plugins/core.c

   1 /*
   2  * QEMU Plugin Core code
   3  *
   4  * This is the core code that deals with injecting instrumentation into the code
   5  *
   6  * Copyright (C) 2017, Emilio G. Cota <cota@braap.org>
   7  * Copyright (C) 2019, Linaro
   8  *
   9  * License: GNU GPL, version 2 or later.
  10  *   See the COPYING file in the top-level directory.
  11  *
  12  * SPDX-License-Identifier: GPL-2.0-or-later
  13  */
  14 #include "qemu/osdep.h"
  15 #include "qemu/error-report.h"
  16 #include "qemu/config-file.h"
  17 #include "qapi/error.h"
  18 #include "qemu/lockable.h"
  19 #include "qemu/option.h"
  20 #include "qemu/plugin.h"
  21 #include "qemu/queue.h"
  22 #include "qemu/rcu_queue.h"
  23 #include "qemu/xxhash.h"
  24 #include "qemu/rcu.h"
  25 #include "hw/core/cpu.h"
  26
  27 #include "exec/exec-all.h"
  28 #include "exec/tb-flush.h"
  29 #include "tcg/tcg.h"
  30 #include "tcg/tcg-op.h"
  31 #include "plugin.h"
  32
  33 struct qemu_plugin_cb {
  34     struct qemu_plugin_ctx *ctx;
  35     union qemu_plugin_cb_sig f;
  36     void *udata;
  37     QLIST_ENTRY(qemu_plugin_cb) entry;
  38 };
  39
  40 struct qemu_plugin_state plugin;
  41
  42 struct qemu_plugin_ctx *plugin_id_to_ctx_locked(qemu_plugin_id_t id)
  43 {
  44     struct qemu_plugin_ctx *ctx;
  45     qemu_plugin_id_t *id_p;
  46
  47     id_p = g_hash_table_lookup(plugin.id_ht, &id);
  48     ctx = container_of(id_p, struct qemu_plugin_ctx, id);
  49     if (ctx == NULL) {
  50         error_report("plugin: invalid plugin id %" PRIu64, id);
  51         abort();
  52     }
  53     return ctx;
  54 }
  55
  56 static void plugin_cpu_update__async(CPUState *cpu, run_on_cpu_data data)
  57 {
  58     bitmap_copy(cpu->plugin_state->event_mask,
  59                 &data.host_ulong, QEMU_PLUGIN_EV_MAX);
  60     tcg_flush_jmp_cache(cpu);
  61 }
  62
  63 static void plugin_cpu_update__locked(gpointer k, gpointer v, gpointer udata)
  64 {
  65     CPUState *cpu = container_of(k, CPUState, cpu_index);
  66     run_on_cpu_data mask = RUN_ON_CPU_HOST_ULONG(*plugin.mask);
  67
  68     if (DEVICE(cpu)->realized) {
  69         async_run_on_cpu(cpu, plugin_cpu_update__async, mask);
  70     } else {
  71         plugin_cpu_update__async(cpu, mask);
  72     }
  73 }
  74
  75 void plugin_unregister_cb__locked(struct qemu_plugin_ctx *ctx,
  76                                   enum qemu_plugin_event ev)
  77 {
  78     struct qemu_plugin_cb *cb = ctx->callbacks[ev];
  79
  80     if (cb == NULL) {
  81         return;
  82     }
  83     QLIST_REMOVE_RCU(cb, entry);
  84     g_free(cb);
  85     ctx->callbacks[ev] = NULL;
  86     if (QLIST_EMPTY_RCU(&plugin.cb_lists[ev])) {
  87         clear_bit(ev, plugin.mask);
  88         g_hash_table_foreach(plugin.cpu_ht, plugin_cpu_update__locked, NULL);
  89     }
  90 }
  91
  92 /*
  93  * Disable CFI checks.
