target/arm: Implement VFP fp16 VCMP
[qemu.git] / migration / postcopy-ram.c
1 /*
2 * Postcopy migration for RAM
3 *
4 * Copyright 2013-2015 Red Hat, Inc. and/or its affiliates
5 *
6 * Authors:
7 * Dave Gilbert <dgilbert@redhat.com>
8 *
9 * This work is licensed under the terms of the GNU GPL, version 2 or later.
10 * See the COPYING file in the top-level directory.
11 *
12 */
13
14 /*
15 * Postcopy is a migration technique where the execution flips from the
16 * source to the destination before all the data has been copied.
17 */
18
19 #include "qemu/osdep.h"
20 #include "exec/target_page.h"
21 #include "migration.h"
22 #include "qemu-file.h"
23 #include "savevm.h"
24 #include "postcopy-ram.h"
25 #include "ram.h"
26 #include "qapi/error.h"
27 #include "qemu/notify.h"
28 #include "qemu/rcu.h"
29 #include "sysemu/sysemu.h"
30 #include "qemu/error-report.h"
31 #include "trace.h"
32 #include "hw/boards.h"
33
34 /* Arbitrary limit on size of each discard command,
35 * keeps them around ~200 bytes
36 */
37 #define MAX_DISCARDS_PER_COMMAND 12
38
39 struct PostcopyDiscardState {
40 const char *ramblock_name;
41 uint16_t cur_entry;
42 /*
43 * Start and length of a discard range (bytes)
44 */
45 uint64_t start_list[MAX_DISCARDS_PER_COMMAND];
46 uint64_t length_list[MAX_DISCARDS_PER_COMMAND];
47 unsigned int nsentwords;
48 unsigned int nsentcmds;
49 };
50
51 static NotifierWithReturnList postcopy_notifier_list;
52
53 void postcopy_infrastructure_init(void)
54 {
55 notifier_with_return_list_init(&postcopy_notifier_list);
56 }
57
58 void postcopy_add_notifier(NotifierWithReturn *nn)
59 {
60 notifier_with_return_list_add(&postcopy_notifier_list, nn);
61 }
62
63 void postcopy_remove_notifier(NotifierWithReturn *n)
64 {
65 notifier_with_return_remove(n);
66 }
67
68 int postcopy_notify(enum PostcopyNotifyReason reason, Error **errp)
69 {
70 struct PostcopyNotifyData pnd;
71 pnd.reason = reason;
72 pnd.errp = errp;
73
74 return notifier_with_return_list_notify(&postcopy_notifier_list,
75 &pnd);
76 }
77
78 /* Postcopy needs to detect accesses to pages that haven't yet been copied
79 * across, and efficiently map new pages in, the techniques for doing this
80 * are target OS specific.
81 */
82 #if defined(__linux__)
83
84 #include <poll.h>
85 #include <sys/ioctl.h>
86 #include <sys/syscall.h>
87 #include <asm/types.h> /* for __u64 */
88 #endif
89
90 #if defined(__linux__) && defined(__NR_userfaultfd) && defined(CONFIG_EVENTFD)
91 #include <sys/eventfd.h>
92 #include <linux/userfaultfd.h>
93
94 typedef struct PostcopyBlocktimeContext {
95 /* time when page fault initiated per vCPU */
96 uint32_t *page_fault_vcpu_time;
97 /* page address per vCPU */
98 uintptr_t *vcpu_addr;
99 uint32_t total_blocktime;
100 /* blocktime per vCPU */
101 uint32_t *vcpu_blocktime;
102 /* point in time when last page fault was initiated */
103 uint32_t last_begin;
104 /* number of vCPU are suspended */
105 int smp_cpus_down;
106 uint64_t start_time;
107
108 /*
109 * Handler for exit event, necessary for
110 * releasing whole blocktime_ctx
111 */
112 Notifier exit_notifier;
113 } PostcopyBlocktimeContext;
114
115 static void destroy_blocktime_context(struct PostcopyBlocktimeContext *ctx)
116 {
117 g_free(ctx->page_fault_vcpu_time);
118 g_free(ctx->vcpu_addr);
119 g_free(ctx->vcpu_blocktime);
120 g_free(ctx);
121 }
122
123 static void migration_exit_cb(Notifier *n, void *data)
124 {
125 PostcopyBlocktimeContext *ctx = container_of(n, PostcopyBlocktimeContext,
126 exit_notifier);
127 destroy_blocktime_context(ctx);
128 }
129
130 static struct PostcopyBlocktimeContext *blocktime_context_new(void)
131 {
132 MachineState *ms = MACHINE(qdev_get_machine());
133 unsigned int smp_cpus = ms->smp.cpus;
134 PostcopyBlocktimeContext *ctx = g_new0(PostcopyBlocktimeContext, 1);
135 ctx->page_fault_vcpu_time = g_new0(uint32_t, smp_cpus);
136 ctx->vcpu_addr = g_new0(uintptr_t, smp_cpus);
137 ctx->vcpu_blocktime = g_new0(uint32_t, smp_cpus);
138
139 ctx->exit_notifier.notify = migration_exit_cb;
140 ctx->start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
141 qemu_add_exit_notifier(&ctx->exit_notifier);
142 return ctx;
143 }
144
145 static uint32List *get_vcpu_blocktime_list(PostcopyBlocktimeContext *ctx)
146 {
147 MachineState *ms = MACHINE(qdev_get_machine());
148 uint32List *list = NULL, *entry = NULL;
149 int i;
150
151 for (i = ms->smp.cpus - 1; i >= 0; i--) {
152 entry = g_new0(uint32List, 1);
153 entry->value = ctx->vcpu_blocktime[i];
154 entry->next = list;
155 list = entry;
156 }
157
158 return list;
159 }
160
161 /*
162 * This function just populates MigrationInfo from postcopy's
163 * blocktime context. It will not populate MigrationInfo,
164 * unless postcopy-blocktime capability was set.
165 *
166 * @info: pointer to MigrationInfo to populate
167 */
168 void fill_destination_postcopy_migration_info(MigrationInfo *info)
169 {
170 MigrationIncomingState *mis = migration_incoming_get_current();
171 PostcopyBlocktimeContext *bc = mis->blocktime_ctx;
172
173 if (!bc) {
174 return;
175 }
176
177 info->has_postcopy_blocktime = true;
178 info->postcopy_blocktime = bc->total_blocktime;
179 info->has_postcopy_vcpu_blocktime = true;
180 info->postcopy_vcpu_blocktime = get_vcpu_blocktime_list(bc);
181 }
182
183 static uint32_t get_postcopy_total_blocktime(void)
184 {
185 MigrationIncomingState *mis = migration_incoming_get_current();
186 PostcopyBlocktimeContext *bc = mis->blocktime_ctx;
187
188 if (!bc) {
189 return 0;
190 }
191
192 return bc->total_blocktime;
193 }
194
195 /**
196 * receive_ufd_features: check userfault fd features, to request only supported
197 * features in the future.
