xref: /openbmc/qemu/hw/virtio/virtio-balloon.c (revision 761d524d) 
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 (!int128_nz(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             memory_region_unref(section.mr);
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 = VIRTIO_BALLOON(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 = 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 = 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                        ((ram_addr_t) 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 = VIRTIO_BALLOON(opaque);
299     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
300 
301     if (target > ram_size) {
302         target = ram_size;
303     }
304     if (target) {
305         dev->num_pages = (ram_size - target) >> VIRTIO_BALLOON_PFN_SHIFT;
306         virtio_notify_config(vdev);
307     }
308 }
309 
310 static void virtio_balloon_save(QEMUFile *f, void *opaque)
311 {
312     VirtIOBalloon *s = VIRTIO_BALLOON(opaque);
313     VirtIODevice *vdev = VIRTIO_DEVICE(s);
314 
315     virtio_save(vdev, f);
316 
317     qemu_put_be32(f, s->num_pages);
318     qemu_put_be32(f, s->actual);
319 }
320 
321 static int virtio_balloon_load(QEMUFile *f, void *opaque, int version_id)
322 {
323     VirtIOBalloon *s = VIRTIO_BALLOON(opaque);
324     VirtIODevice *vdev = VIRTIO_DEVICE(s);
325     int ret;
326 
327     if (version_id != 1)
328         return -EINVAL;
329 
330     ret = virtio_load(vdev, f);
331     if (ret) {
332         return ret;
333     }
334 
335     s->num_pages = qemu_get_be32(f);
336     s->actual = qemu_get_be32(f);
337     return 0;
338 }
339 
340 static int virtio_balloon_device_init(VirtIODevice *vdev)
341 {
342     DeviceState *qdev = DEVICE(vdev);
343     VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
344     int ret;
345 
346     virtio_init(vdev, "virtio-balloon", VIRTIO_ID_BALLOON, 8);
347 
348     ret = qemu_add_balloon_handler(virtio_balloon_to_target,
349                                    virtio_balloon_stat, s);
350 
351     if (ret < 0) {
352         virtio_cleanup(VIRTIO_DEVICE(s));
353         return -1;
354     }
355 
356     s->ivq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output);
357     s->dvq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output);
358     s->svq = virtio_add_queue(vdev, 128, virtio_balloon_receive_stats);
359 
360     register_savevm(qdev, "virtio-balloon", -1, 1,
361                     virtio_balloon_save, virtio_balloon_load, s);
362 
363     object_property_add(OBJECT(qdev), "guest-stats", "guest statistics",
364                         balloon_stats_get_all, NULL, NULL, s, NULL);
365 
366     object_property_add(OBJECT(qdev), "guest-stats-polling-interval", "int",
367                         balloon_stats_get_poll_interval,
368                         balloon_stats_set_poll_interval,
369                         NULL, s, NULL);
370     return 0;
371 }
372 
373 static int virtio_balloon_device_exit(DeviceState *qdev)
374 {
375     VirtIOBalloon *s = VIRTIO_BALLOON(qdev);
376     VirtIODevice *vdev = VIRTIO_DEVICE(qdev);
377 
378     balloon_stats_destroy_timer(s);
379     qemu_remove_balloon_handler(s);
380     unregister_savevm(qdev, "virtio-balloon", s);
381     virtio_cleanup(vdev);
382     return 0;
383 }
384 
385 static Property virtio_balloon_properties[] = {
386     DEFINE_PROP_END_OF_LIST(),
387 };
388 
389 static void virtio_balloon_class_init(ObjectClass *klass, void *data)
390 {
391     DeviceClass *dc = DEVICE_CLASS(klass);
392     VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
393     dc->exit = virtio_balloon_device_exit;
394     dc->props = virtio_balloon_properties;
395     vdc->init = virtio_balloon_device_init;
396     vdc->get_config = virtio_balloon_get_config;
397     vdc->set_config = virtio_balloon_set_config;
398     vdc->get_features = virtio_balloon_get_features;
399 }
400 
401 static const TypeInfo virtio_balloon_info = {
402     .name = TYPE_VIRTIO_BALLOON,
403     .parent = TYPE_VIRTIO_DEVICE,
404     .instance_size = sizeof(VirtIOBalloon),
405     .class_init = virtio_balloon_class_init,
406 };
407 
408 static void virtio_register_types(void)
409 {
410     type_register_static(&virtio_balloon_info);
411 }
412 
413 type_init(virtio_register_types)
414