hw/xen/xen_backend.c

   1 /*
   2  *  xen backend driver infrastructure
   3  *  (c) 2008 Gerd Hoffmann <kraxel@redhat.com>
   4  *
   5  *  This program is free software; you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation; under version 2 of the License.
   8  *
   9  *  This program is distributed in the hope that it will be useful,
  10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  *  GNU General Public License for more details.
  13  *
  14  *  You should have received a copy of the GNU General Public License along
  15  *  with this program; if not, see <http://www.gnu.org/licenses/>.
  16  *
  17  *  Contributions after 2012-01-13 are licensed under the terms of the
  18  *  GNU GPL, version 2 or (at your option) any later version.
  19  */
  20
  21 /*
  22  * TODO: add some xenbus / xenstore concepts overview here.
  23  */
  24
  25 #include "qemu/osdep.h"
  26 #include <sys/signal.h>
  27
  28 #include "hw/hw.h"
  29 #include "hw/sysbus.h"
  30 #include "sysemu/char.h"
  31 #include "qemu/log.h"
  32 #include "hw/xen/xen_backend.h"
  33 #include "hw/xen/xen_pvdev.h"
  34
  35 #include <xen/grant_table.h>
  36
  37 #define TYPE_XENSYSDEV "xensysdev"
  38
  39 DeviceState *xen_sysdev;
  40
  41 /* ------------------------------------------------------------- */
  42
  43 /* public */
  44 xc_interface *xen_xc = NULL;
  45 xenforeignmemory_handle *xen_fmem = NULL;
  46 struct xs_handle *xenstore = NULL;
  47 const char *xen_protocol;
  48
  49 /* private */
  50 static int debug;
  51
  52 int xenstore_write_be_str(struct XenDevice *xendev, const char *node, const char *val)
  53 {
  54     return xenstore_write_str(xendev->be, node, val);
  55 }
  56
  57 int xenstore_write_be_int(struct XenDevice *xendev, const char *node, int ival)
  58 {
  59     return xenstore_write_int(xendev->be, node, ival);
  60 }
  61
  62 int xenstore_write_be_int64(struct XenDevice *xendev, const char *node, int64_t ival)
  63 {
  64     return xenstore_write_int64(xendev->be, node, ival);
  65 }
  66
  67 char *xenstore_read_be_str(struct XenDevice *xendev, const char *node)
  68 {
  69     return xenstore_read_str(xendev->be, node);
  70 }
  71
  72 int xenstore_read_be_int(struct XenDevice *xendev, const char *node, int *ival)
  73 {
  74     return xenstore_read_int(xendev->be, node, ival);
  75 }
  76
  77 char *xenstore_read_fe_str(struct XenDevice *xendev, const char *node)
  78 {
  79     return xenstore_read_str(xendev->fe, node);
  80 }
  81
  82 int xenstore_read_fe_int(struct XenDevice *xendev, const char *node, int *ival)
  83 {
  84     return xenstore_read_int(xendev->fe, node, ival);
  85 }
  86
  87 int xenstore_read_fe_uint64(struct XenDevice *xendev, const char *node,
  88                             uint64_t *uval)
  89 {
  90     return xenstore_read_uint64(xendev->fe, node, uval);
  91 }
  92
  93 /* ------------------------------------------------------------- */
  94
  95 int xen_be_set_state(struct XenDevice *xendev, enum xenbus_state state)
  96 {
  97     int rc;
  98
  99     rc = xenstore_write_be_int(xendev, "state", state);
 100     if (rc < 0) {
 101         return rc;
 102     }
 103     xen_be_printf(xendev, 1, "backend state: %s -> %s\n",
 104                   xenbus_strstate(xendev->be_state), xenbus_strstate(state));
 105     xendev->be_state = state;
 106     return 0;
 107 }
 108
 109 /*
 110  * get xen backend device, allocate a new one if it doesn't exist.