198 *
199 * Returns: true on success
200 *
201 * __NR_userfaultfd - should be checked before
202 * @features: out parameter will contain uffdio_api.features provided by kernel
203 * in case of success
204 */
205 static bool receive_ufd_features(uint64_t *features)
206 {
207 struct uffdio_api api_struct = {0};
208 int ufd;
209 bool ret = true;
210
211 /* if we are here __NR_userfaultfd should exists */
212 ufd = syscall(__NR_userfaultfd, O_CLOEXEC);
213 if (ufd == -1) {
214 error_report("%s: syscall __NR_userfaultfd failed: %s", __func__,
215 strerror(errno));
216 return false;
217 }
218
219 /* ask features */
220 api_struct.api = UFFD_API;
221 api_struct.features = 0;
222 if (ioctl(ufd, UFFDIO_API, &api_struct)) {
223 error_report("%s: UFFDIO_API failed: %s", __func__,
224 strerror(errno));
225 ret = false;
226 goto release_ufd;
227 }
228
229 *features = api_struct.features;
230
231 release_ufd:
232 close(ufd);
233 return ret;
234 }
235
236 /**
237 * request_ufd_features: this function should be called only once on a newly
238 * opened ufd, subsequent calls will lead to error.
239 *
240 * Returns: true on succes
241 *
242 * @ufd: fd obtained from userfaultfd syscall
243 * @features: bit mask see UFFD_API_FEATURES
244 */
245 static bool request_ufd_features(int ufd, uint64_t features)
246 {
247 struct uffdio_api api_struct = {0};
248 uint64_t ioctl_mask;
249
250 api_struct.api = UFFD_API;
251 api_struct.features = features;
252 if (ioctl(ufd, UFFDIO_API, &api_struct)) {
253 error_report("%s failed: UFFDIO_API failed: %s", __func__,
254 strerror(errno));
255 return false;
256 }
257
258 ioctl_mask = (__u64)1 << _UFFDIO_REGISTER |
259 (__u64)1 << _UFFDIO_UNREGISTER;
260 if ((api_struct.ioctls & ioctl_mask) != ioctl_mask) {
261 error_report("Missing userfault features: %" PRIx64,
262 (uint64_t)(~api_struct.ioctls & ioctl_mask));
263 return false;
264 }
265
266 return true;
267 }
268
269 static bool ufd_check_and_apply(int ufd, MigrationIncomingState *mis)
270 {
271 uint64_t asked_features = 0;
272 static uint64_t supported_features;
273
274 /*
275 * it's not possible to
276 * request UFFD_API twice per one fd
277 * userfault fd features is persistent
278 */
279 if (!supported_features) {
280 if (!receive_ufd_features(&supported_features)) {
281 error_report("%s failed", __func__);
282 return false;
283 }
284 }
285
286 #ifdef UFFD_FEATURE_THREAD_ID
287 if (migrate_postcopy_blocktime() && mis &&
288 UFFD_FEATURE_THREAD_ID & supported_features) {
289 /* kernel supports that feature */
290 /* don't create blocktime_context if it exists */
291 if (!mis->blocktime_ctx) {
292 mis->blocktime_ctx = blocktime_context_new();
293 }
294
295 asked_features |= UFFD_FEATURE_THREAD_ID;
296 }
297 #endif
298
299 /*
300 * request features, even if asked_features is 0, due to
301 * kernel expects UFFD_API before UFFDIO_REGISTER, per
302 * userfault file descriptor
303 */
304 if (!request_ufd_features(ufd, asked_features)) {
305 error_report("%s failed: features %" PRIu64, __func__,
306 asked_features);
307 return false;
308 }
309
310 if (qemu_real_host_page_size != ram_pagesize_summary()) {
311 bool have_hp = false;
312 /* We've got a huge page */
313 #ifdef UFFD_FEATURE_MISSING_HUGETLBFS
314 have_hp = supported_features & UFFD_FEATURE_MISSING_HUGETLBFS;
315 #endif
316 if (!have_hp) {
317 error_report("Userfault on this host does not support huge pages");
318 return false;
319 }
320 }
321 return true;
322 }
323
324 /* Callback from postcopy_ram_supported_by_host block iterator.
325 */
326 static int test_ramblock_postcopiable(RAMBlock *rb, void *opaque)
327 {
328 const char *block_name = qemu_ram_get_idstr(rb);
329 ram_addr_t length = qemu_ram_get_used_length(rb);
330 size_t pagesize = qemu_ram_pagesize(rb);
331
332 if (length % pagesize) {
333 error_report("Postcopy requires RAM blocks to be a page size multiple,"
334 " block %s is 0x" RAM_ADDR_FMT " bytes with a "
335 "page size of 0x%zx", block_name, length, pagesize);
336 return 1;
337 }
338 return 0;
339 }
340
341 /*
342 * Note: This has the side effect of munlock'ing all of RAM, that's
343 * normally fine since if the postcopy succeeds it gets turned back on at the
344 * end.
345 */
346 bool postcopy_ram_supported_by_host(MigrationIncomingState *mis)
347 {
348 long pagesize = qemu_real_host_page_size;
349 int ufd = -1;
350 bool ret = false; /* Error unless we change it */
351 void *testarea = NULL;
352 struct uffdio_register reg_struct;
353 struct uffdio_range range_struct;
354 uint64_t feature_mask;
355 Error *local_err = NULL;
356
357 if (qemu_target_page_size() > pagesize) {
358 error_report("Target page size bigger than host page size");
359 goto out;
360 }
361
362 ufd = syscall(__NR_userfaultfd, O_CLOEXEC);
363 if (ufd == -1) {
364 error_report("%s: userfaultfd not available: %s", __func__,
365 strerror(errno));
366 goto out;
367 }
368
369 /* Give devices a chance to object */
370 if (postcopy_notify(POSTCOPY_NOTIFY_PROBE, &local_err)) {
371 error_report_err(local_err);
372 goto out;
373 }
374
375 /* Version and features check */
376 if (!ufd_check_and_apply(ufd, mis)) {
377 goto out;
378 }
379
380 /* We don't support postcopy with shared RAM yet */
381 if (foreach_not_ignored_block(test_ramblock_postcopiable, NULL)) {
382 goto out;
383 }
384
385 /*
386 * userfault and mlock don't go together; we'll put it back later if
387 * it was enabled.
