2 * Postcopy migration for RAM
4 * Copyright 2013-2015 Red Hat, Inc. and/or its affiliates
7 * Dave Gilbert <dgilbert@redhat.com>
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.
15 * Postcopy is a migration technique where the execution flips from the
16 * source to the destination before all the data has been copied.
19 #include "qemu/osdep.h"
20 #include "qemu/madvise.h"
21 #include "exec/target_page.h"
22 #include "migration.h"
23 #include "qemu-file.h"
25 #include "postcopy-ram.h"
27 #include "qapi/error.h"
28 #include "qemu/notify.h"
30 #include "sysemu/sysemu.h"
31 #include "qemu/error-report.h"
33 #include "hw/boards.h"
34 #include "exec/ramblock.h"
36 #include "yank_functions.h"
38 #include "qemu/userfaultfd.h"
39 #include "qemu/mmap-alloc.h"
42 /* Arbitrary limit on size of each discard command,
43 * keeps them around ~200 bytes
45 #define MAX_DISCARDS_PER_COMMAND 12
47 struct PostcopyDiscardState
{
48 const char *ramblock_name
;
51 * Start and length of a discard range (bytes)
53 uint64_t start_list
[MAX_DISCARDS_PER_COMMAND
];
54 uint64_t length_list
[MAX_DISCARDS_PER_COMMAND
];
55 unsigned int nsentwords
;
56 unsigned int nsentcmds
;
59 static NotifierWithReturnList postcopy_notifier_list
;
61 void postcopy_infrastructure_init(void)
63 notifier_with_return_list_init(&postcopy_notifier_list
);
66 void postcopy_add_notifier(NotifierWithReturn
*nn
)
68 notifier_with_return_list_add(&postcopy_notifier_list
, nn
);
71 void postcopy_remove_notifier(NotifierWithReturn
*n
)
73 notifier_with_return_remove(n
);
76 int postcopy_notify(enum PostcopyNotifyReason reason
, Error
**errp
)
78 struct PostcopyNotifyData pnd
;
82 return notifier_with_return_list_notify(&postcopy_notifier_list
,
87 * NOTE: this routine is not thread safe, we can't call it concurrently. But it
88 * should be good enough for migration's purposes.
90 void postcopy_thread_create(MigrationIncomingState
*mis
,
91 QemuThread
*thread
, const char *name
,
92 void *(*fn
)(void *), int joinable
)
94 qemu_sem_init(&mis
->thread_sync_sem
, 0);
95 qemu_thread_create(thread
, name
, fn
, mis
, joinable
);
96 qemu_sem_wait(&mis
->thread_sync_sem
);
97 qemu_sem_destroy(&mis
->thread_sync_sem
);
100 /* Postcopy needs to detect accesses to pages that haven't yet been copied
101 * across, and efficiently map new pages in, the techniques for doing this
102 * are target OS specific.
104 #if defined(__linux__)
106 #include <sys/ioctl.h>
107 #include <sys/syscall.h>
110 #if defined(__linux__) && defined(__NR_userfaultfd) && defined(CONFIG_EVENTFD)
111 #include <sys/eventfd.h>
112 #include <linux/userfaultfd.h>
114 typedef struct PostcopyBlocktimeContext
{
115 /* time when page fault initiated per vCPU */
116 uint32_t *page_fault_vcpu_time
;
117 /* page address per vCPU */
118 uintptr_t *vcpu_addr
;
119 uint32_t total_blocktime
;
120 /* blocktime per vCPU */
121 uint32_t *vcpu_blocktime
;
122 /* point in time when last page fault was initiated */
124 /* number of vCPU are suspended */
129 * Handler for exit event, necessary for
130 * releasing whole blocktime_ctx
132 Notifier exit_notifier
;
133 } PostcopyBlocktimeContext
;
135 static void destroy_blocktime_context(struct PostcopyBlocktimeContext
*ctx
)
137 g_free(ctx
->page_fault_vcpu_time
);
138 g_free(ctx
->vcpu_addr
);
139 g_free(ctx
->vcpu_blocktime
);
143 static void migration_exit_cb(Notifier
*n
, void *data
)
145 PostcopyBlocktimeContext
*ctx
= container_of(n
, PostcopyBlocktimeContext
,
147 destroy_blocktime_context(ctx
);
150 static struct PostcopyBlocktimeContext
*blocktime_context_new(void)
152 MachineState
*ms
= MACHINE(qdev_get_machine());
153 unsigned int smp_cpus
= ms
->smp
.cpus
;
154 PostcopyBlocktimeContext
*ctx
= g_new0(PostcopyBlocktimeContext
, 1);
155 ctx
->page_fault_vcpu_time
= g_new0(uint32_t, smp_cpus
);
156 ctx
->vcpu_addr
= g_new0(uintptr_t, smp_cpus
);
157 ctx
->vcpu_blocktime
= g_new0(uint32_t, smp_cpus
);
159 ctx
->exit_notifier
.notify
= migration_exit_cb
;
160 ctx
->start_time
= qemu_clock_get_ms(QEMU_CLOCK_REALTIME
);
161 qemu_add_exit_notifier(&ctx
->exit_notifier
);
165 static uint32List
*get_vcpu_blocktime_list(PostcopyBlocktimeContext
*ctx
)
167 MachineState
*ms
= MACHINE(qdev_get_machine());
168 uint32List
*list
= NULL
;
171 for (i
= ms
->smp
.cpus
- 1; i
>= 0; i
--) {
172 QAPI_LIST_PREPEND(list
, ctx
->vcpu_blocktime
[i
]);
179 * This function just populates MigrationInfo from postcopy's
180 * blocktime context. It will not populate MigrationInfo,
181 * unless postcopy-blocktime capability was set.
183 * @info: pointer to MigrationInfo to populate
185 void fill_destination_postcopy_migration_info(MigrationInfo
*info
)
187 MigrationIncomingState
*mis
= migration_incoming_get_current();
188 PostcopyBlocktimeContext
*bc
= mis
->blocktime_ctx
;
194 info
->has_postcopy_blocktime
= true;
195 info
->postcopy_blocktime
= bc
->total_blocktime
;
196 info
->has_postcopy_vcpu_blocktime
= true;
197 info
->postcopy_vcpu_blocktime
= get_vcpu_blocktime_list(bc
);
200 static uint32_t get_postcopy_total_blocktime(void)
202 MigrationIncomingState
*mis
= migration_incoming_get_current();
203 PostcopyBlocktimeContext
*bc
= mis
->blocktime_ctx
;
209 return bc
->total_blocktime
;
213 * receive_ufd_features: check userfault fd features, to request only supported
214 * features in the future.
216 * Returns: true on success
218 * __NR_userfaultfd - should be checked before
219 * @features: out parameter will contain uffdio_api.features provided by kernel
222 static bool receive_ufd_features(uint64_t *features
)
224 struct uffdio_api api_struct
= {0};
228 ufd
= uffd_open(O_CLOEXEC
);
230 error_report("%s: uffd_open() failed: %s", __func__
, strerror(errno
));
235 api_struct
.api
= UFFD_API
;
236 api_struct
.features
= 0;
237 if (ioctl(ufd
, UFFDIO_API
, &api_struct
)) {
238 error_report("%s: UFFDIO_API failed: %s", __func__
,
244 *features
= api_struct
.features
;
252 * request_ufd_features: this function should be called only once on a newly
253 * opened ufd, subsequent calls will lead to error.
