hw/virtio/virtio-balloon.c

   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/i386/pc.h"
  22 #include "sysemu/balloon.h"
  23 #include "hw/virtio/virtio-balloon.h"
  24 #include "sysemu/kvm.h"
  25 #include "exec/address-spaces.h"
  26 #include "qapi/visitor.h"
  27 #include "qapi-event.h"
  28 #include "trace.h"
  29
  30 #include "hw/virtio/virtio-bus.h"
  31 #include "hw/virtio/virtio-access.h"
  32
  33 #define BALLOON_PAGE_SIZE  (1 << VIRTIO_BALLOON_PFN_SHIFT)
  34
  35 static void balloon_page(void *addr, int deflate)
  36 {
  37     if (!qemu_balloon_is_inhibited() && (!kvm_enabled() ||
  38                                          kvm_has_sync_mmu())) {
  39         qemu_madvise(addr, BALLOON_PAGE_SIZE,
  40                 deflate ? QEMU_MADV_WILLNEED : QEMU_MADV_DONTNEED);
  41     }
  42 }
  43
  44 static const char *balloon_stat_names[] = {
  45    [VIRTIO_BALLOON_S_SWAP_IN] = "stat-swap-in",
  46    [VIRTIO_BALLOON_S_SWAP_OUT] = "stat-swap-out",
  47    [VIRTIO_BALLOON_S_MAJFLT] = "stat-major-faults",
  48    [VIRTIO_BALLOON_S_MINFLT] = "stat-minor-faults",
  49    [VIRTIO_BALLOON_S_MEMFREE] = "stat-free-memory",
  50    [VIRTIO_BALLOON_S_MEMTOT] = "stat-total-memory",
  51    [VIRTIO_BALLOON_S_AVAIL] = "stat-available-memory",
  52    [VIRTIO_BALLOON_S_NR] = NULL
  53 };
  54
  55 /*
  56  * reset_stats - Mark all items in the stats array as unset
  57  *
  58  * This function needs to be called at device initialization and before
  59  * updating to a set of newly-generated stats.  This will ensure that no
  60  * stale values stick around in case the guest reports a subset of the supported
  61  * statistics.
  62  */
  63 static inline void reset_stats(VirtIOBalloon *dev)
  64 {
  65     int i;
  66     for (i = 0; i < VIRTIO_BALLOON_S_NR; dev->stats[i++] = -1);
  67 }
  68
  69 static bool balloon_stats_supported(const VirtIOBalloon *s)
  70 {
  71     VirtIODevice *vdev = VIRTIO_DEVICE(s);
  72     return virtio_vdev_has_feature(vdev, VIRTIO_BALLOON_F_STATS_VQ);
  73 }
  74
  75 static bool balloon_stats_enabled(const VirtIOBalloon *s)
  76 {
  77     return s->stats_poll_interval > 0;
  78 }
  79
  80 static void balloon_stats_destroy_timer(VirtIOBalloon *s)
  81 {
  82     if (balloon_stats_enabled(s)) {
  83         timer_del(s->stats_timer);
  84         timer_free(s->stats_timer);
  85         s->stats_timer = NULL;
  86         s->stats_poll_interval = 0;
  87     }
  88 }
  89
  90 static void balloon_stats_change_timer(VirtIOBalloon *s, int64_t secs)
  91 {
  92     timer_mod(s->stats_timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + secs * 1000);
  93 }
  94
  95 static void balloon_stats_poll_cb(void *opaque)
  96 {
  97     VirtIOBalloon *s = opaque;
  98     VirtIODevice *vdev = VIRTIO_DEVICE(s);
  99
 100     if (s->stats_vq_elem == NULL || !balloon_stats_supported(s)) {
 101         /* re-schedule */
 102         balloon_stats_change_timer(s, s->stats_poll_interval);
 103         return;
 104     }
 105
 106     virtqueue_push(s->svq, s->stats_vq_elem, s->stats_vq_offset);
 107     virtio_notify(vdev, s->svq);
 108     g_free(s->stats_vq_elem);
 109     s->stats_vq_elem = NULL;
 110 }
 111
 112 static void balloon_stats_get_all(Object *obj, Visitor *v, const char *name,
 113                                   void *opaque, Error **errp)
 114 {
 115     Error *err = NULL;
 116     VirtIOBalloon *s = opaque;
 117     int i;
 118
 119     visit_start_struct(v, name, NULL, 0, &err);
 120     if (err) {
 121         goto out;
 122     }
 123     visit_type_int(v, "last-update", &s->stats_last_update, &err);