  94  * The callback function has been loaded from an external library so we do not
  95  * have type information
  96  */
  97 QEMU_DISABLE_CFI
  98 static void plugin_vcpu_cb__simple(CPUState *cpu, enum qemu_plugin_event ev)
  99 {
 100     struct qemu_plugin_cb *cb, *next;
 101
 102     switch (ev) {
 103     case QEMU_PLUGIN_EV_VCPU_INIT:
 104     case QEMU_PLUGIN_EV_VCPU_EXIT:
 105     case QEMU_PLUGIN_EV_VCPU_IDLE:
 106     case QEMU_PLUGIN_EV_VCPU_RESUME:
 107         /* iterate safely; plugins might uninstall themselves at any time */
 108         QLIST_FOREACH_SAFE_RCU(cb, &plugin.cb_lists[ev], entry, next) {
 109             qemu_plugin_vcpu_simple_cb_t func = cb->f.vcpu_simple;
 110
 111             func(cb->ctx->id, cpu->cpu_index);
 112         }
 113         break;
 114     default:
 115         g_assert_not_reached();
 116     }
 117 }
 118
 119 /*
 120  * Disable CFI checks.
 121  * The callback function has been loaded from an external library so we do not
 122  * have type information
 123  */
 124 QEMU_DISABLE_CFI
 125 static void plugin_cb__simple(enum qemu_plugin_event ev)
 126 {
 127     struct qemu_plugin_cb *cb, *next;
 128
 129     switch (ev) {
 130     case QEMU_PLUGIN_EV_FLUSH:
 131         QLIST_FOREACH_SAFE_RCU(cb, &plugin.cb_lists[ev], entry, next) {
 132             qemu_plugin_simple_cb_t func = cb->f.simple;
 133
 134             func(cb->ctx->id);
 135         }
 136         break;
 137     default:
 138         g_assert_not_reached();
 139     }
 140 }
 141
 142 /*
 143  * Disable CFI checks.
 144  * The callback function has been loaded from an external library so we do not
 145  * have type information
 146  */
 147 QEMU_DISABLE_CFI
 148 static void plugin_cb__udata(enum qemu_plugin_event ev)
 149 {
 150     struct qemu_plugin_cb *cb, *next;
 151
 152     switch (ev) {
 153     case QEMU_PLUGIN_EV_ATEXIT:
 154         QLIST_FOREACH_SAFE_RCU(cb, &plugin.cb_lists[ev], entry, next) {
 155             qemu_plugin_udata_cb_t func = cb->f.udata;
 156
 157             func(cb->ctx->id, cb->udata);
 158         }
 159         break;
 160     default:
 161         g_assert_not_reached();
 162     }
 163 }
 164
 165 static void
 166 do_plugin_register_cb(qemu_plugin_id_t id, enum qemu_plugin_event ev,
 167                       void *func, void *udata)
 168 {
 169     struct qemu_plugin_ctx *ctx;
 170
 171     QEMU_LOCK_GUARD(&plugin.lock);
 172     ctx = plugin_id_to_ctx_locked(id);
 173     /* if the plugin is on its way out, ignore this request */
 174     if (unlikely(ctx->uninstalling)) {
 175         return;
 176     }
 177     if (func) {
 178         struct qemu_plugin_cb *cb = ctx->callbacks[ev];
 179
 180         if (cb) {
 181             cb->f.generic = func;
 182             cb->udata = udata;
 183         } else {
 184             cb = g_new(struct qemu_plugin_cb, 1);
 185             cb->ctx = ctx;
 186             cb->f.generic = func;
 187             cb->udata = udata;
 188             ctx->callbacks[ev] = cb;
 189             QLIST_INSERT_HEAD_RCU(&plugin.cb_lists[ev], cb, entry);
 190             if (!test_bit(ev, plugin.mask)) {
 191                 set_bit(ev, plugin.mask);
 192                 g_hash_table_foreach(plugin.cpu_ht, plugin_cpu_update__locked,