255 * Returns: true on success
257 * @ufd: fd obtained from userfaultfd syscall
258 * @features: bit mask see UFFD_API_FEATURES
260 static bool request_ufd_features(int ufd
, uint64_t features
)
262 struct uffdio_api api_struct
= {0};
265 api_struct
.api
= UFFD_API
;
266 api_struct
.features
= features
;
267 if (ioctl(ufd
, UFFDIO_API
, &api_struct
)) {
268 error_report("%s failed: UFFDIO_API failed: %s", __func__
,
273 ioctl_mask
= 1ULL << _UFFDIO_REGISTER
|
274 1ULL << _UFFDIO_UNREGISTER
;
275 if ((api_struct
.ioctls
& ioctl_mask
) != ioctl_mask
) {
276 error_report("Missing userfault features: %" PRIx64
,
277 (uint64_t)(~api_struct
.ioctls
& ioctl_mask
));
284 static bool ufd_check_and_apply(int ufd
, MigrationIncomingState
*mis
,
287 uint64_t asked_features
= 0;
288 static uint64_t supported_features
;
292 * it's not possible to
293 * request UFFD_API twice per one fd
294 * userfault fd features is persistent
296 if (!supported_features
) {
297 if (!receive_ufd_features(&supported_features
)) {
298 error_setg(errp
, "Userfault feature detection failed");
303 #ifdef UFFD_FEATURE_THREAD_ID
304 if (UFFD_FEATURE_THREAD_ID
& supported_features
) {
305 asked_features
|= UFFD_FEATURE_THREAD_ID
;
306 if (migrate_postcopy_blocktime()) {
307 if (!mis
->blocktime_ctx
) {
308 mis
->blocktime_ctx
= blocktime_context_new();
315 * request features, even if asked_features is 0, due to
316 * kernel expects UFFD_API before UFFDIO_REGISTER, per
317 * userfault file descriptor
319 if (!request_ufd_features(ufd
, asked_features
)) {
320 error_setg(errp
, "Failed features %" PRIu64
, asked_features
);
324 if (qemu_real_host_page_size() != ram_pagesize_summary()) {
325 bool have_hp
= false;
326 /* We've got a huge page */
327 #ifdef UFFD_FEATURE_MISSING_HUGETLBFS
328 have_hp
= supported_features
& UFFD_FEATURE_MISSING_HUGETLBFS
;
332 "Userfault on this host does not support huge pages");
339 /* Callback from postcopy_ram_supported_by_host block iterator.
341 static int test_ramblock_postcopiable(RAMBlock
*rb
, Error
**errp
)
343 const char *block_name
= qemu_ram_get_idstr(rb
);
344 ram_addr_t length
= qemu_ram_get_used_length(rb
);
345 size_t pagesize
= qemu_ram_pagesize(rb
);
348 if (length
% pagesize
) {
350 "Postcopy requires RAM blocks to be a page size multiple,"
351 " block %s is 0x" RAM_ADDR_FMT
" bytes with a "
352 "page size of 0x%zx", block_name
, length
, pagesize
);
357 fs
= qemu_fd_getfs(rb
->fd
);
358 if (fs
!= QEMU_FS_TYPE_TMPFS
&& fs
!= QEMU_FS_TYPE_HUGETLBFS
) {
360 "Host backend files need to be TMPFS or HUGETLBFS only");
369 * Note: This has the side effect of munlock'ing all of RAM, that's
370 * normally fine since if the postcopy succeeds it gets turned back on at the
373 bool postcopy_ram_supported_by_host(MigrationIncomingState
*mis
, Error
**errp
)
375 long pagesize
= qemu_real_host_page_size();
377 bool ret
= false; /* Error unless we change it */
378 void *testarea
= NULL
;
379 struct uffdio_register reg_struct
;
380 struct uffdio_range range_struct
;
381 uint64_t feature_mask
;
385 if (qemu_target_page_size() > pagesize
) {
386 error_setg(errp
, "Target page size bigger than host page size");
390 ufd
= uffd_open(O_CLOEXEC
);
392 error_setg(errp
, "Userfaultfd not available: %s", strerror(errno
));
396 /* Give devices a chance to object */
397 if (postcopy_notify(POSTCOPY_NOTIFY_PROBE
, errp
)) {
401 /* Version and features check */
402 if (!ufd_check_and_apply(ufd
, mis
, errp
)) {
407 * We don't support postcopy with some type of ramblocks.
409 * NOTE: we explicitly ignored migrate_ram_is_ignored() instead we checked
410 * all possible ramblocks. This is because this function can be called
411 * when creating the migration object, during the phase RAM_MIGRATABLE
412 * is not even properly set for all the ramblocks.
414 * A side effect of this is we'll also check against RAM_SHARED
415 * ramblocks even if migrate_ignore_shared() is set (in which case
416 * we'll never migrate RAM_SHARED at all), but normally this shouldn't
417 * affect in reality, or we can revisit.
419 RAMBLOCK_FOREACH(block
) {
420 if (test_ramblock_postcopiable(block
, errp
)) {
426 * userfault and mlock don't go together; we'll put it back later if
430 error_setg(errp
, "munlockall() failed: %s", strerror(errno
));
435 * We need to check that the ops we need are supported on anon memory
436 * To do that we need to register a chunk and see the flags that
439 testarea
= mmap(NULL
, pagesize
, PROT_READ
| PROT_WRITE
, MAP_PRIVATE
|
440 MAP_ANONYMOUS
, -1, 0);
441 if (testarea
== MAP_FAILED
) {
442 error_setg(errp
, "Failed to map test area: %s", strerror(errno
));
445 g_assert(QEMU_PTR_IS_ALIGNED(testarea
, pagesize
));
447 reg_struct
.range
.start
= (uintptr_t)testarea
;
448 reg_struct
.range
.len
= pagesize
;
449 reg_struct
.mode
= UFFDIO_REGISTER_MODE_MISSING
;
451 if (ioctl(ufd
, UFFDIO_REGISTER
, ®_struct
)) {
452 error_setg(errp
, "UFFDIO_REGISTER failed: %s", strerror(errno
));
456 range_struct
.start
= (uintptr_t)testarea
;
457 range_struct
.len
= pagesize
;
458 if (ioctl(ufd
, UFFDIO_UNREGISTER
, &range_struct
)) {
459 error_setg(errp
, "UFFDIO_UNREGISTER failed: %s", strerror(errno
));
463 feature_mask
= 1ULL << _UFFDIO_WAKE
|
464 1ULL << _UFFDIO_COPY
|
465 1ULL << _UFFDIO_ZEROPAGE
;
466 if ((reg_struct
.ioctls
& feature_mask
) != feature_mask
) {
467 error_setg(errp
, "Missing userfault map features: %" PRIx64
,
468 (uint64_t)(~reg_struct
.ioctls
& feature_mask
));
476 munmap(testarea
, pagesize
);
485 * Setup an area of RAM so that it *can* be used for postcopy later; this
486 * must be done right at the start prior to pre-copy.
487 * opaque should be the MIS.
