hw/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/iov.h"
  17 #include "qemu/timer.h"
  18 #include "qemu-common.h"
  19 #include "virtio.h"
  20 #include "pc.h"
  21 #include "cpu.h"
  22 #include "sysemu/balloon.h"
  23 #include "virtio-balloon.h"
  24 #include "sysemu/kvm.h"
  25 #include "exec/address-spaces.h"
  26 #include "qapi/visitor.h"
  27
  28 #if defined(__linux__)
  29 #include <sys/mman.h>
  30 #endif
  31
  32 typedef struct VirtIOBalloon
  33 {
  34     VirtIODevice vdev;
  35     VirtQueue *ivq, *dvq, *svq;
  36     uint32_t num_pages;
  37     uint32_t actual;
  38     uint64_t stats[VIRTIO_BALLOON_S_NR];
  39     VirtQueueElement stats_vq_elem;
  40     size_t stats_vq_offset;
  41     QEMUTimer *stats_timer;
  42     int64_t stats_last_update;
  43     int64_t stats_poll_interval;
  44     DeviceState *qdev;
  45 } VirtIOBalloon;
  46
  47 static VirtIOBalloon *to_virtio_balloon(VirtIODevice *vdev)
  48 {
  49     return (VirtIOBalloon *)vdev;
  50 }
  51
  52 static void balloon_page(void *addr, int deflate)
  53 {
  54 #if defined(__linux__)
  55     if (!kvm_enabled() || kvm_has_sync_mmu())
  56         qemu_madvise(addr, TARGET_PAGE_SIZE,
  57                 deflate ? QEMU_MADV_WILLNEED : QEMU_MADV_DONTNEED);
  58 #endif
  59 }
  60
  61 static const char *balloon_stat_names[] = {
  62    [VIRTIO_BALLOON_S_SWAP_IN] = "stat-swap-in",
  63    [VIRTIO_BALLOON_S_SWAP_OUT] = "stat-swap-out",
  64    [VIRTIO_BALLOON_S_MAJFLT] = "stat-major-faults",
  65    [VIRTIO_BALLOON_S_MINFLT] = "stat-minor-faults",
  66    [VIRTIO_BALLOON_S_MEMFREE] = "stat-free-memory",
  67    [VIRTIO_BALLOON_S_MEMTOT] = "stat-total-memory",
  68    [VIRTIO_BALLOON_S_NR] = NULL
  69 };
  70
  71 /*
  72  * reset_stats - Mark all items in the stats array as unset
  73  *
  74  * This function needs to be called at device intialization and before
  75  * before updating to a set of newly-generated stats.  This will ensure that no
  76  * stale values stick around in case the guest reports a subset of the supported
  77  * statistics.
  78  */
  79 static inline void reset_stats(VirtIOBalloon *dev)
  80 {
  81     int i;
  82     for (i = 0; i < VIRTIO_BALLOON_S_NR; dev->stats[i++] = -1);
  83 }
  84
  85 static bool balloon_stats_supported(const VirtIOBalloon *s)
  86 {
  87     return s->vdev.guest_features & (1 << VIRTIO_BALLOON_F_STATS_VQ);
  88 }
  89
  90 static bool balloon_stats_enabled(const VirtIOBalloon *s)
  91 {
  92     return s->stats_poll_interval > 0;
  93 }
  94
  95 static void balloon_stats_destroy_timer(VirtIOBalloon *s)
  96 {
  97     if (balloon_stats_enabled(s)) {
  98         qemu_del_timer(s->stats_timer);
  99         qemu_free_timer(s->stats_timer);
 100         s->stats_timer = NULL;
 101         s->stats_poll_interval = 0;
 102     }
 103 }
 104
 105 static void balloon_stats_change_timer(VirtIOBalloon *s, int secs)
 106 {
 107     qemu_mod_timer(s->stats_timer, qemu_get_clock_ms(vm_clock) + secs * 1000);
 108 }
 109
 110 static void balloon_stats_poll_cb(void *opaque)
 111 {
 112     VirtIOBalloon *s = opaque;
 113
 114     if (!balloon_stats_supported(s)) {
 115         /* re-schedule */
 116         balloon_stats_change_timer(s, s->stats_poll_interval);
 117         return;
 118     }
 119
 120     virtqueue_push(s->svq, &s->stats_vq_elem, s->stats_vq_offset);
 121     virtio_notify(&s->vdev, s->svq);
 122 }
 123
 124 static void balloon_stats_get_all(Object *obj, struct Visitor *v,
 125                                   void *opaque, const char *name, Error **errp)
 126 {
 127     VirtIOBalloon *s = opaque;
 128     int i;
 129
 130     if (!s->stats_last_update) {
 131         error_setg(errp, "guest hasn't updated any stats yet");
 132         return;
 133     }
 134
 135     visit_start_struct(v, NULL, "guest-stats", name, 0, errp);
