Merge tag 'edgar/xilinx-next-2022-09-21.for-upstream' of https://github.com/edgarigl...
[qemu.git] / hw / virtio / virtio-balloon.c
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/module.h"
19 #include "qemu/timer.h"
20 #include "hw/virtio/virtio.h"
21 #include "hw/mem/pc-dimm.h"
22 #include "hw/qdev-properties.h"
23 #include "hw/boards.h"
24 #include "sysemu/balloon.h"
25 #include "hw/virtio/virtio-balloon.h"
26 #include "exec/address-spaces.h"
27 #include "qapi/error.h"
28 #include "qapi/qapi-events-machine.h"
29 #include "qapi/visitor.h"
30 #include "trace.h"
31 #include "qemu/error-report.h"
32 #include "migration/misc.h"
33 #include "migration/migration.h"
34
35 #include "hw/virtio/virtio-bus.h"
36 #include "hw/virtio/virtio-access.h"
37
38 #define BALLOON_PAGE_SIZE (1 << VIRTIO_BALLOON_PFN_SHIFT)
39
40 typedef struct PartiallyBalloonedPage {
41 ram_addr_t base_gpa;
42 unsigned long *bitmap;
43 } PartiallyBalloonedPage;
44
45 static void virtio_balloon_pbp_free(PartiallyBalloonedPage *pbp)
46 {
47 if (!pbp->bitmap) {
48 return;
49 }
50 g_free(pbp->bitmap);
51 pbp->bitmap = NULL;
52 }
53
54 static void virtio_balloon_pbp_alloc(PartiallyBalloonedPage *pbp,
55 ram_addr_t base_gpa,
56 long subpages)
57 {
58 pbp->base_gpa = base_gpa;
59 pbp->bitmap = bitmap_new(subpages);
60 }
61
62 static bool virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp,
63 ram_addr_t base_gpa)
64 {
65 return pbp->base_gpa == base_gpa;
66 }
67
68 static bool virtio_balloon_inhibited(void)
69 {
70 /*
71 * Postcopy cannot deal with concurrent discards,
72 * so it's special, as well as background snapshots.
73 */
74 return ram_block_discard_is_disabled() || migration_in_incoming_postcopy() ||
75 migration_in_bg_snapshot();
76 }
77
78 static void balloon_inflate_page(VirtIOBalloon *balloon,
79 MemoryRegion *mr, hwaddr mr_offset,
80 PartiallyBalloonedPage *pbp)
81 {
82 void *addr = memory_region_get_ram_ptr(mr) + mr_offset;
83 ram_addr_t rb_offset, rb_aligned_offset, base_gpa;
84 RAMBlock *rb;
85 size_t rb_page_size;
86 int subpages;
87
88 /* XXX is there a better way to get to the RAMBlock than via a
89 * host address? */
90 rb = qemu_ram_block_from_host(addr, false, &rb_offset);
91 rb_page_size = qemu_ram_pagesize(rb);
92
93 if (rb_page_size == BALLOON_PAGE_SIZE) {
94 /* Easy case */
95
96 ram_block_discard_range(rb, rb_offset, rb_page_size);
97 /* We ignore errors from ram_block_discard_range(), because it
98 * has already reported them, and failing to discard a balloon
99 * page is not fatal */
100 return;
101 }
102
103 /* Hard case
104 *
105 * We've put a piece of a larger host page into the balloon - we
106 * need to keep track until we have a whole host page to
107 * discard
108 */
109 warn_report_once(
110 "Balloon used with backing page size > 4kiB, this may not be reliable");
111
112 rb_aligned_offset = QEMU_ALIGN_DOWN(rb_offset, rb_page_size);
113 subpages = rb_page_size / BALLOON_PAGE_SIZE;
114 base_gpa = memory_region_get_ram_addr(mr) + mr_offset -
115 (rb_offset - rb_aligned_offset);
116
117 if (pbp->bitmap && !virtio_balloon_pbp_matches(pbp, base_gpa)) {
118 /* We've partially ballooned part of a host page, but now
119 * we're trying to balloon part of a different one. Too hard,
120 * give up on the old partial page */
121 virtio_balloon_pbp_free(pbp);
122 }
123
124 if (!pbp->bitmap) {
125 virtio_balloon_pbp_alloc(pbp, base_gpa, subpages);
126 }
127
128 set_bit((rb_offset - rb_aligned_offset) / BALLOON_PAGE_SIZE,
129 pbp->bitmap);
130
131 if (bitmap_full(pbp->bitmap, subpages)) {
132 /* We've accumulated a full host page, we can actually discard
133 * it now */
134
135 ram_block_discard_range(rb, rb_aligned_offset, rb_page_size);
136 /* We ignore errors from ram_block_discard_range(), because it
137 * has already reported them, and failing to discard a balloon
138 * page is not fatal */
139 virtio_balloon_pbp_free(pbp);
140 }
141 }
142
143 static void balloon_deflate_page(VirtIOBalloon *balloon,
144 MemoryRegion *mr, hwaddr mr_offset)
145 {
146 void *addr = memory_region_get_ram_ptr(mr) + mr_offset;
147 ram_addr_t rb_offset;
148 RAMBlock *rb;
149 size_t rb_page_size;
150 void *host_addr;
151 int ret;
152
153 /* XXX is there a better way to get to the RAMBlock than via a
154 * host address? */
155 rb = qemu_ram_block_from_host(addr, false, &rb_offset);
156 rb_page_size = qemu_ram_pagesize(rb);
157
158 host_addr = (void *)((uintptr_t)addr & ~(rb_page_size - 1));
159
160 /* When a page is deflated, we hint the whole host page it lives
