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__)
107 #include <sys/ioctl.h>
108 #include <sys/syscall.h>
109 #include <asm/types.h> /* for __u64 */
112 #if defined(__linux__) && defined(__NR_userfaultfd) && defined(CONFIG_EVENTFD)
113 #include <sys/eventfd.h>
114 #include <linux/userfaultfd.h>
116 typedef struct PostcopyBlocktimeContext
{
117 /* time when page fault initiated per vCPU */
118 uint32_t *page_fault_vcpu_time
;
119 /* page address per vCPU */
120 uintptr_t *vcpu_addr
;
121 uint32_t total_blocktime
;
122 /* blocktime per vCPU */
123 uint32_t *vcpu_blocktime
;
124 /* point in time when last page fault was initiated */
126 /* number of vCPU are suspended */
131 * Handler for exit event, necessary for
132 * releasing whole blocktime_ctx
134 Notifier exit_notifier
;
135 } PostcopyBlocktimeContext
;
137 static void destroy_blocktime_context(struct PostcopyBlocktimeContext
*ctx
)
139 g_free(ctx
->page_fault_vcpu_time
);
140 g_free(ctx
->vcpu_addr
);
141 g_free(ctx
->vcpu_blocktime
);
145 static void migration_exit_cb(Notifier
*n
, void *data
)
147 PostcopyBlocktimeContext
*ctx
= container_of(n
, PostcopyBlocktimeContext
,
149 destroy_blocktime_context(ctx
);
152 static struct PostcopyBlocktimeContext
*blocktime_context_new(void)
154 MachineState
*ms
= MACHINE(qdev_get_machine());
155 unsigned int smp_cpus
= ms
->smp
.cpus
;
156 PostcopyBlocktimeContext
*ctx
= g_new0(PostcopyBlocktimeContext
, 1);
157 ctx
->page_fault_vcpu_time
= g_new0(uint32_t, smp_cpus
);
158 ctx
->vcpu_addr
= g_new0(uintptr_t, smp_cpus
);
159 ctx
->vcpu_blocktime
= g_new0(uint32_t, smp_cpus
);
161 ctx
->exit_notifier
.notify
= migration_exit_cb
;
162 ctx
->start_time
= qemu_clock_get_ms(QEMU_CLOCK_REALTIME
);
163 qemu_add_exit_notifier(&ctx
->exit_notifier
);
167 static uint32List
*get_vcpu_blocktime_list(PostcopyBlocktimeContext
*ctx
)
169 MachineState
*ms
= MACHINE(qdev_get_machine());
170 uint32List
*list
= NULL
;
173 for (i
= ms
->smp
.cpus
- 1; i
>= 0; i
--) {
174 QAPI_LIST_PREPEND(list
, ctx
->vcpu_blocktime
[i
]);
181 * This function just populates MigrationInfo from postcopy's
182 * blocktime context. It will not populate MigrationInfo,
183 * unless postcopy-blocktime capability was set.
185 * @info: pointer to MigrationInfo to populate
187 void fill_destination_postcopy_migration_info(MigrationInfo
*info
)
189 MigrationIncomingState
*mis
= migration_incoming_get_current();
190 PostcopyBlocktimeContext
*bc
= mis
->blocktime_ctx
;
196 info
->has_postcopy_blocktime
= true;
197 info
->postcopy_blocktime
= bc
->total_blocktime
;
198 info
->has_postcopy_vcpu_blocktime
= true;
199 info
->postcopy_vcpu_blocktime
= get_vcpu_blocktime_list(bc
);
202 static uint32_t get_postcopy_total_blocktime(void)
204 MigrationIncomingState
*mis
= migration_incoming_get_current();
205 PostcopyBlocktimeContext
*bc
= mis
->blocktime_ctx
;
211 return bc
->total_blocktime
;
215 * receive_ufd_features: check userfault fd features, to request only supported
216 * features in the future.
218 * Returns: true on success
220 * __NR_userfaultfd - should be checked before
221 * @features: out parameter will contain uffdio_api.features provided by kernel
224 static bool receive_ufd_features(uint64_t *features
)
226 struct uffdio_api api_struct
= {0};
230 ufd
= uffd_open(O_CLOEXEC
);
232 error_report("%s: uffd_open() failed: %s", __func__
, strerror(errno
));
237 api_struct
.api
= UFFD_API
;
238 api_struct
.features
= 0;
239 if (ioctl(ufd
, UFFDIO_API
, &api_struct
)) {
240 error_report("%s: UFFDIO_API failed: %s", __func__
,
246 *features
= api_struct
.features
;
254 * request_ufd_features: this function should be called only once on a newly
255 * opened ufd, subsequent calls will lead to error.
