1 /* 2 * Virtio Balloon Device 3 * 4 * Copyright IBM, Corp. 2008 5 * Copyright (C) 2011 Red Hat, Inc. 6 * Copyright (C) 2011 Amit Shah <amit.shah@redhat.com> 7 * 8 * Authors: 9 * Anthony Liguori <aliguori@us.ibm.com> 10 * 11 * This work is licensed under the terms of the GNU GPL, version 2. See 12 * the COPYING file in the top-level directory. 13 * 14 */ 15 16 #include "qemu/osdep.h" 17 #include "qemu/iov.h" 18 #include "qemu/timer.h" 19 #include "qemu-common.h" 20 #include "hw/virtio/virtio.h" 21 #include "hw/mem/pc-dimm.h" 22 #include "sysemu/balloon.h" 23 #include "hw/virtio/virtio-balloon.h" 24 #include "exec/address-spaces.h" 25 #include "qapi/error.h" 26 #include "qapi/qapi-events-misc.h" 27 #include "qapi/visitor.h" 28 #include "trace.h" 29 #include "qemu/error-report.h" 30 #include "migration/misc.h" 31 32 #include "hw/virtio/virtio-bus.h" 33 #include "hw/virtio/virtio-access.h" 34 35 #define BALLOON_PAGE_SIZE (1 << VIRTIO_BALLOON_PFN_SHIFT) 36 37 struct PartiallyBalloonedPage { 38 RAMBlock *rb; 39 ram_addr_t base; 40 unsigned long bitmap[]; 41 }; 42 43 static void balloon_inflate_page(VirtIOBalloon *balloon, 44 MemoryRegion *mr, hwaddr offset) 45 { 46 void *addr = memory_region_get_ram_ptr(mr) + offset; 47 RAMBlock *rb; 48 size_t rb_page_size; 49 int subpages; 50 ram_addr_t ram_offset, host_page_base; 51 52 /* XXX is there a better way to get to the RAMBlock than via a 53 * host address? */ 54 rb = qemu_ram_block_from_host(addr, false, &ram_offset); 55 rb_page_size = qemu_ram_pagesize(rb); 56 host_page_base = ram_offset & ~(rb_page_size - 1); 57 58 if (rb_page_size == BALLOON_PAGE_SIZE) { 59 /* Easy case */ 60 61 ram_block_discard_range(rb, ram_offset, rb_page_size); 62 /* We ignore errors from ram_block_discard_range(), because it 63 * has already reported them, and failing to discard a balloon 64 * page is not fatal */ 65 return; 66 } 67 68 /* Hard case 69 * 70 * We've put a piece of a larger host page into the balloon - we 71 * need to keep track until we have a whole host page to 72 * discard 73 */ 74 warn_report_once( 75 "Balloon used with backing page size > 4kiB, this may not be reliable"); 76 77 subpages = rb_page_size / BALLOON_PAGE_SIZE; 78 79 if (balloon->pbp 80 && (rb != balloon->pbp->rb 81 || host_page_base != balloon->pbp->base)) { 82 /* We've partially ballooned part of a host page, but now 83 * we're trying to balloon part of a different one. Too hard, 84 * give up on the old partial page */ 85 g_free(balloon->pbp); 86 balloon->pbp = NULL; 87 } 88 89 if (!balloon->pbp) { 90 /* Starting on a new host page */ 91 size_t bitlen = BITS_TO_LONGS(subpages) * sizeof(unsigned long); 92 balloon->pbp = g_malloc0(sizeof(PartiallyBalloonedPage) + bitlen); 93 balloon->pbp->rb = rb; 94 balloon->pbp->base = host_page_base; 95 } 96 97 bitmap_set(balloon->pbp->bitmap, 98 (ram_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE, 99 subpages); 100 101 if (bitmap_full(balloon->pbp->bitmap, subpages)) { 102 /* We've accumulated a full host page, we can actually discard 103 * it now */ 104 105 ram_block_discard_range(rb, balloon->pbp->base, rb_page_size); 106 /* We ignore errors from ram_block_discard_range(), because it 107 * has already reported them, and failing to discard a balloon 108 * page is not fatal */ 109 110 g_free(balloon->pbp); 111 balloon->pbp = NULL; 112 } 113 } 114 115 static void balloon_deflate_page(VirtIOBalloon *balloon, 116 MemoryRegion *mr, hwaddr offset) 117 { 118 void *addr = memory_region_get_ram_ptr(mr) + offset; 