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 "hw/boards.h"
  31 #include "sysemu/char.h"
  32 #include "qemu/log.h"
  33 #include "qapi/error.h"
  34 #include "hw/xen/xen_backend.h"
  35 #include "hw/xen/xen_pvdev.h"
  36 #include "monitor/qdev.h"
  37
  38 #include <xen/grant_table.h>
  39
  40 DeviceState *xen_sysdev;
  41 BusState *xen_sysbus;
  42
  43 /* ------------------------------------------------------------- */
  44
  45 /* public */
  46 xc_interface *xen_xc = NULL;
  47 xenforeignmemory_handle *xen_fmem = NULL;
  48 struct xs_handle *xenstore = NULL;
  49 const char *xen_protocol;
  50
  51 /* private */
  52 static int debug;
  53
  54 int xenstore_write_be_str(struct XenDevice *xendev, const char *node, const char *val)
  55 {
  56     return xenstore_write_str(xendev->be, node, val);
  57 }
  58
  59 int xenstore_write_be_int(struct XenDevice *xendev, const char *node, int ival)
  60 {
  61     return xenstore_write_int(xendev->be, node, ival);
  62 }
  63
  64 int xenstore_write_be_int64(struct XenDevice *xendev, const char *node, int64_t ival)
  65 {
  66     return xenstore_write_int64(xendev->be, node, ival);
  67 }
  68
  69 char *xenstore_read_be_str(struct XenDevice *xendev, const char *node)
  70 {
  71     return xenstore_read_str(xendev->be, node);
  72 }
  73
  74 int xenstore_read_be_int(struct XenDevice *xendev, const char *node, int *ival)
  75 {
  76     return xenstore_read_int(xendev->be, node, ival);
  77 }
  78
  79 char *xenstore_read_fe_str(struct XenDevice *xendev, const char *node)
  80 {
  81     return xenstore_read_str(xendev->fe, node);
  82 }
  83
  84 int xenstore_read_fe_int(struct XenDevice *xendev, const char *node, int *ival)
  85 {
  86     return xenstore_read_int(xendev->fe, node, ival);
  87 }
  88
  89 int xenstore_read_fe_uint64(struct XenDevice *xendev, const char *node,
  90                             uint64_t *uval)
  91 {
  92     return xenstore_read_uint64(xendev->fe, node, uval);
  93 }
  94
  95 /* ------------------------------------------------------------- */
  96
  97 int xen_be_set_state(struct XenDevice *xendev, enum xenbus_state state)
  98 {
  99     int rc;
 100
 101     rc = xenstore_write_be_int(xendev, "state", state);
 102     if (rc < 0) {
 103         return rc;
 104     }
 105     xen_pv_printf(xendev, 1, "backend state: %s -> %s\n",
 106                   xenbus_strstate(xendev->be_state), xenbus_strstate(state));
 107     xendev->be_state = state;
 108     return 0;
 109 }
 110
 111 /*
 112  * get xen backend device, allocate a new one if it doesn't exist.