257 * Returns: true on success
259 * @ufd: fd obtained from userfaultfd syscall
260 * @features: bit mask see UFFD_API_FEATURES
262 static bool request_ufd_features(int ufd
, uint64_t features
)
264 struct uffdio_api api_struct
= {0};
267 api_struct
.api
= UFFD_API
;
268 api_struct
.features
= features
;
269 if (ioctl(ufd
, UFFDIO_API
, &api_struct
)) {
270 error_report("%s failed: UFFDIO_API failed: %s", __func__
,
275 ioctl_mask
= (__u64
)1 << _UFFDIO_REGISTER
|
276 (__u64
)1 << _UFFDIO_UNREGISTER
;
277 if ((api_struct
.ioctls
& ioctl_mask
) != ioctl_mask
) {
278 error_report("Missing userfault features: %" PRIx64
,
279 (uint64_t)(~api_struct
.ioctls
& ioctl_mask
));
286 static bool ufd_check_and_apply(int ufd
, MigrationIncomingState
*mis
)
288 uint64_t asked_features
= 0;
289 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_report("%s failed", __func__
);
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_report("%s failed: features %" PRIu64
, __func__
,
325 if (qemu_real_host_page_size() != ram_pagesize_summary()) {
326 bool have_hp
= false;
327 /* We've got a huge page */
328 #ifdef UFFD_FEATURE_MISSING_HUGETLBFS
329 have_hp
= supported_features
& UFFD_FEATURE_MISSING_HUGETLBFS
;
332 error_report("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
)
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
) {
349 error_report("Postcopy requires RAM blocks to be a page size multiple,"
350 " block %s is 0x" RAM_ADDR_FMT
" bytes with a "
351 "page size of 0x%zx", block_name
, length
, pagesize
);
356 fs
= qemu_fd_getfs(rb
->fd
);
357 if (fs
!= QEMU_FS_TYPE_TMPFS
&& fs
!= QEMU_FS_TYPE_HUGETLBFS
) {
358 error_report("Host backend files need to be TMPFS or HUGETLBFS only");
367 * Note: This has the side effect of munlock'ing all of RAM, that's
368 * normally fine since if the postcopy succeeds it gets turned back on at the
371 bool postcopy_ram_supported_by_host(MigrationIncomingState
*mis
)
373 long pagesize
= qemu_real_host_page_size();
375 bool ret
= false; /* Error unless we change it */
376 void *testarea
= NULL
;
377 struct uffdio_register reg_struct
;
378 struct uffdio_range range_struct
;
379 uint64_t feature_mask
;
380 Error
*local_err
= NULL
;
383 if (qemu_target_page_size() > pagesize
) {
384 error_report("Target page size bigger than host page size");
388 ufd
= uffd_open(O_CLOEXEC
);
390 error_report("%s: userfaultfd not available: %s", __func__
,
395 /* Give devices a chance to object */
396 if (postcopy_notify(POSTCOPY_NOTIFY_PROBE
, &local_err
)) {
397 error_report_err(local_err
);
401 /* Version and features check */
402 if (!ufd_check_and_apply(ufd
, mis
)) {
407 * We don't support postcopy with some type of ramblocks.
409 * NOTE: we explicitly ignored ramblock_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
)) {
426 * userfault and mlock don't go together; we'll put it back later if
430 error_report("%s: munlockall: %s", __func__
, 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_report("%s: Failed to map test area: %s", __func__
,
446 g_assert(QEMU_PTR_IS_ALIGNED(testarea
, pagesize
));
448 reg_struct
.range
.start
= (uintptr_t)testarea
;
449 reg_struct
.range
.len
= pagesize
;
450 reg_struct
.mode
= UFFDIO_REGISTER_MODE_MISSING
;
452 if (ioctl(ufd
, UFFDIO_REGISTER
, ®_struct
)) {
453 error_report("%s userfault register: %s", __func__
, strerror(errno
));
457 range_struct
.start
= (uintptr_t)testarea
;
458 range_struct
.len
= pagesize
;
459 if (ioctl(ufd
, UFFDIO_UNREGISTER
, &range_struct
)) {
460 error_report("%s userfault unregister: %s", __func__
, strerror(errno
));
464 feature_mask
= (__u64
)1 << _UFFDIO_WAKE
|
465 (__u64
)1 << _UFFDIO_COPY
|
466 (__u64
)1 << _UFFDIO_ZEROPAGE
;
467 if ((reg_struct
.ioctls
& feature_mask
) != feature_mask
) {
468 error_report("Missing userfault map features: %" PRIx64
,
469 (uint64_t)(~reg_struct
.ioctls
& feature_mask
));
477 munmap(testarea
, pagesize
);
486 * Setup an area of RAM so that it *can* be used for postcopy later; this
487 * must be done right at the start prior to pre-copy.
488 * opaque should be the MIS.
490 static int init_range(RAMBlock
*rb
, void *opaque
)
492 const char *block_name
= qemu_ram_get_idstr(rb
);
493 void *host_addr
= qemu_ram_get_host_addr(rb
);
494 ram_addr_t offset
= qemu_ram_get_offset(rb
);
495 ram_addr_t length
= qemu_ram_get_used_length(rb
);
496 trace_postcopy_init_range(block_name
, host_addr
, offset
, length
);
499 * Save the used_length before running the guest. In case we have to
500 * resize RAM blocks when syncing RAM block sizes from the source during
501 * precopy, we'll update it manually via the ram block notifier.
503 rb
->postcopy_length
= length
;
506 * We need the whole of RAM to be truly empty for postcopy, so things
507 * like ROMs and any data tables built during init must be zero'd
508 * - we're going to get the copy from the source anyway.
