen
 182  */
 183 static int dom0_write_console(uint32_t vtermno, const char *str, int len)
 184 {
 185         int rc = HYPERVISOR_console_io(CONSOLEIO_write, len, (char *)str);
 186         if (rc < 0)
 187                 return rc;
 188
 189         return len;
 190 }
 191
 192 static const struct hv_ops dom0_hvc_ops = {
 193         .get_chars = dom0_read_console,
 194         .put_chars = dom0_write_console,
 195         .notifier_add = notifier_add_irq,
 196         .notifier_del = notifier_del_irq,
 197         .notifier_hangup = notifier_hangup_irq,
 198 };
 199
 200 static int xen_hvm_console_init(void)
 201 {
 202         int r;
 203         uint64_t v = 0;
 204         unsigned long gfn;
 205         struct xencons_info *info;
 206
 207         if (!xen_hvm_domain())
 208                 return -ENODEV;
 209
 210         info = vtermno_to_xencons(HVC_COOKIE);
 211         if (!info) {
 212                 info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
 213                 if (!info)
 214                         return -ENOMEM;
 215         } else if (info->intf != NULL) {
 216                 /* already configured */
 217                 return 0;
 218         }
 219         /*
 220          * If the toolstack (or the hypervisor) hasn't set these values, the
 221          * default value is 0. Even though gfn = 0 and evtchn = 0 are
 222          * theoretically correct values, in practice they never are and they
 223          * mean that a legacy toolstack hasn't initialized the pv console correctly.
 224          */
 225         r = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v);
 226         if (r < 0 || v == 0)
 227                 goto err;
 228         info->evtchn = v;
 229         v = 0;
 230         r = hvm_get_parameter(HVM_PARAM_CONSOLE_PFN, &v);
 231         if (r < 0 || v == 0)
 232                 goto err;
 233         gfn = v;
 234         info->intf = xen_remap(gfn << XEN_PAGE_SHIFT, XEN_PAGE_SIZE);
 235         if (info->intf == NULL)
 236                 goto err;
 237         info->vtermno = HVC_COOKIE;
 238
 239         spin_lock(&xencons_lock);
 240         list_add_tail(&info->list, &xenconsoles);
 241         spin_unlock(&xencons_lock);
 242
 243         return 0;
 244 err:
 245         kfree(info);
 246         return -ENODEV;
 247 }
 248
 249 static int xencons_info_pv_init(struct xencons_info *info, int vtermno)
 250 {
 251         info->evtchn = xen_start_info->console.domU.evtchn;
 252         /* GFN == MFN for PV guest */
 253         info->intf = gfn_to_virt(xen_start_info->console.domU.mfn);
 254         info->vtermno = vtermno;
 255
 256         list_add_tail(&info->list, &xenconsoles);
 257
 258         return 0;
 259 }
 260
 261 static int xen_pv_console_init(void)
 262 {
 263         struct xencons_info *info;
 264
 265         if (!xen_pv_domain())
 266                 return -ENODEV;
 267
 268         if (!xen_start_info->console.domU.evtchn)
 269                 return -ENODEV;
 270
 271         info = vtermno_to_xencons(HVC_COOKIE);
 272         if (!info) {
 273                 info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
 274                 if (!info)
 275                         return -ENOMEM;
 276         } else if (info->intf != NULL) {
 277                 /* already configured */
 278                 return 0;
 279         }
 280         spin_lock(&xencons_lock);
 281         xencons_info_pv_init(info, HVC_COOKIE);
 282         spin_unlock(&xencons_lock);
 283
 284         return 0;
 285 }
 286
 287 static int xen_initial_domain_console_init(void)
 288 {
 289         struct xencons_info *info;
 290
 291         if (!xen_initial_domain())
 292                 return -ENODEV;
 293
 294         info = vtermno_to_xencons(HVC_COOKIE);
 295         if (!info) {
 296                 info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
 297                 if (!info)
 298                         return -ENOMEM;
 299         }
 300
 301         info->irq = bind_virq_to_irq(VIRQ_CONSOLE, 0, false);
 302         info->vtermno = HVC_COOKIE;
 303
 304         spin_lock(&xencons_lock);
 305         list_add_tail(&info->list, &xenconsoles);
 306         spin_unlock(&xencons_lock);
 307
 308         return 0;
 309 }
 310
 311 static void xen_console_update_evtchn(struct xencons_info *info)
 312 {
 313         if (xen_hvm_domain()) {
 314                 uint64_t v = 0;
 315                 int err;
