xref: /qemu/hw/virtio/virtio-balloon.c (revision 3d5b3ec6) 
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 
28 #if defined(__linux__)
29 #include <sys/mman.h>
30 #endif
31 
32 #include "hw/virtio/virtio-bus.h"
33 
34 static void balloon_page(void *addr, int deflate)
35 {
36 #if defined(__linux__)
37     if (!kvm_enabled() || kvm_has_sync_mmu())
38         qemu_madvise(addr, TARGET_PAGE_SIZE,
39                 deflate ? QEMU_MADV_WILLNEED : QEMU_MADV_DONTNEED);
40 #endif
41 }
42 
43 static const char *balloon_stat_names[] = {
44    [VIRTIO_BALLOON_S_SWAP_IN] = "stat-swap-in",
45    [VIRTIO_BALLOON_S_SWAP_OUT] = "stat-swap-out",
46    [VIRTIO_BALLOON_S_MAJFLT] = "stat-major-faults",
47    [VIRTIO_BALLOON_S_MINFLT] = "stat-minor-faults",
48    [VIRTIO_BALLOON_S_MEMFREE] = "stat-free-memory",
49    [VIRTIO_BALLOON_S_MEMTOT] = "stat-total-memory",
50    [VIRTIO_BALLOON_S_NR] = NULL
51 };
52 
53 /*
54  * reset_stats - Mark all items in the stats array as unset
55  *
56  * This function needs to be called at device intialization and before
57  * before updating to a set of newly-generated stats.  This will ensure that no
58  * stale values stick around in case the guest reports a subset of the supported
59  * statistics.
60  */
61 static inline void reset_stats(VirtIOBalloon *dev)
62 {
63     int i;
64     for (i = 0; i < VIRTIO_BALLOON_S_NR; dev->stats[i++] = -1);
65 }
66 
67 static bool balloon_stats_supported(const VirtIOBalloon *s)
68 {
69     VirtIODevice *vdev = VIRTIO_DEVICE(s);
70     return vdev->guest_features & (1 << VIRTIO_BALLOON_F_STATS_VQ);
71 }
72 
73 static bool balloon_stats_enabled(const VirtIOBalloon *s)
74 {
75     return s->stats_poll_interval > 0;
76 }
77 
78 static void balloon_stats_destroy_timer(VirtIOBalloon *s)
79 {
80     if (balloon_stats_enabled(s)) {
81         qemu_del_timer(s->stats_timer);
82         qemu_free_timer(s->stats_timer);
83         s->stats_timer = NULL;
84         s->stats_poll_interval = 0;
85     }
86 }
87 
88 static void balloon_stats_change_timer(VirtIOBalloon *s, int secs)
89 {
90     qemu_mod_timer(s->stats_timer, qemu_get_clock_ms(vm_clock) + secs * 1000);
91 }
92 
93 static void balloon_stats_poll_cb(void *opaque)
94 {
95     VirtIOBalloon *s = opaque;
96     VirtIODevice *vdev = VIRTIO_DEVICE(s);
97 
98     if (!balloon_stats_supported(s)) {
99         /* re-schedule */
100         balloon_stats_change_timer(s, s->stats_poll_interval);
101         return;
102     }
103 
104     virtqueue_push(s->svq, &s->stats_vq_elem, s->stats_vq_offset);
105     virtio_notify(vdev, s->svq);
106 }
107 
108 static void balloon_stats_get_all(Object *obj, struct Visitor *v,
109                                   void *opaque, const char *name, Error **errp)
110 {
111     VirtIOBalloon *s = opaque;
112     int i;
113 
114     if (!s->stats_last_update) {
115         error_setg(errp, "guest hasn't updated any stats yet");
116         return;
117     }
118 
119     visit_start_struct(v, NULL, "guest-stats", name, 0, errp);
120     visit_type_int(v, &s->stats_last_update, "last-update", errp);
121 
122     visit_start_struct(v, NULL, NULL, "stats", 0, errp);
123     for (i = 0; i < VIRTIO_BALLOON_S_NR; i++) {
124         visit_type_int64(v, (int64_t *) &s->stats[i], balloon_stat_names[i],
125                          errp);
126     }
127     visit_end_struct(v, errp);
128 
129     visit_end_struct(v, errp);
130 }
131 
132 static void balloon_stats_get_poll_interval(Object *obj, struct Visitor *v,
133                                             void *opaque, const char *name,
134                                             Error **errp)
135 {
136     VirtIOBalloon *s = opaque;
137     visit_type_int(v, &s->stats_poll_interval, name, errp);
138 }
139 
140 static void balloon_stats_set_poll_interval(Object *obj, struct Visitor *v,
141                                             void *opaque, const char *name,
142                                             Error **errp)
143 {
144     VirtIOBalloon *s = opaque;
145     int64_t value;
146 
147     visit_type_int(v, &value, name, errp);
148     if (error_is_set(errp)) {
149         return;
150     }
151 
152     if (value < 0) {