 136     visit_type_int(v, &s->stats_last_update, "last-update", errp);
 137
 138     visit_start_struct(v, NULL, NULL, "stats", 0, errp);
 139     for (i = 0; i < VIRTIO_BALLOON_S_NR; i++) {
 140         visit_type_int64(v, (int64_t *) &s->stats[i], balloon_stat_names[i],
 141                          errp);
 142     }
 143     visit_end_struct(v, errp);
 144
 145     visit_end_struct(v, errp);
 146 }
 147
 148 static void balloon_stats_get_poll_interval(Object *obj, struct Visitor *v,
 149                                             void *opaque, const char *name,
 150                                             Error **errp)
 151 {
 152     VirtIOBalloon *s = opaque;
 153     visit_type_int(v, &s->stats_poll_interval, name, errp);
 154 }
 155
 156 static void balloon_stats_set_poll_interval(Object *obj, struct Visitor *v,
 157                                             void *opaque, const char *name,
 158                                             Error **errp)
 159 {
 160     VirtIOBalloon *s = opaque;
 161     int64_t value;
 162
 163     visit_type_int(v, &value, name, errp);
 164     if (error_is_set(errp)) {
 165         return;
 166     }
 167
 168     if (value < 0) {
 169         error_setg(errp, "timer value must be greater than zero");
 170         return;
 171     }
 172
 173     if (value == s->stats_poll_interval) {
 174         return;
 175     }
 176
 177     if (value == 0) {
 178         /* timer=0 disables the timer */
 179         balloon_stats_destroy_timer(s);
 180         return;
 181     }
 182
 183     if (balloon_stats_enabled(s)) {
 184         /* timer interval change */
 185         s->stats_poll_interval = value;
 186         balloon_stats_change_timer(s, value);
 187         return;
 188     }
 189
 190     /* create a new timer */
 191     g_assert(s->stats_timer == NULL);
 192     s->stats_timer = qemu_new_timer_ms(vm_clock, balloon_stats_poll_cb, s);
 193     s->stats_poll_interval = value;
 194     balloon_stats_change_timer(s, 0);
 195 }
 196
 197 static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
 198 {
 199     VirtIOBalloon *s = to_virtio_balloon(vdev);
 200     VirtQueueElement elem;
 201     MemoryRegionSection section;
 202
 203     while (virtqueue_pop(vq, &elem)) {
 204         size_t offset = 0;
 205         uint32_t pfn;
 206
 207         while (iov_to_buf(elem.out_sg, elem.out_num, offset, &pfn, 4) == 4) {
 208             ram_addr_t pa;
 209             ram_addr_t addr;
 210
 211             pa = (ram_addr_t)ldl_p(&pfn) << VIRTIO_BALLOON_PFN_SHIFT;
 212             offset += 4;
 213
 214             /* FIXME: remove get_system_memory(), but how? */
 215             section = memory_region_find(get_system_memory(), pa, 1);
 216             if (!section.size || !memory_region_is_ram(section.mr))
 217                 continue;
 218
 219             /* Using memory_region_get_ram_ptr is bending the rules a bit, but
 220                should be OK because we only want a single page.  */
 221             addr = section.offset_within_region;
 222             balloon_page(memory_region_get_ram_ptr(section.mr) + addr,
 223                          !!(vq == s->dvq));
 224         }
 225
 226         virtqueue_push(vq, &elem, offset);
 227         virtio_notify(vdev, vq);
 228     }
 229 }
 230
 231 static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq)
 232 {
 233     VirtIOBalloon *s = DO_UPCAST(VirtIOBalloon, vdev, vdev);
 234     VirtQueueElement *elem = &s->stats_vq_elem;
 235     VirtIOBalloonStat stat;
 236     size_t offset = 0;
 237     qemu_timeval tv;
 238
 239     if (!virtqueue_pop(vq, elem)) {
 240         goto out;
 241     }
 242
 243     /* Initialize the stats to get rid of any stale values.  This is only
 244      * needed to handle the case where a guest supports fewer stats than it
 245      * used to (ie. it has booted into an old kernel).