 316
 317                 err = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v);
 318                 if (!err && v)
 319                         info->evtchn = v;
 320         } else
 321                 info->evtchn = xen_start_info->console.domU.evtchn;
 322 }
 323
 324 void xen_console_resume(void)
 325 {
 326         struct xencons_info *info = vtermno_to_xencons(HVC_COOKIE);
 327         if (info != NULL && info->irq) {
 328                 if (!xen_initial_domain())
 329                         xen_console_update_evtchn(info);
 330                 rebind_evtchn_irq(info->evtchn, info->irq);
 331         }
 332 }
 333
 334 #ifdef CONFIG_HVC_XEN_FRONTEND
 335 static void xencons_disconnect_backend(struct xencons_info *info)
 336 {
 337         if (info->irq > 0)
 338                 unbind_from_irqhandler(info->irq, NULL);
 339         info->irq = 0;
 340         if (info->evtchn > 0)
 341                 xenbus_free_evtchn(info->xbdev, info->evtchn);
 342         info->evtchn = 0;
 343         if (info->gntref > 0)
 344                 gnttab_free_grant_references(info->gntref);
 345         info->gntref = 0;
 346         if (info->hvc != NULL)
 347                 hvc_remove(info->hvc);
 348         info->hvc = NULL;
 349 }
 350
 351 static void xencons_free(struct xencons_info *info)
 352 {
 353         free_page((unsigned long)info->intf);
 354         info->intf = NULL;
 355         info->vtermno = 0;
 356         kfree(info);
 357 }
 358
 359 static int xen_console_remove(struct xencons_info *info)
 360 {
 361         xencons_disconnect_backend(info);
 362         spin_lock(&xencons_lock);
 363         list_del(&info->list);
 364         spin_unlock(&xencons_lock);
 365         if (info->xbdev != NULL)
 366                 xencons_free(info);
 367         else {
 368                 if (xen_hvm_domain())
 369                         iounmap(info->intf);
 370                 kfree(info);
 371         }
 372         return 0;
 373 }
 374
 375 static int xencons_remove(struct xenbus_device *dev)
 376 {
 377         return xen_console_remove(dev_get_drvdata(&dev->dev));
 378 }
 379
 380 static int xencons_connect_backend(struct xenbus_device *dev,
 381                                   struct xencons_info *info)
 382 {
 383         int ret, evtchn, devid, ref, irq;
 384         struct xenbus_transaction xbt;
 385         grant_ref_t gref_head;
 386
 387         ret = xenbus_alloc_evtchn(dev, &evtchn);
 388         if (ret)
 389                 return ret;
 390         info->evtchn = evtchn;
 391         irq = bind_evtchn_to_irq(evtchn);
 392         if (irq < 0)
 393                 return irq;
 394         info->irq = irq;
 395         devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
 396         info->hvc = hvc_alloc(xenbus_devid_to_vtermno(devid),
 397                         irq, &domU_hvc_ops, 256);
 398         if (IS_ERR(info->hvc))
 399                 return PTR_ERR(info->hvc);
 400         ret = gnttab_alloc_grant_references(1, &gref_head);
 401         if (ret < 0)
 402                 return ret;
 403         info->gntref = gref_head;
 404         ref = gnttab_claim_grant_reference(&gref_head);
 405         if (ref < 0)
 406                 return ref;
 407         gnttab_grant_foreign_access_ref(ref, info->xbdev->otherend_id,
 408                                         virt_to_gfn(info->intf), 0);
 409
 410  again:
 411         ret = xenbus_transaction_start(&xbt);
 412         if (ret) {
 413                 xenbus_dev_fatal(dev, ret, "starting transaction");
 414                 return ret;
 415         }
 416         ret = xenbus_printf(xbt, dev->nodename, "ring-ref", "%d", ref);
 417         if (ret)
 418                 goto error_xenbus;
 419         ret = xenbus_printf(xbt, dev->nodename, "port", "%u",
 420                             evtchn);
 421         if (ret)
 422                 goto error_xenbus;
 423         ret = xenbus_transaction_end(xbt, 0);
 424         if (ret) {
 425                 if (ret == -EAGAIN)
 426                         goto again;
 427                 xenbus_dev_fatal(dev, ret, "completing transaction");
 428                 return ret;
 429         }
 430
 431         xenbus_switch_state(dev, XenbusStateInitialised);
 432         return 0;
 433
 434  error_xenbus:
 435         xenbus_transaction_end(xbt, 1);
 436         xenbus_dev_fatal(dev, ret, "writing xenstore");
 437         return ret;
 438 }