388 */
389 if (munlockall()) {
390 error_report("%s: munlockall: %s", __func__, strerror(errno));
391 goto out;
392 }
393
394 /*
395 * We need to check that the ops we need are supported on anon memory
396 * To do that we need to register a chunk and see the flags that
397 * are returned.
398 */
399 testarea = mmap(NULL, pagesize, PROT_READ | PROT_WRITE, MAP_PRIVATE |
400 MAP_ANONYMOUS, -1, 0);
401 if (testarea == MAP_FAILED) {
402 error_report("%s: Failed to map test area: %s", __func__,
403 strerror(errno));
404 goto out;
405 }
406 g_assert(((size_t)testarea & (pagesize-1)) == 0);
407
408 reg_struct.range.start = (uintptr_t)testarea;
409 reg_struct.range.len = pagesize;
410 reg_struct.mode = UFFDIO_REGISTER_MODE_MISSING;
411
412 if (ioctl(ufd, UFFDIO_REGISTER, &reg_struct)) {
413 error_report("%s userfault register: %s", __func__, strerror(errno));
414 goto out;
415 }
416
417 range_struct.start = (uintptr_t)testarea;
418 range_struct.len = pagesize;
419 if (ioctl(ufd, UFFDIO_UNREGISTER, &range_struct)) {
420 error_report("%s userfault unregister: %s", __func__, strerror(errno));
421 goto out;
422 }
423
424 feature_mask = (__u64)1 << _UFFDIO_WAKE |
425 (__u64)1 << _UFFDIO_COPY |
426 (__u64)1 << _UFFDIO_ZEROPAGE;
427 if ((reg_struct.ioctls & feature_mask) != feature_mask) {
428 error_report("Missing userfault map features: %" PRIx64,
429 (uint64_t)(~reg_struct.ioctls & feature_mask));
430 goto out;
431 }
432
433 /* Success! */
434 ret = true;
435 out:
436 if (testarea) {
437 munmap(testarea, pagesize);
438 }
439 if (ufd != -1) {
440 close(ufd);
441 }
442 return ret;
443 }
444
445 /*
446 * Setup an area of RAM so that it *can* be used for postcopy later; this
447 * must be done right at the start prior to pre-copy.
448 * opaque should be the MIS.
449 */
450 static int init_range(RAMBlock *rb, void *opaque)
451 {
452 const char *block_name = qemu_ram_get_idstr(rb);
453 void *host_addr = qemu_ram_get_host_addr(rb);
454 ram_addr_t offset = qemu_ram_get_offset(rb);
455 ram_addr_t length = qemu_ram_get_used_length(rb);
456 trace_postcopy_init_range(block_name, host_addr, offset, length);
457
458 /*
459 * We need the whole of RAM to be truly empty for postcopy, so things
460 * like ROMs and any data tables built during init must be zero'd
461 * - we're going to get the copy from the source anyway.
462 * (Precopy will just overwrite this data, so doesn't need the discard)
463 */
464 if (ram_discard_range(block_name, 0, length)) {
465 return -1;
466 }
467
468 return 0;
469 }
470
471 /*
472 * At the end of migration, undo the effects of init_range
473 * opaque should be the MIS.
474 */
475 static int cleanup_range(RAMBlock *rb, void *opaque)
476 {
477 const char *block_name = qemu_ram_get_idstr(rb);
478 void *host_addr = qemu_ram_get_host_addr(rb);
479 ram_addr_t offset = qemu_ram_get_offset(rb);
480 ram_addr_t length = qemu_ram_get_used_length(rb);
481 MigrationIncomingState *mis = opaque;
482 struct uffdio_range range_struct;
483 trace_postcopy_cleanup_range(block_name, host_addr, offset, length);
484
485 /*
486 * We turned off hugepage for the precopy stage with postcopy enabled
487 * we can turn it back on now.
488 */
489 qemu_madvise(host_addr, length, QEMU_MADV_HUGEPAGE);
490
491 /*
492 * We can also turn off userfault now since we should have all the
493 * pages. It can be useful to leave it on to debug postcopy
494 * if you're not sure it's always getting every page.
495 */
496 range_struct.start = (uintptr_t)host_addr;
497 range_struct.len = length;
498
499 if (ioctl(mis->userfault_fd, UFFDIO_UNREGISTER, &range_struct)) {
500 error_report("%s: userfault unregister %s", __func__, strerror(errno));
501
502 return -1;
503 }
504
505 return 0;
506 }
507
508 /*
509 * Initialise postcopy-ram, setting the RAM to a state where we can go into
510 * postcopy later; must be called prior to any precopy.
511 * called from arch_init's similarly named ram_postcopy_incoming_init
512 */
513 int postcopy_ram_incoming_init(MigrationIncomingState *mis)
514 {
515 if (foreach_not_ignored_block(init_range, NULL)) {
516 return -1;
517 }
518
519 return 0;
520 }
521
522 /*
523 * At the end of a migration where postcopy_ram_incoming_init was called.
524 */
525 int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis)
526 {
527 trace_postcopy_ram_incoming_cleanup_entry();
528
529 if (mis->have_fault_thread) {
530 Error *local_err = NULL;
531
532 /* Let the fault thread quit */
533 atomic_set(&mis->fault_thread_quit, 1);
534 postcopy_fault_thread_notify(mis);
535 trace_postcopy_ram_incoming_cleanup_join();
536 qemu_thread_join(&mis->fault_thread);
537
538 if (postcopy_notify(POSTCOPY_NOTIFY_INBOUND_END, &local_err)) {
539 error_report_err(local_err);
540 return -1;
541 }
542
543 if (foreach_not_ignored_block(cleanup_range, mis)) {
544 return -1;
545 }
546
547 trace_postcopy_ram_incoming_cleanup_closeuf();
548 close(mis->userfault_fd);
549 close(mis->userfault_event_fd);
550 mis->have_fault_thread = false;
551 }
552
553 if (enable_mlock) {
554 if (os_mlock() < 0) {
555 error_report("mlock: %s", strerror(errno));
556 /*
557 * It doesn't feel right to fail at this point, we have a valid
558 * VM state.