161 * on, since we can't do anything smaller */
162 ret = qemu_madvise(host_addr, rb_page_size, QEMU_MADV_WILLNEED);
163 if (ret != 0) {
164 warn_report("Couldn't MADV_WILLNEED on balloon deflate: %s",
165 strerror(errno));
166 /* Otherwise ignore, failing to page hint shouldn't be fatal */
167 }
168 }
169
170 static const char *balloon_stat_names[] = {
171 [VIRTIO_BALLOON_S_SWAP_IN] = "stat-swap-in",
172 [VIRTIO_BALLOON_S_SWAP_OUT] = "stat-swap-out",
173 [VIRTIO_BALLOON_S_MAJFLT] = "stat-major-faults",
174 [VIRTIO_BALLOON_S_MINFLT] = "stat-minor-faults",
175 [VIRTIO_BALLOON_S_MEMFREE] = "stat-free-memory",
176 [VIRTIO_BALLOON_S_MEMTOT] = "stat-total-memory",
177 [VIRTIO_BALLOON_S_AVAIL] = "stat-available-memory",
178 [VIRTIO_BALLOON_S_CACHES] = "stat-disk-caches",
179 [VIRTIO_BALLOON_S_HTLB_PGALLOC] = "stat-htlb-pgalloc",
180 [VIRTIO_BALLOON_S_HTLB_PGFAIL] = "stat-htlb-pgfail",
181 [VIRTIO_BALLOON_S_NR] = NULL
182 };
183
184 /*
185 * reset_stats - Mark all items in the stats array as unset
186 *
187 * This function needs to be called at device initialization and before
188 * updating to a set of newly-generated stats. This will ensure that no
189 * stale values stick around in case the guest reports a subset of the supported
190 * statistics.
191 */
192 static inline void reset_stats(VirtIOBalloon *dev)
193 {
194 int i;
195 for (i = 0; i < VIRTIO_BALLOON_S_NR; dev->stats[i++] = -1);
196 }
197
198 static bool balloon_stats_supported(const VirtIOBalloon *s)
199 {
200 VirtIODevice *vdev = VIRTIO_DEVICE(s);
201 return virtio_vdev_has_feature(vdev, VIRTIO_BALLOON_F_STATS_VQ);
202 }
203
204 static bool balloon_stats_enabled(const VirtIOBalloon *s)
205 {
206 return s->stats_poll_interval > 0;
207 }
208
209 static void balloon_stats_destroy_timer(VirtIOBalloon *s)
210 {
211 if (balloon_stats_enabled(s)) {
212 timer_free(s->stats_timer);
213 s->stats_timer = NULL;
214 s->stats_poll_interval = 0;
215 }
216 }
217
218 static void balloon_stats_change_timer(VirtIOBalloon *s, int64_t secs)
219 {
220 timer_mod(s->stats_timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + secs * 1000);
221 }
222
223 static void balloon_stats_poll_cb(void *opaque)
224 {
225 VirtIOBalloon *s = opaque;
226 VirtIODevice *vdev = VIRTIO_DEVICE(s);
227
228 if (s->stats_vq_elem == NULL || !balloon_stats_supported(s)) {
229 /* re-schedule */
230 balloon_stats_change_timer(s, s->stats_poll_interval);
231 return;
232 }
233
234 virtqueue_push(s->svq, s->stats_vq_elem, 0);
235 virtio_notify(vdev, s->svq);
236 g_free(s->stats_vq_elem);
237 s->stats_vq_elem = NULL;
238 }
239
240 static void balloon_stats_get_all(Object *obj, Visitor *v, const char *name,
241 void *opaque, Error **errp)
242 {
243 Error *err = NULL;
244 VirtIOBalloon *s = opaque;
245 int i;
246
247 if (!visit_start_struct(v, name, NULL, 0, &err)) {
248 goto out;
249 }
250 if (!visit_type_int(v, "last-update", &s->stats_last_update, &err)) {
251 goto out_end;
252 }
253
254 if (!visit_start_struct(v, "stats", NULL, 0, &err)) {
255 goto out_end;
256 }
257 for (i = 0; i < VIRTIO_BALLOON_S_NR; i++) {
258 if (!visit_type_uint64(v, balloon_stat_names[i], &s->stats[i], &err)) {
259 goto out_nested;
260 }
261 }
262 visit_check_struct(v, &err);
263 out_nested:
264 visit_end_struct(v, NULL);
265
266 if (!err) {
267 visit_check_struct(v, &err);
268 }
269 out_end:
270 visit_end_struct(v, NULL);
271 out:
272 error_propagate(errp, err);
273 }
274
275 static void balloon_stats_get_poll_interval(Object *obj, Visitor *v,
276 const char *name, void *opaque,
277 Error **errp)
278 {
279 VirtIOBalloon *s = opaque;
280 visit_type_int(v, name, &s->stats_poll_interval, errp);
281 }
282
283 static void balloon_stats_set_poll_interval(Object *obj, Visitor *v,
284 const char *name, void *opaque,
285 Error **errp)
286 {
287 VirtIOBalloon *s = opaque;
288 int64_t value;
289
290 if (!visit_type_int(v, name, &value, errp)) {
291 return;
292 }
293
294 if (value < 0) {
295 error_setg(errp, "timer value must be greater than zero");
296 return;
297 }
298
299 if (value > UINT32_MAX) {
300 error_setg(errp, "timer value is too big");
301 return;
302 }
303
304 if (value == s->stats_poll_interval) {
305 return;
306 }
307
308 if (value == 0) {
309 /* timer=0 disables the timer */
310 balloon_stats_destroy_timer(s);
311 return;
312 }
313
314 if (balloon_stats_enabled(s)) {
315 /* timer interval change */
316 s->stats_poll_interval = value;
317 balloon_stats_change_timer(s, value);
318 return;
319 }
320
321 /* create a new timer */
322 g_assert(s->stats_timer == NULL);
