1 /* 2 * QEMU Xen emulation: Shared/overlay pages support 3 * 4 * Copyright © 2022 Amazon.com, Inc. or its affiliates. All Rights Reserved. 5 * 6 * Authors: David Woodhouse <dwmw2@infradead.org> 7 * 8 * This work is licensed under the terms of the GNU GPL, version 2 or later. 9 * See the COPYING file in the top-level directory. 10 */ 11 12 #include "qemu/osdep.h" 13 14 #include "qemu/host-utils.h" 15 #include "qemu/module.h" 16 #include "qemu/main-loop.h" 17 #include "qemu/cutils.h" 18 #include "qemu/error-report.h" 19 #include "qapi/error.h" 20 #include "qom/object.h" 21 #include "migration/vmstate.h" 22 23 #include "hw/sysbus.h" 24 #include "hw/xen/xen.h" 25 #include "hw/xen/xen_backend_ops.h" 26 #include "xen_overlay.h" 27 #include "xen_evtchn.h" 28 #include "xen_primary_console.h" 29 #include "xen_xenstore.h" 30 31 #include "sysemu/kvm.h" 32 #include "sysemu/kvm_xen.h" 33 34 #include "trace.h" 35 36 #include "xenstore_impl.h" 37 38 #include "hw/xen/interface/io/xs_wire.h" 39 #include "hw/xen/interface/event_channel.h" 40 #include "hw/xen/interface/grant_table.h" 41 42 #define TYPE_XEN_XENSTORE "xen-xenstore" 43 OBJECT_DECLARE_SIMPLE_TYPE(XenXenstoreState, XEN_XENSTORE) 44 45 #define ENTRIES_PER_FRAME_V1 (XEN_PAGE_SIZE / sizeof(grant_entry_v1_t)) 46 #define ENTRIES_PER_FRAME_V2 (XEN_PAGE_SIZE / sizeof(grant_entry_v2_t)) 47 48 #define XENSTORE_HEADER_SIZE ((unsigned int)sizeof(struct xsd_sockmsg)) 49 50 struct XenXenstoreState { 51 /*< private >*/ 52 SysBusDevice busdev; 53 /*< public >*/ 54 55 XenstoreImplState *impl; 56 GList *watch_events; /* for the guest */ 57 58 MemoryRegion xenstore_page; 59 struct xenstore_domain_interface *xs; 60 uint8_t req_data[XENSTORE_HEADER_SIZE + XENSTORE_PAYLOAD_MAX]; 61 uint8_t rsp_data[XENSTORE_HEADER_SIZE + XENSTORE_PAYLOAD_MAX]; 62 uint32_t req_offset; 63 uint32_t rsp_offset; 64 bool rsp_pending; 65 bool fatal_error; 66 67 evtchn_port_t guest_port; 68 evtchn_port_t be_port; 69 struct xenevtchn_handle *eh; 70 71 uint8_t *impl_state; 72 uint32_t impl_state_size; 73 74 struct xengntdev_handle *gt; 75 void *granted_xs; 76 }; 77 78 struct XenXenstoreState *xen_xenstore_singleton; 79 80 static void xen_xenstore_event(void *opaque); 81 static void fire_watch_cb(void *opaque, const char *path, const char *token); 82 83 static struct xenstore_backend_ops emu_xenstore_backend_ops; 84 85 static void G_GNUC_PRINTF (4, 5) relpath_printf(XenXenstoreState *s, 86 GList *perms, 87 const char *relpath, 88 const char *fmt, ...) 89 { 90 gchar *abspath; 91 gchar *value; 92 va_list args; 93 GByteArray *data; 94 int err; 95 96 abspath = g_strdup_printf("/local/domain/%u/%s", xen_domid, relpath); 97 va_start(args, fmt); 98 value = g_strdup_vprintf(fmt, args); 99 va_end(args); 100 101 data = g_byte_array_new_take((void *)value, strlen(value)); 102 103 err = xs_impl_write(s->impl, DOMID_QEMU, XBT_NULL, abspath, data); 104 assert(!err); 105 106 g_byte_array_unref(data); 107 108 err = xs_impl_set_perms(s->impl, DOMID_QEMU, XBT_NULL, abspath, perms); 109 assert(!err); 110 111 g_free(abspath); 112 } 113 114 static void xen_xenstore_realize(DeviceState *dev, Error **errp) 115 { 116 XenXenstoreState *s = XEN_XENSTORE(dev); 117 GList *perms; 118 119 if (xen_mode != XEN_EMULATE) { 120 error_setg(errp, "Xen xenstore support is for Xen emulation"); 121 return; 122 } 123 memory_region_init_ram(&s->xenstore_page, OBJECT(dev), "xen:xenstore_page", 124 XEN_PAGE_SIZE, &error_abort); 125 memory_region_set_enabled(&s->xenstore_page, true); 126 s->xs = memory_region_get_ram_ptr(&s->xenstore_page); 127 memset(s->xs, 0, XEN_PAGE_SIZE); 128 129 /* We can't map it this early as KVM isn't ready */ 130 xen_xenstore_singleton = s; 131 132 s->eh = xen_be_evtchn_open(); 133 if (!s->eh) { 134 error_setg(errp, "Xenstore evtchn port init failed"); 135 return; 136 } 137 aio_set_fd_handler(qemu_get_aio_context(), xen_be_evtchn_fd(s->eh), 138 xen_xenstore_event, NULL, NULL, NULL, s); 139 140 s->impl = xs_impl_create(xen_domid); 141 142 /* Populate the default nodes */ 143 144 /* Nodes owned by 'dom0' but readable by the guest */ 145 perms = g_list_append(NULL, xs_perm_as_string(XS_PERM_NONE, DOMID_QEMU)); 146 perms = g_list_append(perms, xs_perm_as_string(XS_PERM_READ, xen_domid)); 147 148 relpath_printf(s, perms, "", "%s", ""); 149 150 relpath_printf(s, perms, "domid", "%u", xen_domid); 151 152 relpath_printf(s, perms, "control/platform-feature-xs_reset_watches", "%u", 1); 153 relpath_printf(s, perms, "control/platform-feature-multiprocessor-suspend", "%u", 1); 154 155 relpath_printf(s, perms, "platform/acpi", "%u", 1); 156 relpath_printf(s, perms, "platform/acpi_s3", "%u", 1); 157 relpath_printf(s, perms, "platform/acpi_s4", "%u", 1); 158 relpath_printf(s, perms, "platform/acpi_laptop_slate", "%u", 0); 159 160 g_list_free_full(perms, g_free); 161 162 /* Nodes owned by the guest */ 163 perms = g_list_append(NULL, xs_perm_as_string(XS_PERM_NONE, xen_domid)); 164 165 relpath_printf(s, perms, "attr", "%s", ""); 166 167 relpath_printf(s, perms, "control/shutdown", "%s", ""); 168 relpath_printf(s, perms, "control/feature-poweroff", "%u", 1); 169 relpath_printf(s, perms, "control/feature-reboot", "%u", 1); 170 relpath_printf(s, perms, "control/feature-suspend", "%u", 1); 171 relpath_printf(s, perms, "control/feature-s3", "%u", 1); 172 relpath_printf(s, perms, "control/feature-s4", "%u", 1); 173 174 relpath_printf(s, perms, "data", "%s", ""); 175 relpath_printf(s, perms, "device", "%s", ""); 176 relpath_printf(s, perms, "drivers", "%s", ""); 177 relpath_printf(s, perms, "error", "%s", ""); 178 relpath_printf(s, perms, "feature", "%s", ""); 179 180 g_list_free_full(perms, g_free); 181 182 xen_xenstore_ops = &emu_xenstore_backend_ops; 183 } 184 185 static bool xen_xenstore_is_needed(void *opaque) 186 { 187 return xen_mode == XEN_EMULATE; 188 } 189 190 static int xen_xenstore_pre_save(void *opaque) 191 { 192 XenXenstoreState *s = opaque; 193 GByteArray *save; 194 195 if (s->eh) { 196 s->guest_port = xen_be_evtchn_get_guest_port(s->eh); 197 } 198 199 g_free(s->impl_state); 200 save = xs_impl_serialize(s->impl); 201 s->impl_state = save->data; 202 s->impl_state_size = save->len; 203 g_byte_array_free(save, false); 204 205 return 0; 206 } 207 208 static int xen_xenstore_post_load(void *opaque, int ver) 209 { 210 XenXenstoreState *s = opaque; 211 GByteArray *save; 212 int ret; 213 214 /* 215 * As qemu/dom0, rebind to the guest's port. The Windows drivers may 216 * unbind the XenStore evtchn and rebind to it, having obtained the 217 * "remote" port through EVTCHNOP_status. In the case that migration 218 * occurs while it's unbound, the "remote" port needs to be the same 219 * as before so that the guest can find it, but should remain unbound. 