 124     if (err) {
 125         goto out_end;
 126     }
 127
 128     visit_start_struct(v, "stats", NULL, 0, &err);
 129     if (err) {
 130         goto out_end;
 131     }
 132     for (i = 0; i < VIRTIO_BALLOON_S_NR; i++) {
 133         visit_type_uint64(v, balloon_stat_names[i], &s->stats[i], &err);
 134         if (err) {
 135             goto out_nested;
 136         }
 137     }
 138     visit_check_struct(v, &err);
 139 out_nested:
 140     visit_end_struct(v, NULL);
 141
 142     if (!err) {
 143         visit_check_struct(v, &err);
 144     }
 145 out_end:
 146     visit_end_struct(v, NULL);
 147 out:
 148     error_propagate(errp, err);
 149 }
 150
 151 static void balloon_stats_get_poll_interval(Object *obj, Visitor *v,
 152                                             const char *name, void *opaque,
 153                                             Error **errp)
 154 {
 155     VirtIOBalloon *s = opaque;
 156     visit_type_int(v, name, &s->stats_poll_interval, errp);
 157 }
 158
 159 static void balloon_stats_set_poll_interval(Object *obj, Visitor *v,
 160                                             const char *name, void *opaque,
 161                                             Error **errp)
 162 {
 163     VirtIOBalloon *s = opaque;
 164     Error *local_err = NULL;
 165     int64_t value;
 166
 167     visit_type_int(v, name, &value, &local_err);
 168     if (local_err) {
 169         error_propagate(errp, local_err);
 170         return;
 171     }
 172
 173     if (value < 0) {
 174         error_setg(errp, "timer value must be greater than zero");
 175         return;
 176     }
 177
 178     if (value > UINT32_MAX) {
 179         error_setg(errp, "timer value is too big");
 180         return;
 181     }
 182
 183     if (value == s->stats_poll_interval) {
 184         return;
 185     }
 186
 187     if (value == 0) {
 188         /* timer=0 disables the timer */
 189         balloon_stats_destroy_timer(s);
 190         return;
 191     }
 192
 193     if (balloon_stats_enabled(s)) {
 194         /* timer interval change */
 195         s->stats_poll_interval = value;
 196         balloon_stats_change_timer(s, value);
 197         return;
 198     }
 199
 200     /* create a new timer */
 201     g_assert(s->stats_timer == NULL);
 202     s->stats_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL, balloon_stats_poll_cb, s);
 203     s->stats_poll_interval = value;
 204     balloon_stats_change_timer(s, 0);
 205 }
 206
 207 static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
 208 {
 209     VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
 210     VirtQueueElement *elem;
 211     MemoryRegionSection section;
 212
 213     for (;;) {
 214         size_t offset = 0;
 215         uint32_t pfn;
 216         elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
 217         if (!elem) {
 218             return;
 219         }
 220
 221         while (iov_to_buf(elem->out_sg, elem->out_num, offset, &pfn, 4) == 4) {
 222             ram_addr_t pa;
 223             ram_addr_t addr;
 224             int p = virtio_ldl_p(vdev, &pfn);
 225
 226             pa = (ram_addr_t) p << VIRTIO_BALLOON_PFN_SHIFT;
 227             offset += 4;
 228
 229             /* FIXME: remove get_system_memory(), but how? */
 230             section = memory_region_find(get_system_memory(), pa, 1);
 231             if (!int128_nz(section.size) || !memory_region_is_ram(section.mr))
 232                 continue;
 233
 234             trace_virtio_balloon_handle_output(memory_region_name(section.mr),
 235                                                pa);