323 s->stats_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL, balloon_stats_poll_cb, s);
324 s->stats_poll_interval = value;
325 balloon_stats_change_timer(s, 0);
326 }
327
328 static void virtio_balloon_handle_report(VirtIODevice *vdev, VirtQueue *vq)
329 {
330 VirtIOBalloon *dev = VIRTIO_BALLOON(vdev);
331 VirtQueueElement *elem;
332
333 while ((elem = virtqueue_pop(vq, sizeof(VirtQueueElement)))) {
334 unsigned int i;
335
336 /*
337 * When we discard the page it has the effect of removing the page
338 * from the hypervisor itself and causing it to be zeroed when it
339 * is returned to us. So we must not discard the page if it is
340 * accessible by another device or process, or if the guest is
341 * expecting it to retain a non-zero value.
342 */
343 if (virtio_balloon_inhibited() || dev->poison_val) {
344 goto skip_element;
345 }
346
347 for (i = 0; i < elem->in_num; i++) {
348 void *addr = elem->in_sg[i].iov_base;
349 size_t size = elem->in_sg[i].iov_len;
350 ram_addr_t ram_offset;
351 RAMBlock *rb;
352
353 /*
354 * There is no need to check the memory section to see if
355 * it is ram/readonly/romd like there is for handle_output
356 * below. If the region is not meant to be written to then
357 * address_space_map will have allocated a bounce buffer
358 * and it will be freed in address_space_unmap and trigger
359 * and unassigned_mem_write before failing to copy over the
360 * buffer. If more than one bad descriptor is provided it
361 * will return NULL after the first bounce buffer and fail
362 * to map any resources.
363 */
364 rb = qemu_ram_block_from_host(addr, false, &ram_offset);
365 if (!rb) {
366 trace_virtio_balloon_bad_addr(elem->in_addr[i]);
367 continue;
368 }
369
370 /*
371 * For now we will simply ignore unaligned memory regions, or
372 * regions that overrun the end of the RAMBlock.
373 */
374 if (!QEMU_IS_ALIGNED(ram_offset | size, qemu_ram_pagesize(rb)) ||
375 (ram_offset + size) > qemu_ram_get_used_length(rb)) {
376 continue;
377 }
378
379 ram_block_discard_range(rb, ram_offset, size);
380 }
381
382 skip_element:
383 virtqueue_push(vq, elem, 0);
384 virtio_notify(vdev, vq);
385 g_free(elem);
386 }
387 }
388
389 static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
390 {
391 VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
392 VirtQueueElement *elem;
393 MemoryRegionSection section;
394
395 for (;;) {
396 PartiallyBalloonedPage pbp = {};
397 size_t offset = 0;
398 uint32_t pfn;
399
400 elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
401 if (!elem) {
402 break;
403 }
404
405 while (iov_to_buf(elem->out_sg, elem->out_num, offset, &pfn, 4) == 4) {
406 unsigned int p = virtio_ldl_p(vdev, &pfn);
407 hwaddr pa;
408
409 pa = (hwaddr) p << VIRTIO_BALLOON_PFN_SHIFT;
410 offset += 4;
411
412 section = memory_region_find(get_system_memory(), pa,
413 BALLOON_PAGE_SIZE);
414 if (!section.mr) {
415 trace_virtio_balloon_bad_addr(pa);
416 continue;
417 }
418 if (!memory_region_is_ram(section.mr) ||
419 memory_region_is_rom(section.mr) ||
420 memory_region_is_romd(section.mr)) {
421 trace_virtio_balloon_bad_addr(pa);
422 memory_region_unref(section.mr);
423 continue;
424 }
425
426 trace_virtio_balloon_handle_output(memory_region_name(section.mr),
427 pa);
428 if (!virtio_balloon_inhibited()) {
429 if (vq == s->ivq) {
430 balloon_inflate_page(s, section.mr,
431 section.offset_within_region, &pbp);
432 } else if (vq == s->dvq) {
433 balloon_deflate_page(s, section.mr, section.offset_within_region);
434 } else {
435 g_assert_not_reached();
436 }
437 }
438 memory_region_unref(section.mr);
439 }
440
441 virtqueue_push(vq, elem, 0);
442 virtio_notify(vdev, vq);
443 g_free(elem);
444 virtio_balloon_pbp_free(&pbp);
445 }
446 }
447
448 static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq)
449 {
450 VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
451 VirtQueueElement *elem;
452 VirtIOBalloonStat stat;
453 size_t offset = 0;
454 qemu_timeval tv;
455
456 elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
457 if (!elem) {
458 goto out;
459 }
460
461 if (s->stats_vq_elem != NULL) {
462 /* This should never happen if the driver follows the spec. */
463 virtqueue_push(vq, s->stats_vq_elem, 0);
464 virtio_notify(vdev, vq);
465 g_free(s->stats_vq_elem);
466 }
467
468 s->stats_vq_elem = elem;
469
470 /* Initialize the stats to get rid of any stale values. This is only
471 * needed to handle the case where a guest supports fewer stats than it
472 * used to (ie. it has booted into an old kernel).