 193                                      NULL);
 194             }
 195         }
 196     } else {
 197         plugin_unregister_cb__locked(ctx, ev);
 198     }
 199 }
 200
 201 void plugin_register_cb(qemu_plugin_id_t id, enum qemu_plugin_event ev,
 202                         void *func)
 203 {
 204     do_plugin_register_cb(id, ev, func, NULL);
 205 }
 206
 207 void
 208 plugin_register_cb_udata(qemu_plugin_id_t id, enum qemu_plugin_event ev,
 209                          void *func, void *udata)
 210 {
 211     do_plugin_register_cb(id, ev, func, udata);
 212 }
 213
 214 CPUPluginState *qemu_plugin_create_vcpu_state(void)
 215 {
 216     return g_new0(CPUPluginState, 1);
 217 }
 218
 219 static void plugin_grow_scoreboards__locked(CPUState *cpu)
 220 {
 221     if (cpu->cpu_index < plugin.scoreboard_alloc_size) {
 222         return;
 223     }
 224
 225     bool need_realloc = FALSE;
 226     while (cpu->cpu_index >= plugin.scoreboard_alloc_size) {
 227         plugin.scoreboard_alloc_size *= 2;
 228         need_realloc = TRUE;
 229     }
 230
 231
 232     if (!need_realloc || QLIST_EMPTY(&plugin.scoreboards)) {
 233         /* nothing to do, we just updated sizes for future scoreboards */
 234         return;
 235     }
 236
 237     /* cpus must be stopped, as tb might still use an existing scoreboard. */
 238     start_exclusive();
 239     struct qemu_plugin_scoreboard *score;
 240     QLIST_FOREACH(score, &plugin.scoreboards, entry) {
 241         g_array_set_size(score->data, plugin.scoreboard_alloc_size);
 242     }
 243     /* force all tb to be flushed, as scoreboard pointers were changed. */
 244     tb_flush(cpu);
 245     end_exclusive();
 246 }
 247
 248 void qemu_plugin_vcpu_init_hook(CPUState *cpu)
 249 {
 250     bool success;
 251
 252     qemu_rec_mutex_lock(&plugin.lock);
 253     plugin.num_vcpus = MAX(plugin.num_vcpus, cpu->cpu_index + 1);
 254     plugin_cpu_update__locked(&cpu->cpu_index, NULL, NULL);
 255     success = g_hash_table_insert(plugin.cpu_ht, &cpu->cpu_index,
 256                                   &cpu->cpu_index);
 257     g_assert(success);
 258     plugin_grow_scoreboards__locked(cpu);
 259     qemu_rec_mutex_unlock(&plugin.lock);
 260
 261     plugin_vcpu_cb__simple(cpu, QEMU_PLUGIN_EV_VCPU_INIT);
 262 }
 263
 264 void qemu_plugin_vcpu_exit_hook(CPUState *cpu)
 265 {
 266     bool success;
 267
 268     plugin_vcpu_cb__simple(cpu, QEMU_PLUGIN_EV_VCPU_EXIT);
 269
 270     qemu_rec_mutex_lock(&plugin.lock);
 271     success = g_hash_table_remove(plugin.cpu_ht, &cpu->cpu_index);
 272     g_assert(success);
 273     qemu_rec_mutex_unlock(&plugin.lock);
 274 }
 275
 276 struct plugin_for_each_args {
 277     struct qemu_plugin_ctx *ctx;
 278     qemu_plugin_vcpu_simple_cb_t cb;
 279 };
 280
 281 static void plugin_vcpu_for_each(gpointer k, gpointer v, gpointer udata)
 282 {
 283     struct plugin_for_each_args *args = udata;
 284     int cpu_index = *(int *)k;
 285
 286     args->cb(args->ctx->id, cpu_index);
 287 }
 288
 289 void qemu_plugin_vcpu_for_each(qemu_plugin_id_t id,
 290                                qemu_plugin_vcpu_simple_cb_t cb)
 291 {
 292     struct plugin_for_each_args args;
 293
