xref: /qemu/hw/virtio/virtio-balloon.c (revision a942d8fa) 
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 defined(__linux__)
38     if (!qemu_balloon_is_inhibited() && (!kvm_enabled() ||
39                                          kvm_has_sync_mmu())) {
40         qemu_madvise(addr, BALLOON_PAGE_SIZE,
41                 deflate ? QEMU_MADV_WILLNEED : QEMU_MADV_DONTNEED);
42     }
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_AVAIL] = "stat-available-memory",
54    [VIRTIO_BALLOON_S_NR] = NULL
55 };
56 
57 /*
58  * reset_stats - Mark all items in the stats array as unset
59  *
60  * This function needs to be called at device initialization and before
61  * updating to a set of newly-generated stats.  This will ensure that no
62  * stale values stick around in case the guest reports a subset of the supported
63  * statistics.
64  */
65 static inline void reset_stats(VirtIOBalloon *dev)
66 {
67     int i;
68     for (i = 0; i < VIRTIO_BALLOON_S_NR; dev->stats[i++] = -1);
69 }
70 
71 static bool balloon_stats_supported(const VirtIOBalloon *s)
72 {
73     VirtIODevice *vdev = VIRTIO_DEVICE(s);
74     return virtio_vdev_has_feature(vdev, VIRTIO_BALLOON_F_STATS_VQ);
75 }
76 
77 static bool balloon_stats_enabled(const VirtIOBalloon *s)
78 {
79     return s->stats_poll_interval > 0;
80 }
81 
82 static void balloon_stats_destroy_timer(VirtIOBalloon *s)
83 {
84     if (balloon_stats_enabled(s)) {
85         timer_del(s->stats_timer);
86         timer_free(s->stats_timer);
87         s->stats_timer = NULL;
88         s->stats_poll_interval = 0;
89     }
90 }
91 
92 static void balloon_stats_change_timer(VirtIOBalloon *s, int64_t secs)
93 {
94     timer_mod(s->stats_timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + secs * 1000);
95 }
96 
97 static void balloon_stats_poll_cb(void *opaque)
98 {
99     VirtIOBalloon *s = opaque;
100     VirtIODevice *vdev = VIRTIO_DEVICE(s);
101 
102     if (s->stats_vq_elem == NULL || !balloon_stats_supported(s)) {
103         /* re-schedule */
104         balloon_stats_change_timer(s, s->stats_poll_interval);
105         return;
106     }
107 
108     virtqueue_push(s->svq, s->stats_vq_elem, s->stats_vq_offset);
109     virtio_notify(vdev, s->svq);
110     g_free(s->stats_vq_elem);
111     s->stats_vq_elem = NULL;
112 }
113 
114 static void balloon_stats_get_all(Object *obj, Visitor *v, const char *name,
115                                   void *opaque, Error **errp)
116 {
117     Error *err = NULL;
118     VirtIOBalloon *s = opaque;
119     int i;
120 
121     visit_start_struct(v, name, NULL, 0, &err);
122     if (err) {
123         goto out;
124     }
125     visit_type_int(v, "last-update", &s->stats_last_update, &err);
126     if (err) {
127         goto out_end;
128     }
129 
130     visit_start_struct(v, "stats", NULL, 0, &err);
131     if (err) {
132         goto out_end;
133     }
134     for (i = 0; i < VIRTIO_BALLOON_S_NR; i++) {
135         visit_type_uint64(v, balloon_stat_names[i], &s->stats[i], &err);
136         if (err) {
137             goto out_nested;
138         }
139     }
140     visit_check_struct(v, &err);
141 out_nested:
142     visit_end_struct(v, NULL);
143 
144     if (!err) {
145         visit_check_struct(v, &err);
146     }
147 out_end:
148     visit_end_struct(v, NULL);
149 out:
150     error_propagate(errp, err);
151 }
152 
153 static void balloon_stats_get_poll_interval(Object *obj, Visitor *v,
154                                             const char *name, void *opaque,
155                                             Error **errp)
156 {
157     VirtIOBalloon *s = opaque;
158     visit_type_int(v, name, &s->stats_poll_interval, errp);
159 }
160 
161 static void balloon_stats_set_poll_interval(Object *obj, Visitor *v,
162                                             const char *name, void *opaque,