473 */
474 reset_stats(s);
475
476 while (iov_to_buf(elem->out_sg, elem->out_num, offset, &stat, sizeof(stat))
477 == sizeof(stat)) {
478 uint16_t tag = virtio_tswap16(vdev, stat.tag);
479 uint64_t val = virtio_tswap64(vdev, stat.val);
480
481 offset += sizeof(stat);
482 if (tag < VIRTIO_BALLOON_S_NR)
483 s->stats[tag] = val;
484 }
485 s->stats_vq_offset = offset;
486
487 if (qemu_gettimeofday(&tv) < 0) {
488 warn_report("%s: failed to get time of day", __func__);
489 goto out;
490 }
491
492 s->stats_last_update = tv.tv_sec;
493
494 out:
495 if (balloon_stats_enabled(s)) {
496 balloon_stats_change_timer(s, s->stats_poll_interval);
497 }
498 }
499
500 static void virtio_balloon_handle_free_page_vq(VirtIODevice *vdev,
501 VirtQueue *vq)
502 {
503 VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
504 qemu_bh_schedule(s->free_page_bh);
505 }
506
507 static bool get_free_page_hints(VirtIOBalloon *dev)
508 {
509 VirtQueueElement *elem;
510 VirtIODevice *vdev = VIRTIO_DEVICE(dev);
511 VirtQueue *vq = dev->free_page_vq;
512 bool ret = true;
513 int i;
514
515 while (dev->block_iothread) {
516 qemu_cond_wait(&dev->free_page_cond, &dev->free_page_lock);
517 }
518
519 elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
520 if (!elem) {
521 return false;
522 }
523
524 if (elem->out_num) {
525 uint32_t id;
526 size_t size = iov_to_buf(elem->out_sg, elem->out_num, 0,
527 &id, sizeof(id));
528
529 virtio_tswap32s(vdev, &id);
530 if (unlikely(size != sizeof(id))) {
531 virtio_error(vdev, "received an incorrect cmd id");
532 ret = false;
533 goto out;
534 }
535 if (dev->free_page_hint_status == FREE_PAGE_HINT_S_REQUESTED &&
536 id == dev->free_page_hint_cmd_id) {
537 dev->free_page_hint_status = FREE_PAGE_HINT_S_START;
538 } else if (dev->free_page_hint_status == FREE_PAGE_HINT_S_START) {
539 /*
540 * Stop the optimization only when it has started. This
541 * avoids a stale stop sign for the previous command.
542 */
543 dev->free_page_hint_status = FREE_PAGE_HINT_S_STOP;
544 }
545 }
546
547 if (elem->in_num && dev->free_page_hint_status == FREE_PAGE_HINT_S_START) {
548 for (i = 0; i < elem->in_num; i++) {
549 qemu_guest_free_page_hint(elem->in_sg[i].iov_base,
550 elem->in_sg[i].iov_len);
551 }
552 }
553
554 out:
555 virtqueue_push(vq, elem, 0);
556 g_free(elem);
557 return ret;
558 }
559
560 static void virtio_ballloon_get_free_page_hints(void *opaque)
561 {
562 VirtIOBalloon *dev = opaque;
563 VirtIODevice *vdev = VIRTIO_DEVICE(dev);
564 VirtQueue *vq = dev->free_page_vq;
565 bool continue_to_get_hints;
566
567 do {
568 qemu_mutex_lock(&dev->free_page_lock);
569 virtio_queue_set_notification(vq, 0);
570 continue_to_get_hints = get_free_page_hints(dev);
571 qemu_mutex_unlock(&dev->free_page_lock);
572 virtio_notify(vdev, vq);
573 /*
574 * Start to poll the vq once the hinting started. Otherwise, continue
575 * only when there are entries on the vq, which need to be given back.