489 static int init_range(RAMBlock
*rb
, void *opaque
)
491 const char *block_name
= qemu_ram_get_idstr(rb
);
492 void *host_addr
= qemu_ram_get_host_addr(rb
);
493 ram_addr_t offset
= qemu_ram_get_offset(rb
);
494 ram_addr_t length
= qemu_ram_get_used_length(rb
);
495 trace_postcopy_init_range(block_name
, host_addr
, offset
, length
);
498 * Save the used_length before running the guest. In case we have to
499 * resize RAM blocks when syncing RAM block sizes from the source during
500 * precopy, we'll update it manually via the ram block notifier.
502 rb
->postcopy_length
= length
;
505 * We need the whole of RAM to be truly empty for postcopy, so things
506 * like ROMs and any data tables built during init must be zero'd
507 * - we're going to get the copy from the source anyway.
508 * (Precopy will just overwrite this data, so doesn't need the discard)
510 if (ram_discard_range(block_name
, 0, length
)) {
518 * At the end of migration, undo the effects of init_range
519 * opaque should be the MIS.
521 static int cleanup_range(RAMBlock
*rb
, void *opaque
)
523 const char *block_name
= qemu_ram_get_idstr(rb
);
524 void *host_addr
= qemu_ram_get_host_addr(rb
);
525 ram_addr_t offset
= qemu_ram_get_offset(rb
);
526 ram_addr_t length
= rb
->postcopy_length
;
527 MigrationIncomingState
*mis
= opaque
;
528 struct uffdio_range range_struct
;
529 trace_postcopy_cleanup_range(block_name
, host_addr
, offset
, length
);
532 * We turned off hugepage for the precopy stage with postcopy enabled
533 * we can turn it back on now.
535 qemu_madvise(host_addr
, length
, QEMU_MADV_HUGEPAGE
);
538 * We can also turn off userfault now since we should have all the
539 * pages. It can be useful to leave it on to debug postcopy
540 * if you're not sure it's always getting every page.
542 range_struct
.start
= (uintptr_t)host_addr
;
543 range_struct
.len
= length
;
545 if (ioctl(mis
->userfault_fd
, UFFDIO_UNREGISTER
, &range_struct
)) {
546 error_report("%s: userfault unregister %s", __func__
, strerror(errno
));
555 * Initialise postcopy-ram, setting the RAM to a state where we can go into
556 * postcopy later; must be called prior to any precopy.
557 * called from arch_init's similarly named ram_postcopy_incoming_init
559 int postcopy_ram_incoming_init(MigrationIncomingState
*mis
)
561 if (foreach_not_ignored_block(init_range
, NULL
)) {
568 static void postcopy_temp_pages_cleanup(MigrationIncomingState
*mis
)
572 if (mis
->postcopy_tmp_pages
) {
573 for (i
= 0; i
< mis
->postcopy_channels
; i
++) {
574 if (mis
->postcopy_tmp_pages
[i
].tmp_huge_page
) {
575 munmap(mis
->postcopy_tmp_pages
[i
].tmp_huge_page
,
576 mis
->largest_page_size
);
577 mis
->postcopy_tmp_pages
[i
].tmp_huge_page
= NULL
;
580 g_free(mis
->postcopy_tmp_pages
);
581 mis
->postcopy_tmp_pages
= NULL
;
584 if (mis
->postcopy_tmp_zero_page
) {
585 munmap(mis
->postcopy_tmp_zero_page
, mis
->largest_page_size
);
586 mis
->postcopy_tmp_zero_page
= NULL
;
591 * At the end of a migration where postcopy_ram_incoming_init was called.
593 int postcopy_ram_incoming_cleanup(MigrationIncomingState
*mis
)
595 trace_postcopy_ram_incoming_cleanup_entry();
597 if (mis
->preempt_thread_status
== PREEMPT_THREAD_CREATED
) {
598 /* Notify the fast load thread to quit */
599 mis
->preempt_thread_status
= PREEMPT_THREAD_QUIT
;
601 * Update preempt_thread_status before reading count. Note: mutex
602 * lock only provide ACQUIRE semantic, and it doesn't stops this
603 * write to be reordered after reading the count.
607 * It's possible that the preempt thread is still handling the last
608 * pages to arrive which were requested by guest page faults.
609 * Making sure nothing is left behind by waiting on the condvar if
610 * that unlikely case happened.
612 WITH_QEMU_LOCK_GUARD(&mis
->page_request_mutex
) {
613 if (qatomic_read(&mis
->page_requested_count
)) {
615 * It is guaranteed to receive a signal later, because the
616 * count>0 now, so it's destined to be decreased to zero
617 * very soon by the preempt thread.
619 qemu_cond_wait(&mis
->page_request_cond
,
620 &mis
->page_request_mutex
);
623 /* Notify the fast load thread to quit */
624 if (mis
->postcopy_qemufile_dst
) {
625 qemu_file_shutdown(mis
->postcopy_qemufile_dst
);
627 qemu_thread_join(&mis
->postcopy_prio_thread
);
628 mis
->preempt_thread_status
= PREEMPT_THREAD_NONE
;
631 if (mis
->have_fault_thread
) {
632 Error
*local_err
= NULL
;
634 /* Let the fault thread quit */
635 qatomic_set(&mis
->fault_thread_quit
, 1);
636 postcopy_fault_thread_notify(mis
);
637 trace_postcopy_ram_incoming_cleanup_join();
638 qemu_thread_join(&mis
->fault_thread
);
640 if (postcopy_notify(POSTCOPY_NOTIFY_INBOUND_END
, &local_err
)) {
641 error_report_err(local_err
);
645 if (foreach_not_ignored_block(cleanup_range
, mis
)) {
649 trace_postcopy_ram_incoming_cleanup_closeuf();
650 close(mis
->userfault_fd
);
651 close(mis
->userfault_event_fd
);
652 mis
->have_fault_thread
= false;
656 if (os_mlock() < 0) {
657 error_report("mlock: %s", strerror(errno
));
659 * It doesn't feel right to fail at this point, we have a valid
665 postcopy_temp_pages_cleanup(mis
);
667 trace_postcopy_ram_incoming_cleanup_blocktime(
668 get_postcopy_total_blocktime());
670 trace_postcopy_ram_incoming_cleanup_exit();
675 * Disable huge pages on an area
677 static int nhp_range(RAMBlock
*rb
, void *opaque
)
679 const char *block_name
= qemu_ram_get_idstr(rb
);
680 void *host_addr
= qemu_ram_get_host_addr(rb
);
681 ram_addr_t offset
= qemu_ram_get_offset(rb
);
682 ram_addr_t length
= rb
->postcopy_length
;
683 trace_postcopy_nhp_range(block_name
, host_addr
, offset
, length
);
686 * Before we do discards we need to ensure those discards really
687 * do delete areas of the page, even if THP thinks a hugepage would
688 * be a good idea, so force hugepages off.
690 qemu_madvise(host_addr
, length
, QEMU_MADV_NOHUGEPAGE
);
696 * Userfault requires us to mark RAM as NOHUGEPAGE prior to discard
697 * however leaving it until after precopy means that most of the precopy
700 int postcopy_ram_prepare_discard(MigrationIncomingState
*mis
)
702 if (foreach_not_ignored_block(nhp_range
, mis
)) {
706 postcopy_state_set(POSTCOPY_INCOMING_DISCARD
);
712 * Mark the given area of RAM as requiring notification to unwritten areas
713 * Used as a callback on foreach_not_ignored_block.