509 * (Precopy will just overwrite this data, so doesn't need the discard)
511 if (ram_discard_range(block_name
, 0, length
)) {
519 * At the end of migration, undo the effects of init_range
520 * opaque should be the MIS.
522 static int cleanup_range(RAMBlock
*rb
, void *opaque
)
524 const char *block_name
= qemu_ram_get_idstr(rb
);
525 void *host_addr
= qemu_ram_get_host_addr(rb
);
526 ram_addr_t offset
= qemu_ram_get_offset(rb
);
527 ram_addr_t length
= rb
->postcopy_length
;
528 MigrationIncomingState
*mis
= opaque
;
529 struct uffdio_range range_struct
;
530 trace_postcopy_cleanup_range(block_name
, host_addr
, offset
, length
);
533 * We turned off hugepage for the precopy stage with postcopy enabled
534 * we can turn it back on now.
536 qemu_madvise(host_addr
, length
, QEMU_MADV_HUGEPAGE
);
539 * We can also turn off userfault now since we should have all the
540 * pages. It can be useful to leave it on to debug postcopy
541 * if you're not sure it's always getting every page.
543 range_struct
.start
= (uintptr_t)host_addr
;
544 range_struct
.len
= length
;
546 if (ioctl(mis
->userfault_fd
, UFFDIO_UNREGISTER
, &range_struct
)) {
547 error_report("%s: userfault unregister %s", __func__
, strerror(errno
));
556 * Initialise postcopy-ram, setting the RAM to a state where we can go into
557 * postcopy later; must be called prior to any precopy.
558 * called from arch_init's similarly named ram_postcopy_incoming_init
560 int postcopy_ram_incoming_init(MigrationIncomingState
*mis
)
562 if (foreach_not_ignored_block(init_range
, NULL
)) {
569 static void postcopy_temp_pages_cleanup(MigrationIncomingState
*mis
)
573 if (mis
->postcopy_tmp_pages
) {
574 for (i
= 0; i
< mis
->postcopy_channels
; i
++) {
575 if (mis
->postcopy_tmp_pages
[i
].tmp_huge_page
) {
576 munmap(mis
->postcopy_tmp_pages
[i
].tmp_huge_page
,
577 mis
->largest_page_size
);
578 mis
->postcopy_tmp_pages
[i
].tmp_huge_page
= NULL
;
581 g_free(mis
->postcopy_tmp_pages
);
582 mis
->postcopy_tmp_pages
= NULL
;
585 if (mis
->postcopy_tmp_zero_page
) {
586 munmap(mis
->postcopy_tmp_zero_page
, mis
->largest_page_size
);
587 mis
->postcopy_tmp_zero_page
= NULL
;
592 * At the end of a migration where postcopy_ram_incoming_init was called.
594 int postcopy_ram_incoming_cleanup(MigrationIncomingState
*mis
)
596 trace_postcopy_ram_incoming_cleanup_entry();
598 if (mis
->preempt_thread_status
== PREEMPT_THREAD_CREATED
) {
599 /* Notify the fast load thread to quit */
600 mis
->preempt_thread_status
= PREEMPT_THREAD_QUIT
;
601 if (mis
->postcopy_qemufile_dst
) {
602 qemu_file_shutdown(mis
->postcopy_qemufile_dst
);
604 qemu_thread_join(&mis
->postcopy_prio_thread
);
605 mis
->preempt_thread_status
= PREEMPT_THREAD_NONE
;
608 if (mis
->have_fault_thread
) {
609 Error
*local_err
= NULL
;
611 /* Let the fault thread quit */
612 qatomic_set(&mis
->fault_thread_quit
, 1);
613 postcopy_fault_thread_notify(mis
);
614 trace_postcopy_ram_incoming_cleanup_join();
615 qemu_thread_join(&mis
->fault_thread
);
617 if (postcopy_notify(POSTCOPY_NOTIFY_INBOUND_END
, &local_err
)) {
618 error_report_err(local_err
);
622 if (foreach_not_ignored_block(cleanup_range
, mis
)) {
626 trace_postcopy_ram_incoming_cleanup_closeuf();
627 close(mis
->userfault_fd
);
628 close(mis
->userfault_event_fd
);
629 mis
->have_fault_thread
= false;
633 if (os_mlock() < 0) {
634 error_report("mlock: %s", strerror(errno
));
636 * It doesn't feel right to fail at this point, we have a valid
642 postcopy_temp_pages_cleanup(mis
);
644 trace_postcopy_ram_incoming_cleanup_blocktime(
645 get_postcopy_total_blocktime());
647 trace_postcopy_ram_incoming_cleanup_exit();
652 * Disable huge pages on an area
654 static int nhp_range(RAMBlock
*rb
, void *opaque
)
656 const char *block_name
= qemu_ram_get_idstr(rb
);
657 void *host_addr
= qemu_ram_get_host_addr(rb
);
658 ram_addr_t offset
= qemu_ram_get_offset(rb
);
659 ram_addr_t length
= rb
->postcopy_length
;
660 trace_postcopy_nhp_range(block_name
, host_addr
, offset
, length
);
663 * Before we do discards we need to ensure those discards really
664 * do delete areas of the page, even if THP thinks a hugepage would
665 * be a good idea, so force hugepages off.