576 */
577 } while (continue_to_get_hints ||
578 dev->free_page_hint_status == FREE_PAGE_HINT_S_START);
579 virtio_queue_set_notification(vq, 1);
580 }
581
582 static bool virtio_balloon_free_page_support(void *opaque)
583 {
584 VirtIOBalloon *s = opaque;
585 VirtIODevice *vdev = VIRTIO_DEVICE(s);
586
587 return virtio_vdev_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT);
588 }
589
590 static void virtio_balloon_free_page_start(VirtIOBalloon *s)
591 {
592 VirtIODevice *vdev = VIRTIO_DEVICE(s);
593
594 qemu_mutex_lock(&s->free_page_lock);
595
596 if (s->free_page_hint_cmd_id == UINT_MAX) {
597 s->free_page_hint_cmd_id = VIRTIO_BALLOON_FREE_PAGE_HINT_CMD_ID_MIN;
598 } else {
599 s->free_page_hint_cmd_id++;
600 }
601
602 s->free_page_hint_status = FREE_PAGE_HINT_S_REQUESTED;
603 qemu_mutex_unlock(&s->free_page_lock);
604
605 virtio_notify_config(vdev);
606 }
607
608 static void virtio_balloon_free_page_stop(VirtIOBalloon *s)
609 {
610 VirtIODevice *vdev = VIRTIO_DEVICE(s);
611
612 if (s->free_page_hint_status != FREE_PAGE_HINT_S_STOP) {
613 /*
614 * The lock also guarantees us that the
615 * virtio_ballloon_get_free_page_hints exits after the
616 * free_page_hint_status is set to S_STOP.
617 */
618 qemu_mutex_lock(&s->free_page_lock);
619 /*
620 * The guest isn't done hinting, so send a notification
621 * to the guest to actively stop the hinting.
622 */
623 s->free_page_hint_status = FREE_PAGE_HINT_S_STOP;
624 qemu_mutex_unlock(&s->free_page_lock);
625 virtio_notify_config(vdev);
626 }
627 }
628
629 static void virtio_balloon_free_page_done(VirtIOBalloon *s)
630 {
631 VirtIODevice *vdev = VIRTIO_DEVICE(s);
632
633 if (s->free_page_hint_status != FREE_PAGE_HINT_S_DONE) {
634 /* See virtio_balloon_free_page_stop() */
635 qemu_mutex_lock(&s->free_page_lock);
636 s->free_page_hint_status = FREE_PAGE_HINT_S_DONE;
637 qemu_mutex_unlock(&s->free_page_lock);
638 virtio_notify_config(vdev);
639 }
640 }
641
642 static int
643 virtio_balloon_free_page_hint_notify(NotifierWithReturn *n, void *data)
644 {
645 VirtIOBalloon *dev = container_of(n, VirtIOBalloon, free_page_hint_notify);
646 VirtIODevice *vdev = VIRTIO_DEVICE(dev);
647 PrecopyNotifyData *pnd = data;
648
649 if (!virtio_balloon_free_page_support(dev)) {
650 /*
651 * This is an optimization provided to migration, so just return 0 to
652 * have the normal migration process not affected when this feature is
653 * not supported.
654 */
655 return 0;
656 }
657
658 /*
659 * Pages hinted via qemu_guest_free_page_hint() are cleared from the dirty
660 * bitmap and will not get migrated, especially also not when the postcopy
661 * destination starts using them and requests migration from the source; the
662 * faulting thread will stall until postcopy migration finishes and
663 * all threads are woken up. Let's not start free page hinting if postcopy
664 * is possible.
665 */
666 if (migrate_postcopy_ram()) {
667 return 0;
668 }
669
670 switch (pnd->reason) {
671 case PRECOPY_NOTIFY_BEFORE_BITMAP_SYNC:
672 virtio_balloon_free_page_stop(dev);
673 break;
674 case PRECOPY_NOTIFY_AFTER_BITMAP_SYNC:
675 if (vdev->vm_running) {
676 virtio_balloon_free_page_start(dev);
677 break;
678 }
679 /*
680 * Set S_DONE before migrating the vmstate, so the guest will reuse
681 * all hinted pages once running on the destination. Fall through.
682 */
683 case PRECOPY_NOTIFY_CLEANUP:
684 /*
685 * Especially, if something goes wrong during precopy or if migration
686 * is canceled, we have to properly communicate S_DONE to the VM.