 113  */
 114 static struct XenDevice *xen_be_get_xendev(const char *type, int dom, int dev,
 115                                            struct XenDevOps *ops)
 116 {
 117     struct XenDevice *xendev;
 118
 119     xendev = xen_pv_find_xendev(type, dom, dev);
 120     if (xendev) {
 121         return xendev;
 122     }
 123
 124     /* init new xendev */
 125     xendev = g_malloc0(ops->size);
 126     object_initialize(&xendev->qdev, ops->size, TYPE_XENBACKEND);
 127     qdev_set_parent_bus(&xendev->qdev, xen_sysbus);
 128     qdev_set_id(&xendev->qdev, g_strdup_printf("xen-%s-%d", type, dev));
 129     qdev_init_nofail(&xendev->qdev);
 130     object_unref(OBJECT(&xendev->qdev));
 131
 132     xendev->type  = type;
 133     xendev->dom   = dom;
 134     xendev->dev   = dev;
 135     xendev->ops   = ops;
 136
 137     snprintf(xendev->be, sizeof(xendev->be), "backend/%s/%d/%d",
 138              xendev->type, xendev->dom, xendev->dev);
 139     snprintf(xendev->name, sizeof(xendev->name), "%s-%d",
 140              xendev->type, xendev->dev);
 141
 142     xendev->debug      = debug;
 143     xendev->local_port = -1;
 144
 145     xendev->evtchndev = xenevtchn_open(NULL, 0);
 146     if (xendev->evtchndev == NULL) {
 147         xen_pv_printf(NULL, 0, "can't open evtchn device\n");
 148         g_free(xendev);
 149         return NULL;
 150     }
 151     fcntl(xenevtchn_fd(xendev->evtchndev), F_SETFD, FD_CLOEXEC);
 152
 153     if (ops->flags & DEVOPS_FLAG_NEED_GNTDEV) {
 154         xendev->gnttabdev = xengnttab_open(NULL, 0);
 155         if (xendev->gnttabdev == NULL) {
 156             xen_pv_printf(NULL, 0, "can't open gnttab device\n");
 157             xenevtchn_close(xendev->evtchndev);
 158             g_free(xendev);
 159             return NULL;
 160         }
 161     } else {
 162         xendev->gnttabdev = NULL;
 163     }
 164
 165     xen_pv_insert_xendev(xendev);
 166
 167     if (xendev->ops->alloc) {
 168         xendev->ops->alloc(xendev);
 169     }
 170
 171     return xendev;
 172 }
 173
 174
 175 /*
 176  * Sync internal data structures on xenstore updates.
 177  * Node specifies the changed field.  node = NULL means
 178  * update all fields (used for initialization).
 179  */
 180 static void xen_be_backend_changed(struct XenDevice *xendev, const char *node)
 181 {
 182     if (node == NULL  ||  strcmp(node, "online") == 0) {
 183         if (xenstore_read_be_int(xendev, "online", &xendev->online) == -1) {
 184             xendev->online = 0;
 185         }
 186     }
 187
 188     if (node) {
 189         xen_pv_printf(xendev, 2, "backend update: %s\n", node);
 190         if (xendev->ops->backend_changed) {
 191             xendev->ops->backend_changed(xendev, node);
 192         }
 193     }
 194 }
 195
 196 static void xen_be_frontend_changed(struct XenDevice *xendev, const char *node)
 197 {
 198     int fe_state;
 199
 200     if (node == NULL  ||  strcmp(node, "state") == 0) {
 201         if (xenstore_read_fe_int(xendev, "state", &fe_state) == -1) {
 202             fe_state = XenbusStateUnknown;
 203         }
 204         if (xendev->fe_state != fe_state) {
 205             xen_pv_printf(xendev, 1, "frontend state: %s -> %s\n",
 206                           xenbus_strstate(xendev->fe_state),
 207                           xenbus_strstate(fe_state));
 208         }
 209         xendev->fe_state = fe_state;
 210     }
 211     if (node == NULL  ||  strcmp(node, "protocol") == 0) {
 212         g_free(xendev->protocol);
 213         xendev->protocol = xenstore_read_fe_str(xendev, "protocol");
 214         if (xendev->protocol) {
 215             xen_pv_printf(xendev, 1, "frontend protocol: %s\n",
 216                           xendev->protocol);
 217         }
 218     }
 219
 220     if (node) {
 221         xen_pv_printf(xendev, 2, "frontend update: %s\n", node);
 222         if (xendev->ops->frontend_changed) {
 223             xendev->ops->frontend_changed(xendev, node);
 224         }
 225     }
 226 }
 227
 228 /* ------------------------------------------------------------- */
 229 /* Check for possible state transitions and perform them.        */
 230
 231 /*
 232  * Initial xendev setup.  Read frontend path, register watch for it.
 233  * Should succeed once xend finished setting up the backend device.
 234  *
 235  * Also sets initial state (-> Initializing) when done.  Which
 236  * only affects the xendev->be_state variable as xenbus should
 237  * already be put into that state by xend.