119 RAMBlock *rb; 120 size_t rb_page_size; 121 ram_addr_t ram_offset, host_page_base; 122 void *host_addr; 123 int ret; 124 125 /* XXX is there a better way to get to the RAMBlock than via a 126 * host address? */ 127 rb = qemu_ram_block_from_host(addr, false, &ram_offset); 128 rb_page_size = qemu_ram_pagesize(rb); 129 host_page_base = ram_offset & ~(rb_page_size - 1); 130 131 if (balloon->pbp 132 && rb == balloon->pbp->rb 133 && host_page_base == balloon->pbp->base) { 134 int subpages = rb_page_size / BALLOON_PAGE_SIZE; 135 136 /* 137 * This means the guest has asked to discard some of the 4kiB 138 * subpages of a host page, but then changed its mind and 139 * asked to keep them after all. It's exceedingly unlikely 140 * for a guest to do this in practice, but handle it anyway, 141 * since getting it wrong could mean discarding memory the 142 * guest is still using. */ 143 bitmap_clear(balloon->pbp->bitmap, 144 (ram_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE, 145 subpages); 146 147 if (bitmap_empty(balloon->pbp->bitmap, subpages)) { 148 g_free(balloon->pbp); 149 balloon->pbp = NULL; 150 } 151 } 152 153 host_addr = (void *)((uintptr_t)addr & ~(rb_page_size - 1)); 154 155 /* When a page is deflated, we hint the whole host page it lives 156 * on, since we can't do anything smaller */ 157 ret = qemu_madvise(host_addr, rb_page_size, QEMU_MADV_WILLNEED); 158 if (ret != 0) { 159 warn_report("Couldn't MADV_WILLNEED on balloon deflate: %s", 160 strerror(errno)); 161 /* Otherwise ignore, failing to page hint shouldn't be fatal */ 162 } 163 } 164 165 static const char *balloon_stat_names[] = { 166 [VIRTIO_BALLOON_S_SWAP_IN] = "stat-swap-in", 167 [VIRTIO_BALLOON_S_SWAP_OUT] = "stat-swap-out", 168 [VIRTIO_BALLOON_S_MAJFLT] = "stat-major-faults", 169 [VIRTIO_BALLOON_S_MINFLT] = "stat-minor-faults", 170 [VIRTIO_BALLOON_S_MEMFREE] = "stat-free-memory", 171 [VIRTIO_BALLOON_S_MEMTOT] = "stat-total-memory", 172 [VIRTIO_BALLOON_S_AVAIL] = "stat-available-memory", 173 [VIRTIO_BALLOON_S_CACHES] = "stat-disk-caches", 174 [VIRTIO_BALLOON_S_HTLB_PGALLOC] = "stat-htlb-pgalloc", 175 [VIRTIO_BALLOON_S_HTLB_PGFAIL] = "stat-htlb-pgfail", 176 [VIRTIO_BALLOON_S_NR] = NULL 177 }; 178 179 /* 180 * reset_stats - Mark all items in the stats array as unset 181 * 182 * This function needs to be called at device initialization and before 183 * updating to a set of newly-generated stats. This will ensure that no 184 * stale values stick around in case the guest reports a subset of the supported 185 * statistics. 186 */ 187 static inline void reset_stats(VirtIOBalloon *dev) 188 { 189 int i; 190 for (i = 0; i < VIRTIO_BALLOON_S_NR; dev->stats[i++] = -1); 191 } 192 193 static bool balloon_stats_supported(const VirtIOBalloon *s) 194 { 195 VirtIODevice *vdev = VIRTIO_DEVICE(s); 196 return virtio_vdev_has_feature(vdev, VIRTIO_BALLOON_F_STATS_VQ); 197 } 198 199 static bool balloon_stats_enabled(const VirtIOBalloon *s) 200 { 201 return s->stats_poll_interval > 0; 202 } 203 204 static void balloon_stats_destroy_timer(VirtIOBalloon *s) 205 { 206 if (balloon_stats_enabled(s)) { 207 timer_del(s->stats_timer); 208 timer_free(s->stats_timer); 209 s->stats_timer = NULL; 210 s->stats_poll_interval = 0; 211 } 212 } 213 214 static void balloon_stats_change_timer(VirtIOBalloon *s, int64_t secs) 215 { 216 timer_mod(s->stats_timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + secs * 1000); 217 } 218 219 static void balloon_stats_poll_cb(void *opaque) 220 { 221 VirtIOBalloon *s = opaque; 222 VirtIODevice *vdev = VIRTIO_DEVICE(s); 223 224 if (s->stats_vq_elem == NULL || !balloon_stats_supported(s)) { 225 /* re-schedule */ 226 balloon_stats_change_timer(s, s->stats_poll_interval); 227 return; 228 } 229 230 virtqueue_push(s->svq, s->stats_vq_elem, s->stats_vq_offset); 231 virtio_notify(vdev, s->svq); 232 g_free(s->stats_vq_elem); 233 s->stats_vq_elem = NULL; 234 } 235 236 static void balloon_stats_get_all(Object *obj, Visitor *v, const char *name, 237 void *opaque, Error **errp) 238 { 239 Error *err = NULL; 240 VirtIOBalloon *s = opaque; 241 int i; 242 243 visit_start_struct(v, name, NULL, 0, &err); 244 if (err) { 245 goto out; 246 } 247 visit_type_int(v, "last-update", &s->stats_last_update, &err); 248 if (err) { 249 goto out_end; 250 } 251 252 visit_start_struct(v, "stats", NULL, 0, &err); 253 if (err) { 254 goto out_end; 255 } 256 for (i = 0; i < VIRTIO_BALLOON_S_NR; i++) { 257 visit_type_uint64(v, balloon_stat_names[i], &s->stats[i], &err); 258 if (err) { 259 goto out_nested; 260 } 261 } 262 visit_check_struct(v, &err); 263 out_nested: 264 visit_end_struct(v, NULL); 265 266 if (!err) { 267 visit_check_struct(v, &err); 268 } 269 out_end: 270 visit_end_struct(v, NULL); 271 out: 272 error_propagate(errp, err); 273 } 274 275 static void balloon_stats_get_poll_interval(Object *obj, Visitor *v, 276 const char *name, void *opaque, 277 Error **errp) 278 { 279 VirtIOBalloon *s = opaque; 280 visit_type_int(v, name, &s->stats_poll_interval, errp); 281 } 282 283 static void balloon_stats_set_poll_interval(Object *obj, Visitor *v, 284 const char *name, void *opaque, 285 Error **errp) 286 { 287 VirtIOBalloon *s = opaque; 288 Error *local_err = NULL; 289 int64_t value; 290 291 visit_type_int(v, name, &value, &local_err); 292 if (local_err) { 293 error_propagate(errp, local_err); 294 return; 295 } 296 297 if (value < 0) { 298 error_setg(errp, "timer value must be greater than zero"); 299 return; 300 } 301 302 if (value > UINT32_MAX) { 303 error_setg(errp, "timer value is too big"); 304 return; 305 } 306 307 if (value == s->stats_poll_interval) { 308 return; 309 } 310 311 if (value == 0) { 312 /* timer=0 disables the timer */ 313 balloon_stats_destroy_timer(s); 314 return; 315 } 316 317 if (balloon_stats_enabled(s)) { 318 /* timer interval change */ 319 s->stats_poll_interval = value; 320 balloon_stats_change_timer(s, value); 321 return; 322 } 323 324 /* create a new timer */ 325 g_assert(s->stats_timer == NULL); 326 s->stats_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL, balloon_stats_poll_cb, s); 327 s->stats_poll_interval = value; 328 balloon_stats_change_timer(s, 0); 329 } 330 331 static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq) 332 { 333 VirtIOBalloon *s = VIRTIO_BALLOON(vdev); 334 VirtQueueElement *elem; 335 MemoryRegionSection section; 336 337 for (;;) { 338 size_t offset = 0; 339 uint32_t pfn; 340 elem = virtqueue_pop(vq, sizeof(VirtQueueElement)); 341 if (!elem) { 342 return; 343 } 344 345 while (iov_to_buf(elem->out_sg, elem->out_num, offset, &pfn, 4) == 4) { 346 hwaddr pa; 347 int p = virtio_ldl_p(vdev, &pfn); 348 349 pa = (hwaddr) p << VIRTIO_BALLOON_PFN_SHIFT; 350 offset += 4; 351 352 section = memory_region_find(get_system_memory(), pa, 353 BALLOON_PAGE_SIZE); 354 if (!section.mr) { 355 trace_virtio_balloon_bad_addr(pa); 356 continue; 357 } 358 if (!memory_region_is_ram(section.mr) || 359 memory_region_is_rom(section.mr) || 360 memory_region_is_romd(section.mr)) { 