220 */ 221 if (s->guest_port) { 222 int be_port = xen_be_evtchn_bind_interdomain(s->eh, xen_domid, 223 s->guest_port); 224 if (be_port < 0) { 225 return be_port; 226 } 227 s->be_port = be_port; 228 } 229 230 save = g_byte_array_new_take(s->impl_state, s->impl_state_size); 231 s->impl_state = NULL; 232 s->impl_state_size = 0; 233 234 ret = xs_impl_deserialize(s->impl, save, xen_domid, fire_watch_cb, s); 235 return ret; 236 } 237 238 static const VMStateDescription xen_xenstore_vmstate = { 239 .name = "xen_xenstore", 240 .unmigratable = 1, /* The PV back ends don't migrate yet */ 241 .version_id = 1, 242 .minimum_version_id = 1, 243 .needed = xen_xenstore_is_needed, 244 .pre_save = xen_xenstore_pre_save, 245 .post_load = xen_xenstore_post_load, 246 .fields = (const VMStateField[]) { 247 VMSTATE_UINT8_ARRAY(req_data, XenXenstoreState, 248 sizeof_field(XenXenstoreState, req_data)), 249 VMSTATE_UINT8_ARRAY(rsp_data, XenXenstoreState, 250 sizeof_field(XenXenstoreState, rsp_data)), 251 VMSTATE_UINT32(req_offset, XenXenstoreState), 252 VMSTATE_UINT32(rsp_offset, XenXenstoreState), 253 VMSTATE_BOOL(rsp_pending, XenXenstoreState), 254 VMSTATE_UINT32(guest_port, XenXenstoreState), 255 VMSTATE_BOOL(fatal_error, XenXenstoreState), 256 VMSTATE_UINT32(impl_state_size, XenXenstoreState), 257 VMSTATE_VARRAY_UINT32_ALLOC(impl_state, XenXenstoreState, 258 impl_state_size, 0, 259 vmstate_info_uint8, uint8_t), 260 VMSTATE_END_OF_LIST() 261 } 262 }; 263 264 static void xen_xenstore_class_init(ObjectClass *klass, void *data) 265 { 266 DeviceClass *dc = DEVICE_CLASS(klass); 267 268 dc->realize = xen_xenstore_realize; 269 dc->vmsd = &xen_xenstore_vmstate; 270 } 271 272 static const TypeInfo xen_xenstore_info = { 273 .name = TYPE_XEN_XENSTORE, 274 .parent = TYPE_SYS_BUS_DEVICE, 275 .instance_size = sizeof(XenXenstoreState), 276 .class_init = xen_xenstore_class_init, 277 }; 278 279 void xen_xenstore_create(void) 280 { 281 DeviceState *dev = sysbus_create_simple(TYPE_XEN_XENSTORE, -1, NULL); 282 283 xen_xenstore_singleton = XEN_XENSTORE(dev); 284 285 /* 286 * Defer the init (xen_xenstore_reset()) until KVM is set up and the 287 * overlay page can be mapped. 288 */ 289 } 290 291 static void xen_xenstore_register_types(void) 292 { 293 type_register_static(&xen_xenstore_info); 294 } 295 296 type_init(xen_xenstore_register_types) 297 298 uint16_t xen_xenstore_get_port(void) 299 { 300 XenXenstoreState *s = xen_xenstore_singleton; 301 if (!s) { 302 return 0; 303 } 304 return s->guest_port; 305 } 306 307 static bool req_pending(XenXenstoreState *s) 308 { 309 struct xsd_sockmsg *req = (struct xsd_sockmsg *)s->req_data; 310 311 return s->req_offset == XENSTORE_HEADER_SIZE + req->len; 312 } 313 314 static void reset_req(XenXenstoreState *s) 315 { 316 memset(s->req_data, 0, sizeof(s->req_data)); 317 s->req_offset = 0; 318 } 319 320 static void reset_rsp(XenXenstoreState *s) 321 { 322 s->rsp_pending = false; 323 324 memset(s->rsp_data, 0, sizeof(s->rsp_data)); 325 s->rsp_offset = 0; 326 } 327 328 static void xs_error(XenXenstoreState *s, unsigned int id, 329 xs_transaction_t tx_id, int errnum) 330 { 331 struct xsd_sockmsg *rsp = (struct xsd_sockmsg *)s->rsp_data; 332 const char *errstr = NULL; 333 334 for (unsigned int i = 0; i < ARRAY_SIZE(xsd_errors); i++) { 335 const struct xsd_errors *xsd_error = &xsd_errors[i]; 336 337 if (xsd_error->errnum == errnum) { 338 errstr = xsd_error->errstring; 339 break; 340 } 341 } 342 assert(errstr); 343 344 trace_xenstore_error(id, tx_id, errstr); 345 346 rsp->type = XS_ERROR; 347 rsp->req_id = id; 348 rsp->tx_id = tx_id; 349 rsp->len = (uint32_t)strlen(errstr) + 1; 350 351 memcpy(&rsp[1], errstr, rsp->len); 352 } 353 354 static void xs_ok(XenXenstoreState *s, unsigned int type, unsigned int req_id, 355 xs_transaction_t tx_id) 356 { 357 struct xsd_sockmsg *rsp = (struct xsd_sockmsg *)s->rsp_data; 358 const char *okstr = "OK"; 359 360 rsp->type = type; 361 rsp->req_id = req_id; 362 rsp->tx_id = tx_id; 363 rsp->len = (uint32_t)strlen(okstr) + 1; 364 365 memcpy(&rsp[1], okstr, rsp->len); 366 } 367 368 /* 369 * The correct request and response formats are documented in xen.git: 370 * docs/misc/xenstore.txt. A summary is given below for convenience. 371 * The '|' symbol represents a NUL character. 372 * 373 * ---------- Database read, write and permissions operations ---------- 374 * 375 * READ <path>| <value|> 376 * WRITE <path>|<value|> 377 * Store and read the octet string <value> at <path>. 378 * WRITE creates any missing parent paths, with empty values. 379 * 380 * MKDIR <path>| 381 * Ensures that the <path> exists, by necessary by creating 382 * it and any missing parents with empty values. If <path> 383 * or any parent already exists, its value is left unchanged. 384 * 385 * RM <path>| 386 * Ensures that the <path> does not exist, by deleting 387 * it and all of its children. It is not an error if <path> does 388 * not exist, but it _is_ an error if <path>'s immediate parent 389 * does not exist either. 390 * 391 * DIRECTORY <path>| <child-leaf-name>|* 392 * Gives a list of the immediate children of <path>, as only the 393 * leafnames. The resulting children are each named 394 * <path>/<child-leaf-name>. 