 238  */
 239 static int xen_be_try_setup(struct XenDevice *xendev)
 240 {
 241     char token[XEN_BUFSIZE];
 242     int be_state;
 243
 244     if (xenstore_read_be_int(xendev, "state", &be_state) == -1) {
 245         xen_pv_printf(xendev, 0, "reading backend state failed\n");
 246         return -1;
 247     }
 248
 249     if (be_state != XenbusStateInitialising) {
 250         xen_pv_printf(xendev, 0, "initial backend state is wrong (%s)\n",
 251                       xenbus_strstate(be_state));
 252         return -1;
 253     }
 254
 255     xendev->fe = xenstore_read_be_str(xendev, "frontend");
 256     if (xendev->fe == NULL) {
 257         xen_pv_printf(xendev, 0, "reading frontend path failed\n");
 258         return -1;
 259     }
 260
 261     /* setup frontend watch */
 262     snprintf(token, sizeof(token), "fe:%p", xendev);
 263     if (!xs_watch(xenstore, xendev->fe, token)) {
 264         xen_pv_printf(xendev, 0, "watching frontend path (%s) failed\n",
 265                       xendev->fe);
 266         return -1;
 267     }
 268     xen_be_set_state(xendev, XenbusStateInitialising);
 269
 270     xen_be_backend_changed(xendev, NULL);
 271     xen_be_frontend_changed(xendev, NULL);
 272     return 0;
 273 }
 274
 275 /*
 276  * Try initialize xendev.  Prepare everything the backend can do
 277  * without synchronizing with the frontend.  Fakes hotplug-status.  No
 278  * hotplug involved here because this is about userspace drivers, thus
 279  * there are kernel backend devices which could invoke hotplug.
 280  *
 281  * Goes to InitWait on success.
 282  */
 283 static int xen_be_try_init(struct XenDevice *xendev)
 284 {
 285     int rc = 0;
 286
 287     if (!xendev->online) {
 288         xen_pv_printf(xendev, 1, "not online\n");
 289         return -1;
 290     }
 291
 292     if (xendev->ops->init) {
 293         rc = xendev->ops->init(xendev);
 294     }
 295     if (rc != 0) {
 296         xen_pv_printf(xendev, 1, "init() failed\n");
 297         return rc;
 298     }
 299
 300     xenstore_write_be_str(xendev, "hotplug-status", "connected");
 301     xen_be_set_state(xendev, XenbusStateInitWait);
 302     return 0;
 303 }
 304
 305 /*
 306  * Try to initialise xendev.  Depends on the frontend being ready
 307  * for it (shared ring and evtchn info in xenstore, state being
 308  * Initialised or Connected).
 309  *
 310  * Goes to Connected on success.
 311  */
 312 static int xen_be_try_initialise(struct XenDevice *xendev)
 313 {
 314     int rc = 0;
 315
 316     if (xendev->fe_state != XenbusStateInitialised  &&
 317         xendev->fe_state != XenbusStateConnected) {
 318         if (xendev->ops->flags & DEVOPS_FLAG_IGNORE_STATE) {
 319             xen_pv_printf(xendev, 2, "frontend not ready, ignoring\n");
 320         } else {
 321             xen_pv_printf(xendev, 2, "frontend not ready (yet)\n");
 322             return -1;
 323         }
 324     }
 325
 326     if (xendev->ops->initialise) {
 327         rc = xendev->ops->initialise(xendev);
 328     }
 329     if (rc != 0) {
 330         xen_pv_printf(xendev, 0, "initialise() failed\n");
 331         return rc;
 332     }
 333
 334     xen_be_set_state(xendev, XenbusStateConnected);
 335     return 0;
 336 }
 337
 338 /*
 339  * Try to let xendev know that it is connected.  Depends on the
 340  * frontend being Connected.  Note that this may be called more
 341  * than once since the backend state is not modified.