 111  */
 112 static struct XenDevice *xen_be_get_xendev(const char *type, int dom, int dev,
 113                                            struct XenDevOps *ops)
 114 {
 115     struct XenDevice *xendev;
 116
 117     xendev = xen_be_find_xendev(type, dom, dev);
 118     if (xendev) {
 119         return xendev;
 120     }
 121
 122     /* init new xendev */
 123     xendev = g_malloc0(ops->size);
 124     xendev->type  = type;
 125     xendev->dom   = dom;
 126     xendev->dev   = dev;
 127     xendev->ops   = ops;
 128
 129     snprintf(xendev->be, sizeof(xendev->be), "backend/%s/%d/%d",
 130              xendev->type, xendev->dom, xendev->dev);
 131     snprintf(xendev->name, sizeof(xendev->name), "%s-%d",
 132              xendev->type, xendev->dev);
 133
 134     xendev->debug      = debug;
 135     xendev->local_port = -1;
 136
 137     xendev->evtchndev = xenevtchn_open(NULL, 0);
 138     if (xendev->evtchndev == NULL) {
 139         xen_be_printf(NULL, 0, "can't open evtchn device\n");
 140         g_free(xendev);
 141         return NULL;
 142     }
 143     fcntl(xenevtchn_fd(xendev->evtchndev), F_SETFD, FD_CLOEXEC);
 144
 145     if (ops->flags & DEVOPS_FLAG_NEED_GNTDEV) {
 146         xendev->gnttabdev = xengnttab_open(NULL, 0);
 147         if (xendev->gnttabdev == NULL) {
 148             xen_be_printf(NULL, 0, "can't open gnttab device\n");
 149             xenevtchn_close(xendev->evtchndev);
 150             g_free(xendev);
 151             return NULL;
 152         }
 153     } else {
 154         xendev->gnttabdev = NULL;
 155     }
 156
 157     xen_pv_insert_xendev(xendev);
 158
 159     if (xendev->ops->alloc) {
 160         xendev->ops->alloc(xendev);
 161     }
 162
 163     return xendev;
 164 }
 165
 166
 167 /*
 168  * Sync internal data structures on xenstore updates.
 169  * Node specifies the changed field.  node = NULL means
 170  * update all fields (used for initialization).
 171  */
 172 static void xen_be_backend_changed(struct XenDevice *xendev, const char *node)
 173 {
 174     if (node == NULL  ||  strcmp(node, "online") == 0) {
 175         if (xenstore_read_be_int(xendev, "online", &xendev->online) == -1) {
 176             xendev->online = 0;
 177         }
 178     }
 179
 180     if (node) {
 181         xen_be_printf(xendev, 2, "backend update: %s\n", node);
 182         if (xendev->ops->backend_changed) {
 183             xendev->ops->backend_changed(xendev, node);
 184         }
 185     }
 186 }
 187
 188 static void xen_be_frontend_changed(struct XenDevice *xendev, const char *node)
 189 {
 190     int fe_state;
 191
 192     if (node == NULL  ||  strcmp(node, "state") == 0) {
 193         if (xenstore_read_fe_int(xendev, "state", &fe_state) == -1) {
 194             fe_state = XenbusStateUnknown;
 195         }
 196         if (xendev->fe_state != fe_state) {
 197             xen_be_printf(xendev, 1, "frontend state: %s -> %s\n",
 198                           xenbus_strstate(xendev->fe_state),
 199                           xenbus_strstate(fe_state));
 200         }
 201         xendev->fe_state = fe_state;
 202     }
 203     if (node == NULL  ||  strcmp(node, "protocol") == 0) {
 204         g_free(xendev->protocol);
 205         xendev->protocol = xenstore_read_fe_str(xendev, "protocol");
 206         if (xendev->protocol) {
 207             xen_be_printf(xendev, 1, "frontend protocol: %s\n",
 208                           xendev->protocol);
 209         }
 210     }
 211
 212     if (node) {
 213         xen_be_printf(xendev, 2, "frontend update: %s\n", node);
 214         if (xendev->ops->frontend_changed) {
 215             xendev->ops->frontend_changed(xendev, node);
 216         }
 217     }
 218 }
 219
 220 /* ------------------------------------------------------------- */
 221 /* Check for possible state transitions and perform them.        */
 222
 223 /*
 224  * Initial xendev setup.  Read frontend path, register watch for it.
 225  * Should succeed once xend finished setting up the backend device.
 226  *
 227  * Also sets initial state (-> Initializing) when done.  Which
 228  * only affects the xendev->be_state variable as xenbus should
 229  * already be put into that state by xend.