395 * 396 * DIRECTORY_PART <path>|<offset> <gencnt>|<child-leaf-name>|* 397 * Same as DIRECTORY, but to be used for children lists longer than 398 * XENSTORE_PAYLOAD_MAX. Input are <path> and the byte offset into 399 * the list of children to return. Return values are the generation 400 * count <gencnt> of the node (to be used to ensure the node hasn't 401 * changed between two reads: <gencnt> being the same for multiple 402 * reads guarantees the node hasn't changed) and the list of children 403 * starting at the specified <offset> of the complete list. 404 * 405 * GET_PERMS <path>| <perm-as-string>|+ 406 * SET_PERMS <path>|<perm-as-string>|+? 407 * <perm-as-string> is one of the following 408 * w<domid> write only 409 * r<domid> read only 410 * b<domid> both read and write 411 * n<domid> no access 412 * See https://wiki.xen.org/wiki/XenBus section 413 * `Permissions' for details of the permissions system. 414 * It is possible to set permissions for the special watch paths 415 * "@introduceDomain" and "@releaseDomain" to enable receiving those 416 * watches in unprivileged domains. 417 * 418 * ---------- Watches ---------- 419 * 420 * WATCH <wpath>|<token>|? 421 * Adds a watch. 422 * 423 * When a <path> is modified (including path creation, removal, 424 * contents change or permissions change) this generates an event 425 * on the changed <path>. Changes made in transactions cause an 426 * event only if and when committed. Each occurring event is 427 * matched against all the watches currently set up, and each 428 * matching watch results in a WATCH_EVENT message (see below). 429 * 430 * The event's path matches the watch's <wpath> if it is an child 431 * of <wpath>. 432 * 433 * <wpath> can be a <path> to watch or @<wspecial>. In the 434 * latter case <wspecial> may have any syntax but it matches 435 * (according to the rules above) only the following special 436 * events which are invented by xenstored: 437 * @introduceDomain occurs on INTRODUCE 438 * @releaseDomain occurs on any domain crash or 439 * shutdown, and also on RELEASE 440 * and domain destruction 441 * <wspecial> events are sent to privileged callers or explicitly 442 * via SET_PERMS enabled domains only. 443 * 444 * When a watch is first set up it is triggered once straight 445 * away, with <path> equal to <wpath>. Watches may be triggered 446 * spuriously. The tx_id in a WATCH request is ignored. 447 * 448 * Watches are supposed to be restricted by the permissions 449 * system but in practice the implementation is imperfect. 450 * Applications should not rely on being sent a notification for 451 * paths that they cannot read; however, an application may rely 452 * on being sent a watch when a path which it _is_ able to read 453 * is deleted even if that leaves only a nonexistent unreadable 454 * parent. A notification may omitted if a node's permissions 455 * are changed so as to make it unreadable, in which case future 456 * notifications may be suppressed (and if the node is later made 457 * readable, some notifications may have been lost). 458 * 459 * WATCH_EVENT <epath>|<token>| 460 * Unsolicited `reply' generated for matching modification events 461 * as described above. req_id and tx_id are both 0. 462 * 463 * <epath> is the event's path, ie the actual path that was 464 * modified; however if the event was the recursive removal of an 465 * parent of <wpath>, <epath> is just 466 * <wpath> (rather than the actual path which was removed). So 467 * <epath> is a child of <wpath>, regardless. 468 * 469 * Iff <wpath> for the watch was specified as a relative pathname, 470 * the <epath> path will also be relative (with the same base, 471 * obviously). 472 * 473 * UNWATCH <wpath>|<token>|? 474 * 475 * RESET_WATCHES | 476 * Reset all watches and transactions of the caller. 477 * 478 * ---------- Transactions ---------- 479 * 480 * TRANSACTION_START | <transid>| 481 * <transid> is an opaque uint32_t allocated by xenstored 482 * represented as unsigned decimal. After this, transaction may 483 * be referenced by using <transid> (as 32-bit binary) in the 484 * tx_id request header field. When transaction is started whole 485 * db is copied; reads and writes happen on the copy. 486 * It is not legal to send non-0 tx_id in TRANSACTION_START. 487 * 488 * TRANSACTION_END T| 489 * TRANSACTION_END F| 490 * tx_id must refer to existing transaction. After this 491 * request the tx_id is no longer valid and may be reused by 492 * xenstore. If F, the transaction is discarded. If T, 493 * it is committed: if there were any other intervening writes 494 * then our END gets get EAGAIN. 495 * 496 * The plan is that in the future only intervening `conflicting' 497 * writes cause EAGAIN, meaning only writes or other commits 498 * which changed paths which were read or written in the 499 * transaction at hand. 500 * 501 */ 502 503 static void xs_read(XenXenstoreState *s, unsigned int req_id, 504 xs_transaction_t tx_id, uint8_t *req_data, unsigned int len) 505 { 506 const char *path = (const char *)req_data; 507 struct xsd_sockmsg *rsp = (struct xsd_sockmsg *)s->rsp_data; 508 uint8_t *rsp_data = (uint8_t *)&rsp[1]; 509 g_autoptr(GByteArray) data = g_byte_array_new(); 510 int err; 511 512 if (len == 0 || req_data[len - 1] != '\0') { 513 xs_error(s, req_id, tx_id, EINVAL); 514 return; 515 } 516 517 trace_xenstore_read(tx_id, path); 518 err = xs_impl_read(s->impl, xen_domid, tx_id, path, data); 519 if (err) { 520 xs_error(s, req_id, tx_id, err); 521 return; 522 } 523 524 rsp->type = XS_READ; 525 rsp->req_id = req_id; 526 rsp->tx_id = tx_id; 527 rsp->len = 0; 528 529 len = data->len; 530 if (len > XENSTORE_PAYLOAD_MAX) { 531 xs_error(s, req_id, tx_id, E2BIG); 532 return; 533 } 534 535 memcpy(&rsp_data[rsp->len], data->data, len); 536 rsp->len += len; 537 } 538 539 static void xs_write(XenXenstoreState *s, unsigned int req_id, 540 xs_transaction_t tx_id, uint8_t *req_data, 541 unsigned int len) 542 { 543 g_autoptr(GByteArray) data = g_byte_array_new(); 544 const char *path; 545 int err; 546 547 if (len == 0) { 548 xs_error(s, req_id, tx_id, EINVAL); 549 return; 550 } 551 552 path = (const char *)req_data; 553 554 while (len--) { 555 if (*req_data++ == '\0') { 556 break; 557 } 558 if (len == 0) { 559 xs_error(s, req_id, tx_id, EINVAL); 560 return; 561 } 562 } 563 564 g_byte_array_append(data, req_data, len); 565 566 