xref: /openbmc/qemu/hw/virtio/virtio-balloon.c (revision 10500ce2) 
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/virtio.h"
20 #include "hw/i386/pc.h"
21 #include "cpu.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 #if defined(__linux__)
31 #include <sys/mman.h>
32 #endif
33 
34 #include "hw/virtio/virtio-bus.h"
35 #include "hw/virtio/virtio-access.h"
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 initialization and before
60  * 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     VirtIODevice *vdev = VIRTIO_DEVICE(s);
73     return virtio_has_feature(vdev, VIRTIO_BALLOON_F_STATS_VQ);
74 }
75 
76 static bool balloon_stats_enabled(const VirtIOBalloon *s)
77 {
78     return s->stats_poll_interval > 0;
79 }
80 
81 static void balloon_stats_destroy_timer(VirtIOBalloon *s)
82 {
83     if (balloon_stats_enabled(s)) {
84         timer_del(s->stats_timer);
85         timer_free(s->stats_timer);
86         s->stats_timer = NULL;
87         s->stats_poll_interval = 0;
88     }
89 }
90 
91 static void balloon_stats_change_timer(VirtIOBalloon *s, int64_t secs)
92 {
93     timer_mod(s->stats_timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + secs * 1000);
94 }
95 
96 static void balloon_stats_poll_cb(void *opaque)
97 {
98     VirtIOBalloon *s = opaque;
99     VirtIODevice *vdev = VIRTIO_DEVICE(s);
100 
101     if (!balloon_stats_supported(s)) {
102         /* re-schedule */
103         balloon_stats_change_timer(s, s->stats_poll_interval);
104         return;
105     }
106 
107     virtqueue_push(s->svq, &s->stats_vq_elem, s->stats_vq_offset);
108     virtio_notify(vdev, s->svq);
109 }
110 
111 static void balloon_stats_get_all(Object *obj, struct Visitor *v,
112                                   void *opaque, const char *name, Error **errp)
113 {
114     Error *err = NULL;
115     VirtIOBalloon *s = opaque;
116     int i;
117 
118     visit_start_struct(v, NULL, "guest-stats", name, 0, &err);
119     if (err) {
120         goto out;
121     }
122     visit_type_int(v, &s->stats_last_update, "last-update", &err);
123     if (err) {
124         goto out_end;
125     }
126 
127     visit_start_struct(v, NULL, NULL, "stats", 0, &err);
128     if (err) {
129         goto out_end;
130     }
131     for (i = 0; !err && i < VIRTIO_BALLOON_S_NR; i++) {
132         visit_type_int64(v, (int64_t *) &s->stats[i], balloon_stat_names[i],
133                          &err);
134     }
135     error_propagate(errp, err);
136     err = NULL;
137     visit_end_struct(v, &err);
138 
139 out_end:
140     error_propagate(errp, err);
141     err = NULL;
142     visit_end_struct(v, &err);
143 out:
144     error_propagate(errp, err);
145 }
146 
147 static void balloon_stats_get_poll_interval(Object *obj, struct Visitor *v,
148                                             void *opaque, const char *name,
149                                             Error **errp)
150 {
151     VirtIOBalloon *s = opaque;
152     visit_type_int(v, &s->stats_poll_interval, name, errp);
153 }
154 
155 static void balloon_stats_set_poll_interval(Object *obj, struct Visitor *v,
156                                             void *opaque, const char *name,
157                                             Error **errp)
158 {
159     VirtIOBalloon *s = opaque;
160     Error *local_err = NULL;
161     int64_t value;
162 
163     visit_type_int(v, &value, name, &local_err);
164     if (local_err) {
165         error_propagate(errp, local_err);
166         return;
167     }
168 
169     if (value < 0) {
170         error_setg(errp, "timer value must be greater than zero");
171         return;
172     }
173 
174     if (value > UINT32_MAX) {
175         error_setg(errp, "timer value is too big");
176         return;
177     }
178 
179     if (value == s->stats_poll_interval) {
180         return;
181     }
182 
183     if (value == 0) {
184         /* timer=0 disables the timer */
185         balloon_stats_destroy_timer(s);
186         return;
187     }
188 
189     if (balloon_stats_enabled(s)) {
190         /* timer interval change */
191         s->stats_poll_interval = value;
192         balloon_stats_change_timer(s, value);
193         return;
194     }
195 
196     /* create a new timer */
197     g_assert(s->stats_timer == NULL);
198     s->stats_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL, balloon_stats_poll_cb, s);
199     s->stats_poll_interval = value;
200     balloon_stats_change_timer(s, 0);
201 }
202 
203 static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
204 {