 294     if (cb == NULL) {
 295         return;
 296     }
 297     qemu_rec_mutex_lock(&plugin.lock);
 298     args.ctx = plugin_id_to_ctx_locked(id);
 299     args.cb = cb;
 300     g_hash_table_foreach(plugin.cpu_ht, plugin_vcpu_for_each, &args);
 301     qemu_rec_mutex_unlock(&plugin.lock);
 302 }
 303
 304 /* Allocate and return a callback record */
 305 static struct qemu_plugin_dyn_cb *plugin_get_dyn_cb(GArray **arr)
 306 {
 307     GArray *cbs = *arr;
 308
 309     if (!cbs) {
 310         cbs = g_array_sized_new(false, false,
 311                                 sizeof(struct qemu_plugin_dyn_cb), 1);
 312         *arr = cbs;
 313     }
 314
 315     g_array_set_size(cbs, cbs->len + 1);
 316     return &g_array_index(cbs, struct qemu_plugin_dyn_cb, cbs->len - 1);
 317 }
 318
 319 void plugin_register_inline_op_on_entry(GArray **arr,
 320                                         enum qemu_plugin_mem_rw rw,
 321                                         enum qemu_plugin_op op,
 322                                         qemu_plugin_u64 entry,
 323                                         uint64_t imm)
 324 {
 325     struct qemu_plugin_dyn_cb *dyn_cb;
 326
 327     dyn_cb = plugin_get_dyn_cb(arr);
 328     dyn_cb->userp = NULL;
 329     dyn_cb->type = PLUGIN_CB_INLINE;
 330     dyn_cb->rw = rw;
 331     dyn_cb->inline_insn.entry = entry;
 332     dyn_cb->inline_insn.op = op;
 333     dyn_cb->inline_insn.imm = imm;
 334 }
 335
 336 void plugin_register_dyn_cb__udata(GArray **arr,
 337                                    qemu_plugin_vcpu_udata_cb_t cb,
 338                                    enum qemu_plugin_cb_flags flags,
 339                                    void *udata)
 340 {
 341     struct qemu_plugin_dyn_cb *dyn_cb = plugin_get_dyn_cb(arr);
 342
 343     dyn_cb->userp = udata;
 344     /* Note flags are discarded as unused. */
 345     dyn_cb->f.vcpu_udata = cb;
 346     dyn_cb->type = PLUGIN_CB_REGULAR;
 347 }
 348
 349 void plugin_register_vcpu_mem_cb(GArray **arr,
 350                                  void *cb,
 351                                  enum qemu_plugin_cb_flags flags,
 352                                  enum qemu_plugin_mem_rw rw,
 353                                  void *udata)
 354 {
 355     struct qemu_plugin_dyn_cb *dyn_cb;
 356
 357     dyn_cb = plugin_get_dyn_cb(arr);
 358     dyn_cb->userp = udata;
 359     /* Note flags are discarded as unused. */
 360     dyn_cb->type = PLUGIN_CB_REGULAR;
 361     dyn_cb->rw = rw;
 362     dyn_cb->f.generic = cb;
 363 }
 364
 365 /*
 366  * Disable CFI checks.
 367  * The callback function has been loaded from an external library so we do not
 368  * have type information
 369  */
 370 QEMU_DISABLE_CFI
 371 void qemu_plugin_tb_trans_cb(CPUState *cpu, struct qemu_plugin_tb *tb)
 372 {
 373     struct qemu_plugin_cb *cb, *next;
 374     enum qemu_plugin_event ev = QEMU_PLUGIN_EV_VCPU_TB_TRANS;
 375
 376     /* no plugin_mask check here; caller should have checked */
 377
 378     QLIST_FOREACH_SAFE_RCU(cb, &plugin.cb_lists[ev], entry, next) {
 379         qemu_plugin_vcpu_tb_trans_cb_t func = cb->f.vcpu_tb_trans;
 380
 381         func(cb->ctx->id, tb);
 382     }
 383 }
 384
 385 /*
 386  * Disable CFI checks.