 236             /* Using memory_region_get_ram_ptr is bending the rules a bit, but
 237                should be OK because we only want a single page.  */
 238             addr = section.offset_within_region;
 239             balloon_page(memory_region_get_ram_ptr(section.mr) + addr,
 240                          !!(vq == s->dvq));
 241             memory_region_unref(section.mr);
 242         }
 243
 244         virtqueue_push(vq, elem, offset);
 245         virtio_notify(vdev, vq);
 246         g_free(elem);
 247     }
 248 }
 249
 250 static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq)
 251 {
 252     VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
 253     VirtQueueElement *elem;
 254     VirtIOBalloonStat stat;
 255     size_t offset = 0;
 256     qemu_timeval tv;
 257
 258     elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
 259     if (!elem) {
 260         goto out;
 261     }
 262
 263     if (s->stats_vq_elem != NULL) {
 264         /* This should never happen if the driver follows the spec. */
 265         virtqueue_push(vq, s->stats_vq_elem, 0);
 266         virtio_notify(vdev, vq);
 267         g_free(s->stats_vq_elem);
 268     }
 269
 270     s->stats_vq_elem = elem;
 271
 272     /* Initialize the stats to get rid of any stale values.  This is only
 273      * needed to handle the case where a guest supports fewer stats than it
 274      * used to (ie. it has booted into an old kernel).
 275      */
 276     reset_stats(s);
 277
 278     while (iov_to_buf(elem->out_sg, elem->out_num, offset, &stat, sizeof(stat))
 279            == sizeof(stat)) {
 280         uint16_t tag = virtio_tswap16(vdev, stat.tag);
 281         uint64_t val = virtio_tswap64(vdev, stat.val);
 282
 283         offset += sizeof(stat);
 284         if (tag < VIRTIO_BALLOON_S_NR)
 285             s->stats[tag] = val;
 286     }
 287     s->stats_vq_offset = offset;
 288
 289     if (qemu_gettimeofday(&tv) < 0) {
 290         fprintf(stderr, "warning: %s: failed to get time of day\n", __func__);
 291         goto out;
 292     }
 293
 294     s->stats_last_update = tv.tv_sec;
 295
 296 out:
 297     if (balloon_stats_enabled(s)) {
 298         balloon_stats_change_timer(s, s->stats_poll_interval);
 299     }
 300 }
 301
 302 static void virtio_balloon_get_config(VirtIODevice *vdev, uint8_t *config_data)
 303 {
 304     VirtIOBalloon *dev = VIRTIO_BALLOON(vdev);
 305     struct virtio_balloon_config config;
 306
 307     config.num_pages = cpu_to_le32(dev->num_pages);
 308     config.actual = cpu_to_le32(dev->actual);
 309
 310     trace_virtio_balloon_get_config(config.num_pages, config.actual);
 311     memcpy(config_data, &config, sizeof(struct virtio_balloon_config));
 312 }
 313
 314 static int build_dimm_list(Object *obj, void *opaque)
 315 {
 316     GSList **list = opaque;
 317
 318     if (object_dynamic_cast(obj, TYPE_PC_DIMM)) {
 319         DeviceState *dev = DEVICE(obj);
 320         if (dev->realized) { /* only realized DIMMs matter */
 321             *list = g_slist_prepend(*list, dev);
 322         }
 323     }
 324
 325     object_child_foreach(obj, build_dimm_list, opaque);
 326     return 0;
 327 }
 328
 329 static ram_addr_t get_current_ram_size(void)
 330 {
 331     GSList *list = NULL, *item;
 332     ram_addr_t size = ram_size;
 333
 334     build_dimm_list(qdev_get_machine(), &list);
 335     for (item = list; item; item = g_slist_next(item)) {
 336         Object *obj = OBJECT(item->data);
 337         if (!strcmp(object_get_typename(obj), TYPE_PC_DIMM)) {
 338             size += object_property_get_int(obj, PC_DIMM_SIZE_PROP,