559 */
560 }
561 }
562
563 if (mis->postcopy_tmp_page) {
564 munmap(mis->postcopy_tmp_page, mis->largest_page_size);
565 mis->postcopy_tmp_page = NULL;
566 }
567 if (mis->postcopy_tmp_zero_page) {
568 munmap(mis->postcopy_tmp_zero_page, mis->largest_page_size);
569 mis->postcopy_tmp_zero_page = NULL;
570 }
571 trace_postcopy_ram_incoming_cleanup_blocktime(
572 get_postcopy_total_blocktime());
573
574 trace_postcopy_ram_incoming_cleanup_exit();
575 return 0;
576 }
577
578 /*
579 * Disable huge pages on an area
580 */
581 static int nhp_range(RAMBlock *rb, void *opaque)
582 {
583 const char *block_name = qemu_ram_get_idstr(rb);
584 void *host_addr = qemu_ram_get_host_addr(rb);
585 ram_addr_t offset = qemu_ram_get_offset(rb);
586 ram_addr_t length = qemu_ram_get_used_length(rb);
587 trace_postcopy_nhp_range(block_name, host_addr, offset, length);
588
589 /*
590 * Before we do discards we need to ensure those discards really
591 * do delete areas of the page, even if THP thinks a hugepage would
592 * be a good idea, so force hugepages off.
593 */
594 qemu_madvise(host_addr, length, QEMU_MADV_NOHUGEPAGE);
595
596 return 0;
597 }
598
599 /*
600 * Userfault requires us to mark RAM as NOHUGEPAGE prior to discard
601 * however leaving it until after precopy means that most of the precopy
602 * data is still THPd
603 */
604 int postcopy_ram_prepare_discard(MigrationIncomingState *mis)
605 {
606 if (foreach_not_ignored_block(nhp_range, mis)) {
607 return -1;
608 }
609
610 postcopy_state_set(POSTCOPY_INCOMING_DISCARD);
611
612 return 0;
613 }
614
615 /*
616 * Mark the given area of RAM as requiring notification to unwritten areas
617 * Used as a callback on foreach_not_ignored_block.
618 * host_addr: Base of area to mark
619 * offset: Offset in the whole ram arena
620 * length: Length of the section
621 * opaque: MigrationIncomingState pointer
622 * Returns 0 on success
623 */
624 static int ram_block_enable_notify(RAMBlock *rb, void *opaque)
625 {
626 MigrationIncomingState *mis = opaque;
627 struct uffdio_register reg_struct;
628
629 reg_struct.range.start = (uintptr_t)qemu_ram_get_host_addr(rb);
630 reg_struct.range.len = qemu_ram_get_used_length(rb);
631 reg_struct.mode = UFFDIO_REGISTER_MODE_MISSING;
632
633 /* Now tell our userfault_fd that it's responsible for this area */
634 if (ioctl(mis->userfault_fd, UFFDIO_REGISTER, &reg_struct)) {
635 error_report("%s userfault register: %s", __func__, strerror(errno));
636 return -1;
637 }
638 if (!(reg_struct.ioctls & ((__u64)1 << _UFFDIO_COPY))) {
639 error_report("%s userfault: Region doesn't support COPY", __func__);
640 return -1;
641 }
642 if (reg_struct.ioctls & ((__u64)1 << _UFFDIO_ZEROPAGE)) {
643 qemu_ram_set_uf_zeroable(rb);
644 }
645
646 return 0;
647 }
648
649 int postcopy_wake_shared(struct PostCopyFD *pcfd,
650 uint64_t client_addr,
651 RAMBlock *rb)
652 {
653 size_t pagesize = qemu_ram_pagesize(rb);
654 struct uffdio_range range;
655 int ret;
656 trace_postcopy_wake_shared(client_addr, qemu_ram_get_idstr(rb));
657 range.start = client_addr & ~(pagesize - 1);
658 range.len = pagesize;
659 ret = ioctl(pcfd->fd, UFFDIO_WAKE, &range);
660 if (ret) {
661 error_report("%s: Failed to wake: %zx in %s (%s)",
662 __func__, (size_t)client_addr, qemu_ram_get_idstr(rb),
663 strerror(errno));
664 }
665 return ret;
666 }
667
668 /*
669 * Callback from shared fault handlers to ask for a page,
670 * the page must be specified by a RAMBlock and an offset in that rb
671 * Note: Only for use by shared fault handlers (in fault thread)
672 */
673 int postcopy_request_shared_page(struct PostCopyFD *pcfd, RAMBlock *rb,
674 uint64_t client_addr, uint64_t rb_offset)
675 {
676 size_t pagesize = qemu_ram_pagesize(rb);
677 uint64_t aligned_rbo = rb_offset & ~(pagesize - 1);
678 MigrationIncomingState *mis = migration_incoming_get_current();
679
680 trace_postcopy_request_shared_page(pcfd->idstr, qemu_ram_get_idstr(rb),
681 rb_offset);
682 if (ramblock_recv_bitmap_test_byte_offset(rb, aligned_rbo)) {
683 trace_postcopy_request_shared_page_present(pcfd->idstr,
684 qemu_ram_get_idstr(rb), rb_offset);
685 return postcopy_wake_shared(pcfd, client_addr, rb);
686 }
687 if (rb != mis->last_rb) {
688 mis->last_rb = rb;
689 migrate_send_rp_req_pages(mis, qemu_ram_get_idstr(rb),
690 aligned_rbo, pagesize);
691 } else {
692 /* Save some space */
693 migrate_send_rp_req_pages(mis, NULL, aligned_rbo, pagesize);
694 }
695 return 0;
696 }
697
698 static int get_mem_fault_cpu_index(uint32_t pid)
699 {
700 CPUState *cpu_iter;
701
702 CPU_FOREACH(cpu_iter) {
703 if (cpu_iter->thread_id == pid) {
704 trace_get_mem_fault_cpu_index(cpu_iter->cpu_index, pid);
705 return cpu_iter->cpu_index;
706 }
707 }
708 trace_get_mem_fault_cpu_index(-1, pid);
709 return -1;
710 }
711
712 static uint32_t get_low_time_offset(PostcopyBlocktimeContext *dc)
713 {
714 int64_t start_time_offset = qemu_clock_get_ms(QEMU_CLOCK_REALTIME) -
715 dc->start_time;
716 return start_time_offset < 1 ? 1 : start_time_offset & UINT32_MAX;
717 }
718
719 /*
720 * This function is being called when pagefault occurs. It
721 * tracks down vCPU blocking time.