 387  * The callback function has been loaded from an external library so we do not
 388  * have type information
 389  */
 390 QEMU_DISABLE_CFI
 391 void
 392 qemu_plugin_vcpu_syscall(CPUState *cpu, int64_t num, uint64_t a1, uint64_t a2,
 393                          uint64_t a3, uint64_t a4, uint64_t a5,
 394                          uint64_t a6, uint64_t a7, uint64_t a8)
 395 {
 396     struct qemu_plugin_cb *cb, *next;
 397     enum qemu_plugin_event ev = QEMU_PLUGIN_EV_VCPU_SYSCALL;
 398
 399     if (!test_bit(ev, cpu->plugin_state->event_mask)) {
 400         return;
 401     }
 402
 403     QLIST_FOREACH_SAFE_RCU(cb, &plugin.cb_lists[ev], entry, next) {
 404         qemu_plugin_vcpu_syscall_cb_t func = cb->f.vcpu_syscall;
 405
 406         func(cb->ctx->id, cpu->cpu_index, num, a1, a2, a3, a4, a5, a6, a7, a8);
 407     }
 408 }
 409
 410 /*
 411  * Disable CFI checks.
 412  * The callback function has been loaded from an external library so we do not
 413  * have type information
 414  */
 415 QEMU_DISABLE_CFI
 416 void qemu_plugin_vcpu_syscall_ret(CPUState *cpu, int64_t num, int64_t ret)
 417 {
 418     struct qemu_plugin_cb *cb, *next;
 419     enum qemu_plugin_event ev = QEMU_PLUGIN_EV_VCPU_SYSCALL_RET;
 420
 421     if (!test_bit(ev, cpu->plugin_state->event_mask)) {
 422         return;
 423     }
 424
 425     QLIST_FOREACH_SAFE_RCU(cb, &plugin.cb_lists[ev], entry, next) {
 426         qemu_plugin_vcpu_syscall_ret_cb_t func = cb->f.vcpu_syscall_ret;
 427
 428         func(cb->ctx->id, cpu->cpu_index, num, ret);
 429     }
 430 }
 431
 432 void qemu_plugin_vcpu_idle_cb(CPUState *cpu)
 433 {
 434     /* idle and resume cb may be called before init, ignore in this case */
 435     if (cpu->cpu_index < plugin.num_vcpus) {
 436         plugin_vcpu_cb__simple(cpu, QEMU_PLUGIN_EV_VCPU_IDLE);
 437     }
 438 }
 439
 440 void qemu_plugin_vcpu_resume_cb(CPUState *cpu)
 441 {
 442     if (cpu->cpu_index < plugin.num_vcpus) {
 443         plugin_vcpu_cb__simple(cpu, QEMU_PLUGIN_EV_VCPU_RESUME);
 444     }
 445 }
 446
 447 void qemu_plugin_register_vcpu_idle_cb(qemu_plugin_id_t id,
 448                                        qemu_plugin_vcpu_simple_cb_t cb)
 449 {
 450     plugin_register_cb(id, QEMU_PLUGIN_EV_VCPU_IDLE, cb);
 451 }
 452
 453 void qemu_plugin_register_vcpu_resume_cb(qemu_plugin_id_t id,
 454                                          qemu_plugin_vcpu_simple_cb_t cb)
 455 {
 456     plugin_register_cb(id, QEMU_PLUGIN_EV_VCPU_RESUME, cb);
 457 }
 458
 459 void qemu_plugin_register_flush_cb(qemu_plugin_id_t id,
 460                                    qemu_plugin_simple_cb_t cb)
 461 {
 462     plugin_register_cb(id, QEMU_PLUGIN_EV_FLUSH, cb);
 463 }
 464
 465 static bool free_dyn_cb_arr(void *p, uint32_t h, void *userp)
 466 {
 467     g_array_free((GArray *) p, true);
 468     return true;
 469 }
 470
 471 void qemu_plugin_flush_cb(void)
 472 {