trace_xenstore_write(tx_id, path); 567 err = xs_impl_write(s->impl, xen_domid, tx_id, path, data); 568 if (err) { 569 xs_error(s, req_id, tx_id, err); 570 return; 571 } 572 573 xs_ok(s, XS_WRITE, req_id, tx_id); 574 } 575 576 static void xs_mkdir(XenXenstoreState *s, unsigned int req_id, 577 xs_transaction_t tx_id, uint8_t *req_data, 578 unsigned int len) 579 { 580 g_autoptr(GByteArray) data = g_byte_array_new(); 581 const char *path; 582 int err; 583 584 if (len == 0 || req_data[len - 1] != '\0') { 585 xs_error(s, req_id, tx_id, EINVAL); 586 return; 587 } 588 589 path = (const char *)req_data; 590 591 trace_xenstore_mkdir(tx_id, path); 592 err = xs_impl_read(s->impl, xen_domid, tx_id, path, data); 593 if (err == ENOENT) { 594 err = xs_impl_write(s->impl, xen_domid, tx_id, path, data); 595 } 596 597 if (!err) { 598 xs_error(s, req_id, tx_id, err); 599 return; 600 } 601 602 xs_ok(s, XS_MKDIR, req_id, tx_id); 603 } 604 605 static void xs_append_strings(XenXenstoreState *s, struct xsd_sockmsg *rsp, 606 GList *strings, unsigned int start, bool truncate) 607 { 608 uint8_t *rsp_data = (uint8_t *)&rsp[1]; 609 GList *l; 610 611 for (l = strings; l; l = l->next) { 612 size_t len = strlen(l->data) + 1; /* Including the NUL termination */ 613 char *str = l->data; 614 615 if (rsp->len + len > XENSTORE_PAYLOAD_MAX) { 616 if (truncate) { 617 len = XENSTORE_PAYLOAD_MAX - rsp->len; 618 if (!len) { 619 return; 620 } 621 } else { 622 xs_error(s, rsp->req_id, rsp->tx_id, E2BIG); 623 return; 624 } 625 } 626 627 if (start) { 628 if (start >= len) { 629 start -= len; 630 continue; 631 } 632 633 str += start; 634 len -= start; 635 start = 0; 636 } 637 638 memcpy(&rsp_data[rsp->len], str, len); 639 rsp->len += len; 640 } 641 /* XS_DIRECTORY_PART wants an extra NUL to indicate the end */ 642 if (truncate && rsp->len < XENSTORE_PAYLOAD_MAX) { 643 rsp_data[rsp->len++] = '\0'; 644 } 645 } 646 647 static void xs_directory(XenXenstoreState *s, unsigned int req_id, 648 xs_transaction_t tx_id, uint8_t *req_data, 649 unsigned int len) 650 { 651 struct xsd_sockmsg *rsp = (struct xsd_sockmsg *)s->rsp_data; 652 GList *items = NULL; 653 const char *path; 654 int err; 655 656 if (len == 0 || req_data[len - 1] != '\0') { 657 xs_error(s, req_id, tx_id, EINVAL); 658 return; 659 } 660 661 path = (const char *)req_data; 662 663 trace_xenstore_directory(tx_id, path); 664 err = xs_impl_directory(s->impl, xen_domid, tx_id, path, NULL, &items); 665 if (err != 0) { 666 xs_error(s, req_id, tx_id, err); 667 return; 668 } 669 670 rsp->type = XS_DIRECTORY; 671 rsp->req_id = req_id; 672 rsp->tx_id = tx_id; 673 rsp->len = 0; 674 675 xs_append_strings(s, rsp, items, 0, false); 676 677 g_list_free_full(items, g_free); 678 } 679 680 static void xs_directory_part(XenXenstoreState *s, unsigned int req_id, 681 xs_transaction_t tx_id, uint8_t *req_data, 682 unsigned int len) 683 { 684 const char *offset_str, *path = (const char *)req_data; 685 struct xsd_sockmsg *rsp = (struct xsd_sockmsg *)s->rsp_data; 686 char *rsp_data = (char *)&rsp[1]; 687 uint64_t gencnt = 0; 688 unsigned int offset; 689 GList *items = NULL; 690 int err; 691 692 if (len == 0) { 693 xs_error(s, req_id, tx_id, EINVAL); 694 return; 695 } 696 697 while (len--) { 698 if (*req_data++ == '\0') { 699 break; 700 } 701 if (len == 0) { 702 xs_error(s, req_id, tx_id, EINVAL); 703 return; 704 } 705 } 706 707 offset_str = (const char *)req_data; 708 while (len--) { 709 if (*req_data++ == '\0') { 710 break; 711 } 712 if (len == 0) { 713 xs_error(s, req_id, tx_id, EINVAL); 714 return; 715 } 716 } 717 718 if (len) { 719 xs_error(s, req_id, tx_id, EINVAL); 720 return; 721 } 722 723 if (qemu_strtoui(offset_str, NULL, 10, &offset) < 0) { 724 xs_error(s, req_id, tx_id, EINVAL); 725 return; 726 } 727 728 trace_xenstore_directory_part(tx_id, path, offset); 729 err = xs_impl_directory(s->impl, xen_domid, tx_id, path, &gencnt, &items); 730 if (err != 0) { 731 xs_error(s, req_id, tx_id, err); 732 return; 733 } 734 735 rsp->type = XS_DIRECTORY_PART; 736 rsp->req_id = req_id; 737 rsp->tx_id = tx_id; 738 rsp->len = snprintf(rsp_data, XENSTORE_PAYLOAD_MAX, "%" PRIu64, gencnt) + 1; 739 740 xs_append_strings(s, rsp, items, offset, true); 741 742 g_list_free_full(items, g_free); 743 } 744 745 static void xs_transaction_start(XenXenstoreState *s, unsigned int req_id, 746 xs_transaction_t tx_id, uint8_t *req_data, 747 unsigned int len) 748 { 749 struct xsd_sockmsg *rsp = (struct xsd_sockmsg *)s->rsp_data; 750 char *rsp_data = (char *)&rsp[1]; 751 int err; 752 753 if (len != 1 || req_data[0] != '\0') { 754 xs_error(s, req_id, tx_id, EINVAL); 755 return; 756 } 757 758 rsp->type = XS_TRANSACTION_START; 759 rsp->req_id = req_id; 760 rsp->tx_id = tx_id; 761 rsp->len = 0; 762 763 err = xs_impl_transaction_start(s->impl, xen_domid, &tx_id); 764 if (err) { 765 xs_error(s, req_id, tx_id, err); 766 return; 767 } 768 769 trace_xenstore_transaction_start(tx_id); 770 771 rsp->len = snprintf(rsp_data, XENSTORE_PAYLOAD_MAX, "%u", tx_id); 772 assert(rsp->len < XENSTORE_PAYLOAD_MAX); 773 rsp->len++; 774 } 775 776 static void xs_transaction_end(XenXenstoreState *s, unsigned int req_id, 777 xs_transaction_t tx_id, uint8_t *req_data, 778 unsigned int len) 779 { 780 bool commit; 781 int err; 782 783 if (len != 2 || req_data[1] != '\0') { 784 xs_error(s, req_id, tx_id, EINVAL); 785 return; 786 } 787 788 switch (req_data[0]) { 789 case 'T': 790 commit = true; 791 break; 792 case 'F': 793 commit = false; 794 break; 795 default: 796 xs_error(s, req_id, tx_id, EINVAL); 797 return; 798 } 799 800 trace_xenstore_transaction_end(tx_id, commit); 801 err = xs_impl_transaction_end(s->impl, xen_domid, tx_id, commit); 802 if (err) { 803 xs_error(s, req_id, tx_id, err); 804 return; 805 } 806 807 xs_ok(s, XS_TRANSACTION_END, req_id, tx_id); 808 } 809 810 static void xs_rm(XenXenstoreState *s, unsigned int req_id, 811 xs_transaction_t tx_id, uint8_t *req_data, unsigned int len) 812 { 813 const char *path = (const char *)req_data; 814 int err; 815 816 if (len == 0 || req_data[len - 1] != '\0') { 817 xs_error(s, req_id, tx_id, EINVAL); 818 return; 819 } 