 230  */
 231 static int xen_be_try_setup(struct XenDevice *xendev)
 232 {
 233     char token[XEN_BUFSIZE];
 234     int be_state;
 235
 236     if (xenstore_read_be_int(xendev, "state", &be_state) == -1) {
 237         xen_be_printf(xendev, 0, "reading backend state failed\n");
 238         return -1;
 239     }
 240
 241     if (be_state != XenbusStateInitialising) {
 242         xen_be_printf(xendev, 0, "initial backend state is wrong (%s)\n",
 243                       xenbus_strstate(be_state));
 244         return -1;
 245     }
 246
 247     xendev->fe = xenstore_read_be_str(xendev, "frontend");
 248     if (xendev->fe == NULL) {
 249         xen_be_printf(xendev, 0, "reading frontend path failed\n");
 250         return -1;
 251     }
 252
 253     /* setup frontend watch */
 254     snprintf(token, sizeof(token), "fe:%p", xendev);
 255     if (!xs_watch(xenstore, xendev->fe, token)) {
 256         xen_be_printf(xendev, 0, "watching frontend path (%s) failed\n",
 257                       xendev->fe);
 258         return -1;
 259     }
 260     xen_be_set_state(xendev, XenbusStateInitialising);
 261
 262     xen_be_backend_changed(xendev, NULL);
 263     xen_be_frontend_changed(xendev, NULL);
 264     return 0;
 265 }
 266
 267 /*
 268  * Try initialize xendev.  Prepare everything the backend can do
 269  * without synchronizing with the frontend.  Fakes hotplug-status.  No
 270  * hotplug involved here because this is about userspace drivers, thus
 271  * there are kernel backend devices which could invoke hotplug.
 272  *
 273  * Goes to InitWait on success.
 274  */
 275 static int xen_be_try_init(struct XenDevice *xendev)
 276 {
 277     int rc = 0;
 278
 279     if (!xendev->online) {
 280         xen_be_printf(xendev, 1, "not online\n");
 281         return -1;
 282     }
 283
 284     if (xendev->ops->init) {
 285         rc = xendev->ops->init(xendev);
 286     }
 287     if (rc != 0) {
 288         xen_be_printf(xendev, 1, "init() failed\n");
 289         return rc;
 290     }
 291
 292     xenstore_write_be_str(xendev, "hotplug-status", "connected");
 293     xen_be_set_state(xendev, XenbusStateInitWait);
 294     return 0;
 295 }
 296
 297 /*
 298  * Try to initialise xendev.  Depends on the frontend being ready
 299  * for it (shared ring and evtchn info in xenstore, state being
 300  * Initialised or Connected).
 301  *
 302  * Goes to Connected on success.
 303  */
 304 static int xen_be_try_initialise(struct XenDevice *xendev)
 305 {
 306     int rc = 0;
 307
 308     if (xendev->fe_state != XenbusStateInitialised  &&
 309         xendev->fe_state != XenbusStateConnected) {
 310         if (xendev->ops->flags & DEVOPS_FLAG_IGNORE_STATE) {
 311             xen_be_printf(xendev, 2, "frontend not ready, ignoring\n");
 312         } else {
 313             xen_be_printf(xendev, 2, "frontend not ready (yet)\n");
 314             return -1;
 315         }
 316     }
 317
 318     if (xendev->ops->initialise) {
 319         rc = xendev->ops->initialise(xendev);
 320     }
 321     if (rc != 0) {
 322         xen_be_printf(xendev, 0, "initialise() failed\n");
 323         return rc;
 324     }
 325
 326     xen_be_set_state(xendev, XenbusStateConnected);
 327     return 0;
 328 }
 329
 330 /*
 331  * Try to let xendev know that it is connected.  Depends on the
 332  * frontend being Connected.  Note that this may be called more
 333  * than once since the backend state is not modified.
 334  */
 335 static void xen_be_try_connected(struct XenDevice *xendev)
 336 {
 337     if (!xendev->ops->connected) {
 338         return;
 339     }
 340
 341     if (xendev->fe_state != XenbusStateConnected) {
 342         if (xendev->ops->flags & DEVOPS_FLAG_IGNORE_STATE) {
 343             xen_be_printf(xendev, 2, "frontend not ready, ignoring\n");
 344         } else {
 345             xen_be_printf(xendev, 2, "frontend not ready (yet)\n");
 346             return;
 347         }
 348     }
 349
 350     xendev->ops->connected(xendev);
 351 }
 352
 353 /*
 354  * Teardown connection.
 355  *
 356  * Goes to Closed when done.
