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