205     VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
206     VirtQueueElement elem;
207     MemoryRegionSection section;
208 
209     while (virtqueue_pop(vq, &elem)) {
210         size_t offset = 0;
211         uint32_t pfn;
212 
213         while (iov_to_buf(elem.out_sg, elem.out_num, offset, &pfn, 4) == 4) {
214             ram_addr_t pa;
215             ram_addr_t addr;
216             int p = virtio_ldl_p(vdev, &pfn);
217 
218             pa = (ram_addr_t) p << VIRTIO_BALLOON_PFN_SHIFT;
219             offset += 4;
220 
221             /* FIXME: remove get_system_memory(), but how? */
222             section = memory_region_find(get_system_memory(), pa, 1);
223             if (!int128_nz(section.size) || !memory_region_is_ram(section.mr))
224                 continue;
225 
226             trace_virtio_balloon_handle_output(memory_region_name(section.mr),
227                                                pa);
228             /* Using memory_region_get_ram_ptr is bending the rules a bit, but
229                should be OK because we only want a single page.  */
230             addr = section.offset_within_region;
231             balloon_page(memory_region_get_ram_ptr(section.mr) + addr,
232                          !!(vq == s->dvq));
233             memory_region_unref(section.mr);
234         }
235 
236         virtqueue_push(vq, &elem, offset);
237         virtio_notify(vdev, vq);
238     }
239 }
240 
241 static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq)
242 {
243     VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
244     VirtQueueElement *elem = &s->stats_vq_elem;
245     VirtIOBalloonStat stat;
246     size_t offset = 0;
247     qemu_timeval tv;
248 
249     if (!virtqueue_pop(vq, elem)) {
250         goto out;
251     }
252 
253     /* Initialize the stats to get rid of any stale values.  This is only
254      * needed to handle the case where a guest supports fewer stats than it
255      * used to (ie. it has booted into an old kernel).
256      */
257     reset_stats(s);
258 
259     while (iov_to_buf(elem->out_sg, elem->out_num, offset, &stat, sizeof(stat))
260            == sizeof(stat)) {
261         uint16_t tag = virtio_tswap16(vdev, stat.tag);
262         uint64_t val = virtio_tswap64(vdev, stat.val);
263 
264         offset += sizeof(stat);
265         if (tag < VIRTIO_BALLOON_S_NR)
266             s->stats[tag] = val;
267     }
268     s->stats_vq_offset = offset;
269 
270     if (qemu_gettimeofday(&tv) < 0) {
271         fprintf(stderr, "warning: %s: failed to get time of day\n", __func__);
272         goto out;
273     }
274 
275     s->stats_last_update = tv.tv_sec;
276 
277 out:
278     if (balloon_stats_enabled(s)) {
279         balloon_stats_change_timer(s, s->stats_poll_interval);
280     }
281 }
282 
283 static void virtio_balloon_get_config(VirtIODevice *vdev, uint8_t *config_data)
284 {
285     VirtIOBalloon *dev = VIRTIO_BALLOON(vdev);
286     struct virtio_balloon_config config;
287 
288     config.num_pages = cpu_to_le32(dev->num_pages);
289     config.actual = cpu_to_le32(dev->actual);
290 
291     trace_virtio_balloon_get_config(config.num_pages, config.actual);
292     memcpy(config_data, &config, sizeof(struct virtio_balloon_config));
293 }
294 
295 static void virtio_balloon_set_config(VirtIODevice *vdev,
296                                       const uint8_t *config_data)
297 {
298     VirtIOBalloon *dev = VIRTIO_BALLOON(vdev);
299     struct virtio_balloon_config config;
300     uint32_t oldactual = dev->actual;
301     ram_addr_t vm_ram_size = get_current_ram_size();
302 
303     memcpy(&config, config_data, sizeof(struct virtio_balloon_config));
304     dev->actual = le32_to_cpu(config.actual);
305     if (dev->actual != oldactual) {
306         qapi_event_send_balloon_change(vm_ram_size -
307                         ((ram_addr_t) dev->actual << VIRTIO_BALLOON_PFN_SHIFT),
308                         &error_abort);
309     }
310     trace_virtio_balloon_set_config(dev->actual, oldactual);
311 }
312 
313 static uint64_t virtio_balloon_get_features(VirtIODevice *vdev, uint64_t f)
314 {
315     virtio_add_feature(&f, VIRTIO_BALLOON_F_STATS_VQ);
316     return f;
317 }
318 
319 static void virtio_balloon_stat(void *opaque, BalloonInfo *info)
320 {
321     VirtIOBalloon *dev = opaque;
322     info->actual = get_current_ram_size() - ((uint64_t) dev->actual <<
323                                              VIRTIO_BALLOON_PFN_SHIFT);
324 }
325 
326 static void virtio_balloon_to_target(void *opaque, ram_addr_t target)