714 * host_addr: Base of area to mark
715 * offset: Offset in the whole ram arena
716 * length: Length of the section
717 * opaque: MigrationIncomingState pointer
718 * Returns 0 on success
720 static int ram_block_enable_notify(RAMBlock
*rb
, void *opaque
)
722 MigrationIncomingState
*mis
= opaque
;
723 struct uffdio_register reg_struct
;
725 reg_struct
.range
.start
= (uintptr_t)qemu_ram_get_host_addr(rb
);
726 reg_struct
.range
.len
= rb
->postcopy_length
;
727 reg_struct
.mode
= UFFDIO_REGISTER_MODE_MISSING
;
729 /* Now tell our userfault_fd that it's responsible for this area */
730 if (ioctl(mis
->userfault_fd
, UFFDIO_REGISTER
, ®_struct
)) {
731 error_report("%s userfault register: %s", __func__
, strerror(errno
));
734 if (!(reg_struct
.ioctls
& (1ULL << _UFFDIO_COPY
))) {
735 error_report("%s userfault: Region doesn't support COPY", __func__
);
738 if (reg_struct
.ioctls
& (1ULL << _UFFDIO_ZEROPAGE
)) {
739 qemu_ram_set_uf_zeroable(rb
);
745 int postcopy_wake_shared(struct PostCopyFD
*pcfd
,
746 uint64_t client_addr
,
749 size_t pagesize
= qemu_ram_pagesize(rb
);
750 struct uffdio_range range
;
752 trace_postcopy_wake_shared(client_addr
, qemu_ram_get_idstr(rb
));
753 range
.start
= ROUND_DOWN(client_addr
, pagesize
);
754 range
.len
= pagesize
;
755 ret
= ioctl(pcfd
->fd
, UFFDIO_WAKE
, &range
);
757 error_report("%s: Failed to wake: %zx in %s (%s)",
758 __func__
, (size_t)client_addr
, qemu_ram_get_idstr(rb
),
764 static int postcopy_request_page(MigrationIncomingState
*mis
, RAMBlock
*rb
,
765 ram_addr_t start
, uint64_t haddr
)
767 void *aligned
= (void *)(uintptr_t)ROUND_DOWN(haddr
, qemu_ram_pagesize(rb
));
770 * Discarded pages (via RamDiscardManager) are never migrated. On unlikely
771 * access, place a zeropage, which will also set the relevant bits in the
772 * recv_bitmap accordingly, so we won't try placing a zeropage twice.
774 * Checking a single bit is sufficient to handle pagesize > TPS as either
775 * all relevant bits are set or not.
777 assert(QEMU_IS_ALIGNED(start
, qemu_ram_pagesize(rb
)));
778 if (ramblock_page_is_discarded(rb
, start
)) {
779 bool received
= ramblock_recv_bitmap_test_byte_offset(rb
, start
);
781 return received
? 0 : postcopy_place_page_zero(mis
, aligned
, rb
);
784 return migrate_send_rp_req_pages(mis
, rb
, start
, haddr
);
788 * Callback from shared fault handlers to ask for a page,
789 * the page must be specified by a RAMBlock and an offset in that rb
790 * Note: Only for use by shared fault handlers (in fault thread)
792 int postcopy_request_shared_page(struct PostCopyFD
*pcfd
, RAMBlock
*rb
,
793 uint64_t client_addr
, uint64_t rb_offset
)
795 uint64_t aligned_rbo
= ROUND_DOWN(rb_offset
, qemu_ram_pagesize(rb
));
796 MigrationIncomingState
*mis
= migration_incoming_get_current();
798 trace_postcopy_request_shared_page(pcfd
->idstr
, qemu_ram_get_idstr(rb
),
800 if (ramblock_recv_bitmap_test_byte_offset(rb
, aligned_rbo
)) {
801 trace_postcopy_request_shared_page_present(pcfd
->idstr
,
802 qemu_ram_get_idstr(rb
), rb_offset
);
803 return postcopy_wake_shared(pcfd
, client_addr
, rb
);
805 postcopy_request_page(mis
, rb
, aligned_rbo
, client_addr
);
809 static int get_mem_fault_cpu_index(uint32_t pid
)
813 CPU_FOREACH(cpu_iter
) {
814 if (cpu_iter
->thread_id
== pid
) {
815 trace_get_mem_fault_cpu_index(cpu_iter
->cpu_index
, pid
);
816 return cpu_iter
->cpu_index
;
819 trace_get_mem_fault_cpu_index(-1, pid
);
823 static uint32_t get_low_time_offset(PostcopyBlocktimeContext
*dc
)
825 int64_t start_time_offset
= qemu_clock_get_ms(QEMU_CLOCK_REALTIME
) -
827 return start_time_offset
< 1 ? 1 : start_time_offset
& UINT32_MAX
;
831 * This function is being called when pagefault occurs. It
832 * tracks down vCPU blocking time.
834 * @addr: faulted host virtual address
835 * @ptid: faulted process thread id
836 * @rb: ramblock appropriate to addr
838 static void mark_postcopy_blocktime_begin(uintptr_t addr
, uint32_t ptid
,
841 int cpu
, already_received
;
842 MigrationIncomingState
*mis
= migration_incoming_get_current();
843 PostcopyBlocktimeContext
*dc
= mis
->blocktime_ctx
;
844 uint32_t low_time_offset
;
846 if (!dc
|| ptid
== 0) {
849 cpu
= get_mem_fault_cpu_index(ptid
);
854 low_time_offset
= get_low_time_offset(dc
);
855 if (dc
->vcpu_addr
[cpu
] == 0) {
856 qatomic_inc(&dc
->smp_cpus_down
);
859 qatomic_xchg(&dc
->last_begin
, low_time_offset
);
860 qatomic_xchg(&dc
->page_fault_vcpu_time
[cpu
], low_time_offset
);
861 qatomic_xchg(&dc
->vcpu_addr
[cpu
], addr
);
864 * check it here, not at the beginning of the function,
865 * due to, check could occur early than bitmap_set in
866 * qemu_ufd_copy_ioctl
868 already_received
= ramblock_recv_bitmap_test(rb
, (void *)addr
);
869 if (already_received
) {
870 qatomic_xchg(&dc
->vcpu_addr
[cpu
], 0);
871 qatomic_xchg(&dc
->page_fault_vcpu_time
[cpu
], 0);
872 qatomic_dec(&dc
->smp_cpus_down
);
874 trace_mark_postcopy_blocktime_begin(addr
, dc
, dc
->page_fault_vcpu_time
[cpu
],
875 cpu
, already_received
);
879 * This function just provide calculated blocktime per cpu and trace it.
880 * Total blocktime is calculated in mark_postcopy_blocktime_end.
883 * Assume we have 3 CPU
886 * -----***********------------xxx***************------------------------> CPU1
889 * ------------****************xxx---------------------------------------> CPU2
892 * ------------------------****xxx********-------------------------------> CPU3
894 * We have sequence S1,S2,E1,S3,S1,E2,E3,E1
895 * S2,E1 - doesn't match condition due to sequence S1,S2,E1 doesn't include CPU3
896 * S3,S1,E2 - sequence includes all CPUs, in this case overlap will be S1,E2 -
897 * it's a part of total blocktime.