 339                                             &error_abort);
 340         }
 341     }
 342     g_slist_free(list);
 343
 344     return size;
 345 }
 346
 347 static void virtio_balloon_set_config(VirtIODevice *vdev,
 348                                       const uint8_t *config_data)
 349 {
 350     VirtIOBalloon *dev = VIRTIO_BALLOON(vdev);
 351     struct virtio_balloon_config config;
 352     uint32_t oldactual = dev->actual;
 353     ram_addr_t vm_ram_size = get_current_ram_size();
 354
 355     memcpy(&config, config_data, sizeof(struct virtio_balloon_config));
 356     dev->actual = le32_to_cpu(config.actual);
 357     if (dev->actual != oldactual) {
 358         qapi_event_send_balloon_change(vm_ram_size -
 359                         ((ram_addr_t) dev->actual << VIRTIO_BALLOON_PFN_SHIFT),
 360                         &error_abort);
 361     }
 362     trace_virtio_balloon_set_config(dev->actual, oldactual);
 363 }
 364
 365 static uint64_t virtio_balloon_get_features(VirtIODevice *vdev, uint64_t f,
 366                                             Error **errp)
 367 {
 368     VirtIOBalloon *dev = VIRTIO_BALLOON(vdev);
 369     f |= dev->host_features;
 370     virtio_add_feature(&f, VIRTIO_BALLOON_F_STATS_VQ);
 371     return f;
 372 }
 373
 374 static void virtio_balloon_stat(void *opaque, BalloonInfo *info)
 375 {
 376     VirtIOBalloon *dev = opaque;
 377     info->actual = get_current_ram_size() - ((uint64_t) dev->actual <<
 378                                              VIRTIO_BALLOON_PFN_SHIFT);
 379 }
 380
 381 static void virtio_balloon_to_target(void *opaque, ram_addr_t target)
 382 {
 383     VirtIOBalloon *dev = VIRTIO_BALLOON(opaque);
 384     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
 385     ram_addr_t vm_ram_size = get_current_ram_size();
 386
 387     if (target > vm_ram_size) {
 388         target = vm_ram_size;
 389     }
 390     if (target) {
 391         dev->num_pages = (vm_ram_size - target) >> VIRTIO_BALLOON_PFN_SHIFT;
 392         virtio_notify_config(vdev);
 393     }
 394     trace_virtio_balloon_to_target(target, dev->num_pages);
 395 }
 396
 397 static int virtio_balloon_post_load_device(void *opaque, int version_id)
 398 {
 399     VirtIOBalloon *s = VIRTIO_BALLOON(opaque);
 400
 401     if (balloon_stats_enabled(s)) {
 402         balloon_stats_change_timer(s, s->stats_poll_interval);
 403     }
 404     return 0;
 405 }
 406
 407 static const VMStateDescription vmstate_virtio_balloon_device = {
 408     .name = "virtio-balloon-device",
 409     .version_id = 1,
 410     .minimum_version_id = 1,
 411     .post_load = virtio_balloon_post_load_device,
 412     .fields = (VMStateField[]) {
 413         VMSTATE_UINT32(num_pages, VirtIOBalloon),
 414         VMSTATE_UINT32(actual, VirtIOBalloon),
 415         VMSTATE_END_OF_LIST()
 416     },
 417 };
 418
 419 static void virtio_balloon_device_realize(DeviceState *dev, Error **errp)
 420 {
 421     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
 422     VirtIOBalloon *s = VIRTIO_BALLOON(dev);
 423     int ret;
 424
 425     virtio_init(vdev, "virtio-balloon", VIRTIO_ID_BALLOON,
 426                 sizeof(struct virtio_balloon_config));
 427
 428     ret = qemu_add_balloon_handler(virtio_balloon_to_target,
 429                                    virtio_balloon_stat, s);
 430
 431     if (ret < 0) {
 432         error_setg(errp, "Only one balloon device is supported");
 433         virtio_cleanup(vdev);
 434         return;
 435     }
 436
 437     s->ivq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output);
