xref: /openbmc/qemu/hw/virtio/virtio-balloon.c (revision a82400cf) 
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 "sysemu/kvm.h"
25 #include "exec/address-spaces.h"
26 #include "qapi/error.h"
27 #include "qapi/visitor.h"
28 #include "qapi-event.h"
29 #include "trace.h"
30 #include "qemu/error-report.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 static void balloon_page(void *addr, int deflate)
38 {
39     if (!qemu_balloon_is_inhibited() && (!kvm_enabled() ||
40                                          kvm_has_sync_mmu())) {
41         qemu_madvise(addr, BALLOON_PAGE_SIZE,
42                 deflate ? QEMU_MADV_WILLNEED : QEMU_MADV_DONTNEED);
43     }
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) ||
234                 !memory_region_is_ram(section.mr) ||
235                 memory_region_is_rom(section.mr) ||
236                 memory_region_is_romd(section.mr)) {
237                 trace_virtio_balloon_bad_addr(pa);
238                 continue;
239             }
240 
241             trace_virtio_balloon_handle_output(memory_region_name(section.mr),
242                                                pa);
243             /* Using memory_region_get_ram_ptr is bending the rules a bit, but
244                should be OK because we only want a single page.  */
245             addr = section.offset_within_region;
246             balloon_page(memory_region_get_ram_ptr(section.mr) + addr,
247                          !!(vq == s->dvq));
248             memory_region_unref(section.mr);
249         }
250 
251         virtqueue_push(vq, elem, offset);
252         virtio_notify(vdev, vq);
253         g_free(elem);
254     }
255 }
256 
257 static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq)
258 {
259     VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
260     VirtQueueElement *elem;
261     VirtIOBalloonStat stat;
262     size_t offset = 0;
263     qemu_timeval tv;
264 
265     elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
266     if (!elem) {
267         goto out;
268     }
269 
270     if (s->stats_vq_elem != NULL) {
271         /* This should never happen if the driver follows the spec. */
272         virtqueue_push(vq, s->stats_vq_elem, 0);
273         virtio_notify(vdev, vq);
274         g_free(s->stats_vq_elem);
275     }
276 
277     s->stats_vq_elem = elem;
278 
279     /* Initialize the stats to get rid of any stale values.  This is only
280      * needed to handle the case where a guest supports fewer stats than it
281      * used to (ie. it has booted into an old kernel).
282      */
283     reset_stats(s);
284 
285     while (iov_to_buf(elem->out_sg, elem->out_num, offset, &stat, sizeof(stat))
286            == sizeof(stat)) {
287         uint16_t tag = virtio_tswap16(vdev, stat.tag);
288         uint64_t val = virtio_tswap64(vdev, stat.val);
289 
290         offset += sizeof(stat);
291         if (tag < VIRTIO_BALLOON_S_NR)
292             s->stats[tag] = val;
293     }
294     s->stats_vq_offset = offset;
295 
296     if (qemu_gettimeofday(&tv) < 0) {
297         warn_report("%s: failed to get time of day", __func__);
298         goto out;
299     }
300 
301     s->stats_last_update = tv.tv_sec;
302 
303 out:
304     if (balloon_stats_enabled(s)) {
305         balloon_stats_change_timer(s, s->stats_poll_interval);
306     }
307 }
308 
309 static void virtio_balloon_get_config(VirtIODevice *vdev, uint8_t *config_data)
310 {
311     VirtIOBalloon *dev = VIRTIO_BALLOON(vdev);
312     struct virtio_balloon_config config;
313 
314     config.num_pages = cpu_to_le32(dev->num_pages);
315     config.actual = cpu_to_le32(dev->actual);
316 
317     trace_virtio_balloon_get_config(config.num_pages, config.actual);
318     memcpy(config_data, &config, sizeof(struct virtio_balloon_config));
319 }
320 
321 static int build_dimm_list(Object *obj, void *opaque)
322 {
323     GSList **list = opaque;
324 