 357  */
 358 static void xen_be_disconnect(struct XenDevice *xendev, enum xenbus_state state)
 359 {
 360     if (xendev->be_state != XenbusStateClosing &&
 361         xendev->be_state != XenbusStateClosed  &&
 362         xendev->ops->disconnect) {
 363         xendev->ops->disconnect(xendev);
 364     }
 365     if (xendev->be_state != state) {
 366         xen_be_set_state(xendev, state);
 367     }
 368 }
 369
 370 /*
 371  * Try to reset xendev, for reconnection by another frontend instance.
 372  */
 373 static int xen_be_try_reset(struct XenDevice *xendev)
 374 {
 375     if (xendev->fe_state != XenbusStateInitialising) {
 376         return -1;
 377     }
 378
 379     xen_be_printf(xendev, 1, "device reset (for re-connect)\n");
 380     xen_be_set_state(xendev, XenbusStateInitialising);
 381     return 0;
 382 }
 383
 384 /*
 385  * state change dispatcher function
 386  */
 387 void xen_be_check_state(struct XenDevice *xendev)
 388 {
 389     int rc = 0;
 390
 391     /* frontend may request shutdown from almost anywhere */
 392     if (xendev->fe_state == XenbusStateClosing ||
 393         xendev->fe_state == XenbusStateClosed) {
 394         xen_be_disconnect(xendev, xendev->fe_state);
 395         return;
 396     }
 397
 398     /* check for possible backend state transitions */
 399     for (;;) {
 400         switch (xendev->be_state) {
 401         case XenbusStateUnknown:
 402             rc = xen_be_try_setup(xendev);
 403             break;
 404         case XenbusStateInitialising:
 405             rc = xen_be_try_init(xendev);
 406             break;
 407         case XenbusStateInitWait:
 408             rc = xen_be_try_initialise(xendev);
 409             break;
 410         case XenbusStateConnected:
 411             /* xendev->be_state doesn't change */
 412             xen_be_try_connected(xendev);
 413             rc = -1;
 414             break;
 415         case XenbusStateClosed:
 416             rc = xen_be_try_reset(xendev);
 417             break;
 418         default:
 419             rc = -1;
 420         }
 421         if (rc != 0) {
 422             break;
 423         }
 424     }
 425 }
 426
 427 /* ------------------------------------------------------------- */
 428
 429 static int xenstore_scan(const char *type, int dom, struct XenDevOps *ops)
 430 {
 431     struct XenDevice *xendev;
 432     char path[XEN_BUFSIZE], token[XEN_BUFSIZE];
 433     char **dev = NULL;
 434     unsigned int cdev, j;
 435
 436     /* setup watch */
 437     snprintf(token, sizeof(token), "be:%p:%d:%p", type, dom, ops);
 438     snprintf(path, sizeof(path), "backend/%s/%d", type, dom);
 439     if (!xs_watch(xenstore, path, token)) {
 440         xen_be_printf(NULL, 0, "xen be: watching backend path (%s) failed\n",
 441                       path);
 442         return -1;
 443     }
 444
 445     /* look for backends */
 446     dev = xs_directory(xenstore, 0, path, &cdev);
 447     if (!dev) {
 448         return 0;
 449     }
 450     for (j = 0; j < cdev; j++) {
 451         xendev = xen_be_get_xendev(type, dom, atoi(dev[j]), ops);
 452         if (xendev == NULL) {
 453             continue;
 454         }
 455         xen_be_check_state(xendev);
 456     }
 457     free(dev);
 458     return 0;
 459 }
 460
 461 void xenstore_update_be(char *watch, char *type, int dom,
 462                         struct XenDevOps *ops)
 463 {
 464     struct XenDevice *xendev;
 465     char path[XEN_BUFSIZE], *bepath;
 466     unsigned int len, dev;
 467
 468     len = snprintf(path, sizeof(path), "backend/%s/%d", type, dom);
 469     if (strncmp(path, watch, len) != 0) {
 470         return;
 471     }
 472     if (sscanf(watch+len, "/%u/%255s", &dev, path) != 2) {
 473         strcpy(path, "");
 474         if (sscanf(watch+len, "/%u", &dev) != 1) {
 475             dev = -1;
 476         }
 477     }
 478     if (dev == -1) {
 479         return;
 480     }
 481
 482     xendev = xen_be_get_xendev(type, dom, dev, ops);