153         error_setg(errp, "timer value must be greater than zero");
154         return;
155     }
156 
157     if (value == s->stats_poll_interval) {
158         return;
159     }
160 
161     if (value == 0) {
162         /* timer=0 disables the timer */
163         balloon_stats_destroy_timer(s);
164         return;
165     }
166 
167     if (balloon_stats_enabled(s)) {
168         /* timer interval change */
169         s->stats_poll_interval = value;
170         balloon_stats_change_timer(s, value);
171         return;
172     }
173 
174     /* create a new timer */
175     g_assert(s->stats_timer == NULL);
176     s->stats_timer = qemu_new_timer_ms(vm_clock, balloon_stats_poll_cb, s);
177     s->stats_poll_interval = value;
178     balloon_stats_change_timer(s, 0);
179 }
180 
181 static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
182 {
183     VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
184     VirtQueueElement elem;
185     MemoryRegionSection section;
186 
187     while (virtqueue_pop(vq, &elem)) {
188         size_t offset = 0;
189         uint32_t pfn;
190 
191         while (iov_to_buf(elem.out_sg, elem.out_num, offset, &pfn, 4) == 4) {
192             ram_addr_t pa;
193             ram_addr_t addr;
194 
195             pa = (ram_addr_t)ldl_p(&pfn) << VIRTIO_BALLOON_PFN_SHIFT;
196             offset += 4;
197 
198             /* FIXME: remove get_system_memory(), but how? */
199             section = memory_region_find(get_system_memory(), pa, 1);
200             if (!section.size || !memory_region_is_ram(section.mr))
201                 continue;
202 
203             /* Using memory_region_get_ram_ptr is bending the rules a bit, but
204                should be OK because we only want a single page.  */
205             addr = section.offset_within_region;
206             balloon_page(memory_region_get_ram_ptr(section.mr) + addr,
207                          !!(vq == s->dvq));
208         }
209 
210         virtqueue_push(vq, &elem, offset);
211         virtio_notify(vdev, vq);
212     }
213 }
214 
215 static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq)
216 {
217     VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
218     VirtQueueElement *elem = &s->stats_vq_elem;
219     VirtIOBalloonStat stat;
220     size_t offset = 0;
221     qemu_timeval tv;
222 
223     if (!virtqueue_pop(vq, elem)) {
224         goto out;
225     }
226 
227     /* Initialize the stats to get rid of any stale values.  This is only
228      * needed to handle the case where a guest supports fewer stats than it
229      * used to (ie. it has booted into an old kernel).
230      */
231     reset_stats(s);
232 
233     while (iov_to_buf(elem->out_sg, elem->out_num, offset, &stat, sizeof(stat))
234            == sizeof(stat)) {
235         uint16_t tag = tswap16(stat.tag);
236         uint64_t val = tswap64(stat.val);
237 
238         offset += sizeof(stat);
239         if (tag < VIRTIO_BALLOON_S_NR)
240             s->stats[tag] = val;
241     }
242     s->stats_vq_offset = offset;
243 
244     if (qemu_gettimeofday(&tv) < 0) {
245         fprintf(stderr, "warning: %s: failed to get time of day\n", __func__);
246         goto out;
247     }
248 
249     s->stats_last_update = tv.tv_sec;
250 
251 out:
252     if (balloon_stats_enabled(s)) {
253         balloon_stats_change_timer(s, s->stats_poll_interval);
254     }
255 }
256 
257 static void virtio_balloon_get_config(VirtIODevice *vdev, uint8_t *config_data)
258 {
259     VirtIOBalloon *dev = VIRTIO_BALLOON(vdev);
260     struct virtio_balloon_config config;
261 
262     config.num_pages = cpu_to_le32(dev->num_pages);
263     config.actual = cpu_to_le32(dev->actual);
264 
265     memcpy(config_data, &config, 8);
266 }
267 
268 static void virtio_balloon_set_config(VirtIODevice *vdev,
269                                       const uint8_t *config_data)
270 {
271     VirtIOBalloon *dev = VIRTIO_BALLOON(vdev);
272     struct virtio_balloon_config config;
273     uint32_t oldactual = dev->actual;
274     memcpy(&config, config_data, 8);
275     dev->actual = le32_to_cpu(config.actual);
276     if (dev->actual != oldactual) {
277         qemu_balloon_changed(ram_size -