361 trace_virtio_balloon_bad_addr(pa); 362 memory_region_unref(section.mr); 363 continue; 364 } 365 366 trace_virtio_balloon_handle_output(memory_region_name(section.mr), 367 pa); 368 if (!qemu_balloon_is_inhibited()) { 369 if (vq == s->ivq) { 370 balloon_inflate_page(s, section.mr, 371 section.offset_within_region); 372 } else if (vq == s->dvq) { 373 balloon_deflate_page(s, section.mr, section.offset_within_region); 374 } else { 375 g_assert_not_reached(); 376 } 377 } 378 memory_region_unref(section.mr); 379 } 380 381 virtqueue_push(vq, elem, offset); 382 virtio_notify(vdev, vq); 383 g_free(elem); 384 } 385 } 386 387 static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq) 388 { 389 VirtIOBalloon *s = VIRTIO_BALLOON(vdev); 390 VirtQueueElement *elem; 391 VirtIOBalloonStat stat; 392 size_t offset = 0; 393 qemu_timeval tv; 394 395 elem = virtqueue_pop(vq, sizeof(VirtQueueElement)); 396 if (!elem) { 397 goto out; 398 } 399 400 if (s->stats_vq_elem != NULL) { 401 /* This should never happen if the driver follows the spec. */ 402 virtqueue_push(vq, s->stats_vq_elem, 0); 403 virtio_notify(vdev, vq); 404 g_free(s->stats_vq_elem); 405 } 406 407 s->stats_vq_elem = elem; 408 409 /* Initialize the stats to get rid of any stale values. This is only 410 * needed to handle the case where a guest supports fewer stats than it 411 * used to (ie. it has booted into an old kernel). 412 */ 413 reset_stats(s); 414 415 while (iov_to_buf(elem->out_sg, elem->out_num, offset, &stat, sizeof(stat)) 416 == sizeof(stat)) { 417 uint16_t tag = virtio_tswap16(vdev, stat.tag); 418 uint64_t val = virtio_tswap64(vdev, stat.val); 419 420 offset += sizeof(stat); 421 if (tag < VIRTIO_BALLOON_S_NR) 422 s->stats[tag] = val; 423 } 424 s->stats_vq_offset = offset; 425 426 if (qemu_gettimeofday(&tv) < 0) { 427 warn_report("%s: failed to get time of day", __func__); 428 goto out; 429 } 430 431 s->stats_last_update = tv.tv_sec; 432 433 out: 434 if (balloon_stats_enabled(s)) { 435 balloon_stats_change_timer(s, s->stats_poll_interval); 436 } 437 } 438 439 static void virtio_balloon_handle_free_page_vq(VirtIODevice *vdev, 440 VirtQueue *vq) 441 { 442 VirtIOBalloon *s = VIRTIO_BALLOON(vdev); 443 qemu_bh_schedule(s->free_page_bh); 444 } 445 446 static bool get_free_page_hints(VirtIOBalloon *dev) 447 { 448 VirtQueueElement *elem; 449 VirtIODevice *vdev = VIRTIO_DEVICE(dev); 450 VirtQueue *vq = dev->free_page_vq; 451 bool ret = true; 452 453 while (dev->block_iothread) { 454 qemu_cond_wait(&dev->free_page_cond, &dev->free_page_lock); 455 } 456 457 elem = virtqueue_pop(vq, sizeof(VirtQueueElement)); 458 if (!elem) { 459 return false; 460 } 461 462 if (elem->out_num) { 463 uint32_t id; 464 size_t size = iov_to_buf(elem->out_sg, elem->out_num, 0, 465 &id, sizeof(id)); 466 467 virtio_tswap32s(vdev, &id); 468 if (unlikely(size != sizeof(id))) { 469 virtio_error(vdev, "received an incorrect cmd id"); 470 ret = false; 471 goto out; 472 } 473 if (id == dev->free_page_report_cmd_id) { 474 dev->free_page_report_status = FREE_PAGE_REPORT_S_START; 475 } else { 476 /* 477 * Stop the optimization only when it has started. This 478 * avoids a stale stop sign for the previous command. 