667 qemu_madvise(host_addr
, length
, QEMU_MADV_NOHUGEPAGE
);
673 * Userfault requires us to mark RAM as NOHUGEPAGE prior to discard
674 * however leaving it until after precopy means that most of the precopy
677 int postcopy_ram_prepare_discard(MigrationIncomingState
*mis
)
679 if (foreach_not_ignored_block(nhp_range
, mis
)) {
683 postcopy_state_set(POSTCOPY_INCOMING_DISCARD
);
689 * Mark the given area of RAM as requiring notification to unwritten areas
690 * Used as a callback on foreach_not_ignored_block.
691 * host_addr: Base of area to mark
692 * offset: Offset in the whole ram arena
693 * length: Length of the section
694 * opaque: MigrationIncomingState pointer
695 * Returns 0 on success
697 static int ram_block_enable_notify(RAMBlock
*rb
, void *opaque
)
699 MigrationIncomingState
*mis
= opaque
;
700 struct uffdio_register reg_struct
;
702 reg_struct
.range
.start
= (uintptr_t)qemu_ram_get_host_addr(rb
);
703 reg_struct
.range
.len
= rb
->postcopy_length
;
704 reg_struct
.mode
= UFFDIO_REGISTER_MODE_MISSING
;
706 /* Now tell our userfault_fd that it's responsible for this area */
707 if (ioctl(mis
->userfault_fd
, UFFDIO_REGISTER
, ®_struct
)) {
708 error_report("%s userfault register: %s", __func__
, strerror(errno
));
711 if (!(reg_struct
.ioctls
& ((__u64
)1 << _UFFDIO_COPY
))) {
712 error_report("%s userfault: Region doesn't support COPY", __func__
);
715 if (reg_struct
.ioctls
& ((__u64
)1 << _UFFDIO_ZEROPAGE
)) {
716 qemu_ram_set_uf_zeroable(rb
);
722 int postcopy_wake_shared(struct PostCopyFD
*pcfd
,
723 uint64_t client_addr
,
726 size_t pagesize
= qemu_ram_pagesize(rb
);
727 struct uffdio_range range
;
729 trace_postcopy_wake_shared(client_addr
, qemu_ram_get_idstr(rb
));
730 range
.start
= ROUND_DOWN(client_addr
, pagesize
);
731 range
.len
= pagesize
;
732 ret
= ioctl(pcfd
->fd
, UFFDIO_WAKE
, &range
);
734 error_report("%s: Failed to wake: %zx in %s (%s)",
735 __func__
, (size_t)client_addr
, qemu_ram_get_idstr(rb
),
741 static int postcopy_request_page(MigrationIncomingState
*mis
, RAMBlock
*rb
,
742 ram_addr_t start
, uint64_t haddr
)
744 void *aligned
= (void *)(uintptr_t)ROUND_DOWN(haddr
, qemu_ram_pagesize(rb
));
747 * Discarded pages (via RamDiscardManager) are never migrated. On unlikely
748 * access, place a zeropage, which will also set the relevant bits in the
749 * recv_bitmap accordingly, so we won't try placing a zeropage twice.
751 * Checking a single bit is sufficient to handle pagesize > TPS as either
752 * all relevant bits are set or not.
754 assert(QEMU_IS_ALIGNED(start
, qemu_ram_pagesize(rb
)));
755 if (ramblock_page_is_discarded(rb
, start
)) {
756 bool received
= ramblock_recv_bitmap_test_byte_offset(rb
, start
);
758 return received
? 0 : postcopy_place_page_zero(mis
, aligned
, rb
);
761 return migrate_send_rp_req_pages(mis
, rb
, start
, haddr
);
765 * Callback from shared fault handlers to ask for a page,
766 * the page must be specified by a RAMBlock and an offset in that rb
767 * Note: Only for use by shared fault handlers (in fault thread)
769 int postcopy_request_shared_page(struct PostCopyFD
*pcfd
, RAMBlock
*rb
,
770 uint64_t client_addr
, uint64_t rb_offset
)
772 uint64_t aligned_rbo
= ROUND_DOWN(rb_offset
, qemu_ram_pagesize(rb
));
773 MigrationIncomingState
*mis
= migration_incoming_get_current();
775 trace_postcopy_request_shared_page(pcfd
->idstr
, qemu_ram_get_idstr(rb
),
777 if (ramblock_recv_bitmap_test_byte_offset(rb
, aligned_rbo
)) {
778 trace_postcopy_request_shared_page_present(pcfd
->idstr
,
779 qemu_ram_get_idstr(rb
), rb_offset
);
780 return postcopy_wake_shared(pcfd
, client_addr
, rb
);
782 postcopy_request_page(mis
, rb
, aligned_rbo
, client_addr
);
786 static int get_mem_fault_cpu_index(uint32_t pid
)
790 CPU_FOREACH(cpu_iter
) {
791 if (cpu_iter
->thread_id
== pid
) {
792 trace_get_mem_fault_cpu_index(cpu_iter
->cpu_index
, pid
);
793 return cpu_iter
->cpu_index
;
796 trace_get_mem_fault_cpu_index(-1, pid
);
800 static uint32_t get_low_time_offset(PostcopyBlocktimeContext
*dc
)
802 int64_t start_time_offset
= qemu_clock_get_ms(QEMU_CLOCK_REALTIME
) -
804 return start_time_offset
< 1 ? 1 : start_time_offset
& UINT32_MAX
;
808 * This function is being called when pagefault occurs. It
809 * tracks down vCPU blocking time.
