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