278                        ((ram_addr_t) dev->actual << VIRTIO_BALLOON_PFN_SHIFT));
279     }
280 }
281 
282 static uint32_t virtio_balloon_get_features(VirtIODevice *vdev, uint32_t f)
283 {
284     f |= (1 << VIRTIO_BALLOON_F_STATS_VQ);
285     return f;
286 }
287 
288 static void virtio_balloon_stat(void *opaque, BalloonInfo *info)
289 {
290     VirtIOBalloon *dev = opaque;
291     info->actual = ram_size - ((uint64_t) dev->actual <<
292                                VIRTIO_BALLOON_PFN_SHIFT);
293 }
294 
295 static void virtio_balloon_to_target(void *opaque, ram_addr_t target)
296 {
297     VirtIOBalloon *dev = VIRTIO_BALLOON(opaque);
298     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
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(vdev);
306     }
307 }
308 
309 static void virtio_balloon_save(QEMUFile *f, void *opaque)
310 {
311     VirtIOBalloon *s = VIRTIO_BALLOON(opaque);
312     VirtIODevice *vdev = VIRTIO_DEVICE(s);
313 
314     virtio_save(vdev, f);
315 
316     qemu_put_be32(f, s->num_pages);
317     qemu_put_be32(f, s->actual);
318 }
319 
320 static int virtio_balloon_load(QEMUFile *f, void *opaque, int version_id)
321 {
322     VirtIOBalloon *s = VIRTIO_BALLOON(opaque);
323     VirtIODevice *vdev = VIRTIO_DEVICE(s);
324     int ret;
325 
326     if (version_id != 1)
327         return -EINVAL;
328 
329     ret = virtio_load(vdev, f);
330     if (ret) {
331         return ret;
332     }
333 
334     s->num_pages = qemu_get_be32(f);
335     s->actual = qemu_get_be32(f);
336     return 0;
337 }
338 
339 static int virtio_balloon_device_init(VirtIODevice *vdev)
340 {
341     DeviceState *qdev = DEVICE(vdev);
342     VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
343     int ret;
344 
345     virtio_init(vdev, "virtio-balloon", VIRTIO_ID_BALLOON, 8);
346 
347     ret = qemu_add_balloon_handler(virtio_balloon_to_target,
348                                    virtio_balloon_stat, s);
349 
350     if (ret < 0) {
351         virtio_cleanup(VIRTIO_DEVICE(s));
352         return -1;
353     }
354 
355     s->ivq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output);
356     s->dvq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output);
357     s->svq = virtio_add_queue(vdev, 128, virtio_balloon_receive_stats);
358 
359     register_savevm(qdev, "virtio-balloon", -1, 1,
360                     virtio_balloon_save, virtio_balloon_load, s);
361 
362     object_property_add(OBJECT(qdev), "guest-stats", "guest statistics",
363                         balloon_stats_get_all, NULL, NULL, s, NULL);
364 
365     object_property_add(OBJECT(qdev), "guest-stats-polling-interval", "int",
366                         balloon_stats_get_poll_interval,
367                         balloon_stats_set_poll_interval,
368                         NULL, s, NULL);
369     return 0;
370 }
371 
372 static int virtio_balloon_device_exit(DeviceState *qdev)
373 {
374     VirtIOBalloon *s = VIRTIO_BALLOON(qdev);
375     VirtIODevice *vdev = VIRTIO_DEVICE(qdev);
376 
377     balloon_stats_destroy_timer(s);
378     qemu_remove_balloon_handler(s);
379     unregister_savevm(qdev, "virtio-balloon", s);
380     virtio_cleanup(vdev);
381     return 0;
382 }
383 
384 static Property virtio_balloon_properties[] = {
385     DEFINE_PROP_END_OF_LIST(),
386 };
387 
388 static void virtio_balloon_class_init(ObjectClass *klass, void *data)
389 {
390     DeviceClass *dc = DEVICE_CLASS(klass);
391     VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
392     dc->exit = virtio_balloon_device_exit;
393     dc->props = virtio_balloon_properties;
394     vdc->init = virtio_balloon_device_init;
395     vdc->get_config = virtio_balloon_get_config;
396     vdc->set_config = virtio_balloon_set_config;
397     vdc->get_features = virtio_balloon_get_features;
398 }
399 
400 static const TypeInfo virtio_balloon_info = {
401     .name = TYPE_VIRTIO_BALLOON,
402     .parent = TYPE_VIRTIO_DEVICE,
403     .instance_size = sizeof(VirtIOBalloon),
404     .class_init = virtio_balloon_class_init,
405 };
406 
407 static void virtio_register_types(void)
408 {
409     type_register_static(&virtio_balloon_info);
410 }
411 
412 type_init(virtio_register_types)
413