722 *
723 * @addr: faulted host virtual address
724 * @ptid: faulted process thread id
725 * @rb: ramblock appropriate to addr
726 */
727 static void mark_postcopy_blocktime_begin(uintptr_t addr, uint32_t ptid,
728 RAMBlock *rb)
729 {
730 int cpu, already_received;
731 MigrationIncomingState *mis = migration_incoming_get_current();
732 PostcopyBlocktimeContext *dc = mis->blocktime_ctx;
733 uint32_t low_time_offset;
734
735 if (!dc || ptid == 0) {
736 return;
737 }
738 cpu = get_mem_fault_cpu_index(ptid);
739 if (cpu < 0) {
740 return;
741 }
742
743 low_time_offset = get_low_time_offset(dc);
744 if (dc->vcpu_addr[cpu] == 0) {
745 atomic_inc(&dc->smp_cpus_down);
746 }
747
748 atomic_xchg(&dc->last_begin, low_time_offset);
749 atomic_xchg(&dc->page_fault_vcpu_time[cpu], low_time_offset);
750 atomic_xchg(&dc->vcpu_addr[cpu], addr);
751
752 /*
753 * check it here, not at the beginning of the function,
754 * due to, check could occur early than bitmap_set in
755 * qemu_ufd_copy_ioctl
756 */
757 already_received = ramblock_recv_bitmap_test(rb, (void *)addr);
758 if (already_received) {
759 atomic_xchg(&dc->vcpu_addr[cpu], 0);
760 atomic_xchg(&dc->page_fault_vcpu_time[cpu], 0);
761 atomic_dec(&dc->smp_cpus_down);
762 }
763 trace_mark_postcopy_blocktime_begin(addr, dc, dc->page_fault_vcpu_time[cpu],
764 cpu, already_received);
765 }
766
767 /*
768 * This function just provide calculated blocktime per cpu and trace it.
769 * Total blocktime is calculated in mark_postcopy_blocktime_end.
770 *
771 *
772 * Assume we have 3 CPU
773 *
774 * S1 E1 S1 E1
775 * -----***********------------xxx***************------------------------> CPU1
776 *
777 * S2 E2
778 * ------------****************xxx---------------------------------------> CPU2
779 *
780 * S3 E3
781 * ------------------------****xxx********-------------------------------> CPU3
782 *
783 * We have sequence S1,S2,E1,S3,S1,E2,E3,E1
784 * S2,E1 - doesn't match condition due to sequence S1,S2,E1 doesn't include CPU3
785 * S3,S1,E2 - sequence includes all CPUs, in this case overlap will be S1,E2 -
786 * it's a part of total blocktime.
787 * S1 - here is last_begin
788 * Legend of the picture is following:
789 * * - means blocktime per vCPU
790 * x - means overlapped blocktime (total blocktime)
791 *
792 * @addr: host virtual address
793 */
794 static void mark_postcopy_blocktime_end(uintptr_t addr)
795 {
796 MigrationIncomingState *mis = migration_incoming_get_current();
797 PostcopyBlocktimeContext *dc = mis->blocktime_ctx;
798 MachineState *ms = MACHINE(qdev_get_machine());
799 unsigned int smp_cpus = ms->smp.cpus;
800 int i, affected_cpu = 0;
801 bool vcpu_total_blocktime = false;
802 uint32_t read_vcpu_time, low_time_offset;
803
804 if (!dc) {
805 return;
806 }
807
808 low_time_offset = get_low_time_offset(dc);
809 /* lookup cpu, to clear it,
810 * that algorithm looks straighforward, but it's not
811 * optimal, more optimal algorithm is keeping tree or hash
812 * where key is address value is a list of */
813 for (i = 0; i < smp_cpus; i++) {
814 uint32_t vcpu_blocktime = 0;
815
816 read_vcpu_time = atomic_fetch_add(&dc->page_fault_vcpu_time[i], 0);
817 if (atomic_fetch_add(&dc->vcpu_addr[i], 0) != addr ||
818 read_vcpu_time == 0) {
819 continue;
820 }
821 atomic_xchg(&dc->vcpu_addr[i], 0);
822 vcpu_blocktime = low_time_offset - read_vcpu_time;
823 affected_cpu += 1;
824 /* we need to know is that mark_postcopy_end was due to
825 * faulted page, another possible case it's prefetched
826 * page and in that case we shouldn't be here */
827 if (!vcpu_total_blocktime &&
828 atomic_fetch_add(&dc->smp_cpus_down, 0) == smp_cpus) {
829 vcpu_total_blocktime = true;
830 }
831 /* continue cycle, due to one page could affect several vCPUs */
832 dc->vcpu_blocktime[i] += vcpu_blocktime;
833 }
834
835 atomic_sub(&dc->smp_cpus_down, affected_cpu);
836 if (vcpu_total_blocktime) {
837 dc->total_blocktime += low_time_offset - atomic_fetch_add(
838 &dc->last_begin, 0);
839 }
840 trace_mark_postcopy_blocktime_end(addr, dc, dc->total_blocktime,
841 affected_cpu);
842 }
843
844 static bool postcopy_pause_fault_thread(MigrationIncomingState *mis)
845 {
846 trace_postcopy_pause_fault_thread();
847
848 qemu_sem_wait(&mis->postcopy_pause_sem_fault);
849
850 trace_postcopy_pause_fault_thread_continued();
851
852 return true;
853 }
854
855 /*
856 * Handle faults detected by the USERFAULT markings
857 */
858 static void *postcopy_ram_fault_thread(void *opaque)
859 {
860 MigrationIncomingState *mis = opaque;
861 struct uffd_msg msg;
862 int ret;
863 size_t index;
864 RAMBlock *rb = NULL;
865
866 trace_postcopy_ram_fault_thread_entry();
867 rcu_register_thread();
868 mis->last_rb = NULL; /* last RAMBlock we sent part of */
869 qemu_sem_post(&mis->fault_thread_sem);
870
871 struct pollfd *pfd;
872 size_t pfd_len = 2 + mis->postcopy_remote_fds->len;
873
874 pfd = g_new0(struct pollfd, pfd_len);
875
876 pfd[0].fd = mis->userfault_fd;
877 pfd[0].events = POLLIN;
878 pfd[1].fd = mis->userfault_event_fd;
879 pfd[1].events = POLLIN; /* Waiting for eventfd to go positive */
880 trace_postcopy_ram_fault_thread_fds_core(pfd[0].fd, pfd[1].fd);
881 for (index = 0; index < mis->postcopy_remote_fds->len; index++) {
882 struct PostCopyFD *pcfd = &g_array_index(mis->postcopy_remote_fds,
883 struct PostCopyFD, index);
884 pfd[2 + index].fd = pcfd->fd;
885 pfd[2 + index].events = POLLIN;
886 trace_postcopy_ram_fault_thread_fds_extra(2 + index, pcfd->idstr,
887 pcfd->fd);
888 }
889
890 while (true) {
891 ram_addr_t rb_offset;
892 int poll_result;
893
894 /*
895 * We're mainly waiting for the kernel to give us a faulting HVA,
896 * however we can be told to quit via userfault_quit_fd which is
897 * an eventfd
898 */
899
900 poll_result = poll(pfd, pfd_len, -1 /* Wait forever */);
901 if (poll_result == -1) {
902 error_report("%s: userfault poll: %s", __func__, strerror(errno));
903 break;
904 }
905
906 if (!mis->to_src_file) {
907 /*
908 * Possibly someone tells us that the return path is
909 * broken already using the event. We should hold until
910 * the channel is rebuilt.