898 * S1 - here is last_begin
899 * Legend of the picture is following:
900 * * - means blocktime per vCPU
901 * x - means overlapped blocktime (total blocktime)
903 * @addr: host virtual address
905 static void mark_postcopy_blocktime_end(uintptr_t addr
)
907 MigrationIncomingState
*mis
= migration_incoming_get_current();
908 PostcopyBlocktimeContext
*dc
= mis
->blocktime_ctx
;
909 MachineState
*ms
= MACHINE(qdev_get_machine());
910 unsigned int smp_cpus
= ms
->smp
.cpus
;
911 int i
, affected_cpu
= 0;
912 bool vcpu_total_blocktime
= false;
913 uint32_t read_vcpu_time
, low_time_offset
;
919 low_time_offset
= get_low_time_offset(dc
);
920 /* lookup cpu, to clear it,
921 * that algorithm looks straightforward, but it's not
922 * optimal, more optimal algorithm is keeping tree or hash
923 * where key is address value is a list of */
924 for (i
= 0; i
< smp_cpus
; i
++) {
925 uint32_t vcpu_blocktime
= 0;
927 read_vcpu_time
= qatomic_fetch_add(&dc
->page_fault_vcpu_time
[i
], 0);
928 if (qatomic_fetch_add(&dc
->vcpu_addr
[i
], 0) != addr
||
929 read_vcpu_time
== 0) {
932 qatomic_xchg(&dc
->vcpu_addr
[i
], 0);
933 vcpu_blocktime
= low_time_offset
- read_vcpu_time
;
935 /* we need to know is that mark_postcopy_end was due to
936 * faulted page, another possible case it's prefetched
937 * page and in that case we shouldn't be here */
938 if (!vcpu_total_blocktime
&&
939 qatomic_fetch_add(&dc
->smp_cpus_down
, 0) == smp_cpus
) {
940 vcpu_total_blocktime
= true;
942 /* continue cycle, due to one page could affect several vCPUs */
943 dc
->vcpu_blocktime
[i
] += vcpu_blocktime
;
946 qatomic_sub(&dc
->smp_cpus_down
, affected_cpu
);
947 if (vcpu_total_blocktime
) {
948 dc
->total_blocktime
+= low_time_offset
- qatomic_fetch_add(
951 trace_mark_postcopy_blocktime_end(addr
, dc
, dc
->total_blocktime
,
955 static void postcopy_pause_fault_thread(MigrationIncomingState
*mis
)
957 trace_postcopy_pause_fault_thread();
958 qemu_sem_wait(&mis
->postcopy_pause_sem_fault
);
959 trace_postcopy_pause_fault_thread_continued();
963 * Handle faults detected by the USERFAULT markings
965 static void *postcopy_ram_fault_thread(void *opaque
)
967 MigrationIncomingState
*mis
= opaque
;
973 trace_postcopy_ram_fault_thread_entry();
974 rcu_register_thread();
975 mis
->last_rb
= NULL
; /* last RAMBlock we sent part of */
976 qemu_sem_post(&mis
->thread_sync_sem
);
979 size_t pfd_len
= 2 + mis
->postcopy_remote_fds
->len
;
981 pfd
= g_new0(struct pollfd
, pfd_len
);
983 pfd
[0].fd
= mis
->userfault_fd
;
984 pfd
[0].events
= POLLIN
;
985 pfd
[1].fd
= mis
->userfault_event_fd
;
986 pfd
[1].events
= POLLIN
; /* Waiting for eventfd to go positive */
987 trace_postcopy_ram_fault_thread_fds_core(pfd
[0].fd
, pfd
[1].fd
);
988 for (index
= 0; index
< mis
->postcopy_remote_fds
->len
; index
++) {
989 struct PostCopyFD
*pcfd
= &g_array_index(mis
->postcopy_remote_fds
,
990 struct PostCopyFD
, index
);
991 pfd
[2 + index
].fd
= pcfd
->fd
;
992 pfd
[2 + index
].events
= POLLIN
;
993 trace_postcopy_ram_fault_thread_fds_extra(2 + index
, pcfd
->idstr
,
998 ram_addr_t rb_offset
;
1002 * We're mainly waiting for the kernel to give us a faulting HVA,
1003 * however we can be told to quit via userfault_quit_fd which is
1007 poll_result
= poll(pfd
, pfd_len
, -1 /* Wait forever */);
1008 if (poll_result
== -1) {
1009 error_report("%s: userfault poll: %s", __func__
, strerror(errno
));
1013 if (!mis
->to_src_file
) {
1015 * Possibly someone tells us that the return path is
1016 * broken already using the event. We should hold until
1017 * the channel is rebuilt.
1019 postcopy_pause_fault_thread(mis
);
1022 if (pfd
[1].revents
) {
1025 /* Consume the signal */
1026 if (read(mis
->userfault_event_fd
, &tmp64
, 8) != 8) {
1027 /* Nothing obviously nicer than posting this error. */
1028 error_report("%s: read() failed", __func__
);
1031 if (qatomic_read(&mis
->fault_thread_quit
)) {
1032 trace_postcopy_ram_fault_thread_quit();
1037 if (pfd
[0].revents
) {
1039 ret
= read(mis
->userfault_fd
, &msg
, sizeof(msg
));
1040 if (ret
!= sizeof(msg
)) {
1041 if (errno
== EAGAIN
) {
1043 * if a wake up happens on the other thread just after
1044 * the poll, there is nothing to read.
1049 error_report("%s: Failed to read full userfault "
1051 __func__
, strerror(errno
));
1054 error_report("%s: Read %d bytes from userfaultfd "
1056 __func__
, ret
, sizeof(msg
));
1057 break; /* Lost alignment, don't know what we'd read next */
1060 if (msg
.event
!= UFFD_EVENT_PAGEFAULT
) {
1061 error_report("%s: Read unexpected event %ud from userfaultfd",
1062 __func__
, msg
.event
);
1063 continue; /* It's not a page fault, shouldn't happen */
1066 rb
= qemu_ram_block_from_host(
1067 (void *)(uintptr_t)msg
.arg
.pagefault
.address
,
1070 error_report("postcopy_ram_fault_thread: Fault outside guest: %"
1071 PRIx64
, (uint64_t)msg
.arg
.pagefault
.address
);
1075 rb_offset
= ROUND_DOWN(rb_offset
, qemu_ram_pagesize(rb
));
1076 trace_postcopy_ram_fault_thread_request(msg
.arg
.pagefault
.address
,
1077 qemu_ram_get_idstr(rb
),
1079 msg
.arg
.pagefault
.feat
.ptid
);
1080 mark_postcopy_blocktime_begin(
1081 (uintptr_t)(msg
.arg
.pagefault
.address
),
1082 msg
.arg
.pagefault
.feat
.ptid
, rb
);
1086 * Send the request to the source - we want to request one
1087 * of our host page sizes (which is >= TPS)
1089 ret
= postcopy_request_page(mis
, rb
, rb_offset
,
1090 msg
.arg
.pagefault
.address
);
1092 /* May be network failure, try to wait for recovery */
1093 postcopy_pause_fault_thread(mis
);
1098 /* Now handle any requests from external processes on shared memory */
1099 /* TODO: May need to handle devices deregistering during postcopy */
1100 for (index
= 2; index
< pfd_len
&& poll_result
; index
++) {
1101 if (pfd
[index
].revents
) {
1102 struct PostCopyFD
*pcfd
=
1103 &g_array_index(mis
->postcopy_remote_fds
,
1104 struct PostCopyFD
, index
- 2);
1107 if (pfd
[index
].revents
& POLLERR
) {
1108 error_report("%s: POLLERR on poll %zd fd=%d",
1109 __func__
, index
, pcfd
->fd
);
1110 pfd
[index
].events
= 0;
1114 ret
= read(pcfd
->fd
, &msg
, sizeof(msg
));
1115 if (ret
!= sizeof(msg
)) {
1116 if (errno
== EAGAIN
) {
1118 * if a wake up happens on the other thread just after
1119 * the poll, there is nothing to read.