 473     qht_iter_remove(&plugin.dyn_cb_arr_ht, free_dyn_cb_arr, NULL);
 474     qht_reset(&plugin.dyn_cb_arr_ht);
 475
 476     plugin_cb__simple(QEMU_PLUGIN_EV_FLUSH);
 477 }
 478
 479 void exec_inline_op(struct qemu_plugin_dyn_cb *cb, int cpu_index)
 480 {
 481     char *ptr = cb->inline_insn.entry.score->data->data;
 482     size_t elem_size = g_array_get_element_size(
 483         cb->inline_insn.entry.score->data);
 484     size_t offset = cb->inline_insn.entry.offset;
 485     uint64_t *val = (uint64_t *)(ptr + offset + cpu_index * elem_size);
 486
 487     switch (cb->inline_insn.op) {
 488     case QEMU_PLUGIN_INLINE_ADD_U64:
 489         *val += cb->inline_insn.imm;
 490         break;
 491     default:
 492         g_assert_not_reached();
 493     }
 494 }
 495
 496 void qemu_plugin_vcpu_mem_cb(CPUState *cpu, uint64_t vaddr,
 497                              MemOpIdx oi, enum qemu_plugin_mem_rw rw)
 498 {
 499     GArray *arr = cpu->plugin_mem_cbs;
 500     size_t i;
 501
 502     if (arr == NULL) {
 503         return;
 504     }
 505     for (i = 0; i < arr->len; i++) {
 506         struct qemu_plugin_dyn_cb *cb =
 507             &g_array_index(arr, struct qemu_plugin_dyn_cb, i);
 508
 509         if (!(rw & cb->rw)) {
 510                 break;
 511         }
 512         switch (cb->type) {
 513         case PLUGIN_CB_REGULAR:
 514             cb->f.vcpu_mem(cpu->cpu_index, make_plugin_meminfo(oi, rw),
 515                            vaddr, cb->userp);
 516             break;
 517         case PLUGIN_CB_INLINE:
 518             exec_inline_op(cb, cpu->cpu_index);
 519             break;
 520         default:
 521             g_assert_not_reached();
 522         }
 523     }
 524 }
 525
 526 void qemu_plugin_atexit_cb(void)
 527 {
 528     plugin_cb__udata(QEMU_PLUGIN_EV_ATEXIT);
 529 }
 530
 531 void qemu_plugin_register_atexit_cb(qemu_plugin_id_t id,
 532                                     qemu_plugin_udata_cb_t cb,
 533                                     void *udata)
 534 {
 535     plugin_register_cb_udata(id, QEMU_PLUGIN_EV_ATEXIT, cb, udata);
 536 }
 537
 538 /*
 539  * Handle exit from linux-user. Unlike the normal atexit() mechanism
 540  * we need to handle the clean-up manually as it's possible threads
 541  * are still running. We need to remove all callbacks from code
 542  * generation, flush the current translations and then we can safely
 543  * trigger the exit callbacks.
 544  */
 545
 546 void qemu_plugin_user_exit(void)
 547 {
 548     enum qemu_plugin_event ev;
 549     CPUState *cpu;
 550
 551     /*
 552      * Locking order: we must acquire locks in an order that is consistent
 553      * with the one in fork_start(). That is:
 554      * - start_exclusive(), which acquires qemu_cpu_list_lock,
 555      *   must be called before acquiring plugin.lock.
 556      * - tb_flush(), which acquires mmap_lock(), must be called
 557      *   while plugin.lock is not held.