820 821 trace_xenstore_rm(tx_id, path); 822 err = xs_impl_rm(s->impl, xen_domid, tx_id, path); 823 if (err) { 824 xs_error(s, req_id, tx_id, err); 825 return; 826 } 827 828 xs_ok(s, XS_RM, req_id, tx_id); 829 } 830 831 static void xs_get_perms(XenXenstoreState *s, unsigned int req_id, 832 xs_transaction_t tx_id, uint8_t *req_data, 833 unsigned int len) 834 { 835 const char *path = (const char *)req_data; 836 struct xsd_sockmsg *rsp = (struct xsd_sockmsg *)s->rsp_data; 837 GList *perms = NULL; 838 int err; 839 840 if (len == 0 || req_data[len - 1] != '\0') { 841 xs_error(s, req_id, tx_id, EINVAL); 842 return; 843 } 844 845 trace_xenstore_get_perms(tx_id, path); 846 err = xs_impl_get_perms(s->impl, xen_domid, tx_id, path, &perms); 847 if (err) { 848 xs_error(s, req_id, tx_id, err); 849 return; 850 } 851 852 rsp->type = XS_GET_PERMS; 853 rsp->req_id = req_id; 854 rsp->tx_id = tx_id; 855 rsp->len = 0; 856 857 xs_append_strings(s, rsp, perms, 0, false); 858 859 g_list_free_full(perms, g_free); 860 } 861 862 static void xs_set_perms(XenXenstoreState *s, unsigned int req_id, 863 xs_transaction_t tx_id, uint8_t *req_data, 864 unsigned int len) 865 { 866 const char *path = (const char *)req_data; 867 uint8_t *perm; 868 GList *perms = NULL; 869 int err; 870 871 if (len == 0) { 872 xs_error(s, req_id, tx_id, EINVAL); 873 return; 874 } 875 876 while (len--) { 877 if (*req_data++ == '\0') { 878 break; 879 } 880 if (len == 0) { 881 xs_error(s, req_id, tx_id, EINVAL); 882 return; 883 } 884 } 885 886 perm = req_data; 887 while (len--) { 888 if (*req_data++ == '\0') { 889 perms = g_list_append(perms, perm); 890 perm = req_data; 891 } 892 } 893 894 /* 895 * Note that there may be trailing garbage at the end of the buffer. 896 * This is explicitly permitted by the '?' at the end of the definition: 897 * 898 * SET_PERMS <path>|<perm-as-string>|+? 899 */ 900 901 trace_xenstore_set_perms(tx_id, path); 902 err = xs_impl_set_perms(s->impl, xen_domid, tx_id, path, perms); 903 g_list_free(perms); 904 if (err) { 905 xs_error(s, req_id, tx_id, err); 906 return; 907 } 908 909 xs_ok(s, XS_SET_PERMS, req_id, tx_id); 910 } 911 912 static void xs_watch(XenXenstoreState *s, unsigned int req_id, 913 xs_transaction_t tx_id, uint8_t *req_data, 914 unsigned int len) 915 { 916 const char *token, *path = (const char *)req_data; 917 int err; 918 919 if (len == 0) { 920 xs_error(s, req_id, tx_id, EINVAL); 921 return; 922 } 923 924 while (len--) { 925 if (*req_data++ == '\0') { 926 break; 927 } 928 if (len == 0) { 929 xs_error(s, req_id, tx_id, EINVAL); 930 return; 931 } 932 } 933 934 token = (const char *)req_data; 935 while (len--) { 936 if (*req_data++ == '\0') { 937 break; 938 } 939 if (len == 0) { 940 xs_error(s, req_id, tx_id, EINVAL); 941 return; 942 } 943 } 944 945 /* 946 * Note that there may be trailing garbage at the end of the buffer. 947 * This is explicitly permitted by the '?' at the end of the definition: 948 * 949 * WATCH <wpath>|<token>|? 950 */ 951 952 trace_xenstore_watch(path, token); 953 err = xs_impl_watch(s->impl, xen_domid, path, token, fire_watch_cb, s); 954 if (err) { 955 xs_error(s, req_id, tx_id, err); 956 return; 957 } 958 959 xs_ok(s, XS_WATCH, req_id, tx_id); 960 } 961 962 static void xs_unwatch(XenXenstoreState *s, unsigned int req_id, 963 xs_transaction_t tx_id, uint8_t *req_data, 964 unsigned int len) 965 { 966 const char *token, *path = (const char *)req_data; 967 int err; 968 969 if (len == 0) { 970 xs_error(s, req_id, tx_id, EINVAL); 971 return; 972 } 973 974 while (len--) { 975 if (*req_data++ == '\0') { 976 break; 977 } 978 if (len == 0) { 979 xs_error(s, req_id, tx_id, EINVAL); 980 return; 981 } 982 } 983 984 token = (const char *)req_data; 985 while (len--) { 986 if (*req_data++ == '\0') { 987 break; 988 } 989 if (len == 0) { 990 xs_error(s, req_id, tx_id, EINVAL); 991 return; 992 } 993 } 994 995 trace_xenstore_unwatch(path, token); 996 err = xs_impl_unwatch(s->impl, xen_domid, path, token, fire_watch_cb, s); 997 if (err) { 998 xs_error(s, req_id, tx_id, err); 999 return; 1000 } 1001 1002 xs_ok(s, XS_UNWATCH, req_id, tx_id); 1003 } 1004 1005 static void xs_reset_watches(XenXenstoreState *s, unsigned int req_id, 1006 xs_transaction_t tx_id, uint8_t *req_data, 1007 unsigned int len) 1008 { 1009 if (len == 0 || req_data[len - 1] != '\0') { 1010 xs_error(s, req_id, tx_id, EINVAL); 1011 return; 1012 } 1013 1014 trace_xenstore_reset_watches(); 1015 xs_impl_reset_watches(s->impl, xen_domid); 1016 1017 xs_ok(s, XS_RESET_WATCHES, req_id, tx_id); 1018 } 1019 1020 static void xs_priv(XenXenstoreState *s, unsigned int req_id, 1021 xs_transaction_t tx_id, uint8_t *data, 1022 unsigned int len) 1023 { 1024 xs_error(s, req_id, tx_id, EACCES); 1025 } 1026 1027 static void xs_unimpl(XenXenstoreState *s, unsigned int req_id, 1028 xs_transaction_t tx_id, uint8_t *data, 1029 unsigned int len) 1030 { 1031 xs_error(s, req_id, tx_id, ENOSYS); 1032 } 1033 1034 typedef void (*xs_impl)(XenXenstoreState *s, unsigned int req_id, 1035 xs_transaction_t tx_id, uint8_t *data, 1036 unsigned int len); 1037 1038 struct xsd_req { 1039 const char *name; 1040 xs_impl fn; 1041 }; 1042 #define XSD_REQ(_type, _fn) \ 1043 [_type] = { .name = #_type, .fn = _fn } 1044 1045 struct xsd_req xsd_reqs[] = { 1046 XSD_REQ(XS_READ, xs_read), 1047 XSD_REQ(XS_WRITE, xs_write), 1048 XSD_REQ(XS_MKDIR, xs_mkdir), 1049 XSD_REQ(XS_DIRECTORY, xs_directory), 1050 XSD_REQ(XS_DIRECTORY_PART, xs_directory_part), 1051 XSD_REQ(XS_TRANSACTION_START, xs_transaction_start), 1052 XSD_REQ(XS_TRANSACTION_END, xs_transaction_end), 1053 XSD_REQ(XS_RM, xs_rm), 1054 XSD_REQ(XS_GET_PERMS, xs_get_perms), 1055 XSD_REQ(XS_SET_PERMS, xs_set_perms), 1056 XSD_REQ(XS_WATCH, xs_watch), 1057 XSD_REQ(XS_UNWATCH, xs_unwatch), 1058 XSD_REQ(XS_CONTROL, xs_priv), 1059 XSD_REQ(XS_INTRODUCE, xs_priv), 1060 XSD_REQ(XS_RELEASE, xs_priv), 1061 XSD_REQ(XS_IS_DOMAIN_INTRODUCED, xs_priv), 1062 XSD_REQ(XS_RESUME, xs_priv), 1063 XSD_REQ(XS_SET_TARGET, xs_priv), 1064 XSD_REQ(XS_RESET_WATCHES, xs_reset_watches), 1065 }; 1066 1067 static void process_req(XenXenstoreState *s) 1068 { 1069 struct