479 */ 480 if (dev->free_page_report_status == FREE_PAGE_REPORT_S_START) { 481 dev->free_page_report_status = FREE_PAGE_REPORT_S_STOP; 482 } 483 } 484 } 485 486 if (elem->in_num) { 487 if (dev->free_page_report_status == FREE_PAGE_REPORT_S_START) { 488 qemu_guest_free_page_hint(elem->in_sg[0].iov_base, 489 elem->in_sg[0].iov_len); 490 } 491 } 492 493 out: 494 virtqueue_push(vq, elem, 1); 495 g_free(elem); 496 return ret; 497 } 498 499 static void virtio_ballloon_get_free_page_hints(void *opaque) 500 { 501 VirtIOBalloon *dev = opaque; 502 VirtIODevice *vdev = VIRTIO_DEVICE(dev); 503 VirtQueue *vq = dev->free_page_vq; 504 bool continue_to_get_hints; 505 506 do { 507 qemu_mutex_lock(&dev->free_page_lock); 508 virtio_queue_set_notification(vq, 0); 509 continue_to_get_hints = get_free_page_hints(dev); 510 qemu_mutex_unlock(&dev->free_page_lock); 511 virtio_notify(vdev, vq); 512 /* 513 * Start to poll the vq once the reporting started. Otherwise, continue 514 * only when there are entries on the vq, which need to be given back. 515 */ 516 } while (continue_to_get_hints || 517 dev->free_page_report_status == FREE_PAGE_REPORT_S_START); 518 virtio_queue_set_notification(vq, 1); 519 } 520 521 static bool virtio_balloon_free_page_support(void *opaque) 522 { 523 VirtIOBalloon *s = opaque; 524 VirtIODevice *vdev = VIRTIO_DEVICE(s); 525 526 return virtio_vdev_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT); 527 } 528 529 static void virtio_balloon_free_page_start(VirtIOBalloon *s) 530 { 531 VirtIODevice *vdev = VIRTIO_DEVICE(s); 532 533 /* For the stop and copy phase, we don't need to start the optimization */ 534 if (!vdev->vm_running) { 535 return; 536 } 537 538 if (s->free_page_report_cmd_id == UINT_MAX) { 539 s->free_page_report_cmd_id = 540 VIRTIO_BALLOON_FREE_PAGE_REPORT_CMD_ID_MIN; 541 } else { 542 s->free_page_report_cmd_id++; 543 } 544 545 s->free_page_report_status = FREE_PAGE_REPORT_S_REQUESTED; 546 virtio_notify_config(vdev); 547 } 548 549 static void virtio_balloon_free_page_stop(VirtIOBalloon *s) 550 { 551 VirtIODevice *vdev = VIRTIO_DEVICE(s); 552 553 if (s->free_page_report_status != FREE_PAGE_REPORT_S_STOP) { 554 /* 555 * The lock also guarantees us that the 556 * virtio_ballloon_get_free_page_hints exits after the 557 * free_page_report_status is set to S_STOP. 558 */ 559 qemu_mutex_lock(&s->free_page_lock); 560 /* 561 * The guest hasn't done the reporting, so host sends a notification 562 * to the guest to actively stop the reporting. 563 */ 564 s->free_page_report_status = FREE_PAGE_REPORT_S_STOP; 565 qemu_mutex_unlock(&s->free_page_lock); 566 virtio_notify_config(vdev); 567 } 568 } 569 570 static void virtio_balloon_free_page_done(VirtIOBalloon *s) 571 { 572 VirtIODevice *vdev = VIRTIO_DEVICE(s); 573 574 s->free_page_report_status = FREE_PAGE_REPORT_S_DONE; 575 virtio_notify_config(vdev); 576 } 577 578 static int 579 virtio_balloon_free_page_report_notify(NotifierWithReturn *n, void *data) 580 { 581 VirtIOBalloon *dev = container_of(n, VirtIOBalloon, 582 free_page_report_notify); 583 VirtIODevice *vdev = VIRTIO_DEVICE(dev); 584 PrecopyNotifyData *pnd = data; 585 586 if (!virtio_balloon_free_page_support(dev)) { 587 /* 588 * This is an optimization provided to migration, so just return 0 to 589 * have the normal migration process not affected when this feature is 590 * not supported. 