1124 error_report("%s: Failed to read full userfault "
1125 "message: %s (shared) revents=%d",
1126 __func__
, strerror(errno
),
1127 pfd
[index
].revents
);
1128 /*TODO: Could just disable this sharer */
1131 error_report("%s: Read %d bytes from userfaultfd "
1132 "expected %zd (shared)",
1133 __func__
, ret
, sizeof(msg
));
1134 /*TODO: Could just disable this sharer */
1135 break; /*Lost alignment,don't know what we'd read next*/
1138 if (msg
.event
!= UFFD_EVENT_PAGEFAULT
) {
1139 error_report("%s: Read unexpected event %ud "
1140 "from userfaultfd (shared)",
1141 __func__
, msg
.event
);
1142 continue; /* It's not a page fault, shouldn't happen */
1144 /* Call the device handler registered with us */
1145 ret
= pcfd
->handler(pcfd
, &msg
);
1147 error_report("%s: Failed to resolve shared fault on %zd/%s",
1148 __func__
, index
, pcfd
->idstr
);
1149 /* TODO: Fail? Disable this sharer? */
1154 rcu_unregister_thread();
1155 trace_postcopy_ram_fault_thread_exit();
1160 static int postcopy_temp_pages_setup(MigrationIncomingState
*mis
)
1162 PostcopyTmpPage
*tmp_page
;
1163 int err
, i
, channels
;
1166 if (migrate_postcopy_preempt()) {
1167 /* If preemption enabled, need extra channel for urgent requests */
1168 mis
->postcopy_channels
= RAM_CHANNEL_MAX
;
1170 /* Both precopy/postcopy on the same channel */
1171 mis
->postcopy_channels
= 1;
1174 channels
= mis
->postcopy_channels
;
1175 mis
->postcopy_tmp_pages
= g_malloc0_n(sizeof(PostcopyTmpPage
), channels
);
1177 for (i
= 0; i
< channels
; i
++) {
1178 tmp_page
= &mis
->postcopy_tmp_pages
[i
];
1179 temp_page
= mmap(NULL
, mis
->largest_page_size
, PROT_READ
| PROT_WRITE
,
1180 MAP_PRIVATE
| MAP_ANONYMOUS
, -1, 0);
1181 if (temp_page
== MAP_FAILED
) {
1183 error_report("%s: Failed to map postcopy_tmp_pages[%d]: %s",
1184 __func__
, i
, strerror(err
));
1185 /* Clean up will be done later */
1188 tmp_page
->tmp_huge_page
= temp_page
;
1189 /* Initialize default states for each tmp page */
1190 postcopy_temp_page_reset(tmp_page
);
1194 * Map large zero page when kernel can't use UFFDIO_ZEROPAGE for hugepages
1196 mis
->postcopy_tmp_zero_page
= mmap(NULL
, mis
->largest_page_size
,
1197 PROT_READ
| PROT_WRITE
,
1198 MAP_PRIVATE
| MAP_ANONYMOUS
, -1, 0);
1199 if (mis
->postcopy_tmp_zero_page
== MAP_FAILED
) {
1201 mis
->postcopy_tmp_zero_page
= NULL
;
1202 error_report("%s: Failed to map large zero page %s",
1203 __func__
, strerror(err
));
1207 memset(mis
->postcopy_tmp_zero_page
, '\0', mis
->largest_page_size
);
1212 int postcopy_ram_incoming_setup(MigrationIncomingState
*mis
)
1214 Error
*local_err
= NULL
;
1216 /* Open the fd for the kernel to give us userfaults */
1217 mis
->userfault_fd
= uffd_open(O_CLOEXEC
| O_NONBLOCK
);
1218 if (mis
->userfault_fd
== -1) {
1219 error_report("%s: Failed to open userfault fd: %s", __func__
,
1225 * Although the host check already tested the API, we need to
1226 * do the check again as an ABI handshake on the new fd.
1228 if (!ufd_check_and_apply(mis
->userfault_fd
, mis
, &local_err
)) {
1229 error_report_err(local_err
);
1233 /* Now an eventfd we use to tell the fault-thread to quit */
1234 mis
->userfault_event_fd
= eventfd(0, EFD_CLOEXEC
);
1235 if (mis
->userfault_event_fd
== -1) {
1236 error_report("%s: Opening userfault_event_fd: %s", __func__
,
1238 close(mis
->userfault_fd
);
1242 postcopy_thread_create(mis
, &mis
->fault_thread
, "fault-default",
1243 postcopy_ram_fault_thread
, QEMU_THREAD_JOINABLE
);
1244 mis
->have_fault_thread
= true;
1246 /* Mark so that we get notified of accesses to unwritten areas */
1247 if (foreach_not_ignored_block(ram_block_enable_notify
, mis
)) {
1248 error_report("ram_block_enable_notify failed");
1252 if (postcopy_temp_pages_setup(mis
)) {
1253 /* Error dumped in the sub-function */
1257 if (migrate_postcopy_preempt()) {
1259 * This thread needs to be created after the temp pages because
1260 * it'll fetch RAM_CHANNEL_POSTCOPY PostcopyTmpPage immediately.
1262 postcopy_thread_create(mis
, &mis
->postcopy_prio_thread
, "fault-fast",
1263 postcopy_preempt_thread
, QEMU_THREAD_JOINABLE
);
1264 mis
->preempt_thread_status
= PREEMPT_THREAD_CREATED
;
1267 trace_postcopy_ram_enable_notify();
1272 static int qemu_ufd_copy_ioctl(MigrationIncomingState
*mis
, void *host_addr
,
1273 void *from_addr
, uint64_t pagesize
, RAMBlock
*rb
)
1275 int userfault_fd
= mis
->userfault_fd
;
1279 struct uffdio_copy copy_struct
;
1280 copy_struct
.dst
= (uint64_t)(uintptr_t)host_addr
;
1281 copy_struct
.src
= (uint64_t)(uintptr_t)from_addr
;
1282 copy_struct
.len
= pagesize
;
1283 copy_struct
.mode
= 0;
1284 ret
= ioctl(userfault_fd
, UFFDIO_COPY
, ©_struct
);
1286 struct uffdio_zeropage zero_struct
;
1287 zero_struct
.range
.start
= (uint64_t)(uintptr_t)host_addr
;
1288 zero_struct
.range
.len
= pagesize
;
1289 zero_struct
.mode
= 0;
1290 ret
= ioctl(userfault_fd
, UFFDIO_ZEROPAGE
, &zero_struct
);
1293 qemu_mutex_lock(&mis
->page_request_mutex
);
1294 ramblock_recv_bitmap_set_range(rb
, host_addr
,
1295 pagesize
/ qemu_target_page_size());
1297 * If this page resolves a page fault for a previous recorded faulted
1298 * address, take a special note to maintain the requested page list.