911 */
912 if (postcopy_pause_fault_thread(mis)) {
913 mis->last_rb = NULL;
914 /* Continue to read the userfaultfd */
915 } else {
916 error_report("%s: paused but don't allow to continue",
917 __func__);
918 break;
919 }
920 }
921
922 if (pfd[1].revents) {
923 uint64_t tmp64 = 0;
924
925 /* Consume the signal */
926 if (read(mis->userfault_event_fd, &tmp64, 8) != 8) {
927 /* Nothing obviously nicer than posting this error. */
928 error_report("%s: read() failed", __func__);
929 }
930
931 if (atomic_read(&mis->fault_thread_quit)) {
932 trace_postcopy_ram_fault_thread_quit();
933 break;
934 }
935 }
936
937 if (pfd[0].revents) {
938 poll_result--;
939 ret = read(mis->userfault_fd, &msg, sizeof(msg));
940 if (ret != sizeof(msg)) {
941 if (errno == EAGAIN) {
942 /*
943 * if a wake up happens on the other thread just after
944 * the poll, there is nothing to read.
945 */
946 continue;
947 }
948 if (ret < 0) {
949 error_report("%s: Failed to read full userfault "
950 "message: %s",
951 __func__, strerror(errno));
952 break;
953 } else {
954 error_report("%s: Read %d bytes from userfaultfd "
955 "expected %zd",
956 __func__, ret, sizeof(msg));
957 break; /* Lost alignment, don't know what we'd read next */
958 }
959 }
960 if (msg.event != UFFD_EVENT_PAGEFAULT) {
961 error_report("%s: Read unexpected event %ud from userfaultfd",
962 __func__, msg.event);
963 continue; /* It's not a page fault, shouldn't happen */
964 }
965
966 rb = qemu_ram_block_from_host(
967 (void *)(uintptr_t)msg.arg.pagefault.address,
968 true, &rb_offset);
969 if (!rb) {
970 error_report("postcopy_ram_fault_thread: Fault outside guest: %"
971 PRIx64, (uint64_t)msg.arg.pagefault.address);
972 break;
973 }
974
975 rb_offset &= ~(qemu_ram_pagesize(rb) - 1);
976 trace_postcopy_ram_fault_thread_request(msg.arg.pagefault.address,
977 qemu_ram_get_idstr(rb),
978 rb_offset,
979 msg.arg.pagefault.feat.ptid);
980 mark_postcopy_blocktime_begin(
981 (uintptr_t)(msg.arg.pagefault.address),
982 msg.arg.pagefault.feat.ptid, rb);
983
984 retry:
985 /*
986 * Send the request to the source - we want to request one
987 * of our host page sizes (which is >= TPS)
988 */
989 if (rb != mis->last_rb) {
990 mis->last_rb = rb;
991 ret = migrate_send_rp_req_pages(mis,
992 qemu_ram_get_idstr(rb),
993 rb_offset,
994 qemu_ram_pagesize(rb));
995 } else {
996 /* Save some space */
997 ret = migrate_send_rp_req_pages(mis,
998 NULL,
999 rb_offset,
1000 qemu_ram_pagesize(rb));
1001 }
1002
1003 if (ret) {
1004 /* May be network failure, try to wait for recovery */
1005 if (ret == -EIO && postcopy_pause_fault_thread(mis)) {
1006 /* We got reconnected somehow, try to continue */
1007 mis->last_rb = NULL;
1008 goto retry;
1009 } else {
1010 /* This is a unavoidable fault */
1011 error_report("%s: migrate_send_rp_req_pages() get %d",
1012 __func__, ret);
1013 break;
1014 }
1015 }
1016 }
1017
1018 /* Now handle any requests from external processes on shared memory */
1019 /* TODO: May need to handle devices deregistering during postcopy */
1020 for (index = 2; index < pfd_len && poll_result; index++) {
1021 if (pfd[index].revents) {
1022 struct PostCopyFD *pcfd =
1023 &g_array_index(mis->postcopy_remote_fds,
1024 struct PostCopyFD, index - 2);
1025
1026 poll_result--;
1027 if (pfd[index].revents & POLLERR) {
1028 error_report("%s: POLLERR on poll %zd fd=%d",
1029 __func__, index, pcfd->fd);
1030 pfd[index].events = 0;
1031 continue;
1032 }
1033
1034 ret = read(pcfd->fd, &msg, sizeof(msg));
1035 if (ret != sizeof(msg)) {
1036 if (errno == EAGAIN) {
1037 /*
1038 * if a wake up happens on the other thread just after
1039 * the poll, there is nothing to read.
1040 */
1041 continue;
1042 }
1043 if (ret < 0) {
1044 error_report("%s: Failed to read full userfault "
1045 "message: %s (shared) revents=%d",
1046 __func__, strerror(errno),
1047 pfd[index].revents);
1048 /*TODO: Could just disable this sharer */
1049 break;
1050 } else {
1051 error_report("%s: Read %d bytes from userfaultfd "
1052 "expected %zd (shared)",
1053 __func__, ret, sizeof(msg));
1054 /*TODO: Could just disable this sharer */
1055 break; /*Lost alignment,don't know what we'd read next*/
1056 }
1057 }
1058 if (msg.event != UFFD_EVENT_PAGEFAULT) {
1059 error_report("%s: Read unexpected event %ud "
1060 "from userfaultfd (shared)",
1061 __func__, msg.event);
1062 continue; /* It's not a page fault, shouldn't happen */
1063 }
1064 /* Call the device handler registered with us */
1065 ret = pcfd->handler(pcfd, &msg);
1066 if (ret) {
1067 error_report("%s: Failed to resolve shared fault on %zd/%s",
1068 __func__, index, pcfd->idstr);
1069 /* TODO: Fail? Disable this sharer? */
1070 }
1071 }
1072 }
1073 }
1074 rcu_unregister_thread();
1075 trace_postcopy_ram_fault_thread_exit();
1076 g_free(pfd);
1077 return NULL;
1078 }
1079
1080 int postcopy_ram_incoming_setup(MigrationIncomingState *mis)
1081 {
1082 /* Open the fd for the kernel to give us userfaults */
1083 mis->userfault_fd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK);
1084 if (mis->userfault_fd == -1) {
1085 error_report("%s: Failed to open userfault fd: %s", __func__,
1086 strerror(errno));
1087 return -1;
1088 }
1089
1090 /*
1091 * Although the host check already tested the API, we need to
1092 * do the check again as an ABI handshake on the new fd.