591 */ 592 return 0; 593 } 594 595 switch (pnd->reason) { 596 case PRECOPY_NOTIFY_SETUP: 597 precopy_enable_free_page_optimization(); 598 break; 599 case PRECOPY_NOTIFY_COMPLETE: 600 case PRECOPY_NOTIFY_CLEANUP: 601 case PRECOPY_NOTIFY_BEFORE_BITMAP_SYNC: 602 virtio_balloon_free_page_stop(dev); 603 break; 604 case PRECOPY_NOTIFY_AFTER_BITMAP_SYNC: 605 if (vdev->vm_running) { 606 virtio_balloon_free_page_start(dev); 607 } else { 608 virtio_balloon_free_page_done(dev); 609 } 610 break; 611 default: 612 virtio_error(vdev, "%s: %d reason unknown", __func__, pnd->reason); 613 } 614 615 return 0; 616 } 617 618 static void virtio_balloon_get_config(VirtIODevice *vdev, uint8_t *config_data) 619 { 620 VirtIOBalloon *dev = VIRTIO_BALLOON(vdev); 621 struct virtio_balloon_config config = {}; 622 623 config.num_pages = cpu_to_le32(dev->num_pages); 624 config.actual = cpu_to_le32(dev->actual); 625 626 if (dev->free_page_report_status == FREE_PAGE_REPORT_S_REQUESTED) { 627 config.free_page_report_cmd_id = 628 cpu_to_le32(dev->free_page_report_cmd_id); 629 } else if (dev->free_page_report_status == FREE_PAGE_REPORT_S_STOP) { 630 config.free_page_report_cmd_id = 631 cpu_to_le32(VIRTIO_BALLOON_CMD_ID_STOP); 632 } else if (dev->free_page_report_status == FREE_PAGE_REPORT_S_DONE) { 633 config.free_page_report_cmd_id = 634 cpu_to_le32(VIRTIO_BALLOON_CMD_ID_DONE); 635 } 636 637 trace_virtio_balloon_get_config(config.num_pages, config.actual); 638 memcpy(config_data, &config, sizeof(struct virtio_balloon_config)); 639 } 640 641 static int build_dimm_list(Object *obj, void *opaque) 642 { 643 GSList **list = opaque; 644 645 if (object_dynamic_cast(obj, TYPE_PC_DIMM)) { 646 DeviceState *dev = DEVICE(obj); 647 if (dev->realized) { /* only realized DIMMs matter */ 648 *list = g_slist_prepend(*list, dev); 649 } 650 } 651 652 object_child_foreach(obj, build_dimm_list, opaque); 653 return 0; 654 } 655 656 static ram_addr_t get_current_ram_size(void) 657 { 658 GSList *list = NULL, *item; 659 ram_addr_t size = ram_size; 660 661 build_dimm_list(qdev_get_machine(), &list); 662 for (item = list; item; item = g_slist_next(item)) { 663 Object *obj = OBJECT(item->data); 664 if (!strcmp(object_get_typename(obj), TYPE_PC_DIMM)) { 665 size += object_property_get_int(obj, PC_DIMM_SIZE_PROP, 666 &error_abort); 667 } 668 } 669 g_slist_free(list); 670 671 return size; 672 } 673 674 static void virtio_balloon_set_config(VirtIODevice *vdev, 675 const uint8_t *config_data) 676 { 677 VirtIOBalloon *dev = VIRTIO_BALLOON(vdev); 678 struct virtio_balloon_config config; 679 uint32_t oldactual = dev->actual; 680 ram_addr_t vm_ram_size = get_current_ram_size(); 681 682 memcpy(&config, config_data, sizeof(struct virtio_balloon_config)); 683 dev->actual = le32_to_cpu(config.actual); 684 if (dev->actual != oldactual) { 685 qapi_event_send_balloon_change(vm_ram_size - 686 ((ram_addr_t) dev->actual << VIRTIO_BALLOON_PFN_SHIFT)); 687 } 688 trace_virtio_balloon_set_config(dev->actual, oldactual); 689 } 690 691 static uint64_t virtio_balloon_get_features(VirtIODevice *vdev, uint64_t f, 692 Error **errp) 693 { 694 VirtIOBalloon *dev = VIRTIO_BALLOON(vdev); 695 f |= dev->host_features; 696 virtio_add_feature(&f, VIRTIO_BALLOON_F_STATS_VQ); 697 698 return f; 699 } 700 701 static void virtio_balloon_stat(void *opaque, BalloonInfo *info) 702 { 703 VirtIOBalloon *dev = opaque; 704 info->actual = get_current_ram_size() - ((uint64_t) dev->actual << 705 VIRTIO_BALLOON_PFN_SHIFT); 706 } 707 708 static void virtio_balloon_to_target(void *opaque, ram_addr_t target) 709 { 710 VirtIOBalloon *dev = VIRTIO_BALLOON(opaque); 711 VirtIODevice *vdev = VIRTIO_DEVICE(dev); 712 ram_addr_t vm_ram_size = get_current_ram_size(); 713 714 if (target > vm_ram_size) { 715 target = vm_ram_size; 716 } 717 if (target) { 718 dev->num_pages = (vm_ram_size - target) >> VIRTIO_BALLOON_PFN_SHIFT; 719 virtio_notify_config(vdev); 720 } 721 