687 */
688 virtio_balloon_free_page_done(dev);
689 break;
690 case PRECOPY_NOTIFY_SETUP:
691 case PRECOPY_NOTIFY_COMPLETE:
692 break;
693 default:
694 virtio_error(vdev, "%s: %d reason unknown", __func__, pnd->reason);
695 }
696
697 return 0;
698 }
699
700 static size_t virtio_balloon_config_size(VirtIOBalloon *s)
701 {
702 uint64_t features = s->host_features;
703
704 if (s->qemu_4_0_config_size) {
705 return sizeof(struct virtio_balloon_config);
706 }
707 if (virtio_has_feature(features, VIRTIO_BALLOON_F_PAGE_POISON)) {
708 return sizeof(struct virtio_balloon_config);
709 }
710 if (virtio_has_feature(features, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
711 return offsetof(struct virtio_balloon_config, poison_val);
712 }
713 return offsetof(struct virtio_balloon_config, free_page_hint_cmd_id);
714 }
715
716 static void virtio_balloon_get_config(VirtIODevice *vdev, uint8_t *config_data)
717 {
718 VirtIOBalloon *dev = VIRTIO_BALLOON(vdev);
719 struct virtio_balloon_config config = {};
720
721 config.num_pages = cpu_to_le32(dev->num_pages);
722 config.actual = cpu_to_le32(dev->actual);
723 config.poison_val = cpu_to_le32(dev->poison_val);
724
725 if (dev->free_page_hint_status == FREE_PAGE_HINT_S_REQUESTED) {
726 config.free_page_hint_cmd_id =
727 cpu_to_le32(dev->free_page_hint_cmd_id);
728 } else if (dev->free_page_hint_status == FREE_PAGE_HINT_S_STOP) {
729 config.free_page_hint_cmd_id =
730 cpu_to_le32(VIRTIO_BALLOON_CMD_ID_STOP);
731 } else if (dev->free_page_hint_status == FREE_PAGE_HINT_S_DONE) {
732 config.free_page_hint_cmd_id =
733 cpu_to_le32(VIRTIO_BALLOON_CMD_ID_DONE);
734 }
735
736 trace_virtio_balloon_get_config(config.num_pages, config.actual);
737 memcpy(config_data, &config, virtio_balloon_config_size(dev));
738 }
739
740 static int build_dimm_list(Object *obj, void *opaque)
741 {
742 GSList **list = opaque;
743
744 if (object_dynamic_cast(obj, TYPE_PC_DIMM)) {
745 DeviceState *dev = DEVICE(obj);
746 if (dev->realized) { /* only realized DIMMs matter */
747 *list = g_slist_prepend(*list, dev);
748 }
749 }
750
751 object_child_foreach(obj, build_dimm_list, opaque);
752 return 0;
753 }
754
755 static ram_addr_t get_current_ram_size(void)
756 {
757 GSList *list = NULL, *item;
758 ram_addr_t size = current_machine->ram_size;
759
760 build_dimm_list(qdev_get_machine(), &list);
761 for (item = list; item; item = g_slist_next(item)) {
762 Object *obj = OBJECT(item->data);
763 if (!strcmp(object_get_typename(obj), TYPE_PC_DIMM)) {
764 size += object_property_get_int(obj, PC_DIMM_SIZE_PROP,
765 &error_abort);
766 }
767 }
768 g_slist_free(list);
769
770 return size;
771 }
772
773 static bool virtio_balloon_page_poison_support(void *opaque)
774 {
775 VirtIOBalloon *s = opaque;
776 VirtIODevice *vdev = VIRTIO_DEVICE(s);
777
778 return virtio_vdev_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON);
779 }
780
781 static void virtio_balloon_set_config(VirtIODevice *vdev,
782 const uint8_t *config_data)
783 {
784 VirtIOBalloon *dev = VIRTIO_BALLOON(vdev);
785 struct virtio_balloon_config config;
786 uint32_t oldactual = dev->actual;
787 ram_addr_t vm_ram_size = get_current_ram_size();
788
789 memcpy(&config, config_data, virtio_balloon_config_size(dev));
790 dev->actual = le32_to_cpu(config.actual);
791 if (dev->actual != oldactual) {
792 qapi_event_send_balloon_change(vm_ram_size -
793 ((ram_addr_t) dev->actual << VIRTIO_BALLOON_PFN_SHIFT));
794 }
795 dev->poison_val = 0;
796 if (virtio_balloon_page_poison_support(dev)) {
797 dev->poison_val = le32_to_cpu(config.poison_val);
798 }
799 trace_virtio_balloon_set_config(dev->actual, oldactual);
800 }
801
802 static uint64_t virtio_balloon_get_features(VirtIODevice *vdev, uint64_t f,
803 Error **errp)
804 {
805 VirtIOBalloon *dev = VIRTIO_BALLOON(vdev);
806 f |= dev->host_features;
807 virtio_add_feature(&f, VIRTIO_BALLOON_F_STATS_VQ);
808
809 return f;
810 }
811
812 static void virtio_balloon_stat(void *opaque, BalloonInfo *info)
813 {
814 VirtIOBalloon *dev = opaque;
815 info->actual = get_current_ram_size() - ((uint64_t) dev->actual <<
816 VIRTIO_BALLOON_PFN_SHIFT);
817 }
818
819 static void virtio_balloon_to_target(void *opaque, ram_addr_t target)
820 {
821 VirtIOBalloon *dev = VIRTIO_BALLOON(opaque);
822 VirtIODevice *vdev = VIRTIO_DEVICE(dev);
823 ram_addr_t vm_ram_size = get_current_ram_size();
824
825 if (target > vm_ram_size) {
826 target = vm_ram_size;
827 }
828 if (target) {
829 dev->num_pages = (vm_ram_size - target) >> VIRTIO_BALLOON_PFN_SHIFT;
830 virtio_notify_config(vdev);
831 }
832 trace_virtio_balloon_to_target(target, dev->num_pages);
833 }
834
835 static int virtio_balloon_post_load_device(void *opaque, int version_id)
836 {
837 VirtIOBalloon *s = VIRTIO_BALLOON(opaque);