 342  */
 343 static void xen_be_try_connected(struct XenDevice *xendev)
 344 {
 345     if (!xendev->ops->connected) {
 346         return;
 347     }
 348
 349     if (xendev->fe_state != XenbusStateConnected) {
 350         if (xendev->ops->flags & DEVOPS_FLAG_IGNORE_STATE) {
 351             xen_pv_printf(xendev, 2, "frontend not ready, ignoring\n");
 352         } else {
 353             xen_pv_printf(xendev, 2, "frontend not ready (yet)\n");
 354             return;
 355         }
 356     }
 357
 358     xendev->ops->connected(xendev);
 359 }
 360
 361 /*
 362  * Teardown connection.
 363  *
 364  * Goes to Closed when done.
 365  */
 366 static void xen_be_disconnect(struct XenDevice *xendev, enum xenbus_state state)
 367 {
 368     if (xendev->be_state != XenbusStateClosing &&
 369         xendev->be_state != XenbusStateClosed  &&
 370         xendev->ops->disconnect) {
 371         xendev->ops->disconnect(xendev);
 372     }
 373     if (xendev->be_state != state) {
 374         xen_be_set_state(xendev, state);
 375     }
 376 }
 377
 378 /*
 379  * Try to reset xendev, for reconnection by another frontend instance.
 380  */
 381 static int xen_be_try_reset(struct XenDevice *xendev)
 382 {
 383     if (xendev->fe_state != XenbusStateInitialising) {
 384         return -1;
 385     }
 386
 387     xen_pv_printf(xendev, 1, "device reset (for re-connect)\n");
 388     xen_be_set_state(xendev, XenbusStateInitialising);
 389     return 0;
 390 }
 391
 392 /*
 393  * state change dispatcher function
 394  */
 395 void xen_be_check_state(struct XenDevice *xendev)
 396 {
 397     int rc = 0;
 398
 399     /* frontend may request shutdown from almost anywhere */
 400     if (xendev->fe_state == XenbusStateClosing ||
 401         xendev->fe_state == XenbusStateClosed) {
 402         xen_be_disconnect(xendev, xendev->fe_state);
 403         return;
 404     }
 405
 406     /* check for possible backend state transitions */
 407     for (;;) {
 408         switch (xendev->be_state) {
 409         case XenbusStateUnknown:
 410             rc = xen_be_try_setup(xendev);
 411             break;
 412         case XenbusStateInitialising:
 413             rc = xen_be_try_init(xendev);
 414             break;
 415         case XenbusStateInitWait:
 416             rc = xen_be_try_initialise(xendev);
 417             break;
 418         case XenbusStateConnected:
 419             /* xendev->be_state doesn't change */
 420             xen_be_try_connected(xendev);
 421             rc = -1;
 422             break;
 423         case XenbusStateClosed:
 424             rc = xen_be_try_reset(xendev);
 425             break;
 426         default:
 427             rc = -1;
 428         }
 429         if (rc != 0) {
 430             break;
 431         }
 432     }
 433 }
 434
 435 /* ------------------------------------------------------------- */
 436
 437 static int xenstore_scan(const char *type, int dom, struct XenDevOps *ops)
 438 {
 439     struct XenDevice *xendev;
 440     char path[XEN_BUFSIZE], token[XEN_BUFSIZE];
 441     char **dev = NULL;
 442     unsigned int cdev, j;
 443
 444     /* setup watch */
 445     snprintf(token, sizeof(token), "be:%p:%d:%p", type, dom, ops);
 446     snprintf(path, sizeof(path), "backend/%s/%d", type, dom);
 447     if (!xs_watch(xenstore, path, token)) {
 448         xen_pv_printf(NULL, 0, "xen be: watching backend path (%s) failed\n",