1093 */
1094 if (!ufd_check_and_apply(mis->userfault_fd, mis)) {
1095 return -1;
1096 }
1097
1098 /* Now an eventfd we use to tell the fault-thread to quit */
1099 mis->userfault_event_fd = eventfd(0, EFD_CLOEXEC);
1100 if (mis->userfault_event_fd == -1) {
1101 error_report("%s: Opening userfault_event_fd: %s", __func__,
1102 strerror(errno));
1103 close(mis->userfault_fd);
1104 return -1;
1105 }
1106
1107 qemu_sem_init(&mis->fault_thread_sem, 0);
1108 qemu_thread_create(&mis->fault_thread, "postcopy/fault",
1109 postcopy_ram_fault_thread, mis, QEMU_THREAD_JOINABLE);
1110 qemu_sem_wait(&mis->fault_thread_sem);
1111 qemu_sem_destroy(&mis->fault_thread_sem);
1112 mis->have_fault_thread = true;
1113
1114 /* Mark so that we get notified of accesses to unwritten areas */
1115 if (foreach_not_ignored_block(ram_block_enable_notify, mis)) {
1116 error_report("ram_block_enable_notify failed");
1117 return -1;
1118 }
1119
1120 mis->postcopy_tmp_page = mmap(NULL, mis->largest_page_size,
1121 PROT_READ | PROT_WRITE, MAP_PRIVATE |
1122 MAP_ANONYMOUS, -1, 0);
1123 if (mis->postcopy_tmp_page == MAP_FAILED) {
1124 mis->postcopy_tmp_page = NULL;
1125 error_report("%s: Failed to map postcopy_tmp_page %s",
1126 __func__, strerror(errno));
1127 return -1;
1128 }
1129
1130 /*
1131 * Map large zero page when kernel can't use UFFDIO_ZEROPAGE for hugepages
1132 */
1133 mis->postcopy_tmp_zero_page = mmap(NULL, mis->largest_page_size,
1134 PROT_READ | PROT_WRITE,
1135 MAP_PRIVATE | MAP_ANONYMOUS,
1136 -1, 0);
1137 if (mis->postcopy_tmp_zero_page == MAP_FAILED) {
1138 int e = errno;
1139 mis->postcopy_tmp_zero_page = NULL;
1140 error_report("%s: Failed to map large zero page %s",
1141 __func__, strerror(e));
1142 return -e;
1143 }
1144 memset(mis->postcopy_tmp_zero_page, '\0', mis->largest_page_size);
1145
1146 trace_postcopy_ram_enable_notify();
1147
1148 return 0;
1149 }
1150
1151 static int qemu_ufd_copy_ioctl(int userfault_fd, void *host_addr,
1152 void *from_addr, uint64_t pagesize, RAMBlock *rb)
1153 {
1154 int ret;
1155 if (from_addr) {
1156 struct uffdio_copy copy_struct;
1157 copy_struct.dst = (uint64_t)(uintptr_t)host_addr;
1158 copy_struct.src = (uint64_t)(uintptr_t)from_addr;
1159 copy_struct.len = pagesize;
1160 copy_struct.mode = 0;
1161 ret = ioctl(userfault_fd, UFFDIO_COPY, &copy_struct);
1162 } else {
1163 struct uffdio_zeropage zero_struct;
1164 zero_struct.range.start = (uint64_t)(uintptr_t)host_addr;
1165 zero_struct.range.len = pagesize;
1166 zero_struct.mode = 0;
1167 ret = ioctl(userfault_fd, UFFDIO_ZEROPAGE, &zero_struct);
1168 }
1169 if (!ret) {
1170 ramblock_recv_bitmap_set_range(rb, host_addr,
1171 pagesize / qemu_target_page_size());
1172 mark_postcopy_blocktime_end((uintptr_t)host_addr);
1173
1174 }
1175 return ret;
1176 }
1177
1178 int postcopy_notify_shared_wake(RAMBlock *rb, uint64_t offset)
1179 {
1180 int i;
1181 MigrationIncomingState *mis = migration_incoming_get_current();
1182 GArray *pcrfds = mis->postcopy_remote_fds;
1183
1184 for (i = 0; i < pcrfds->len; i++) {
1185 struct PostCopyFD *cur = &g_array_index(pcrfds, struct PostCopyFD, i);
1186 int ret = cur->waker(cur, rb, offset);
1187 if (ret) {
1188 return ret;
1189 }
1190 }
1191 return 0;
1192 }
1193
1194 /*
1195 * Place a host page (from) at (host) atomically
1196 * returns 0 on success
1197 */
1198 int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from,
1199 RAMBlock *rb)
1200 {
1201 size_t pagesize = qemu_ram_pagesize(rb);
1202
1203 /* copy also acks to the kernel waking the stalled thread up
1204 * TODO: We can inhibit that ack and only do it if it was requested
1205 * which would be slightly cheaper, but we'd have to be careful
1206 * of the order of updating our page state.