1300 if (g_tree_lookup(mis
->page_requested
, host_addr
)) {
1301 g_tree_remove(mis
->page_requested
, host_addr
);
1302 int left_pages
= qatomic_dec_fetch(&mis
->page_requested_count
);
1304 trace_postcopy_page_req_del(host_addr
, mis
->page_requested_count
);
1305 /* Order the update of count and read of preempt status */
1307 if (mis
->preempt_thread_status
== PREEMPT_THREAD_QUIT
&&
1310 * This probably means the main thread is waiting for us.
1311 * Notify that we've finished receiving the last requested
1314 qemu_cond_signal(&mis
->page_request_cond
);
1317 qemu_mutex_unlock(&mis
->page_request_mutex
);
1318 mark_postcopy_blocktime_end((uintptr_t)host_addr
);
1323 int postcopy_notify_shared_wake(RAMBlock
*rb
, uint64_t offset
)
1326 MigrationIncomingState
*mis
= migration_incoming_get_current();
1327 GArray
*pcrfds
= mis
->postcopy_remote_fds
;
1329 for (i
= 0; i
< pcrfds
->len
; i
++) {
1330 struct PostCopyFD
*cur
= &g_array_index(pcrfds
, struct PostCopyFD
, i
);
1331 int ret
= cur
->waker(cur
, rb
, offset
);
1340 * Place a host page (from) at (host) atomically
1341 * returns 0 on success
1343 int postcopy_place_page(MigrationIncomingState
*mis
, void *host
, void *from
,
1346 size_t pagesize
= qemu_ram_pagesize(rb
);
1348 /* copy also acks to the kernel waking the stalled thread up
1349 * TODO: We can inhibit that ack and only do it if it was requested
1350 * which would be slightly cheaper, but we'd have to be careful
1351 * of the order of updating our page state.
1353 if (qemu_ufd_copy_ioctl(mis
, host
, from
, pagesize
, rb
)) {
1355 error_report("%s: %s copy host: %p from: %p (size: %zd)",
1356 __func__
, strerror(e
), host
, from
, pagesize
);
1361 trace_postcopy_place_page(host
);
1362 return postcopy_notify_shared_wake(rb
,
1363 qemu_ram_block_host_offset(rb
, host
));
1367 * Place a zero page at (host) atomically
1368 * returns 0 on success
1370 int postcopy_place_page_zero(MigrationIncomingState
*mis
, void *host
,
1373 size_t pagesize
= qemu_ram_pagesize(rb
);
1374 trace_postcopy_place_page_zero(host
);
1376 /* Normal RAMBlocks can zero a page using UFFDIO_ZEROPAGE
1377 * but it's not available for everything (e.g. hugetlbpages)
1379 if (qemu_ram_is_uf_zeroable(rb
)) {
1380 if (qemu_ufd_copy_ioctl(mis
, host
, NULL
, pagesize
, rb
)) {
1382 error_report("%s: %s zero host: %p",
1383 __func__
, strerror(e
), host
);
1387 return postcopy_notify_shared_wake(rb
,
1388 qemu_ram_block_host_offset(rb
,
1391 return postcopy_place_page(mis
, host
, mis
->postcopy_tmp_zero_page
, rb
);
1396 /* No target OS support, stubs just fail */
1397 void fill_destination_postcopy_migration_info(MigrationInfo
*info
)
1401 bool postcopy_ram_supported_by_host(MigrationIncomingState
*mis
, Error
**errp
)
1403 error_report("%s: No OS support", __func__
);
1407 int postcopy_ram_incoming_init(MigrationIncomingState
*mis
)
1409 error_report("postcopy_ram_incoming_init: No OS support");
1413 int postcopy_ram_incoming_cleanup(MigrationIncomingState
*mis
)
1419 int postcopy_ram_prepare_discard(MigrationIncomingState
*mis
)
1425 int postcopy_request_shared_page(struct PostCopyFD
*pcfd
, RAMBlock
*rb
,
1426 uint64_t client_addr
, uint64_t rb_offset
)
1432 int postcopy_ram_incoming_setup(MigrationIncomingState
*mis
)
1438 int postcopy_place_page(MigrationIncomingState
*mis
, void *host
, void *from
,
1445 int postcopy_place_page_zero(MigrationIncomingState
*mis
, void *host
,
1452 int postcopy_wake_shared(struct PostCopyFD
*pcfd
,
1453 uint64_t client_addr
,
1461 /* ------------------------------------------------------------------------- */
1462 void postcopy_temp_page_reset(PostcopyTmpPage
*tmp_page
)
1464 tmp_page
->target_pages
= 0;
1465 tmp_page
->host_addr
= NULL
;
1467 * This is set to true when reset, and cleared as long as we received any
1468 * of the non-zero small page within this huge page.
1470 tmp_page
->all_zero
= true;
1473 void postcopy_fault_thread_notify(MigrationIncomingState
*mis
)
1478 * Wakeup the fault_thread. It's an eventfd that should currently
1479 * be at 0, we're going to increment it to 1
1481 if (write(mis
->userfault_event_fd
, &tmp64
, 8) != 8) {
1482 /* Not much we can do here, but may as well report it */
1483 error_report("%s: incrementing failed: %s", __func__
,
1489 * postcopy_discard_send_init: Called at the start of each RAMBlock before
1490 * asking to discard individual ranges.
1492 * @ms: The current migration state.
1493 * @offset: the bitmap offset of the named RAMBlock in the migration bitmap.
1494 * @name: RAMBlock that discards will operate on.
1496 static PostcopyDiscardState pds
= {0};
1497 void postcopy_discard_send_init(MigrationState
*ms
, const char *name
)
1499 pds
.ramblock_name
= name
;
1506 * postcopy_discard_send_range: Called by the bitmap code for each chunk to
1507 * discard. May send a discard message, may just leave it queued to
1510 * @ms: Current migration state.
1511 * @start,@length: a range of pages in the migration bitmap in the
1512 * RAM block passed to postcopy_discard_send_init() (length=1 is one page)
1514 void postcopy_discard_send_range(MigrationState
*ms
, unsigned long start
,
1515 unsigned long length
)
1517 size_t tp_size
= qemu_target_page_size();
1518 /* Convert to byte offsets within the RAM block */
1519 pds
.start_list
[pds
.cur_entry
] = start
* tp_size
;
1520 pds
.length_list
[pds
.cur_entry
] = length
* tp_size
;
1521 trace_postcopy_discard_send_range(pds
.ramblock_name
, start
, length
);
1525 if (pds
.cur_entry
== MAX_DISCARDS_PER_COMMAND
) {
1526 /* Full set, ship it! */
1527 qemu_savevm_send_postcopy_ram_discard(ms
->to_dst_file
,
1538 * postcopy_discard_send_finish: Called at the end of each RAMBlock by the
1539 * bitmap code. Sends any outstanding discard messages, frees the PDS
1541 * @ms: Current migration state.
1543 void postcopy_discard_send_finish(MigrationState
*ms
)
1545 /* Anything unsent? */
1546 if (pds
.cur_entry
) {
1547 qemu_savevm_send_postcopy_ram_discard(ms
->to_dst_file
,
1555 trace_postcopy_discard_send_finish(pds
.ramblock_name
, pds
.nsentwords
,
1560 * Current state of incoming postcopy; note this is not part of
1561 * MigrationIncomingState since it's state is used during cleanup
1562 * at the end as MIS is being freed.