163                                             Error **errp)
164 {
165     VirtIOBalloon *s = opaque;
166     Error *local_err = NULL;
167     int64_t value;
168 
169     visit_type_int(v, name, &value, &local_err);
170     if (local_err) {
171         error_propagate(errp, local_err);
172         return;
173     }
174 
175     if (value < 0) {
176         error_setg(errp, "timer value must be greater than zero");
177         return;
178     }
179 
180     if (value > UINT32_MAX) {
181         error_setg(errp, "timer value is too big");
182         return;
183     }
184 
185     if (value == s->stats_poll_interval) {
186         return;
187     }
188 
189     if (value == 0) {
190         /* timer=0 disables the timer */
191         balloon_stats_destroy_timer(s);
192         return;
193     }
194 
195     if (balloon_stats_enabled(s)) {
196         /* timer interval change */
197         s->stats_poll_interval = value;
198         balloon_stats_change_timer(s, value);
199         return;
200     }
201 
202     /* create a new timer */
203     g_assert(s->stats_timer == NULL);
204     s->stats_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL, balloon_stats_poll_cb, s);
205     s->stats_poll_interval = value;
206     balloon_stats_change_timer(s, 0);
207 }
208 
209 static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
210 {
211     VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
212     VirtQueueElement *elem;
213     MemoryRegionSection section;
214 
215     for (;;) {
216         size_t offset = 0;
217         uint32_t pfn;
218         elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
219         if (!elem) {
220             return;
221         }
222 
223         while (iov_to_buf(elem->out_sg, elem->out_num, offset, &pfn, 4) == 4) {
224             ram_addr_t pa;
225             ram_addr_t addr;
226             int p = virtio_ldl_p(vdev, &pfn);
227 
228             pa = (ram_addr_t) p << VIRTIO_BALLOON_PFN_SHIFT;
229             offset += 4;
230 
231             /* FIXME: remove get_system_memory(), but how? */
232             section = memory_region_find(get_system_memory(), pa, 1);
233             if (!int128_nz(section.size) || !memory_region_is_ram(section.mr))
234                 continue;
235 
236             trace_virtio_balloon_handle_output(memory_region_name(section.mr),
237                                                pa);
238             /* Using memory_region_get_ram_ptr is bending the rules a bit, but
239                should be OK because we only want a single page.  */
240             addr = section.offset_within_region;
241             balloon_page(memory_region_get_ram_ptr(section.mr) + addr,
242                          !!(vq == s->dvq));
243             memory_region_unref(section.mr);
244         }
245 
246         virtqueue_push(vq, elem, offset);
247         virtio_notify(vdev, vq);
248         g_free(elem);
249     }
250 }
251 
252 static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq)
253 {
254     VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
255     VirtQueueElement *elem;
256     VirtIOBalloonStat stat;
257     size_t offset = 0;
258     qemu_timeval tv;
259 
260     elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
261     if (!elem) {
262         goto out;
263     }
264 
265     if (s->stats_vq_elem != NULL) {
266         /* This should never happen if the driver follows the spec. */
267         virtqueue_push(vq, s->stats_vq_elem, 0);
268         virtio_notify(vdev, vq);
269         g_free(s->stats_vq_elem);
270     }
271 
272     s->stats_vq_elem = elem;
273 
274     /* Initialize the stats to get rid of any stale values.  This is only
275      * needed to handle the case where a guest supports fewer stats than it
276      * used to (ie. it has booted into an old kernel).