trace_virtio_balloon_to_target(target, dev->num_pages); 722 } 723 724 static int virtio_balloon_post_load_device(void *opaque, int version_id) 725 { 726 VirtIOBalloon *s = VIRTIO_BALLOON(opaque); 727 728 if (balloon_stats_enabled(s)) { 729 balloon_stats_change_timer(s, s->stats_poll_interval); 730 } 731 return 0; 732 } 733 734 static const VMStateDescription vmstate_virtio_balloon_free_page_report = { 735 .name = "virtio-balloon-device/free-page-report", 736 .version_id = 1, 737 .minimum_version_id = 1, 738 .needed = virtio_balloon_free_page_support, 739 .fields = (VMStateField[]) { 740 VMSTATE_UINT32(free_page_report_cmd_id, VirtIOBalloon), 741 VMSTATE_UINT32(free_page_report_status, VirtIOBalloon), 742 VMSTATE_END_OF_LIST() 743 } 744 }; 745 746 static const VMStateDescription vmstate_virtio_balloon_device = { 747 .name = "virtio-balloon-device", 748 .version_id = 1, 749 .minimum_version_id = 1, 750 .post_load = virtio_balloon_post_load_device, 751 .fields = (VMStateField[]) { 752 VMSTATE_UINT32(num_pages, VirtIOBalloon), 753 VMSTATE_UINT32(actual, VirtIOBalloon), 754 VMSTATE_END_OF_LIST() 755 }, 756 .subsections = (const VMStateDescription * []) { 757 &vmstate_virtio_balloon_free_page_report, 758 NULL 759 } 760 }; 761 762 static void virtio_balloon_device_realize(DeviceState *dev, Error **errp) 763 { 764 VirtIODevice *vdev = VIRTIO_DEVICE(dev); 765 VirtIOBalloon *s = VIRTIO_BALLOON(dev); 766 int ret; 767 768 virtio_init(vdev, "virtio-balloon", VIRTIO_ID_BALLOON, 769 sizeof(struct virtio_balloon_config)); 770 771 ret = qemu_add_balloon_handler(virtio_balloon_to_target, 772 virtio_balloon_stat, s); 773 774 if (ret < 0) { 775 error_setg(errp, "Only one balloon device is supported"); 776 virtio_cleanup(vdev); 777 return; 778 } 779 780 s->ivq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output); 781 s->dvq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output); 782 s->svq = virtio_add_queue(vdev, 128, virtio_balloon_receive_stats); 783 784 if (virtio_has_feature(s->host_features, 785 VIRTIO_BALLOON_F_FREE_PAGE_HINT)) { 786 s->free_page_vq = virtio_add_queue(vdev, VIRTQUEUE_MAX_SIZE, 787 virtio_balloon_handle_free_page_vq); 788 s->free_page_report_status = FREE_PAGE_REPORT_S_STOP; 789 s->free_page_report_cmd_id = 790 VIRTIO_BALLOON_FREE_PAGE_REPORT_CMD_ID_MIN; 791 s->free_page_report_notify.notify = 792 virtio_balloon_free_page_report_notify; 793 precopy_add_notifier(&s->free_page_report_notify); 794 if (s->iothread) { 795 object_ref(OBJECT(s->iothread)); 796 s->free_page_bh = aio_bh_new(iothread_get_aio_context(s->iothread), 797 virtio_ballloon_get_free_page_hints, s); 798 qemu_mutex_init(&s->free_page_lock); 799 qemu_cond_init(&s->free_page_cond); 800 s->block_iothread = false; 801 } else { 802 /* Simply disable this feature if the iothread wasn't created. */ 803 s->host_features &= ~(1 << VIRTIO_BALLOON_F_FREE_PAGE_HINT); 804 virtio_error(vdev, "iothread is missing"); 805 } 806 } 807 reset_stats(s); 808 } 809 810 static void virtio_balloon_device_unrealize(DeviceState *dev, Error **errp) 811 { 812 VirtIODevice *vdev = VIRTIO_DEVICE(dev); 813 VirtIOBalloon *s = VIRTIO_BALLOON(dev); 814 815 if (virtio_balloon_free_page_support(s)) { 816 qemu_bh_delete(s->free_page_bh); 817 virtio_balloon_free_page_stop(s); 818 precopy_remove_notifier(&s->free_page_report_notify); 819 } 820 balloon_stats_destroy_timer(s); 821 qemu_remove_balloon_handler(s); 822 virtio_cleanup(vdev); 823 } 824 825 static void virtio_balloon_device_reset(VirtIODevice *vdev) 826 { 827 