1564 static PostcopyState incoming_postcopy_state
;
1566 PostcopyState
postcopy_state_get(void)
1568 return qatomic_load_acquire(&incoming_postcopy_state
);
1571 /* Set the state and return the old state */
1572 PostcopyState
postcopy_state_set(PostcopyState new_state
)
1574 return qatomic_xchg(&incoming_postcopy_state
, new_state
);
1577 /* Register a handler for external shared memory postcopy
1578 * called on the destination.
1580 void postcopy_register_shared_ufd(struct PostCopyFD
*pcfd
)
1582 MigrationIncomingState
*mis
= migration_incoming_get_current();
1584 mis
->postcopy_remote_fds
= g_array_append_val(mis
->postcopy_remote_fds
,
1588 /* Unregister a handler for external shared memory postcopy
1590 void postcopy_unregister_shared_ufd(struct PostCopyFD
*pcfd
)
1593 MigrationIncomingState
*mis
= migration_incoming_get_current();
1594 GArray
*pcrfds
= mis
->postcopy_remote_fds
;
1597 /* migration has already finished and freed the array */
1600 for (i
= 0; i
< pcrfds
->len
; i
++) {
1601 struct PostCopyFD
*cur
= &g_array_index(pcrfds
, struct PostCopyFD
, i
);
1602 if (cur
->fd
== pcfd
->fd
) {
1603 mis
->postcopy_remote_fds
= g_array_remove_index(pcrfds
, i
);
1609 void postcopy_preempt_new_channel(MigrationIncomingState
*mis
, QEMUFile
*file
)
1612 * The new loading channel has its own threads, so it needs to be
1613 * blocked too. It's by default true, just be explicit.
1615 qemu_file_set_blocking(file
, true);
1616 mis
->postcopy_qemufile_dst
= file
;
1617 qemu_sem_post(&mis
->postcopy_qemufile_dst_done
);
1618 trace_postcopy_preempt_new_channel();
1622 * Setup the postcopy preempt channel with the IOC. If ERROR is specified,
1623 * setup the error instead. This helper will free the ERROR if specified.
1626 postcopy_preempt_send_channel_done(MigrationState
*s
,
1627 QIOChannel
*ioc
, Error
*local_err
)
1630 migrate_set_error(s
, local_err
);
1631 error_free(local_err
);
1633 migration_ioc_register_yank(ioc
);
1634 s
->postcopy_qemufile_src
= qemu_file_new_output(ioc
);
1635 trace_postcopy_preempt_new_channel();
1639 * Kick the waiter in all cases. The waiter should check upon
1640 * postcopy_qemufile_src to know whether it failed or not.
1642 qemu_sem_post(&s
->postcopy_qemufile_src_sem
);
1646 postcopy_preempt_tls_handshake(QIOTask
*task
, gpointer opaque
)
1648 g_autoptr(QIOChannel
) ioc
= QIO_CHANNEL(qio_task_get_source(task
));
1649 MigrationState
*s
= opaque
;
1650 Error
*local_err
= NULL
;
1652 qio_task_propagate_error(task
, &local_err
);
1653 postcopy_preempt_send_channel_done(s
, ioc
, local_err
);
1657 postcopy_preempt_send_channel_new(QIOTask
*task
, gpointer opaque
)
1659 g_autoptr(QIOChannel
) ioc
= QIO_CHANNEL(qio_task_get_source(task
));
1660 MigrationState
*s
= opaque
;
1661 QIOChannelTLS
*tioc
;
1662 Error
*local_err
= NULL
;
1664 if (qio_task_propagate_error(task
, &local_err
)) {
1668 if (migrate_channel_requires_tls_upgrade(ioc
)) {
1669 tioc
= migration_tls_client_create(ioc
, s
->hostname
, &local_err
);
1673 trace_postcopy_preempt_tls_handshake();
1674 qio_channel_set_name(QIO_CHANNEL(tioc
), "migration-tls-preempt");
1675 qio_channel_tls_handshake(tioc
, postcopy_preempt_tls_handshake
,
1677 /* Setup the channel until TLS handshake finished */
1682 /* This handles both good and error cases */
1683 postcopy_preempt_send_channel_done(s
, ioc
, local_err
);
1687 * This function will kick off an async task to establish the preempt
1688 * channel, and wait until the connection setup completed. Returns 0 if
1689 * channel established, -1 for error.
1691 int postcopy_preempt_establish_channel(MigrationState
*s
)
1693 /* If preempt not enabled, no need to wait */
1694 if (!migrate_postcopy_preempt()) {
1699 * Kick off async task to establish preempt channel. Only do so with
1700 * 8.0+ machines, because 7.1/7.2 require the channel to be created in
1701 * setup phase of migration (even if racy in an unreliable network).
1703 if (!s
->preempt_pre_7_2
) {
1704 postcopy_preempt_setup(s
);
1708 * We need the postcopy preempt channel to be established before
1709 * starting doing anything.
1711 qemu_sem_wait(&s
->postcopy_qemufile_src_sem
);
1713 return s
->postcopy_qemufile_src
? 0 : -1;
1716 void postcopy_preempt_setup(MigrationState
*s
)
1718 /* Kick an async task to connect */
1719 socket_send_channel_create(postcopy_preempt_send_channel_new
, s
);
1722 static void postcopy_pause_ram_fast_load(MigrationIncomingState
*mis
)
1724 trace_postcopy_pause_fast_load();
1725 qemu_mutex_unlock(&mis
->postcopy_prio_thread_mutex
);
1726 qemu_sem_wait(&mis
->postcopy_pause_sem_fast_load
);
1727 qemu_mutex_lock(&mis
->postcopy_prio_thread_mutex
);
1728 trace_postcopy_pause_fast_load_continued();
1731 static bool preempt_thread_should_run(MigrationIncomingState
*mis
)
1733 return mis
->preempt_thread_status
!= PREEMPT_THREAD_QUIT
;
1736 void *postcopy_preempt_thread(void *opaque
)
1738 MigrationIncomingState
*mis
= opaque
;
1741 trace_postcopy_preempt_thread_entry();
1743 rcu_register_thread();
1745 qemu_sem_post(&mis
->thread_sync_sem
);
1748 * The preempt channel is established in asynchronous way. Wait
1749 * for its completion.
1751 qemu_sem_wait(&mis
->postcopy_qemufile_dst_done
);
1753 /* Sending RAM_SAVE_FLAG_EOS to terminate this thread */
1754 qemu_mutex_lock(&mis
->postcopy_prio_thread_mutex
);
1755 while (preempt_thread_should_run(mis
)) {
1756 ret
= ram_load_postcopy(mis
->postcopy_qemufile_dst
,
1757 RAM_CHANNEL_POSTCOPY
);
1758 /* If error happened, go into recovery routine */
1759 if (ret
&& preempt_thread_should_run(mis
)) {
1760 postcopy_pause_ram_fast_load(mis
);
1766 qemu_mutex_unlock(&mis
->postcopy_prio_thread_mutex
);
1768 rcu_unregister_thread();
1770 trace_postcopy_preempt_thread_exit();