277      */
278     reset_stats(s);
279 
280     while (iov_to_buf(elem->out_sg, elem->out_num, offset, &stat, sizeof(stat))
281            == sizeof(stat)) {
282         uint16_t tag = virtio_tswap16(vdev, stat.tag);
283         uint64_t val = virtio_tswap64(vdev, stat.val);
284 
285         offset += sizeof(stat);
286         if (tag < VIRTIO_BALLOON_S_NR)
287             s->stats[tag] = val;
288     }
289     s->stats_vq_offset = offset;
290 
291     if (qemu_gettimeofday(&tv) < 0) {
292         fprintf(stderr, "warning: %s: failed to get time of day\n", __func__);
293         goto out;
294     }
295 
296     s->stats_last_update = tv.tv_sec;
297 
298 out:
299     if (balloon_stats_enabled(s)) {
300         balloon_stats_change_timer(s, s->stats_poll_interval);
301     }
302 }
303 
304 static void virtio_balloon_get_config(VirtIODevice *vdev, uint8_t *config_data)
305 {
306     VirtIOBalloon *dev = VIRTIO_BALLOON(vdev);
307     struct virtio_balloon_config config;
308 
309     config.num_pages = cpu_to_le32(dev->num_pages);
310     config.actual = cpu_to_le32(dev->actual);
311 
312     trace_virtio_balloon_get_config(config.num_pages, config.actual);
313     memcpy(config_data, &config, sizeof(struct virtio_balloon_config));
314 }
315 
316 static int build_dimm_list(Object *obj, void *opaque)
317 {
318     GSList **list = opaque;
319 
320     if (object_dynamic_cast(obj, TYPE_PC_DIMM)) {
321         DeviceState *dev = DEVICE(obj);
322         if (dev->realized) { /* only realized DIMMs matter */
323             *list = g_slist_prepend(*list, dev);
324         }
325     }
326 
327     object_child_foreach(obj, build_dimm_list, opaque);
328     return 0;
329 }
330 
331 static ram_addr_t get_current_ram_size(void)
332 {
333     GSList *list = NULL, *item;
334     ram_addr_t size = ram_size;
335 
336     build_dimm_list(qdev_get_machine(), &list);
337     for (item = list; item; item = g_slist_next(item)) {
338         Object *obj = OBJECT(item->data);
339         if (!strcmp(object_get_typename(obj), TYPE_PC_DIMM)) {
340             size += object_property_get_int(obj, PC_DIMM_SIZE_PROP,
341                                             &error_abort);
342         }
343     }
344     g_slist_free(list);
345 
346     return size;
347 }
348 
349 static void virtio_balloon_set_config(VirtIODevice *vdev,
350                                       const uint8_t *config_data)
351 {
352     VirtIOBalloon *dev = VIRTIO_BALLOON(vdev);
353     struct virtio_balloon_config config;
354     uint32_t oldactual = dev->actual;
355     ram_addr_t vm_ram_size = get_current_ram_size();
356 
357     memcpy(&config, config_data, sizeof(struct virtio_balloon_config));
358     dev->actual = le32_to_cpu(config.actual);
359     if (dev->actual != oldactual) {
360         qapi_event_send_balloon_change(vm_ram_size -
361                         ((ram_addr_t) dev->actual << VIRTIO_BALLOON_PFN_SHIFT),
362                         &error_abort);
363     }
364     trace_virtio_balloon_set_config(dev->actual, oldactual);
365 }
366 
367 static uint64_t virtio_balloon_get_features(VirtIODevice *vdev, uint64_t f,
368                                             Error **errp)
369 {
370     VirtIOBalloon *dev = VIRTIO_BALLOON(vdev);
371     f |= dev->host_features;
372     virtio_add_feature(&f, VIRTIO_BALLOON_F_STATS_VQ);
373     return f;
374 }
375 
376 static void virtio_balloon_stat(void *opaque, BalloonInfo *info)
377 {
378     VirtIOBalloon *dev = opaque;
379     info->actual = get_current_ram_size() - ((uint64_t) dev->actual <<
380                                              VIRTIO_BALLOON_PFN_SHIFT);
381 }
382 
383 static void virtio_balloon_to_target(void *opaque, ram_addr_t target)
384 {
385     VirtIOBalloon *dev = VIRTIO_BALLOON(opaque);
386     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
387     ram_addr_t vm_ram_size = get_current_ram_size();
388 
389     if (target > vm_ram_size) {
390         target = vm_ram_size;
391     }
392     if (target) {
393         dev->num_pages = (vm_ram_size - target) >> VIRTIO_BALLOON_PFN_SHIFT;
394         virtio_notify_config(vdev);
395     }
396     trace_virtio_balloon_to_target(target, dev->num_pages);
397 }
398 
399 static void virtio_balloon_save(QEMUFile *f, void *opaque)
400 {
401     virtio_save(VIRTIO_DEVICE(opaque), f);
402 }
403 
404 static void virtio_balloon_save_device(VirtIODevice *vdev, QEMUFile *f)
405 {