 558      */
 559     start_exclusive();
 560
 561     qemu_rec_mutex_lock(&plugin.lock);
 562     /* un-register all callbacks except the final AT_EXIT one */
 563     for (ev = 0; ev < QEMU_PLUGIN_EV_MAX; ev++) {
 564         if (ev != QEMU_PLUGIN_EV_ATEXIT) {
 565             struct qemu_plugin_cb *cb, *next;
 566
 567             QLIST_FOREACH_SAFE_RCU(cb, &plugin.cb_lists[ev], entry, next) {
 568                 plugin_unregister_cb__locked(cb->ctx, ev);
 569             }
 570         }
 571     }
 572     CPU_FOREACH(cpu) {
 573         qemu_plugin_disable_mem_helpers(cpu);
 574     }
 575     qemu_rec_mutex_unlock(&plugin.lock);
 576
 577     tb_flush(current_cpu);
 578     end_exclusive();
 579
 580     /* now it's safe to handle the exit case */
 581     qemu_plugin_atexit_cb();
 582 }
 583
 584 /*
 585  * Helpers for *-user to ensure locks are sane across fork() events.
 586  */
 587
 588 void qemu_plugin_user_prefork_lock(void)
 589 {
 590     qemu_rec_mutex_lock(&plugin.lock);
 591 }
 592
 593 void qemu_plugin_user_postfork(bool is_child)
 594 {
 595     if (is_child) {
 596         /* should we just reset via plugin_init? */
 597         qemu_rec_mutex_init(&plugin.lock);
 598     } else {
 599         qemu_rec_mutex_unlock(&plugin.lock);
 600     }
 601 }
 602
 603 static bool plugin_dyn_cb_arr_cmp(const void *ap, const void *bp)
 604 {
 605     return ap == bp;
 606 }
 607
 608 static void __attribute__((__constructor__)) plugin_init(void)
 609 {
 610     int i;
 611
 612     for (i = 0; i < QEMU_PLUGIN_EV_MAX; i++) {
 613         QLIST_INIT(&plugin.cb_lists[i]);
 614     }
 615     qemu_rec_mutex_init(&plugin.lock);
 616     plugin.id_ht = g_hash_table_new(g_int64_hash, g_int64_equal);
 617     plugin.cpu_ht = g_hash_table_new(g_int_hash, g_int_equal);
 618     QLIST_INIT(&plugin.scoreboards);
 619     plugin.scoreboard_alloc_size = 16; /* avoid frequent reallocation */
 620     QTAILQ_INIT(&plugin.ctxs);
 621     qht_init(&plugin.dyn_cb_arr_ht, plugin_dyn_cb_arr_cmp, 16,
 622              QHT_MODE_AUTO_RESIZE);
 623     atexit(qemu_plugin_atexit_cb);
 624 }
 625
 626 int plugin_num_vcpus(void)
 627 {
 628     return plugin.num_vcpus;
 629 }
 630
 631 struct qemu_plugin_scoreboard *plugin_scoreboard_new(size_t element_size)
 632 {
 633     struct qemu_plugin_scoreboard *score =
 634         g_malloc0(sizeof(struct qemu_plugin_scoreboard));
 635     score->data = g_array_new(FALSE, TRUE, element_size);
 636     g_array_set_size(score->data, plugin.scoreboard_alloc_size);
 637
 638     qemu_rec_mutex_lock(&plugin.lock);
 639     QLIST_INSERT_HEAD(&plugin.scoreboards, score, entry);
 640     qemu_rec_mutex_unlock(&plugin.lock);
 641
 642     return score;
 643 }
 644
 645 void plugin_scoreboard_free(struct qemu_plugin_scoreboard *score)
 646 {
 647     qemu_rec_mutex_lock(&plugin.lock);
 648     QLIST_REMOVE(score, entry);
 649     qemu_rec_mutex_unlock(&plugin.lock);
 650
 651     g_array_free(score->data, TRUE);
 652     g_free(score);
 653 }