 449                       path);
 450         return -1;
 451     }
 452
 453     /* look for backends */
 454     dev = xs_directory(xenstore, 0, path, &cdev);
 455     if (!dev) {
 456         return 0;
 457     }
 458     for (j = 0; j < cdev; j++) {
 459         xendev = xen_be_get_xendev(type, dom, atoi(dev[j]), ops);
 460         if (xendev == NULL) {
 461             continue;
 462         }
 463         xen_be_check_state(xendev);
 464     }
 465     free(dev);
 466     return 0;
 467 }
 468
 469 void xenstore_update_be(char *watch, char *type, int dom,
 470                         struct XenDevOps *ops)
 471 {
 472     struct XenDevice *xendev;
 473     char path[XEN_BUFSIZE], *bepath;
 474     unsigned int len, dev;
 475
 476     len = snprintf(path, sizeof(path), "backend/%s/%d", type, dom);
 477     if (strncmp(path, watch, len) != 0) {
 478         return;
 479     }
 480     if (sscanf(watch+len, "/%u/%255s", &dev, path) != 2) {
 481         strcpy(path, "");
 482         if (sscanf(watch+len, "/%u", &dev) != 1) {
 483             dev = -1;
 484         }
 485     }
 486     if (dev == -1) {
 487         return;
 488     }
 489
 490     xendev = xen_be_get_xendev(type, dom, dev, ops);
 491     if (xendev != NULL) {
 492         bepath = xs_read(xenstore, 0, xendev->be, &len);
 493         if (bepath == NULL) {
 494             xen_pv_del_xendev(xendev);
 495         } else {
 496             free(bepath);
 497             xen_be_backend_changed(xendev, path);
 498             xen_be_check_state(xendev);
 499         }
 500     }
 501 }
 502
 503 void xenstore_update_fe(char *watch, struct XenDevice *xendev)
 504 {
 505     char *node;
 506     unsigned int len;
 507
 508     len = strlen(xendev->fe);
 509     if (strncmp(xendev->fe, watch, len) != 0) {
 510         return;
 511     }
 512     if (watch[len] != '/') {
 513         return;
 514     }
 515     node = watch + len + 1;
 516
 517     xen_be_frontend_changed(xendev, node);
 518     xen_be_check_state(xendev);
 519 }
 520 /* -------------------------------------------------------------------- */
 521
 522 int xen_be_init(void)
 523 {
 524     xenstore = xs_daemon_open();
 525     if (!xenstore) {
 526         xen_pv_printf(NULL, 0, "can't connect to xenstored\n");
 527         return -1;
 528     }
 529
 530     qemu_set_fd_handler(xs_fileno(xenstore), xenstore_update, NULL, NULL);
 531
 532     if (xen_xc == NULL || xen_fmem == NULL) {
 533         /* Check if xen_init() have been called */
 534         goto err;
 535     }
 536
 537     xen_sysdev = qdev_create(NULL, TYPE_XENSYSDEV);
 538     qdev_init_nofail(xen_sysdev);
 539     xen_sysbus = qbus_create(TYPE_XENSYSBUS, DEVICE(xen_sysdev), "xen-sysbus");
 540     qbus_set_bus_hotplug_handler(xen_sysbus, &error_abort);
 541
 542     return 0;
 543
 544 err:
 545     qemu_set_fd_handler(xs_fileno(xenstore), NULL, NULL, NULL);
 546     xs_daemon_close(xenstore);
 547     xenstore = NULL;
 548
 549     return -1;
 550 }
 551
 552 static void xen_set_dynamic_sysbus(void)
 553 {
 554     Object *machine = qdev_get_machine();
 555     ObjectClass *oc = object_get_class(machine);
 556     MachineClass *mc = MACHINE_CLASS(oc);
 557
 558     mc->has_dynamic_sysbus = true;
 559 }
 560
 561 int xen_be_register(const char *type, struct XenDevOps *ops)
 562 {
 563     char path[50];
 564     int rc;
 565
 566     if (ops->backend_register) {