xsd_sockmsg *req = (struct xsd_sockmsg *)s->req_data; 1070 xs_impl handler = NULL; 1071 1072 assert(req_pending(s)); 1073 assert(!s->rsp_pending); 1074 1075 if (req->type < ARRAY_SIZE(xsd_reqs)) { 1076 handler = xsd_reqs[req->type].fn; 1077 } 1078 if (!handler) { 1079 handler = &xs_unimpl; 1080 } 1081 1082 handler(s, req->req_id, req->tx_id, (uint8_t *)&req[1], req->len); 1083 1084 s->rsp_pending = true; 1085 reset_req(s); 1086 } 1087 1088 static unsigned int copy_from_ring(XenXenstoreState *s, uint8_t *ptr, 1089 unsigned int len) 1090 { 1091 if (!len) { 1092 return 0; 1093 } 1094 1095 XENSTORE_RING_IDX prod = qatomic_read(&s->xs->req_prod); 1096 XENSTORE_RING_IDX cons = qatomic_read(&s->xs->req_cons); 1097 unsigned int copied = 0; 1098 1099 /* Ensure the ring contents don't cross the req_prod access. */ 1100 smp_rmb(); 1101 1102 while (len) { 1103 unsigned int avail = prod - cons; 1104 unsigned int offset = MASK_XENSTORE_IDX(cons); 1105 unsigned int copylen = avail; 1106 1107 if (avail > XENSTORE_RING_SIZE) { 1108 error_report("XenStore ring handling error"); 1109 s->fatal_error = true; 1110 break; 1111 } else if (avail == 0) { 1112 break; 1113 } 1114 1115 if (copylen > len) { 1116 copylen = len; 1117 } 1118 if (copylen > XENSTORE_RING_SIZE - offset) { 1119 copylen = XENSTORE_RING_SIZE - offset; 1120 } 1121 1122 memcpy(ptr, &s->xs->req[offset], copylen); 1123 copied += copylen; 1124 1125 ptr += copylen; 1126 len -= copylen; 1127 1128 cons += copylen; 1129 } 1130 1131 /* 1132 * Not sure this ever mattered except on Alpha, but this barrier 1133 * is to ensure that the update to req_cons is globally visible 1134 * only after we have consumed all the data from the ring, and we 1135 * don't end up seeing data written to the ring *after* the other 1136 * end sees the update and writes more to the ring. Xen's own 1137 * xenstored has the same barrier here (although with no comment 1138 * at all, obviously, because it's Xen code). 1139 */ 1140 smp_mb(); 1141 1142 qatomic_set(&s->xs->req_cons, cons); 1143 1144 return copied; 1145 } 1146 1147 static unsigned int copy_to_ring(XenXenstoreState *s, uint8_t *ptr, 1148 unsigned int len) 1149 { 1150 if (!len) { 1151 return 0; 1152 } 1153 1154 XENSTORE_RING_IDX cons = qatomic_read(&s->xs->rsp_cons); 1155 XENSTORE_RING_IDX prod = qatomic_read(&s->xs->rsp_prod); 1156 unsigned int copied = 0; 1157 1158 /* 1159 * This matches the barrier in copy_to_ring() (or the guest's 1160 * equivalent) between writing the data to the ring and updating 1161 * rsp_prod. It protects against the pathological case (which 1162 * again I think never happened except on Alpha) where our 1163 * subsequent writes to the ring could *cross* the read of 1164 * rsp_cons and the guest could see the new data when it was 1165 * intending to read the old. 1166 */ 1167 smp_mb(); 1168 1169 while (len) { 1170 unsigned int avail = cons + XENSTORE_RING_SIZE - prod; 1171 unsigned int offset = MASK_XENSTORE_IDX(prod); 1172 unsigned int copylen = len; 1173 1174 if (avail > XENSTORE_RING_SIZE) { 1175 error_report("XenStore ring handling error"); 1176 s->fatal_error = true; 1177 break; 1178 } else if (avail == 0) { 1179 break; 1180 } 1181 1182 if (copylen > avail) { 1183 copylen = avail; 1184 } 1185 if (copylen > XENSTORE_RING_SIZE - offset) { 1186 copylen = XENSTORE_RING_SIZE - offset; 1187 } 1188 1189 1190 memcpy(&s->xs->rsp[offset], ptr, copylen); 1191 copied += copylen; 1192 1193 ptr += copylen; 1194 len -= copylen; 1195 1196 prod += copylen; 1197 } 1198 1199 /* Ensure the ring contents are seen before rsp_prod update. */ 1200 smp_wmb(); 1201 1202 qatomic_set(&s->xs->rsp_prod, prod); 1203 1204 return copied; 1205 } 1206 1207 static unsigned int get_req(XenXenstoreState *s) 1208 { 1209 unsigned int copied = 0; 1210 1211 if (s->fatal_error) { 1212 return 0; 1213 } 1214 1215 assert(!req_pending(s)); 1216 1217 if (s->req_offset < XENSTORE_HEADER_SIZE) { 1218 void *ptr = s->req_data + s->req_offset; 1219 unsigned int len = XENSTORE_HEADER_SIZE; 1220 unsigned int copylen = copy_from_ring(s, ptr, len); 1221 1222 copied += copylen; 1223 s->req_offset += copylen; 1224 } 1225 1226 if (s->req_offset >= XENSTORE_HEADER_SIZE) { 1227 struct xsd_sockmsg *req = (struct xsd_sockmsg *)s->req_data; 1228 1229 if (req->len > (uint32_t)XENSTORE_PAYLOAD_MAX) { 1230 error_report("Illegal XenStore request"); 1231 s->fatal_error = true; 1232 return 0; 1233 } 1234 1235 void *ptr = s->req_data + s->req_offset; 1236 unsigned int len = XENSTORE_HEADER_SIZE + req->len - s->req_offset; 1237 unsigned int copylen = copy_from_ring(s, ptr, len); 1238 1239 copied += copylen; 1240 s->req_offset += copylen; 1241 } 1242 1243 return copied; 1244 } 1245 1246 static unsigned int put_rsp(XenXenstoreState *s) 1247 { 1248 if (s->fatal_error) { 1249 return 0; 1250 } 1251 1252 assert(s->rsp_pending); 1253 1254 struct xsd_sockmsg *rsp = (struct xsd_sockmsg *)s->rsp_data; 1255 assert(s->rsp_offset < XENSTORE_HEADER_SIZE + rsp->len); 1256 1257 void *ptr = s->rsp_data + s->rsp_offset; 1258 unsigned int len = XENSTORE_HEADER_SIZE + rsp->len - s->rsp_offset; 1259 unsigned int copylen = copy_to_ring(s, ptr, len); 1260 1261 s->rsp_offset += copylen; 1262 1263 /* Have we produced a complete response? */ 1264 if (s->rsp_offset == XENSTORE_HEADER_SIZE + rsp->len) { 1265 reset_rsp(s); 1266 } 1267 1268 return copylen; 1269 } 1270 1271 static void deliver_watch(XenXenstoreState *s, const char *path, 1272 const char *token) 1273 { 1274 struct xsd_sockmsg *rsp = (struct xsd_sockmsg *)s->rsp_data; 1275 uint8_t *rsp_data = (uint8_t *)&rsp[1]; 1276 unsigned int len; 1277 1278 assert(!s->rsp_pending); 1279 1280 trace_xenstore_watch_event(path, token); 1281 1282 rsp->type = XS_WATCH_EVENT; 1283 rsp->req_id = 0; 1284 rsp->tx_id = 0; 1285 rsp->len = 0; 1286 1287 len = strlen(path); 1288 1289 /* XENSTORE_ABS/REL_PATH_MAX should ensure there can be no overflow */ 1290 assert(rsp->len + len < XENSTORE_PAYLOAD_MAX); 1291 1292 memcpy(&rsp_data[rsp->len], path, len); 1293 rsp->len += len; 1294 rsp_data[rsp->len] = '\0'; 1295 rsp->len++; 1296 1297 len = strlen(token); 1298 /* 1299 * It is possible for the guest to have chosen a token that will 1300 * not fit (along with the patch) into a watch event. We have no 1301 * choice but to drop the event if this is the case. 1302 */ 1303 if (rsp->len + len >= XENSTORE_PAYLOAD_MAX) { 1304 return; 1305 } 1306 1307 memcpy(&rsp_data[rsp->len], token, len); 1308 rsp->len += len; 1309 rsp_data[rsp->len] = '\0'; 1310 rsp->len++; 1311 1312 s->rsp_pending = true; 1313 } 1314 1315 struct watch_event { 1316 char *path; 1317 char *token; 1318 }; 1319 1320 static void free_watch_event(struct watch_event *ev) 1321 { 1322 if (ev) { 1323 g_free(ev->path); 1324 g_free(ev->token); 1325 g_free(ev); 1326 } 1327 } 1328 1329 static void queue_watch(XenXenstoreState *s, const char *path, 1330 const char *token) 1331 { 1332 struct watch_event *ev = g_new0(struct watch_event, 1); 1333 1334 ev->path = g_strdup(path); 1335 ev->token = g_strdup(token); 1336 1337 s->watch_events = g_list_append(s->watch_events, ev); 1338 } 1339 1340 static void fire_watch_cb(void *opaque, const char *path, const char *token) 1341 { 1342 XenXenstoreState *s = opaque; 1343 1344 assert(bql_locked()); 1345 1346 /* 1347 * If there's a response pending, we obviously can't scribble over 1348 * it. But if there's a request pending, it has dibs on the buffer 1349 * too. 1350 * 1351 * In the common case of a watch firing due to backend activity 1352 * when the ring was otherwise idle, we should be able to copy the 1353 * strings directly into the rsp_data and thence the actual ring, 1354 * without needing to perform any allocations and queue them. 1355 */ 1356 if (s->rsp_pending || req_pending(s)) { 1357 queue_watch(s, path, token); 1358 } else { 1359 deliver_watch(s, path, token); 1360 /* 1361 * Attempt to queue the message into the actual ring, and send 1362 * the event channel notification if any bytes are copied. 1363 */ 1364 if (s->rsp_pending && put_rsp(s) > 0) { 1365 xen_be_evtchn_notify(s->eh, s->be_port); 1366 } 1367 } 1368 } 1369 1370 static void process_watch_events(XenXenstoreState *s) 1371 { 1372 struct watch_event *ev = s->watch_events->data; 1373 1374 deliver_watch(s, ev->path, ev->token); 1375 1376 s->watch_events = g_list_remove(s->watch_events, ev); 1377 free_watch_event(ev); 1378 } 1379 1380 static void xen_xenstore_event(void *opaque) 1381 { 1382 XenXenstoreState *s = opaque; 1383 evtchn_port_t port = xen_be_evtchn_pending(s->eh); 1384 unsigned int copied_to, copied_from; 1385 bool processed, notify = false; 1386 1387 if (port != s->be_port) { 1388 return; 1389 } 1390 1391 /* We know this is a no-op. */ 1392 xen_be_evtchn_unmask(s->eh, port); 1393 1394 do { 1395 copied_to = copied_from = 0; 1396 processed = false; 1397 1398 if (!s->rsp_pending && s->watch_events) { 1399 process_watch_events(s); 1400 } 1401 1402 if (s->rsp_pending) { 1403 copied_to = put_rsp(s); 1404 } 1405 1406 if (!req_pending(s)) { 1407 copied_from = get_req(s); 1408 } 1409 1410 if (req_pending(s) && !s->rsp_pending && !s->watch_events) { 1411 process_req(s); 1412 processed = true; 1413 } 1414 1415 notify |= copied_to || copied_from; 1416 } while (copied_to || copied_from || processed); 1417 1418 if (notify) { 1419 xen_be_evtchn_notify(s->eh, s->be_port); 1420 } 1421 } 1422 1423 static void alloc_guest_port(XenXenstoreState *s) 1424 { 1425 struct evtchn_alloc_unbound alloc = { 1426 .dom = DOMID_SELF, 1427 .remote_dom = DOMID_QEMU, 1428 }; 1429 1430 if (!xen_evtchn_alloc_unbound_op(&alloc)) { 1431 s->guest_port = alloc.port; 1432 } 1433 } 1434 1435 int xen_xenstore_reset(void) 1436 { 1437 XenXenstoreState *s = xen_xenstore_singleton; 1438 int console_port; 1439 GList *perms; 1440 int err; 1441 1442 if (!s) { 1443 return -ENOTSUP; 1444 } 1445 1446 s->req_offset = s->rsp_offset = 0; 1447 s->rsp_pending = false; 1448 1449 if (!memory_region_is_mapped(&s->xenstore_page)) { 1450 uint64_t gpa = XEN_SPECIAL_PFN(XENSTORE) << TARGET_PAGE_BITS; 1451 xen_overlay_do_map_page(&s->xenstore_page, gpa); 1452 } 1453 1454 alloc_guest_port(s); 1455 1456 /* 1457 * As qemu/dom0, bind to the guest's port. For incoming migration, this 1458 * will be unbound as the guest's evtchn table is overwritten. We then 1459 * rebind to the correct guest port in xen_xenstore_post_load(). 1460 */ 1461 err = xen_be_evtchn_bind_interdomain(s->eh, xen_domid, s->guest_port); 1462 if (err < 0) { 1463 return err; 1464 } 1465 s->be_port = err; 1466 1467 /* Create frontend store nodes */ 1468 perms = g_list_append(NULL, xs_perm_as_string(XS_PERM_NONE, DOMID_QEMU)); 1469 perms = g_list_append(perms, xs_perm_as_string(XS_PERM_READ, xen_domid)); 1470 1471 relpath_printf(s, perms, "store/port", "%u", s->guest_port); 1472 relpath_printf(s, perms, "store/ring-ref", "%lu", 1473 XEN_SPECIAL_PFN(XENSTORE)); 1474 1475 console_port = xen_primary_console_get_port(); 1476 if (console_port) { 1477 relpath_printf(s, perms, "console/ring-ref", "%lu", 1478 XEN_SPECIAL_PFN(CONSOLE)); 1479 relpath_printf(s, perms, "console/port", "%u", console_port); 1480 relpath_printf(s, perms, "console/state", "%u", XenbusStateInitialised); 1481 } 1482 1483 g_list_free_full(perms, g_free); 1484 1485 /* 1486 * We don't actually access the guest's page through the grant, because 1487 * this isn't real Xen, and we can just use the page we gave it in the 1488 * first place. Map the grant anyway, mostly for cosmetic purposes so 1489 * it *looks* like it's in use in the guest-visible grant table. 