811 * @addr: faulted host virtual address
812 * @ptid: faulted process thread id
813 * @rb: ramblock appropriate to addr
815 static void mark_postcopy_blocktime_begin(uintptr_t addr
, uint32_t ptid
,
818 int cpu
, already_received
;
819 MigrationIncomingState
*mis
= migration_incoming_get_current();
820 PostcopyBlocktimeContext
*dc
= mis
->blocktime_ctx
;
821 uint32_t low_time_offset
;
823 if (!dc
|| ptid
== 0) {
826 cpu
= get_mem_fault_cpu_index(ptid
);
831 low_time_offset
= get_low_time_offset(dc
);
832 if (dc
->vcpu_addr
[cpu
] == 0) {
833 qatomic_inc(&dc
->smp_cpus_down
);
836 qatomic_xchg(&dc
->last_begin
, low_time_offset
);
837 qatomic_xchg(&dc
->page_fault_vcpu_time
[cpu
], low_time_offset
);
838 qatomic_xchg(&dc
->vcpu_addr
[cpu
], addr
);
841 * check it here, not at the beginning of the function,
842 * due to, check could occur early than bitmap_set in
843 * qemu_ufd_copy_ioctl
845 already_received
= ramblock_recv_bitmap_test(rb
, (void *)addr
);
846 if (already_received
) {
847 qatomic_xchg(&dc
->vcpu_addr
[cpu
], 0);
848 qatomic_xchg(&dc
->page_fault_vcpu_time
[cpu
], 0);
849 qatomic_dec(&dc
->smp_cpus_down
);
851 trace_mark_postcopy_blocktime_begin(addr
, dc
, dc
->page_fault_vcpu_time
[cpu
],
852 cpu
, already_received
);
856 * This function just provide calculated blocktime per cpu and trace it.
857 * Total blocktime is calculated in mark_postcopy_blocktime_end.
860 * Assume we have 3 CPU
863 * -----***********------------xxx***************------------------------> CPU1
866 * ------------****************xxx---------------------------------------> CPU2
869 * ------------------------****xxx********-------------------------------> CPU3
871 * We have sequence S1,S2,E1,S3,S1,E2,E3,E1
872 * S2,E1 - doesn't match condition due to sequence S1,S2,E1 doesn't include CPU3
873 * S3,S1,E2 - sequence includes all CPUs, in this case overlap will be S1,E2 -
874 * it's a part of total blocktime.
875 * S1 - here is last_begin
876 * Legend of the picture is following:
877 * * - means blocktime per vCPU
878 * x - means overlapped blocktime (total blocktime)
880 * @addr: host virtual address
882 static void mark_postcopy_blocktime_end(uintptr_t addr
)
884 MigrationIncomingState
*mis
= migration_incoming_get_current();
885 PostcopyBlocktimeContext
*dc
= mis
->blocktime_ctx
;
886 MachineState
*ms
= MACHINE(qdev_get_machine());
887 unsigned int smp_cpus
= ms
->smp
.cpus
;
888 int i
, affected_cpu
= 0;
889 bool vcpu_total_blocktime
= false;
890 uint32_t read_vcpu_time
, low_time_offset
;
896 low_time_offset
= get_low_time_offset(dc
);
897 /* lookup cpu, to clear it,
898 * that algorithm looks straightforward, but it's not
899 * optimal, more optimal algorithm is keeping tree or hash
900 * where key is address value is a list of */
901 for (i
= 0; i
< smp_cpus
; i
++) {
902 uint32_t vcpu_blocktime
= 0;
904 read_vcpu_time
= qatomic_fetch_add(&dc
->page_fault_vcpu_time
[i
], 0);
905 if (qatomic_fetch_add(&dc
->vcpu_addr
[i
], 0) != addr
||
906 read_vcpu_time
== 0) {
909 qatomic_xchg(&dc
->vcpu_addr
[i
], 0);
910 vcpu_blocktime
= low_time_offset
- read_vcpu_time
;
912 /* we need to know is that mark_postcopy_end was due to
913 * faulted page, another possible case it's prefetched
914 * page and in that case we shouldn't be here */
915 if (!vcpu_total_blocktime
&&
916 qatomic_fetch_add(&dc
->smp_cpus_down
, 0) == smp_cpus
) {
917 vcpu_total_blocktime
= true;
919 /* continue cycle, due to one page could affect several vCPUs */
920 dc
->vcpu_blocktime
[i
] += vcpu_blocktime
;
923 qatomic_sub(&dc
->smp_cpus_down
, affected_cpu
);
924 if (vcpu_total_blocktime
) {
925 dc
->total_blocktime
+= low_time_offset
- qatomic_fetch_add(
928 trace_mark_postcopy_blocktime_end(addr
, dc
, dc
->total_blocktime
,
932 static void postcopy_pause_fault_thread(MigrationIncomingState
*mis
)
934 trace_postcopy_pause_fault_thread();
935 qemu_sem_wait(&mis
->postcopy_pause_sem_fault
);
936 trace_postcopy_pause_fault_thread_continued();
940 * Handle faults detected by the USERFAULT markings
942 static void *postcopy_ram_fault_thread(void *opaque
)