406     VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
407 
408     qemu_put_be32(f, s->num_pages);
409     qemu_put_be32(f, s->actual);
410 }
411 
412 static int virtio_balloon_load(QEMUFile *f, void *opaque, int version_id)
413 {
414     if (version_id != 1)
415         return -EINVAL;
416 
417     return virtio_load(VIRTIO_DEVICE(opaque), f, version_id);
418 }
419 
420 static int virtio_balloon_load_device(VirtIODevice *vdev, QEMUFile *f,
421                                       int version_id)
422 {
423     VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
424 
425     s->num_pages = qemu_get_be32(f);
426     s->actual = qemu_get_be32(f);
427 
428     if (balloon_stats_enabled(s)) {
429         balloon_stats_change_timer(s, s->stats_poll_interval);
430     }
431     return 0;
432 }
433 
434 static void virtio_balloon_device_realize(DeviceState *dev, Error **errp)
435 {
436     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
437     VirtIOBalloon *s = VIRTIO_BALLOON(dev);
438     int ret;
439 
440     virtio_init(vdev, "virtio-balloon", VIRTIO_ID_BALLOON,
441                 sizeof(struct virtio_balloon_config));
442 
443     ret = qemu_add_balloon_handler(virtio_balloon_to_target,
444                                    virtio_balloon_stat, s);
445 
446     if (ret < 0) {
447         error_setg(errp, "Only one balloon device is supported");
448         virtio_cleanup(vdev);
449         return;
450     }
451 
452     s->ivq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output);
453     s->dvq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output);
454     s->svq = virtio_add_queue(vdev, 128, virtio_balloon_receive_stats);
455 
456     reset_stats(s);
457 
458     register_savevm(dev, "virtio-balloon", -1, 1,
459                     virtio_balloon_save, virtio_balloon_load, s);
460 }
461 
462 static void virtio_balloon_device_unrealize(DeviceState *dev, Error **errp)
463 {
464     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
465     VirtIOBalloon *s = VIRTIO_BALLOON(dev);
466 
467     balloon_stats_destroy_timer(s);
468     qemu_remove_balloon_handler(s);
469     unregister_savevm(dev, "virtio-balloon", s);
470     virtio_cleanup(vdev);
471 }
472 
473 static void virtio_balloon_device_reset(VirtIODevice *vdev)
474 {
475     VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
476 
477     if (s->stats_vq_elem != NULL) {
478         g_free(s->stats_vq_elem);
479         s->stats_vq_elem = NULL;
480     }
481 }
482 
483 static void virtio_balloon_instance_init(Object *obj)
484 {
485     VirtIOBalloon *s = VIRTIO_BALLOON(obj);
486 
487     object_property_add(obj, "guest-stats", "guest statistics",
488                         balloon_stats_get_all, NULL, NULL, s, NULL);
489 
490     object_property_add(obj, "guest-stats-polling-interval", "int",
491                         balloon_stats_get_poll_interval,
492                         balloon_stats_set_poll_interval,
493                         NULL, s, NULL);
494 }
495 
496 static Property virtio_balloon_properties[] = {
497     DEFINE_PROP_BIT("deflate-on-oom", VirtIOBalloon, host_features,
498                     VIRTIO_BALLOON_F_DEFLATE_ON_OOM, false),
499     DEFINE_PROP_END_OF_LIST(),
500 };
501 
502 static void virtio_balloon_class_init(ObjectClass *klass, void *data)
503 {
504     DeviceClass *dc = DEVICE_CLASS(klass);
505     VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
506 
507     dc->props = virtio_balloon_properties;
508     set_bit(DEVICE_CATEGORY_MISC, dc->categories);
509     vdc->realize = virtio_balloon_device_realize;
510     vdc->unrealize = virtio_balloon_device_unrealize;
511     vdc->reset = virtio_balloon_device_reset;
512     vdc->get_config = virtio_balloon_get_config;
513     vdc->set_config = virtio_balloon_set_config;
514     vdc->get_features = virtio_balloon_get_features;
515     vdc->save = virtio_balloon_save_device;
516     vdc->load = virtio_balloon_load_device;
517 }
518 
519 static const TypeInfo virtio_balloon_info = {
520     .name = TYPE_VIRTIO_BALLOON,
521     .parent = TYPE_VIRTIO_DEVICE,
522     .instance_size = sizeof(VirtIOBalloon),
523     .instance_init = virtio_balloon_instance_init,
524     .class_init = virtio_balloon_class_init,
525 };
526 
527 static void virtio_register_types(void)
528 {
529     type_register_static(&virtio_balloon_info);
530 }
531 
532 type_init(virtio_register_types)
533