 567         rc = ops->backend_register();
 568         if (rc) {
 569             return rc;
 570         }
 571     }
 572
 573     snprintf(path, sizeof(path), "device-model/%u/backends/%s", xen_domid,
 574              type);
 575     xenstore_mkdir(path, XS_PERM_NONE);
 576
 577     return xenstore_scan(type, xen_domid, ops);
 578 }
 579
 580 void xen_be_register_common(void)
 581 {
 582     xen_set_dynamic_sysbus();
 583
 584     xen_be_register("console", &xen_console_ops);
 585     xen_be_register("vkbd", &xen_kbdmouse_ops);
 586     xen_be_register("qdisk", &xen_blkdev_ops);
 587 #ifdef CONFIG_USB_LIBUSB
 588     xen_be_register("qusb", &xen_usb_ops);
 589 #endif
 590 }
 591
 592 int xen_be_bind_evtchn(struct XenDevice *xendev)
 593 {
 594     if (xendev->local_port != -1) {
 595         return 0;
 596     }
 597     xendev->local_port = xenevtchn_bind_interdomain
 598         (xendev->evtchndev, xendev->dom, xendev->remote_port);
 599     if (xendev->local_port == -1) {
 600         xen_pv_printf(xendev, 0, "xenevtchn_bind_interdomain failed\n");
 601         return -1;
 602     }
 603     xen_pv_printf(xendev, 2, "bind evtchn port %d\n", xendev->local_port);
 604     qemu_set_fd_handler(xenevtchn_fd(xendev->evtchndev),
 605                         xen_pv_evtchn_event, NULL, xendev);
 606     return 0;
 607 }
 608
 609
 610 static Property xendev_properties[] = {
 611     DEFINE_PROP_END_OF_LIST(),
 612 };
 613
 614 static void xendev_class_init(ObjectClass *klass, void *data)
 615 {
 616     DeviceClass *dc = DEVICE_CLASS(klass);
 617
 618     dc->props = xendev_properties;
 619     set_bit(DEVICE_CATEGORY_MISC, dc->categories);
 620 }
 621
 622 static const TypeInfo xendev_type_info = {
 623     .name          = TYPE_XENBACKEND,
 624     .parent        = TYPE_XENSYSDEV,
 625     .class_init    = xendev_class_init,
 626     .instance_size = sizeof(struct XenDevice),
 627 };
 628
 629 static void xen_sysbus_class_init(ObjectClass *klass, void *data)
 630 {
 631     HotplugHandlerClass *hc = HOTPLUG_HANDLER_CLASS(klass);
 632
 633     hc->unplug = qdev_simple_device_unplug_cb;
 634 }
 635
 636 static const TypeInfo xensysbus_info = {
 637     .name       = TYPE_XENSYSBUS,
 638     .parent     = TYPE_BUS,
 639     .class_init = xen_sysbus_class_init,
 640     .interfaces = (InterfaceInfo[]) {
 641         { TYPE_HOTPLUG_HANDLER },
 642         { }
 643     }
 644 };
 645
 646 static int xen_sysdev_init(SysBusDevice *dev)
 647 {
 648     return 0;
 649 }
 650
 651 static Property xen_sysdev_properties[] = {
 652     {/* end of property list */},
 653 };
 654
 655 static void xen_sysdev_class_init(ObjectClass *klass, void *data)
 656 {
 657     DeviceClass *dc = DEVICE_CLASS(klass);
 658     SysBusDeviceClass *k = SYS_BUS_DEVICE_CLASS(klass);
 659
 660     k->init = xen_sysdev_init;
 661     dc->props = xen_sysdev_properties;
 662     dc->bus_type = TYPE_XENSYSBUS;
 663 }
 664
 665 static const TypeInfo xensysdev_info = {
 666     .name          = TYPE_XENSYSDEV,
 667     .parent        = TYPE_SYS_BUS_DEVICE,
 668     .instance_size = sizeof(SysBusDevice),
 669     .class_init    = xen_sysdev_class_init,
 670 };
 671
 672 static void xenbe_register_types(void)
 673 {
 674     type_register_static(&xensysbus_info);
 675     type_register_static(&xensysdev_info);
 676     type_register_static(&xendev_type_info);
 677 }
 678
 679 type_init(xenbe_register_types)