 246      */
 247     reset_stats(s);
 248
 249     while (iov_to_buf(elem->out_sg, elem->out_num, offset, &stat, sizeof(stat))
 250            == sizeof(stat)) {
 251         uint16_t tag = tswap16(stat.tag);
 252         uint64_t val = tswap64(stat.val);
 253
 254         offset += sizeof(stat);
 255         if (tag < VIRTIO_BALLOON_S_NR)
 256             s->stats[tag] = val;
 257     }
 258     s->stats_vq_offset = offset;
 259
 260     if (qemu_gettimeofday(&tv) < 0) {
 261         fprintf(stderr, "warning: %s: failed to get time of day\n", __func__);
 262         goto out;
 263     }
 264
 265     s->stats_last_update = tv.tv_sec;
 266
 267 out:
 268     if (balloon_stats_enabled(s)) {
 269         balloon_stats_change_timer(s, s->stats_poll_interval);
 270     }
 271 }
 272
 273 static void virtio_balloon_get_config(VirtIODevice *vdev, uint8_t *config_data)
 274 {
 275     VirtIOBalloon *dev = to_virtio_balloon(vdev);
 276     struct virtio_balloon_config config;
 277
 278     config.num_pages = cpu_to_le32(dev->num_pages);
 279     config.actual = cpu_to_le32(dev->actual);
 280
 281     memcpy(config_data, &config, 8);
 282 }
 283
 284 static void virtio_balloon_set_config(VirtIODevice *vdev,
 285                                       const uint8_t *config_data)
 286 {
 287     VirtIOBalloon *dev = to_virtio_balloon(vdev);
 288     struct virtio_balloon_config config;
 289     uint32_t oldactual = dev->actual;
 290     memcpy(&config, config_data, 8);
 291     dev->actual = le32_to_cpu(config.actual);
 292     if (dev->actual != oldactual) {
 293         qemu_balloon_changed(ram_size -
 294                              (dev->actual << VIRTIO_BALLOON_PFN_SHIFT));
 295     }
 296 }
 297
 298 static uint32_t virtio_balloon_get_features(VirtIODevice *vdev, uint32_t f)
 299 {
 300     f |= (1 << VIRTIO_BALLOON_F_STATS_VQ);
 301     return f;
 302 }
 303
 304 static void virtio_balloon_stat(void *opaque, BalloonInfo *info)
 305 {
 306     VirtIOBalloon *dev = opaque;
 307     info->actual = ram_size - ((uint64_t) dev->actual <<
 308                                VIRTIO_BALLOON_PFN_SHIFT);
 309 }
 310
 311 static void virtio_balloon_to_target(void *opaque, ram_addr_t target)
 312 {
 313     VirtIOBalloon *dev = opaque;
 314
 315     if (target > ram_size) {
 316         target = ram_size;
 317     }
 318     if (target) {
 319         dev->num_pages = (ram_size - target) >> VIRTIO_BALLOON_PFN_SHIFT;
 320         virtio_notify_config(&dev->vdev);
 321     }
 322 }
 323
 324 static void virtio_balloon_save(QEMUFile *f, void *opaque)
 325 {
 326     VirtIOBalloon *s = opaque;
 327
 328     virtio_save(&s->vdev, f);
 329
 330     qemu_put_be32(f, s->num_pages);
 331     qemu_put_be32(f, s->actual);
 332 }
 333
 334 static int virtio_balloon_load(QEMUFile *f, void *opaque, int version_id)
 335 {
 336     VirtIOBalloon *s = opaque;
 337     int ret;
 338
 339     if (version_id != 1)
 340         return -EINVAL;
 341
 342     ret = virtio_load(&s->vdev, f);
 343     if (ret) {
 344         return ret;
 345     }
 346
 347     s->num_pages = qemu_get_be32(f);
 348     s->actual = qemu_get_be32(f);
 349     return 0;
 350 }
 351
 352 VirtIODevice *virtio_balloon_init(DeviceState *dev)
 353 {
 354     VirtIOBalloon *s;
 355     int ret;
 356
 357     s = (VirtIOBalloon *)virtio_common_init("virtio-balloon",
 358                                             VIRTIO_ID_BALLOON,
 359                                             8, sizeof(VirtIOBalloon));
 360
 361     s->vdev.get_config = virtio_balloon_get_config;
 362     s->vdev.set_config = virtio_balloon_set_config;
 363     s->vdev.get_features = virtio_balloon_get_features;
 364
 365     ret = qemu_add_balloon_handler(virtio_balloon_to_target,
 366                                    virtio_balloon_stat, s);
 367     if (ret < 0) {
 368         virtio_cleanup(&s->vdev);
 369         return NULL;
 370     }
 371
 372     s->ivq = virtio_add_queue(&s->vdev, 128, virtio_balloon_handle_output);
 373     s->dvq = virtio_add_queue(&s->vdev, 128, virtio_balloon_handle_output);
 374     s->svq = virtio_add_queue(&s->vdev, 128, virtio_balloon_receive_stats);
 375
 376     s->qdev = dev;
 377     register_savevm(dev, "virtio-balloon", -1, 1,
 378                     virtio_balloon_save, virtio_balloon_load, s);
 379
 380     object_property_add(OBJECT(dev), "guest-stats", "guest statistics",
 381                         balloon_stats_get_all, NULL, NULL, s, NULL);
 382
 383     object_property_add(OBJECT(dev), "guest-stats-polling-interval", "int",
 384                         balloon_stats_get_poll_interval,
 385                         balloon_stats_set_poll_interval,
 386                         NULL, s, NULL);
 387
 388     return &s->vdev;
 389 }
 390
 391 void virtio_balloon_exit(VirtIODevice *vdev)
 392 {
 393     VirtIOBalloon *s = DO_UPCAST(VirtIOBalloon, vdev, vdev);
 394
 395     balloon_stats_destroy_timer(s);
 396     qemu_remove_balloon_handler(s);
 397     unregister_savevm(s->qdev, "virtio-balloon", s);
 398     virtio_cleanup(vdev);
 399 }