1490 */ 1491 s->gt = qemu_xen_gnttab_open(); 1492 uint32_t xs_gntref = GNTTAB_RESERVED_XENSTORE; 1493 s->granted_xs = qemu_xen_gnttab_map_refs(s->gt, 1, xen_domid, &xs_gntref, 1494 PROT_READ | PROT_WRITE); 1495 1496 return 0; 1497 } 1498 1499 struct qemu_xs_handle { 1500 XenstoreImplState *impl; 1501 GList *watches; 1502 QEMUBH *watch_bh; 1503 }; 1504 1505 struct qemu_xs_watch { 1506 struct qemu_xs_handle *h; 1507 char *path; 1508 xs_watch_fn fn; 1509 void *opaque; 1510 GList *events; 1511 }; 1512 1513 static char *xs_be_get_domain_path(struct qemu_xs_handle *h, unsigned int domid) 1514 { 1515 return g_strdup_printf("/local/domain/%u", domid); 1516 } 1517 1518 static char **xs_be_directory(struct qemu_xs_handle *h, xs_transaction_t t, 1519 const char *path, unsigned int *num) 1520 { 1521 GList *items = NULL, *l; 1522 unsigned int i = 0; 1523 char **items_ret; 1524 int err; 1525 1526 err = xs_impl_directory(h->impl, DOMID_QEMU, t, path, NULL, &items); 1527 if (err) { 1528 errno = err; 1529 return NULL; 1530 } 1531 1532 items_ret = g_new0(char *, g_list_length(items) + 1); 1533 *num = 0; 1534 for (l = items; l; l = l->next) { 1535 items_ret[i++] = l->data; 1536 (*num)++; 1537 } 1538 g_list_free(items); 1539 return items_ret; 1540 } 1541 1542 static void *xs_be_read(struct qemu_xs_handle *h, xs_transaction_t t, 1543 const char *path, unsigned int *len) 1544 { 1545 GByteArray *data = g_byte_array_new(); 1546 bool free_segment = false; 1547 int err; 1548 1549 err = xs_impl_read(h->impl, DOMID_QEMU, t, path, data); 1550 if (err) { 1551 free_segment = true; 1552 errno = err; 1553 } else { 1554 if (len) { 1555 *len = data->len; 1556 } 1557 /* The xen-bus-helper code expects to get NUL terminated string! */ 1558 g_byte_array_append(data, (void *)"", 1); 1559 } 1560 1561 return g_byte_array_free(data, free_segment); 1562 } 1563 1564 static bool xs_be_write(struct qemu_xs_handle *h, xs_transaction_t t, 1565 const char *path, const void *data, unsigned int len) 1566 { 1567 GByteArray *gdata = g_byte_array_new(); 1568 int err; 1569 1570 g_byte_array_append(gdata, data, len); 1571 err = xs_impl_write(h->impl, DOMID_QEMU, t, path, gdata); 1572 g_byte_array_unref(gdata); 1573 if (err) { 1574 errno = err; 1575 return false; 1576 } 1577 return true; 1578 } 1579 1580 static bool xs_be_create(struct qemu_xs_handle *h, xs_transaction_t t, 1581 unsigned int owner, unsigned int domid, 1582 unsigned int perms, const char *path) 1583 { 1584 g_autoptr(GByteArray) data = g_byte_array_new(); 1585 GList *perms_list = NULL; 1586 int err; 1587 1588 /* mkdir does this */ 1589 err = xs_impl_read(h->impl, DOMID_QEMU, t, path, data); 1590 if (err == ENOENT) { 1591 err = xs_impl_write(h->impl, DOMID_QEMU, t, path, data); 1592 } 1593 if (err) { 1594 errno = err; 1595 return false; 1596 } 1597 1598 perms_list = g_list_append(perms_list, 1599 xs_perm_as_string(XS_PERM_NONE, owner)); 1600 perms_list = g_list_append(perms_list, 1601 xs_perm_as_string(perms, domid)); 1602 1603 err = xs_impl_set_perms(h->impl, DOMID_QEMU, t, path, perms_list); 1604 g_list_free_full(perms_list, g_free); 1605 if (err) { 1606 errno = err; 1607 return false; 1608 } 1609 return true; 1610 } 1611 1612 static bool xs_be_destroy(struct qemu_xs_handle *h, xs_transaction_t t, 1613 const char *path) 1614 { 1615 int err = xs_impl_rm(h->impl, DOMID_QEMU, t, path); 1616 if (err) { 1617 errno = err; 1618 return false; 1619 } 1620 return true; 1621 } 1622 1623 static void be_watch_bh(void *_h) 1624 { 1625 struct qemu_xs_handle *h = _h; 1626 GList *l; 1627 1628 for (l = h->watches; l; l = l->next) { 1629 struct qemu_xs_watch *w = l->data; 1630 1631 while (w->events) { 1632 struct watch_event *ev = w->events->data; 1633 1634 w->fn(w->opaque, ev->path); 1635 1636 w->events = g_list_remove(w->events, ev); 1637 free_watch_event(ev); 1638 } 1639 } 1640 } 1641 1642 static void xs_be_watch_cb(void *opaque, const char *path, const char *token) 1643 { 1644 struct watch_event *ev = g_new0(struct watch_event, 1); 1645 struct qemu_xs_watch *w = opaque; 1646 1647 /* We don't care about the token */ 1648 ev->path = g_strdup(path); 1649 w->events = g_list_append(w->events, ev); 1650 1651 qemu_bh_schedule(w->h->watch_bh); 1652 } 1653 1654 static struct qemu_xs_watch *xs_be_watch(struct qemu_xs_handle *h, 1655 const char *path, xs_watch_fn fn, 1656 void *opaque) 1657 { 1658 struct qemu_xs_watch *w = g_new0(struct qemu_xs_watch, 1); 1659 int err; 1660 1661 w->h = h; 1662 w->fn = fn; 1663 w->opaque = opaque; 1664 1665 err = xs_impl_watch(h->impl, DOMID_QEMU, path, NULL, xs_be_watch_cb, w); 1666 if (err) { 1667 errno = err; 1668 g_free(w); 1669 return NULL; 1670 } 1671 1672 w->path = g_strdup(path); 1673 h->watches = g_list_append(h->watches, w); 1674 return w; 1675 } 1676 1677 static void xs_be_unwatch(struct qemu_xs_handle *h, struct qemu_xs_watch *w) 1678 { 1679 xs_impl_unwatch(h->impl, DOMID_QEMU, w->path, NULL, xs_be_watch_cb, w); 1680 1681 h->watches = g_list_remove(h->watches, w); 1682 g_list_free_full(w->events, (GDestroyNotify)free_watch_event); 1683 g_free(w->path); 1684 g_free(w); 1685 } 1686 1687 static xs_transaction_t xs_be_transaction_start(struct qemu_xs_handle *h) 1688 { 1689 unsigned int new_tx = XBT_NULL; 1690 int err = xs_impl_transaction_start(h->impl, DOMID_QEMU, &new_tx); 1691 if (err) { 1692 errno = err; 1693 return XBT_NULL; 1694 } 1695 return new_tx; 1696 } 1697 1698 static bool xs_be_transaction_end(struct qemu_xs_handle *h, xs_transaction_t t, 1699 bool abort) 1700 { 1701 int err = xs_impl_transaction_end(h->impl, DOMID_QEMU, t, !abort); 1702 if (err) { 1703 errno = err; 1704 return false; 1705 } 1706 return true; 1707 } 1708 1709 static struct qemu_xs_handle *xs_be_open(void) 1710 { 1711 XenXenstoreState *s = xen_xenstore_singleton; 1712 struct qemu_xs_handle *h; 1713 1714 if (!s || !s->impl) { 1715 errno = -ENOSYS; 1716 return NULL; 1717 } 1718 1719 h = g_new0(struct qemu_xs_handle, 1); 1720 h->impl = s->impl; 1721 1722 h->watch_bh = aio_bh_new(qemu_get_aio_context(), be_watch_bh, h); 1723 1724 return h; 1725 } 1726 1727 static void xs_be_close(struct qemu_xs_handle *h) 1728 { 1729 while (h->watches) { 1730 struct qemu_xs_watch *w = h->watches->data; 1731 xs_be_unwatch(h, w); 1732 } 1733 1734 qemu_bh_delete(h->watch_bh); 1735 g_free(h); 1736 } 1737 1738 static struct xenstore_backend_ops emu_xenstore_backend_ops = { 1739 .open = xs_be_open, 1740 .close = xs_be_close, 1741 .get_domain_path = xs_be_get_domain_path, 1742 .directory = xs_be_directory, 1743 .read = xs_be_read, 1744 .write = xs_be_write, 1745 .create = xs_be_create, 1746 .destroy = xs_be_destroy, 1747 .watch = xs_be_watch, 1748 .unwatch = xs_be_unwatch, 1749 .transaction_start = xs_be_transaction_start, 1750 .transaction_end = xs_be_transaction_end, 1751 }; 1752