325     if (object_dynamic_cast(obj, TYPE_PC_DIMM)) {
326         DeviceState *dev = DEVICE(obj);
327         if (dev->realized) { /* only realized DIMMs matter */
328             *list = g_slist_prepend(*list, dev);
329         }
330     }
331 
332     object_child_foreach(obj, build_dimm_list, opaque);
333     return 0;
334 }
335 
336 static ram_addr_t get_current_ram_size(void)
337 {
338     GSList *list = NULL, *item;
339     ram_addr_t size = ram_size;
340 
341     build_dimm_list(qdev_get_machine(), &list);
342     for (item = list; item; item = g_slist_next(item)) {
343         Object *obj = OBJECT(item->data);
344         if (!strcmp(object_get_typename(obj), TYPE_PC_DIMM)) {
345             size += object_property_get_int(obj, PC_DIMM_SIZE_PROP,
346                                             &error_abort);
347         }
348     }
349     g_slist_free(list);
350 
351     return size;
352 }
353 
354 static void virtio_balloon_set_config(VirtIODevice *vdev,
355                                       const uint8_t *config_data)
356 {
357     VirtIOBalloon *dev = VIRTIO_BALLOON(vdev);
358     struct virtio_balloon_config config;
359     uint32_t oldactual = dev->actual;
360     ram_addr_t vm_ram_size = get_current_ram_size();
361 
362     memcpy(&config, config_data, sizeof(struct virtio_balloon_config));
363     dev->actual = le32_to_cpu(config.actual);
364     if (dev->actual != oldactual) {
365         qapi_event_send_balloon_change(vm_ram_size -
366                         ((ram_addr_t) dev->actual << VIRTIO_BALLOON_PFN_SHIFT),
367                         &error_abort);
368     }
369     trace_virtio_balloon_set_config(dev->actual, oldactual);
370 }
371 
372 static uint64_t virtio_balloon_get_features(VirtIODevice *vdev, uint64_t f,
373                                             Error **errp)
374 {
375     VirtIOBalloon *dev = VIRTIO_BALLOON(vdev);
376     f |= dev->host_features;
377     virtio_add_feature(&f, VIRTIO_BALLOON_F_STATS_VQ);
378     return f;
379 }
380 
381 static void virtio_balloon_stat(void *opaque, BalloonInfo *info)
382 {
383     VirtIOBalloon *dev = opaque;
384     info->actual = get_current_ram_size() - ((uint64_t) dev->actual <<
385                                              VIRTIO_BALLOON_PFN_SHIFT);
386 }
387 
388 static void virtio_balloon_to_target(void *opaque, ram_addr_t target)
389 {
390     VirtIOBalloon *dev = VIRTIO_BALLOON(opaque);
391     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
392     ram_addr_t vm_ram_size = get_current_ram_size();
393 
394     if (target > vm_ram_size) {
395         target = vm_ram_size;
396     }
397     if (target) {
398         dev->num_pages = (vm_ram_size - target) >> VIRTIO_BALLOON_PFN_SHIFT;
399         virtio_notify_config(vdev);
400     }
401     trace_virtio_balloon_to_target(target, dev->num_pages);
402 }
403 
404 static int virtio_balloon_post_load_device(void *opaque, int version_id)
405 {
406     VirtIOBalloon *s = VIRTIO_BALLOON(opaque);
407 
408     if (balloon_stats_enabled(s)) {
409         balloon_stats_change_timer(s, s->stats_poll_interval);
410     }
411     return 0;
412 }
413 
414 static const VMStateDescription vmstate_virtio_balloon_device = {
415     .name = "virtio-balloon-device",
416     .version_id = 1,
417     .minimum_version_id = 1,
418     .post_load = virtio_balloon_post_load_device,
419     .fields = (VMStateField[]) {
420         VMSTATE_UINT32(num_pages, VirtIOBalloon),
421         VMSTATE_UINT32(actual, VirtIOBalloon),
422         VMSTATE_END_OF_LIST()
423     },
424 };
425 
426 static void virtio_balloon_device_realize(DeviceState *dev, Error **errp)
427 {
428     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
429     VirtIOBalloon *s = VIRTIO_BALLOON(dev);
430     int ret;
431 
432     virtio_init(vdev, "virtio-balloon", VIRTIO_ID_BALLOON,
433                 sizeof(struct virtio_balloon_config));
434 