327 {
328     VirtIOBalloon *dev = VIRTIO_BALLOON(opaque);
329     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
330     ram_addr_t vm_ram_size = get_current_ram_size();
331 
332     if (target > vm_ram_size) {
333         target = vm_ram_size;
334     }
335     if (target) {
336         dev->num_pages = (vm_ram_size - target) >> VIRTIO_BALLOON_PFN_SHIFT;
337         virtio_notify_config(vdev);
338     }
339     trace_virtio_balloon_to_target(target, dev->num_pages);
340 }
341 
342 static void virtio_balloon_save(QEMUFile *f, void *opaque)
343 {
344     virtio_save(VIRTIO_DEVICE(opaque), f);
345 }
346 
347 static void virtio_balloon_save_device(VirtIODevice *vdev, QEMUFile *f)
348 {
349     VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
350 
351     qemu_put_be32(f, s->num_pages);
352     qemu_put_be32(f, s->actual);
353 }
354 
355 static int virtio_balloon_load(QEMUFile *f, void *opaque, int version_id)
356 {
357     if (version_id != 1)
358         return -EINVAL;
359 
360     return virtio_load(VIRTIO_DEVICE(opaque), f, version_id);
361 }
362 
363 static int virtio_balloon_load_device(VirtIODevice *vdev, QEMUFile *f,
364                                       int version_id)
365 {
366     VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
367 
368     s->num_pages = qemu_get_be32(f);
369     s->actual = qemu_get_be32(f);
370     return 0;
371 }
372 
373 static void virtio_balloon_device_realize(DeviceState *dev, Error **errp)
374 {
375     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
376     VirtIOBalloon *s = VIRTIO_BALLOON(dev);
377     int ret;
378 
379     virtio_init(vdev, "virtio-balloon", VIRTIO_ID_BALLOON,
380                 sizeof(struct virtio_balloon_config));
381 
382     ret = qemu_add_balloon_handler(virtio_balloon_to_target,
383                                    virtio_balloon_stat, s);
384 
385     if (ret < 0) {
386         error_setg(errp, "Only one balloon device is supported");
387         virtio_cleanup(vdev);
388         return;
389     }
390 
391     s->ivq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output);
392     s->dvq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output);
393     s->svq = virtio_add_queue(vdev, 128, virtio_balloon_receive_stats);
394 
395     reset_stats(s);
396 
397     register_savevm(dev, "virtio-balloon", -1, 1,
398                     virtio_balloon_save, virtio_balloon_load, s);
399 }
400 
401 static void virtio_balloon_device_unrealize(DeviceState *dev, Error **errp)
402 {
403     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
404     VirtIOBalloon *s = VIRTIO_BALLOON(dev);
405 
406     balloon_stats_destroy_timer(s);
407     qemu_remove_balloon_handler(s);
408     unregister_savevm(dev, "virtio-balloon", s);
409     virtio_cleanup(vdev);
410 }
411 
412 static void virtio_balloon_instance_init(Object *obj)
413 {
414     VirtIOBalloon *s = VIRTIO_BALLOON(obj);
415 
416     object_property_add(obj, "guest-stats", "guest statistics",
417                         balloon_stats_get_all, NULL, NULL, s, NULL);
418 
419     object_property_add(obj, "guest-stats-polling-interval", "int",
420                         balloon_stats_get_poll_interval,
421                         balloon_stats_set_poll_interval,
422                         NULL, s, NULL);
423 }
424 
425 static Property virtio_balloon_properties[] = {
426     DEFINE_PROP_END_OF_LIST(),
427 };
428 
429 static void virtio_balloon_class_init(ObjectClass *klass, void *data)
430 {
431     DeviceClass *dc = DEVICE_CLASS(klass);
432     VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
433 
434     dc->props = virtio_balloon_properties;
435     set_bit(DEVICE_CATEGORY_MISC, dc->categories);
436     vdc->realize = virtio_balloon_device_realize;
437     vdc->unrealize = virtio_balloon_device_unrealize;
438     vdc->get_config = virtio_balloon_get_config;
439     vdc->set_config = virtio_balloon_set_config;
440     vdc->get_features = virtio_balloon_get_features;
441     vdc->save = virtio_balloon_save_device;
442     vdc->load = virtio_balloon_load_device;
443 }
444 
445 static const TypeInfo virtio_balloon_info = {
446     .name = TYPE_VIRTIO_BALLOON,
447     .parent = TYPE_VIRTIO_DEVICE,
448     .instance_size = sizeof(VirtIOBalloon),
449     .instance_init = virtio_balloon_instance_init,
450     .class_init = virtio_balloon_class_init,
451 };
452 
453 static void virtio_register_types(void)
454 {
455     type_register_static(&virtio_balloon_info);
456 }
457 
458 type_init(virtio_register_types)
459