 438     s->dvq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output);
 439     s->svq = virtio_add_queue(vdev, 128, virtio_balloon_receive_stats);
 440
 441     reset_stats(s);
 442 }
 443
 444 static void virtio_balloon_device_unrealize(DeviceState *dev, Error **errp)
 445 {
 446     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
 447     VirtIOBalloon *s = VIRTIO_BALLOON(dev);
 448
 449     balloon_stats_destroy_timer(s);
 450     qemu_remove_balloon_handler(s);
 451     virtio_cleanup(vdev);
 452 }
 453
 454 static void virtio_balloon_device_reset(VirtIODevice *vdev)
 455 {
 456     VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
 457
 458     if (s->stats_vq_elem != NULL) {
 459         virtqueue_unpop(s->svq, s->stats_vq_elem, 0);
 460         g_free(s->stats_vq_elem);
 461         s->stats_vq_elem = NULL;
 462     }
 463 }
 464
 465 static void virtio_balloon_set_status(VirtIODevice *vdev, uint8_t status)
 466 {
 467     VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
 468
 469     if (!s->stats_vq_elem && vdev->vm_running &&
 470         (status & VIRTIO_CONFIG_S_DRIVER_OK) && virtqueue_rewind(s->svq, 1)) {
 471         /* poll stats queue for the element we have discarded when the VM
 472          * was stopped */
 473         virtio_balloon_receive_stats(vdev, s->svq);
 474     }
 475 }
 476
 477 static void virtio_balloon_instance_init(Object *obj)
 478 {
 479     VirtIOBalloon *s = VIRTIO_BALLOON(obj);
 480
 481     object_property_add(obj, "guest-stats", "guest statistics",
 482                         balloon_stats_get_all, NULL, NULL, s, NULL);
 483
 484     object_property_add(obj, "guest-stats-polling-interval", "int",
 485                         balloon_stats_get_poll_interval,
 486                         balloon_stats_set_poll_interval,
 487                         NULL, s, NULL);
 488 }
 489
 490 static const VMStateDescription vmstate_virtio_balloon = {
 491     .name = "virtio-balloon",
 492     .minimum_version_id = 1,
 493     .version_id = 1,
 494     .fields = (VMStateField[]) {
 495         VMSTATE_VIRTIO_DEVICE,
 496         VMSTATE_END_OF_LIST()
 497     },
 498 };
 499
 500 static Property virtio_balloon_properties[] = {
 501     DEFINE_PROP_BIT("deflate-on-oom", VirtIOBalloon, host_features,
 502                     VIRTIO_BALLOON_F_DEFLATE_ON_OOM, false),
 503     DEFINE_PROP_END_OF_LIST(),
 504 };
 505
 506 static void virtio_balloon_class_init(ObjectClass *klass, void *data)
 507 {
 508     DeviceClass *dc = DEVICE_CLASS(klass);
 509     VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
 510
 511     dc->props = virtio_balloon_properties;
 512     dc->vmsd = &vmstate_virtio_balloon;
 513     set_bit(DEVICE_CATEGORY_MISC, dc->categories);
 514     vdc->realize = virtio_balloon_device_realize;
 515     vdc->unrealize = virtio_balloon_device_unrealize;
 516     vdc->reset = virtio_balloon_device_reset;
 517     vdc->get_config = virtio_balloon_get_config;
 518     vdc->set_config = virtio_balloon_set_config;
 519     vdc->get_features = virtio_balloon_get_features;
 520     vdc->set_status = virtio_balloon_set_status;
 521     vdc->vmsd = &vmstate_virtio_balloon_device;
 522 }
 523
 524 static const TypeInfo virtio_balloon_info = {
 525     .name = TYPE_VIRTIO_BALLOON,
 526     .parent = TYPE_VIRTIO_DEVICE,
 527     .instance_size = sizeof(VirtIOBalloon),
 528     .instance_init = virtio_balloon_instance_init,
 529     .class_init = virtio_balloon_class_init,
 530 };
 531
 532 static void virtio_register_types(void)
 533 {
 534     type_register_static(&virtio_balloon_info);
 535 }
 536
 537 type_init(virtio_register_types)