944 MigrationIncomingState
*mis
= opaque
;
950 trace_postcopy_ram_fault_thread_entry();
951 rcu_register_thread();
952 mis
->last_rb
= NULL
; /* last RAMBlock we sent part of */
953 qemu_sem_post(&mis
->thread_sync_sem
);
956 size_t pfd_len
= 2 + mis
->postcopy_remote_fds
->len
;
958 pfd
= g_new0(struct pollfd
, pfd_len
);
960 pfd
[0].fd
= mis
->userfault_fd
;
961 pfd
[0].events
= POLLIN
;
962 pfd
[1].fd
= mis
->userfault_event_fd
;
963 pfd
[1].events
= POLLIN
; /* Waiting for eventfd to go positive */
964 trace_postcopy_ram_fault_thread_fds_core(pfd
[0].fd
, pfd
[1].fd
);
965 for (index
= 0; index
< mis
->postcopy_remote_fds
->len
; index
++) {
966 struct PostCopyFD
*pcfd
= &g_array_index(mis
->postcopy_remote_fds
,
967 struct PostCopyFD
, index
);
968 pfd
[2 + index
].fd
= pcfd
->fd
;
969 pfd
[2 + index
].events
= POLLIN
;
970 trace_postcopy_ram_fault_thread_fds_extra(2 + index
, pcfd
->idstr
,
975 ram_addr_t rb_offset
;
979 * We're mainly waiting for the kernel to give us a faulting HVA,
980 * however we can be told to quit via userfault_quit_fd which is
984 poll_result
= poll(pfd
, pfd_len
, -1 /* Wait forever */);
985 if (poll_result
== -1) {
986 error_report("%s: userfault poll: %s", __func__
, strerror(errno
));
990 if (!mis
->to_src_file
) {
992 * Possibly someone tells us that the return path is
993 * broken already using the event. We should hold until
994 * the channel is rebuilt.
996 postcopy_pause_fault_thread(mis
);
999 if (pfd
[1].revents
) {
1002 /* Consume the signal */
1003 if (read(mis
->userfault_event_fd
, &tmp64
, 8) != 8) {
1004 /* Nothing obviously nicer than posting this error. */
1005 error_report("%s: read() failed", __func__
);
1008 if (qatomic_read(&mis
->fault_thread_quit
)) {
1009 trace_postcopy_ram_fault_thread_quit();
1014 if (pfd
[0].revents
) {
1016 ret
= read(mis
->userfault_fd
, &msg
, sizeof(msg
));
1017 if (ret
!= sizeof(msg
)) {
1018 if (errno
== EAGAIN
) {
1020 * if a wake up happens on the other thread just after
1021 * the poll, there is nothing to read.
1026 error_report("%s: Failed to read full userfault "
1028 __func__
, strerror(errno
));
1031 error_report("%s: Read %d bytes from userfaultfd "
1033 __func__
, ret
, sizeof(msg
));
1034 break; /* Lost alignment, don't know what we'd read next */
1037 if (msg
.event
!= UFFD_EVENT_PAGEFAULT
) {
1038 error_report("%s: Read unexpected event %ud from userfaultfd",
1039 __func__
, msg
.event
);
1040 continue; /* It's not a page fault, shouldn't happen */
1043 rb
= qemu_ram_block_from_host(
1044 (void *)(uintptr_t)msg
.arg
.pagefault
.address
,
1047 error_report("postcopy_ram_fault_thread: Fault outside guest: %"
1048 PRIx64
, (uint64_t)msg
.arg
.pagefault
.address
);
1052 rb_offset
= ROUND_DOWN(rb_offset
, qemu_ram_pagesize(rb
));
1053 trace_postcopy_ram_fault_thread_request(msg
.arg
.pagefault
.address
,
1054 qemu_ram_get_idstr(rb
),
1056 msg
.arg
.pagefault
.feat
.ptid
);
1057 mark_postcopy_blocktime_begin(
1058 (uintptr_t)(msg
.arg
.pagefault
.address
),
1059 msg
.arg
.pagefault
.feat
.ptid
, rb
);
1063 * Send the request to the source - we want to request one
1064 * of our host page sizes (which is >= TPS)
1066 ret
= postcopy_request_page(mis
, rb
, rb_offset
,
1067 msg
.arg
.pagefault
.address
);
1069 /* May be network failure, try to wait for recovery */
1070 postcopy_pause_fault_thread(mis
);
1075 /* Now handle any requests from external processes on shared memory */
1076 /* TODO: May need to handle devices deregistering during postcopy */
1077 for (index
= 2; index
< pfd_len
&& poll_result
; index
++) {
1078 if (pfd
[index
].revents
) {
1079 struct PostCopyFD
*pcfd
=
1080 &g_array_index(mis
->postcopy_remote_fds
,
1081 struct PostCopyFD
, index
- 2);
1084 if (pfd
[index
].revents
& POLLERR
) {
1085 error_report("%s: POLLERR on poll %zd fd=%d",
1086 __func__
, index
, pcfd
->fd
);
1087 pfd
[index
].events
= 0;
1091 ret
= read(pcfd
->fd
, &msg
, sizeof(msg
));
1092 if (ret
!= sizeof(msg
)) {
1093 if (errno
== EAGAIN
) {
1095 * if a wake up happens on the other thread just after
1096 * the poll, there is nothing to read.