1207 */
1208 if (qemu_ufd_copy_ioctl(mis->userfault_fd, host, from, pagesize, rb)) {
1209 int e = errno;
1210 error_report("%s: %s copy host: %p from: %p (size: %zd)",
1211 __func__, strerror(e), host, from, pagesize);
1212
1213 return -e;
1214 }
1215
1216 trace_postcopy_place_page(host);
1217 return postcopy_notify_shared_wake(rb,
1218 qemu_ram_block_host_offset(rb, host));
1219 }
1220
1221 /*
1222 * Place a zero page at (host) atomically
1223 * returns 0 on success
1224 */
1225 int postcopy_place_page_zero(MigrationIncomingState *mis, void *host,
1226 RAMBlock *rb)
1227 {
1228 size_t pagesize = qemu_ram_pagesize(rb);
1229 trace_postcopy_place_page_zero(host);
1230
1231 /* Normal RAMBlocks can zero a page using UFFDIO_ZEROPAGE
1232 * but it's not available for everything (e.g. hugetlbpages)
1233 */
1234 if (qemu_ram_is_uf_zeroable(rb)) {
1235 if (qemu_ufd_copy_ioctl(mis->userfault_fd, host, NULL, pagesize, rb)) {
1236 int e = errno;
1237 error_report("%s: %s zero host: %p",
1238 __func__, strerror(e), host);
1239
1240 return -e;
1241 }
1242 return postcopy_notify_shared_wake(rb,
1243 qemu_ram_block_host_offset(rb,
1244 host));
1245 } else {
1246 return postcopy_place_page(mis, host, mis->postcopy_tmp_zero_page, rb);
1247 }
1248 }
1249
1250 #else
1251 /* No target OS support, stubs just fail */
1252 void fill_destination_postcopy_migration_info(MigrationInfo *info)
1253 {
1254 }
1255
1256 bool postcopy_ram_supported_by_host(MigrationIncomingState *mis)
1257 {
1258 error_report("%s: No OS support", __func__);
1259 return false;
1260 }
1261
1262 int postcopy_ram_incoming_init(MigrationIncomingState *mis)
1263 {
1264 error_report("postcopy_ram_incoming_init: No OS support");
1265 return -1;
1266 }
1267
1268 int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis)
1269 {
1270 assert(0);
1271 return -1;
1272 }
1273
1274 int postcopy_ram_prepare_discard(MigrationIncomingState *mis)
1275 {
1276 assert(0);
1277 return -1;
1278 }
1279
1280 int postcopy_request_shared_page(struct PostCopyFD *pcfd, RAMBlock *rb,
1281 uint64_t client_addr, uint64_t rb_offset)
1282 {
1283 assert(0);
1284 return -1;
1285 }
1286
1287 int postcopy_ram_incoming_setup(MigrationIncomingState *mis)
1288 {
1289 assert(0);
1290 return -1;
1291 }
1292
1293 int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from,
1294 RAMBlock *rb)
1295 {
1296 assert(0);
1297 return -1;
1298 }
1299
1300 int postcopy_place_page_zero(MigrationIncomingState *mis, void *host,
1301 RAMBlock *rb)
1302 {
1303 assert(0);
1304 return -1;
1305 }
1306
1307 int postcopy_wake_shared(struct PostCopyFD *pcfd,
1308 uint64_t client_addr,
1309 RAMBlock *rb)
1310 {
1311 assert(0);
1312 return -1;
1313 }
1314 #endif
1315
1316 /* ------------------------------------------------------------------------- */
1317
1318 void postcopy_fault_thread_notify(MigrationIncomingState *mis)
1319 {
1320 uint64_t tmp64 = 1;
1321
1322 /*
1323 * Wakeup the fault_thread. It's an eventfd that should currently
1324 * be at 0, we're going to increment it to 1
1325 */
1326 if (write(mis->userfault_event_fd, &tmp64, 8) != 8) {
1327 /* Not much we can do here, but may as well report it */
1328 error_report("%s: incrementing failed: %s", __func__,
1329 strerror(errno));
1330 }
1331 }
1332
1333 /**
1334 * postcopy_discard_send_init: Called at the start of each RAMBlock before
1335 * asking to discard individual ranges.
1336 *
1337 * @ms: The current migration state.
1338 * @offset: the bitmap offset of the named RAMBlock in the migration bitmap.
1339 * @name: RAMBlock that discards will operate on.
1340 */
1341 static PostcopyDiscardState pds = {0};
1342 void postcopy_discard_send_init(MigrationState *ms, const char *name)
1343 {
1344 pds.ramblock_name = name;
1345 pds.cur_entry = 0;
1346 pds.nsentwords = 0;
1347 pds.nsentcmds = 0;
1348 }
1349
1350 /**
1351 * postcopy_discard_send_range: Called by the bitmap code for each chunk to
1352 * discard. May send a discard message, may just leave it queued to
1353 * be sent later.
1354 *
1355 * @ms: Current migration state.
1356 * @start,@length: a range of pages in the migration bitmap in the
1357 * RAM block passed to postcopy_discard_send_init() (length=1 is one page)
1358 */
1359 void postcopy_discard_send_range(MigrationState *ms, unsigned long start,
1360 unsigned long length)
1361 {
1362 size_t tp_size = qemu_target_page_size();
1363 /* Convert to byte offsets within the RAM block */
1364 pds.start_list[pds.cur_entry] = start * tp_size;
1365 pds.length_list[pds.cur_entry] = length * tp_size;
1366 trace_postcopy_discard_send_range(pds.ramblock_name, start, length);
1367 pds.cur_entry++;
1368 pds.nsentwords++;
1369
1370 if (pds.cur_entry == MAX_DISCARDS_PER_COMMAND) {
1371 /* Full set, ship it! */
1372 qemu_savevm_send_postcopy_ram_discard(ms->to_dst_file,
1373 pds.ramblock_name,
1374 pds.cur_entry,
1375 pds.start_list,
1376 pds.length_list);
1377 pds.nsentcmds++;
1378 pds.cur_entry = 0;
1379 }
1380 }
1381
1382 /**
1383 * postcopy_discard_send_finish: Called at the end of each RAMBlock by the
1384 * bitmap code. Sends any outstanding discard messages, frees the PDS
1385 *
1386 * @ms: Current migration state.
1387 */
1388 void postcopy_discard_send_finish(MigrationState *ms)
1389 {
1390 /* Anything unsent? */
1391 if (pds.cur_entry) {
1392 qemu_savevm_send_postcopy_ram_discard(ms->to_dst_file,
1393 pds.ramblock_name,
1394 pds.cur_entry,
1395 pds.start_list,
1396 pds.length_list);
1397 pds.nsentcmds++;
1398 }
1399
1400 trace_postcopy_discard_send_finish(pds.ramblock_name, pds.nsentwords,
1401 pds.nsentcmds);
1402 }
1403
1404 /*
1405 * Current state of incoming postcopy; note this is not part of
1406 * MigrationIncomingState since it's state is used during cleanup
1407 * at the end as MIS is being freed.
1408 */
1409 static PostcopyState incoming_postcopy_state;
1410
1411 PostcopyState postcopy_state_get(void)
1412 {
1413 return atomic_mb_read(&incoming_postcopy_state);
1414 }
1415
1416 /* Set the state and return the old state */
1417 PostcopyState postcopy_state_set(PostcopyState new_state)
1418 {
1419 return atomic_xchg(&incoming_postcopy_state, new_state);
1420 }
1421
1422 /* Register a handler for external shared memory postcopy
1423 * called on the destination.
1424 */
1425 void postcopy_register_shared_ufd(struct PostCopyFD *pcfd)
1426 {
1427 MigrationIncomingState *mis = migration_incoming_get_current();
1428
1429 mis->postcopy_remote_fds = g_array_append_val(mis->postcopy_remote_fds,
1430 *pcfd);
1431 }
1432
1433 /* Unregister a handler for external shared memory postcopy
1434 */
1435 void postcopy_unregister_shared_ufd(struct PostCopyFD *pcfd)
1436 {
1437 guint i;
1438 MigrationIncomingState *mis = migration_incoming_get_current();
1439 GArray *pcrfds = mis->postcopy_remote_fds;
1440
1441 for (i = 0; i < pcrfds->len; i++) {
1442 struct PostCopyFD *cur = &g_array_index(pcrfds, struct PostCopyFD, i);
1443 if (cur->fd == pcfd->fd) {
1444 mis->postcopy_remote_fds = g_array_remove_index(pcrfds, i);
1445 return;
1446 }
1447 }
1448 }