838
839 if (balloon_stats_enabled(s)) {
840 balloon_stats_change_timer(s, s->stats_poll_interval);
841 }
842 return 0;
843 }
844
845 static const VMStateDescription vmstate_virtio_balloon_free_page_hint = {
846 .name = "virtio-balloon-device/free-page-report",
847 .version_id = 1,
848 .minimum_version_id = 1,
849 .needed = virtio_balloon_free_page_support,
850 .fields = (VMStateField[]) {
851 VMSTATE_UINT32(free_page_hint_cmd_id, VirtIOBalloon),
852 VMSTATE_UINT32(free_page_hint_status, VirtIOBalloon),
853 VMSTATE_END_OF_LIST()
854 }
855 };
856
857 static const VMStateDescription vmstate_virtio_balloon_page_poison = {
858 .name = "virtio-balloon-device/page-poison",
859 .version_id = 1,
860 .minimum_version_id = 1,
861 .needed = virtio_balloon_page_poison_support,
862 .fields = (VMStateField[]) {
863 VMSTATE_UINT32(poison_val, VirtIOBalloon),
864 VMSTATE_END_OF_LIST()
865 }
866 };
867
868 static const VMStateDescription vmstate_virtio_balloon_device = {
869 .name = "virtio-balloon-device",
870 .version_id = 1,
871 .minimum_version_id = 1,
872 .post_load = virtio_balloon_post_load_device,
873 .fields = (VMStateField[]) {
874 VMSTATE_UINT32(num_pages, VirtIOBalloon),
875 VMSTATE_UINT32(actual, VirtIOBalloon),
876 VMSTATE_END_OF_LIST()
877 },
878 .subsections = (const VMStateDescription * []) {
879 &vmstate_virtio_balloon_free_page_hint,
880 &vmstate_virtio_balloon_page_poison,
881 NULL
882 }
883 };
884
885 static void virtio_balloon_device_realize(DeviceState *dev, Error **errp)
886 {
887 VirtIODevice *vdev = VIRTIO_DEVICE(dev);
888 VirtIOBalloon *s = VIRTIO_BALLOON(dev);
889 int ret;
890
891 virtio_init(vdev, "virtio-balloon", VIRTIO_ID_BALLOON,
892 virtio_balloon_config_size(s));
893
894 ret = qemu_add_balloon_handler(virtio_balloon_to_target,
895 virtio_balloon_stat, s);
896
897 if (ret < 0) {
898 error_setg(errp, "Only one balloon device is supported");
899 virtio_cleanup(vdev);
900 return;
901 }
902
903 if (virtio_has_feature(s->host_features, VIRTIO_BALLOON_F_FREE_PAGE_HINT) &&
904 !s->iothread) {
905 error_setg(errp, "'free-page-hint' requires 'iothread' to be set");
906 virtio_cleanup(vdev);
907 return;
908 }
909
910 s->ivq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output);
911 s->dvq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output);
912 s->svq = virtio_add_queue(vdev, 128, virtio_balloon_receive_stats);
913
914 if (virtio_has_feature(s->host_features, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
915 s->free_page_vq = virtio_add_queue(vdev, VIRTQUEUE_MAX_SIZE,
916 virtio_balloon_handle_free_page_vq);
917 precopy_add_notifier(&s->free_page_hint_notify);
918
919 object_ref(OBJECT(s->iothread));
920 s->free_page_bh = aio_bh_new(iothread_get_aio_context(s->iothread),
921 virtio_ballloon_get_free_page_hints, s);
922 }
923
924 if (virtio_has_feature(s->host_features, VIRTIO_BALLOON_F_REPORTING)) {
925 s->reporting_vq = virtio_add_queue(vdev, 32,
926 virtio_balloon_handle_report);
927 }
928
929 reset_stats(s);
930 }
931
932 static void virtio_balloon_device_unrealize(DeviceState *dev)
933 {
934 VirtIODevice *vdev = VIRTIO_DEVICE(dev);
935 VirtIOBalloon *s = VIRTIO_BALLOON(dev);
936
937 if (s->free_page_bh) {
938 qemu_bh_delete(s->free_page_bh);
939 object_unref(OBJECT(s->iothread));
940 virtio_balloon_free_page_stop(s);
941 precopy_remove_notifier(&s->free_page_hint_notify);
942 }
943 balloon_stats_destroy_timer(s);
944 qemu_remove_balloon_handler(s);
945
946 virtio_delete_queue(s->ivq);
947 virtio_delete_queue(s->dvq);
948 virtio_delete_queue(s->svq);
949 if (s->free_page_vq) {
950 virtio_delete_queue(s->free_page_vq);
951 }
952 if (s->reporting_vq) {
953 virtio_delete_queue(s->reporting_vq);
954 }
955 virtio_cleanup(vdev);
956 }
957
958 static void virtio_balloon_device_reset(VirtIODevice *vdev)
959 {
960 VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
961
962 if (virtio_balloon_free_page_support(s)) {
963 virtio_balloon_free_page_stop(s);
964 }
965
966 if (s->stats_vq_elem != NULL) {
967 virtqueue_unpop(s->svq, s->stats_vq_elem, 0);
968 g_free(s->stats_vq_elem);
969 s->stats_vq_elem = NULL;
970 }
971
972 s->poison_val = 0;
973 }
974
975 static void virtio_balloon_set_status(VirtIODevice *vdev, uint8_t status)
976 {
977 VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
978
979 if (!s->stats_vq_elem && vdev->vm_running &&
980 (status & VIRTIO_CONFIG_S_DRIVER_OK) && virtqueue_rewind(s->svq, 1)) {
981 /* poll stats queue for the element we have discarded when the VM
982 * was stopped */
983 virtio_balloon_receive_stats(vdev, s->svq);
984 }
985
986 if (virtio_balloon_free_page_support(s)) {
987 /*
988 * The VM is woken up and the iothread was blocked, so signal it to
989 * continue.