1101 error_report("%s: Failed to read full userfault "
1102 "message: %s (shared) revents=%d",
1103 __func__
, strerror(errno
),
1104 pfd
[index
].revents
);
1105 /*TODO: Could just disable this sharer */
1108 error_report("%s: Read %d bytes from userfaultfd "
1109 "expected %zd (shared)",
1110 __func__
, ret
, sizeof(msg
));
1111 /*TODO: Could just disable this sharer */
1112 break; /*Lost alignment,don't know what we'd read next*/
1115 if (msg
.event
!= UFFD_EVENT_PAGEFAULT
) {
1116 error_report("%s: Read unexpected event %ud "
1117 "from userfaultfd (shared)",
1118 __func__
, msg
.event
);
1119 continue; /* It's not a page fault, shouldn't happen */
1121 /* Call the device handler registered with us */
1122 ret
= pcfd
->handler(pcfd
, &msg
);
1124 error_report("%s: Failed to resolve shared fault on %zd/%s",
1125 __func__
, index
, pcfd
->idstr
);
1126 /* TODO: Fail? Disable this sharer? */
1131 rcu_unregister_thread();
1132 trace_postcopy_ram_fault_thread_exit();
1137 static int postcopy_temp_pages_setup(MigrationIncomingState
*mis
)
1139 PostcopyTmpPage
*tmp_page
;
1140 int err
, i
, channels
;
1143 if (migrate_postcopy_preempt()) {
1144 /* If preemption enabled, need extra channel for urgent requests */
1145 mis
->postcopy_channels
= RAM_CHANNEL_MAX
;
1147 /* Both precopy/postcopy on the same channel */
1148 mis
->postcopy_channels
= 1;
1151 channels
= mis
->postcopy_channels
;
1152 mis
->postcopy_tmp_pages
= g_malloc0_n(sizeof(PostcopyTmpPage
), channels
);
1154 for (i
= 0; i
< channels
; i
++) {
1155 tmp_page
= &mis
->postcopy_tmp_pages
[i
];
1156 temp_page
= mmap(NULL
, mis
->largest_page_size
, PROT_READ
| PROT_WRITE
,
1157 MAP_PRIVATE
| MAP_ANONYMOUS
, -1, 0);
1158 if (temp_page
== MAP_FAILED
) {
1160 error_report("%s: Failed to map postcopy_tmp_pages[%d]: %s",
1161 __func__
, i
, strerror(err
));
1162 /* Clean up will be done later */
1165 tmp_page
->tmp_huge_page
= temp_page
;
1166 /* Initialize default states for each tmp page */
1167 postcopy_temp_page_reset(tmp_page
);
1171 * Map large zero page when kernel can't use UFFDIO_ZEROPAGE for hugepages
1173 mis
->postcopy_tmp_zero_page
= mmap(NULL
, mis
->largest_page_size
,
1174 PROT_READ
| PROT_WRITE
,
1175 MAP_PRIVATE
| MAP_ANONYMOUS
, -1, 0);
1176 if (mis
->postcopy_tmp_zero_page
== MAP_FAILED
) {
1178 mis
->postcopy_tmp_zero_page
= NULL
;
1179 error_report("%s: Failed to map large zero page %s",
1180 __func__
, strerror(err
));
1184 memset(mis
->postcopy_tmp_zero_page
, '\0', mis
->largest_page_size
);
1189 int postcopy_ram_incoming_setup(MigrationIncomingState
*mis
)
1191 /* Open the fd for the kernel to give us userfaults */
1192 mis
->userfault_fd
= uffd_open(O_CLOEXEC
| O_NONBLOCK
);
1193 if (mis
->userfault_fd
== -1) {
1194 error_report("%s: Failed to open userfault fd: %s", __func__
,
1200 * Although the host check already tested the API, we need to
1201 * do the check again as an ABI handshake on the new fd.
1203 if (!ufd_check_and_apply(mis
->userfault_fd
, mis
)) {
1207 /* Now an eventfd we use to tell the fault-thread to quit */
1208 mis
->userfault_event_fd
= eventfd(0, EFD_CLOEXEC
);
1209 if (mis
->userfault_event_fd
== -1) {
1210 error_report("%s: Opening userfault_event_fd: %s", __func__
,
1212 close(mis
->userfault_fd
);
1216 postcopy_thread_create(mis
, &mis
->fault_thread
, "fault-default",
1217 postcopy_ram_fault_thread
, QEMU_THREAD_JOINABLE
);
1218 mis
->have_fault_thread
= true;
1220 /* Mark so that we get notified of accesses to unwritten areas */
1221 if (foreach_not_ignored_block(ram_block_enable_notify
, mis
)) {
1222 error_report("ram_block_enable_notify failed");
1226 if (postcopy_temp_pages_setup(mis
)) {
1227 /* Error dumped in the sub-function */
1231 if (migrate_postcopy_preempt()) {
1233 * This thread needs to be created after the temp pages because
1234 * it'll fetch RAM_CHANNEL_POSTCOPY PostcopyTmpPage immediately.