 439
 440 static int xencons_probe(struct xenbus_device *dev,
 441                                   const struct xenbus_device_id *id)
 442 {
 443         int ret, devid;
 444         struct xencons_info *info;
 445
 446         devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
 447         if (devid == 0)
 448                 return -ENODEV;
 449
 450         info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
 451         if (!info)
 452                 return -ENOMEM;
 453         dev_set_drvdata(&dev->dev, info);
 454         info->xbdev = dev;
 455         info->vtermno = xenbus_devid_to_vtermno(devid);
 456         info->intf = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
 457         if (!info->intf)
 458                 goto error_nomem;
 459
 460         ret = xencons_connect_backend(dev, info);
 461         if (ret < 0)
 462                 goto error;
 463         spin_lock(&xencons_lock);
 464         list_add_tail(&info->list, &xenconsoles);
 465         spin_unlock(&xencons_lock);
 466
 467         return 0;
 468
 469  error_nomem:
 470         ret = -ENOMEM;
 471         xenbus_dev_fatal(dev, ret, "allocating device memory");
 472  error:
 473         xencons_disconnect_backend(info);
 474         xencons_free(info);
 475         return ret;
 476 }
 477
 478 static int xencons_resume(struct xenbus_device *dev)
 479 {
 480         struct xencons_info *info = dev_get_drvdata(&dev->dev);
 481
 482         xencons_disconnect_backend(info);
 483         memset(info->intf, 0, XEN_PAGE_SIZE);
 484         return xencons_connect_backend(dev, info);
 485 }
 486
 487 static void xencons_backend_changed(struct xenbus_device *dev,
 488                                    enum xenbus_state backend_state)
 489 {
 490         switch (backend_state) {
 491         case XenbusStateReconfiguring:
 492         case XenbusStateReconfigured:
 493         case XenbusStateInitialising:
 494         case XenbusStateInitialised:
 495         case XenbusStateUnknown:
 496                 break;
 497
 498         case XenbusStateInitWait:
 499                 break;
 500
 501         case XenbusStateConnected:
 502                 xenbus_switch_state(dev, XenbusStateConnected);
 503                 break;
 504
 505         case XenbusStateClosed:
 506                 if (dev->state == XenbusStateClosed)
 507                         break;
 508                 /* Missed the backend's CLOSING state -- fallthrough */
 509         case XenbusStateClosing:
 510                 xenbus_frontend_closed(dev);
 511                 break;
 512         }
 513 }
 514
 515 static const struct xenbus_device_id xencons_ids[] = {
 516         { "console" },
 517         { "" }
 518 };
 519
 520 static struct xenbus_driver xencons_driver = {
 521         .name = "xenconsole",
 522         .ids = xencons_ids,
 523         .probe = xencons_probe,
 524         .remove = xencons_remove,
 525         .resume = xencons_resume,
 526         .otherend_changed = xencons_backend_changed,
 527 };
 528 #endif /* CONFIG_HVC_XEN_FRONTEND */
 529
 530 static int __init xen_hvc_init(void)
 531 {
 532         int r;
 533         struct xencons_info *info;
 534         const struct hv_ops *ops;
 535
 536         if (!xen_domain())
 537                 return -ENODEV;
 538
 539         if (xen_initial_domain()) {
 540                 ops = &dom0_hvc_ops;
 541                 r = xen_initial_domain_console_init();
 542                 if (r < 0)
 543                         return r;
 544                 info = vtermno_to_xencons(HVC_COOKIE);
 545         } else {
 546                 ops = &domU_hvc_ops;
 547                 if (xen_hvm_domain())
 548                         r = xen_hvm_console_init();
 549                 else
 550                         r = xen_pv_console_init();
 551                 if (r < 0)
 552                         return r;
 553
 554                 info = vtermno_to_xencons(HVC_COOKIE);
 555                 info->irq = bind_evtchn_to_irq(info->evtchn);
 556         }
 557         if (info->irq < 0)
 558                 info->irq = 0; /* NO_IRQ */
 559         else
 560                 irq_set_noprobe(info->irq);
 561
 562         info->hvc = hvc_alloc(HVC_COOKIE, info->irq, ops, 256);
 563         if (IS_ERR(info->hvc)) {
 564                 r = PTR_ERR(info->hvc);
 565                 spin_lock(&xencons_lock);
 566                 list_del(&info->list);