VirtIOBalloon *s = VIRTIO_BALLOON(vdev); 828 829 if (virtio_balloon_free_page_support(s)) { 830 virtio_balloon_free_page_stop(s); 831 } 832 833 if (s->stats_vq_elem != NULL) { 834 virtqueue_unpop(s->svq, s->stats_vq_elem, 0); 835 g_free(s->stats_vq_elem); 836 s->stats_vq_elem = NULL; 837 } 838 } 839 840 static void virtio_balloon_set_status(VirtIODevice *vdev, uint8_t status) 841 { 842 VirtIOBalloon *s = VIRTIO_BALLOON(vdev); 843 844 if (!s->stats_vq_elem && vdev->vm_running && 845 (status & VIRTIO_CONFIG_S_DRIVER_OK) && virtqueue_rewind(s->svq, 1)) { 846 /* poll stats queue for the element we have discarded when the VM 847 * was stopped */ 848 virtio_balloon_receive_stats(vdev, s->svq); 849 } 850 851 if (virtio_balloon_free_page_support(s)) { 852 /* 853 * The VM is woken up and the iothread was blocked, so signal it to 854 * continue. 855 */ 856 if (vdev->vm_running && s->block_iothread) { 857 qemu_mutex_lock(&s->free_page_lock); 858 s->block_iothread = false; 859 qemu_cond_signal(&s->free_page_cond); 860 qemu_mutex_unlock(&s->free_page_lock); 861 } 862 863 /* The VM is stopped, block the iothread. */ 864 if (!vdev->vm_running) { 865 qemu_mutex_lock(&s->free_page_lock); 866 s->block_iothread = true; 867 qemu_mutex_unlock(&s->free_page_lock); 868 } 869 } 870 } 871 872 static void virtio_balloon_instance_init(Object *obj) 873 { 874 VirtIOBalloon *s = VIRTIO_BALLOON(obj); 875 876 object_property_add(obj, "guest-stats", "guest statistics", 877 balloon_stats_get_all, NULL, NULL, s, NULL); 878 879 object_property_add(obj, "guest-stats-polling-interval", "int", 880 balloon_stats_get_poll_interval, 881 balloon_stats_set_poll_interval, 882 NULL, s, NULL); 883 } 884 885 static const VMStateDescription vmstate_virtio_balloon = { 886 .name = "virtio-balloon", 887 .minimum_version_id = 1, 888 .version_id = 1, 889 .fields = (VMStateField[]) { 890 VMSTATE_VIRTIO_DEVICE, 891 VMSTATE_END_OF_LIST() 892 }, 893 }; 894 895 static Property virtio_balloon_properties[] = { 896 DEFINE_PROP_BIT("deflate-on-oom", VirtIOBalloon, host_features, 897 VIRTIO_BALLOON_F_DEFLATE_ON_OOM, false), 898 DEFINE_PROP_BIT("free-page-hint", VirtIOBalloon, host_features, 899 VIRTIO_BALLOON_F_FREE_PAGE_HINT, false), 900 DEFINE_PROP_LINK("iothread", VirtIOBalloon, iothread, TYPE_IOTHREAD, 901 IOThread *), 902 DEFINE_PROP_END_OF_LIST(), 903 }; 904 905 static void virtio_balloon_class_init(ObjectClass *klass, void *data) 906 { 907 DeviceClass *dc = DEVICE_CLASS(klass); 908 VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass); 909 910 dc->props = virtio_balloon_properties; 911 dc->vmsd = &vmstate_virtio_balloon; 912 set_bit(DEVICE_CATEGORY_MISC, dc->categories); 913 vdc->realize = virtio_balloon_device_realize; 914 vdc->unrealize = virtio_balloon_device_unrealize; 915 vdc->reset = virtio_balloon_device_reset; 916 vdc->get_config = virtio_balloon_get_config; 917 vdc->set_config = virtio_balloon_set_config; 918 vdc->get_features = virtio_balloon_get_features; 919 vdc->set_status = virtio_balloon_set_status; 920 vdc->vmsd = &vmstate_virtio_balloon_device; 921 } 922 923 static const TypeInfo virtio_balloon_info = { 924 .name = TYPE_VIRTIO_BALLOON, 925 .parent = TYPE_VIRTIO_DEVICE, 926 .instance_size = sizeof(VirtIOBalloon), 927 .instance_init = virtio_balloon_instance_init, 928 .class_init = virtio_balloon_class_init, 929 }; 930 931 static void virtio_register_types(void) 932 { 933 type_register_static(&virtio_balloon_info); 934 } 935 936 type_init(virtio_register_types) 937