435     ret = qemu_add_balloon_handler(virtio_balloon_to_target,
436                                    virtio_balloon_stat, s);
437 
438     if (ret < 0) {
439         error_setg(errp, "Only one balloon device is supported");
440         virtio_cleanup(vdev);
441         return;
442     }
443 
444     s->ivq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output);
445     s->dvq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output);
446     s->svq = virtio_add_queue(vdev, 128, virtio_balloon_receive_stats);
447 
448     reset_stats(s);
449 }
450 
451 static void virtio_balloon_device_unrealize(DeviceState *dev, Error **errp)
452 {
453     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
454     VirtIOBalloon *s = VIRTIO_BALLOON(dev);
455 
456     balloon_stats_destroy_timer(s);
457     qemu_remove_balloon_handler(s);
458     virtio_cleanup(vdev);
459 }
460 
461 static void virtio_balloon_device_reset(VirtIODevice *vdev)
462 {
463     VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
464 
465     if (s->stats_vq_elem != NULL) {
466         virtqueue_unpop(s->svq, s->stats_vq_elem, 0);
467         g_free(s->stats_vq_elem);
468         s->stats_vq_elem = NULL;
469     }
470 }
471 
472 static void virtio_balloon_set_status(VirtIODevice *vdev, uint8_t status)
473 {
474     VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
475 
476     if (!s->stats_vq_elem && vdev->vm_running &&
477         (status & VIRTIO_CONFIG_S_DRIVER_OK) && virtqueue_rewind(s->svq, 1)) {
478         /* poll stats queue for the element we have discarded when the VM
479          * was stopped */
480         virtio_balloon_receive_stats(vdev, s->svq);
481     }
482 }
483 
484 static void virtio_balloon_instance_init(Object *obj)
485 {
486     VirtIOBalloon *s = VIRTIO_BALLOON(obj);
487 
488     object_property_add(obj, "guest-stats", "guest statistics",
489                         balloon_stats_get_all, NULL, NULL, s, NULL);
490 
491     object_property_add(obj, "guest-stats-polling-interval", "int",
492                         balloon_stats_get_poll_interval,
493                         balloon_stats_set_poll_interval,
494                         NULL, s, NULL);
495 }
496 
497 static const VMStateDescription vmstate_virtio_balloon = {
498     .name = "virtio-balloon",
499     .minimum_version_id = 1,
500     .version_id = 1,
501     .fields = (VMStateField[]) {
502         VMSTATE_VIRTIO_DEVICE,
503         VMSTATE_END_OF_LIST()
504     },
505 };
506 
507 static Property virtio_balloon_properties[] = {
508     DEFINE_PROP_BIT("deflate-on-oom", VirtIOBalloon, host_features,
509                     VIRTIO_BALLOON_F_DEFLATE_ON_OOM, false),
510     DEFINE_PROP_END_OF_LIST(),
511 };
512 
513 static void virtio_balloon_class_init(ObjectClass *klass, void *data)
514 {
515     DeviceClass *dc = DEVICE_CLASS(klass);
516     VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
517 
518     dc->props = virtio_balloon_properties;
519     dc->vmsd = &vmstate_virtio_balloon;
520     set_bit(DEVICE_CATEGORY_MISC, dc->categories);
521     vdc->realize = virtio_balloon_device_realize;
522     vdc->unrealize = virtio_balloon_device_unrealize;
523     vdc->reset = virtio_balloon_device_reset;
524     vdc->get_config = virtio_balloon_get_config;
525     vdc->set_config = virtio_balloon_set_config;
526     vdc->get_features = virtio_balloon_get_features;
527     vdc->set_status = virtio_balloon_set_status;
528     vdc->vmsd = &vmstate_virtio_balloon_device;
529 }
530 
531 static const TypeInfo virtio_balloon_info = {
532     .name = TYPE_VIRTIO_BALLOON,
533     .parent = TYPE_VIRTIO_DEVICE,
534     .instance_size = sizeof(VirtIOBalloon),
535     .instance_init = virtio_balloon_instance_init,
536     .class_init = virtio_balloon_class_init,
537 };
538 
539 static void virtio_register_types(void)
540 {
541     type_register_static(&virtio_balloon_info);
542 }
543 
544 type_init(virtio_register_types)
545