 483     if (xendev != NULL) {
 484         bepath = xs_read(xenstore, 0, xendev->be, &len);
 485         if (bepath == NULL) {
 486             xen_be_del_xendev(xendev);
 487         } else {
 488             free(bepath);
 489             xen_be_backend_changed(xendev, path);
 490             xen_be_check_state(xendev);
 491         }
 492     }
 493 }
 494
 495 void xenstore_update_fe(char *watch, struct XenDevice *xendev)
 496 {
 497     char *node;
 498     unsigned int len;
 499
 500     len = strlen(xendev->fe);
 501     if (strncmp(xendev->fe, watch, len) != 0) {
 502         return;
 503     }
 504     if (watch[len] != '/') {
 505         return;
 506     }
 507     node = watch + len + 1;
 508
 509     xen_be_frontend_changed(xendev, node);
 510     xen_be_check_state(xendev);
 511 }
 512 /* -------------------------------------------------------------------- */
 513
 514 int xen_be_init(void)
 515 {
 516     xenstore = xs_daemon_open();
 517     if (!xenstore) {
 518         xen_be_printf(NULL, 0, "can't connect to xenstored\n");
 519         return -1;
 520     }
 521
 522     qemu_set_fd_handler(xs_fileno(xenstore), xenstore_update, NULL, NULL);
 523
 524     if (xen_xc == NULL || xen_fmem == NULL) {
 525         /* Check if xen_init() have been called */
 526         goto err;
 527     }
 528
 529     xen_sysdev = qdev_create(NULL, TYPE_XENSYSDEV);
 530     qdev_init_nofail(xen_sysdev);
 531
 532     return 0;
 533
 534 err:
 535     qemu_set_fd_handler(xs_fileno(xenstore), NULL, NULL, NULL);
 536     xs_daemon_close(xenstore);
 537     xenstore = NULL;
 538
 539     return -1;
 540 }
 541
 542 int xen_be_register(const char *type, struct XenDevOps *ops)
 543 {
 544     char path[50];
 545     int rc;
 546
 547     if (ops->backend_register) {
 548         rc = ops->backend_register();
 549         if (rc) {
 550             return rc;
 551         }
 552     }
 553
 554     snprintf(path, sizeof(path), "device-model/%u/backends/%s", xen_domid,
 555              type);
 556     xenstore_mkdir(path, XS_PERM_NONE);
 557
 558     return xenstore_scan(type, xen_domid, ops);
 559 }
 560
 561 void xen_be_register_common(void)
 562 {
 563     xen_be_register("console", &xen_console_ops);
 564     xen_be_register("vkbd", &xen_kbdmouse_ops);
 565     xen_be_register("qdisk", &xen_blkdev_ops);
 566 #ifdef CONFIG_USB_LIBUSB
 567     xen_be_register("qusb", &xen_usb_ops);
 568 #endif
 569 }
 570
 571 int xen_be_bind_evtchn(struct XenDevice *xendev)
 572 {
 573     if (xendev->local_port != -1) {
 574         return 0;
 575     }
 576     xendev->local_port = xenevtchn_bind_interdomain
 577         (xendev->evtchndev, xendev->dom, xendev->remote_port);
 578     if (xendev->local_port == -1) {
 579         xen_be_printf(xendev, 0, "xenevtchn_bind_interdomain failed\n");
 580         return -1;
 581     }
 582     xen_be_printf(xendev, 2, "bind evtchn port %d\n", xendev->local_port);
 583     qemu_set_fd_handler(xenevtchn_fd(xendev->evtchndev),
 584                         xen_be_evtchn_event, NULL, xendev);
 585     return 0;
 586 }
 587
 588
 589 static int xen_sysdev_init(SysBusDevice *dev)
 590 {
 591     return 0;
 592 }
 593
 594 static Property xen_sysdev_properties[] = {
 595     {/* end of property list */},
 596 };
 597
 598 static void xen_sysdev_class_init(ObjectClass *klass, void *data)
 599 {
 600     DeviceClass *dc = DEVICE_CLASS(klass);
 601     SysBusDeviceClass *k = SYS_BUS_DEVICE_CLASS(klass);
 602
 603     k->init = xen_sysdev_init;
 604     dc->props = xen_sysdev_properties;
 605 }
 606
 607 static const TypeInfo xensysdev_info = {
 608     .name          = TYPE_XENSYSDEV,
 609     .parent        = TYPE_SYS_BUS_DEVICE,
 610     .instance_size = sizeof(SysBusDevice),
 611     .class_init    = xen_sysdev_class_init,
 612 };
 613
 614 static void xenbe_register_types(void)
 615 {
 616     type_register_static(&xensysdev_info);
 617 }
 618
 619 type_init(xenbe_register_types);