990 */
991 if (vdev->vm_running && s->block_iothread) {
992 qemu_mutex_lock(&s->free_page_lock);
993 s->block_iothread = false;
994 qemu_cond_signal(&s->free_page_cond);
995 qemu_mutex_unlock(&s->free_page_lock);
996 }
997
998 /* The VM is stopped, block the iothread. */
999 if (!vdev->vm_running) {
1000 qemu_mutex_lock(&s->free_page_lock);
1001 s->block_iothread = true;
1002 qemu_mutex_unlock(&s->free_page_lock);
1003 }
1004 }
1005 }
1006
1007 static void virtio_balloon_instance_init(Object *obj)
1008 {
1009 VirtIOBalloon *s = VIRTIO_BALLOON(obj);
1010
1011 qemu_mutex_init(&s->free_page_lock);
1012 qemu_cond_init(&s->free_page_cond);
1013 s->free_page_hint_cmd_id = VIRTIO_BALLOON_FREE_PAGE_HINT_CMD_ID_MIN;
1014 s->free_page_hint_notify.notify = virtio_balloon_free_page_hint_notify;
1015
1016 object_property_add(obj, "guest-stats", "guest statistics",
1017 balloon_stats_get_all, NULL, NULL, s);
1018
1019 object_property_add(obj, "guest-stats-polling-interval", "int",
1020 balloon_stats_get_poll_interval,
1021 balloon_stats_set_poll_interval,
1022 NULL, s);
1023 }
1024
1025 static const VMStateDescription vmstate_virtio_balloon = {
1026 .name = "virtio-balloon",
1027 .minimum_version_id = 1,
1028 .version_id = 1,
1029 .fields = (VMStateField[]) {
1030 VMSTATE_VIRTIO_DEVICE,
1031 VMSTATE_END_OF_LIST()
1032 },
1033 };
1034
1035 static Property virtio_balloon_properties[] = {
1036 DEFINE_PROP_BIT("deflate-on-oom", VirtIOBalloon, host_features,
1037 VIRTIO_BALLOON_F_DEFLATE_ON_OOM, false),
1038 DEFINE_PROP_BIT("free-page-hint", VirtIOBalloon, host_features,
1039 VIRTIO_BALLOON_F_FREE_PAGE_HINT, false),
1040 DEFINE_PROP_BIT("page-poison", VirtIOBalloon, host_features,
1041 VIRTIO_BALLOON_F_PAGE_POISON, true),
1042 DEFINE_PROP_BIT("free-page-reporting", VirtIOBalloon, host_features,
1043 VIRTIO_BALLOON_F_REPORTING, false),
1044 /* QEMU 4.0 accidentally changed the config size even when free-page-hint
1045 * is disabled, resulting in QEMU 3.1 migration incompatibility. This
1046 * property retains this quirk for QEMU 4.1 machine types.
1047 */
1048 DEFINE_PROP_BOOL("qemu-4-0-config-size", VirtIOBalloon,
1049 qemu_4_0_config_size, false),
1050 DEFINE_PROP_LINK("iothread", VirtIOBalloon, iothread, TYPE_IOTHREAD,
1051 IOThread *),
1052 DEFINE_PROP_END_OF_LIST(),
1053 };
1054
1055 static void virtio_balloon_class_init(ObjectClass *klass, void *data)
1056 {
1057 DeviceClass *dc = DEVICE_CLASS(klass);
1058 VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
1059
1060 device_class_set_props(dc, virtio_balloon_properties);
1061 dc->vmsd = &vmstate_virtio_balloon;
1062 set_bit(DEVICE_CATEGORY_MISC, dc->categories);
1063 vdc->realize = virtio_balloon_device_realize;
1064 vdc->unrealize = virtio_balloon_device_unrealize;
1065 vdc->reset = virtio_balloon_device_reset;
1066 vdc->get_config = virtio_balloon_get_config;
1067 vdc->set_config = virtio_balloon_set_config;
1068 vdc->get_features = virtio_balloon_get_features;
1069 vdc->set_status = virtio_balloon_set_status;
1070 vdc->vmsd = &vmstate_virtio_balloon_device;
1071 }
1072
1073 static const TypeInfo virtio_balloon_info = {
1074 .name = TYPE_VIRTIO_BALLOON,
1075 .parent = TYPE_VIRTIO_DEVICE,
1076 .instance_size = sizeof(VirtIOBalloon),
1077 .instance_init = virtio_balloon_instance_init,
1078 .class_init = virtio_balloon_class_init,
1079 };
1080
1081 static void virtio_register_types(void)
1082 {
1083 type_register_static(&virtio_balloon_info);
1084 }
1085
1086 type_init(virtio_register_types)