 567                 spin_unlock(&xencons_lock);
 568                 if (info->irq)
 569                         unbind_from_irqhandler(info->irq, NULL);
 570                 kfree(info);
 571                 return r;
 572         }
 573
 574         r = 0;
 575 #ifdef CONFIG_HVC_XEN_FRONTEND
 576         r = xenbus_register_frontend(&xencons_driver);
 577 #endif
 578         return r;
 579 }
 580 device_initcall(xen_hvc_init);
 581
 582 static int xen_cons_init(void)
 583 {
 584         const struct hv_ops *ops;
 585
 586         if (!xen_domain())
 587                 return 0;
 588
 589         if (xen_initial_domain())
 590                 ops = &dom0_hvc_ops;
 591         else {
 592                 int r;
 593                 ops = &domU_hvc_ops;
 594
 595                 if (xen_hvm_domain())
 596                         r = xen_hvm_console_init();
 597                 else
 598                         r = xen_pv_console_init();
 599                 if (r < 0)
 600                         return r;
 601         }
 602
 603         hvc_instantiate(HVC_COOKIE, 0, ops);
 604         return 0;
 605 }
 606 console_initcall(xen_cons_init);
 607
 608 #ifdef CONFIG_X86
 609 static void xen_hvm_early_write(uint32_t vtermno, const char *str, int len)
 610 {
 611         if (xen_cpuid_base())
 612                 outsb(0xe9, str, len);
 613 }
 614 #else
 615 static void xen_hvm_early_write(uint32_t vtermno, const char *str, int len) { }
 616 #endif
 617
 618 #ifdef CONFIG_EARLY_PRINTK
 619 static int __init xenboot_setup_console(struct console *console, char *string)
 620 {
 621         static struct xencons_info xenboot;
 622
 623         if (xen_initial_domain())
 624                 return 0;
 625         if (!xen_pv_domain())
 626                 return -ENODEV;
 627
 628         return xencons_info_pv_init(&xenboot, 0);
 629 }
 630
 631 static void xenboot_write_console(struct console *console, const char *string,
 632                                   unsigned len)
 633 {
 634         unsigned int linelen, off = 0;
 635         const char *pos;
 636
 637         if (!xen_pv_domain()) {
 638                 xen_hvm_early_write(0, string, len);
 639                 return;
 640         }
 641
 642         dom0_write_console(0, string, len);
 643
 644         if (xen_initial_domain())
 645                 return;
 646
 647         domU_write_console(0, "(early) ", 8);
 648         while (off < len && NULL != (pos = strchr(string+off, '\n'))) {
 649                 linelen = pos-string+off;
 650                 if (off + linelen > len)
 651                         break;
 652                 domU_write_console(0, string+off, linelen);
 653                 domU_write_console(0, "\r\n", 2);
 654                 off += linelen + 1;
 655         }
 656         if (off < len)
 657                 domU_write_console(0, string+off, len-off);
 658 }
 659
 660 struct console xenboot_console = {
 661         .name           = "xenboot",
 662         .write          = xenboot_write_console,
 663         .setup          = xenboot_setup_console,
 664         .flags          = CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
 665         .index          = -1,
 666 };
 667 #endif  /* CONFIG_EARLY_PRINTK */
 668
 669 void xen_raw_console_write(const char *str)
 670 {
 671         ssize_t len = strlen(str);
 672         int rc = 0;
 673
 674         if (xen_domain()) {
 675                 rc = dom0_write_console(0, str, len);
 676                 if (rc != -ENOSYS || !xen_hvm_domain())
 677                         return;
 678         }
 679         xen_hvm_early_write(0, str, len);
 680 }
 681
 682 void xen_raw_printk(const char *fmt, ...)
 683 {
 684         static char buf[512];
 685         va_list ap;
 686
 687         va_start(ap, fmt);
 688         vsnprintf(buf, sizeof(buf), fmt, ap);
 689         va_end(ap);
 690
 691         xen_raw_console_write(buf);
 692 }
 693
 694 static void xenboot_earlycon_write(struct console *console,
 695                                   const char *string,
 696                                   unsigned len)
 697 {
 698         dom0_write_console(0, string, len);
 699 }
 700
 701 static int __init xenboot_earlycon_setup(struct earlycon_device *device,
 702                                             const char *opt)
 703 {
 704         device->con->write = xenboot_earlycon_write;
 705         return 0;
 706 }
 707 EARLYCON_DECLARE(xenboot, xenboot_earlycon_setup);