1236 postcopy_thread_create(mis
, &mis
->postcopy_prio_thread
, "fault-fast",
1237 postcopy_preempt_thread
, QEMU_THREAD_JOINABLE
);
1238 mis
->preempt_thread_status
= PREEMPT_THREAD_CREATED
;
1241 trace_postcopy_ram_enable_notify();
1246 static int qemu_ufd_copy_ioctl(MigrationIncomingState
*mis
, void *host_addr
,
1247 void *from_addr
, uint64_t pagesize
, RAMBlock
*rb
)
1249 int userfault_fd
= mis
->userfault_fd
;
1253 struct uffdio_copy copy_struct
;
1254 copy_struct
.dst
= (uint64_t)(uintptr_t)host_addr
;
1255 copy_struct
.src
= (uint64_t)(uintptr_t)from_addr
;
1256 copy_struct
.len
= pagesize
;
1257 copy_struct
.mode
= 0;
1258 ret
= ioctl(userfault_fd
, UFFDIO_COPY
, ©_struct
);
1260 struct uffdio_zeropage zero_struct
;
1261 zero_struct
.range
.start
= (uint64_t)(uintptr_t)host_addr
;
1262 zero_struct
.range
.len
= pagesize
;
1263 zero_struct
.mode
= 0;
1264 ret
= ioctl(userfault_fd
, UFFDIO_ZEROPAGE
, &zero_struct
);
1267 qemu_mutex_lock(&mis
->page_request_mutex
);
1268 ramblock_recv_bitmap_set_range(rb
, host_addr
,
1269 pagesize
/ qemu_target_page_size());
1271 * If this page resolves a page fault for a previous recorded faulted
1272 * address, take a special note to maintain the requested page list.
1274 if (g_tree_lookup(mis
->page_requested
, host_addr
)) {
1275 g_tree_remove(mis
->page_requested
, host_addr
);
1276 mis
->page_requested_count
--;
1277 trace_postcopy_page_req_del(host_addr
, mis
->page_requested_count
);
1279 qemu_mutex_unlock(&mis
->page_request_mutex
);
1280 mark_postcopy_blocktime_end((uintptr_t)host_addr
);
1285 int postcopy_notify_shared_wake(RAMBlock
*rb
, uint64_t offset
)
1288 MigrationIncomingState
*mis
= migration_incoming_get_current();
1289 GArray
*pcrfds
= mis
->postcopy_remote_fds
;
1291 for (i
= 0; i
< pcrfds
->len
; i
++) {
1292 struct PostCopyFD
*cur
= &g_array_index(pcrfds
, struct PostCopyFD
, i
);
1293 int ret
= cur
->waker(cur
, rb
, offset
);
1302 * Place a host page (from) at (host) atomically
1303 * returns 0 on success
1305 int postcopy_place_page(MigrationIncomingState
*mis
, void *host
, void *from
,
1308 size_t pagesize
= qemu_ram_pagesize(rb
);
1310 /* copy also acks to the kernel waking the stalled thread up
1311 * TODO: We can inhibit that ack and only do it if it was requested
1312 * which would be slightly cheaper, but we'd have to be careful
1313 * of the order of updating our page state.
1315 if (qemu_ufd_copy_ioctl(mis
, host
, from
, pagesize
, rb
)) {
1317 error_report("%s: %s copy host: %p from: %p (size: %zd)",
1318 __func__
, strerror(e
), host
, from
, pagesize
);
1323 trace_postcopy_place_page(host
);
1324 return postcopy_notify_shared_wake(rb
,
1325 qemu_ram_block_host_offset(rb
, host
));
1329 * Place a zero page at (host) atomically
1330 * returns 0 on success
1332 int postcopy_place_page_zero(MigrationIncomingState
*mis
, void *host
,
1335 size_t pagesize
= qemu_ram_pagesize(rb
);
1336 trace_postcopy_place_page_zero(host
);
1338 /* Normal RAMBlocks can zero a page using UFFDIO_ZEROPAGE
1339 * but it's not available for everything (e.g. hugetlbpages)
1341 if (qemu_ram_is_uf_zeroable(rb
)) {
1342 if (qemu_ufd_copy_ioctl(mis
, host
, NULL
, pagesize
, rb
)) {
1344 error_report("%s: %s zero host: %p",
1345 __func__
, strerror(e
), host
);
1349 return postcopy_notify_shared_wake(rb
,
1350 qemu_ram_block_host_offset(rb
,
1353 return postcopy_place_page(mis
, host
, mis
->postcopy_tmp_zero_page
, rb
);
1358 /* No target OS support, stubs just fail */
1359 void fill_destination_postcopy_migration_info(MigrationInfo
*info
)
1363 bool postcopy_ram_supported_by_host(MigrationIncomingState
*mis
)
1365 error_report("%s: No OS support", __func__
);
1369 int postcopy_ram_incoming_init(MigrationIncomingState
*mis
)
1371 error_report("postcopy_ram_incoming_init: No OS support");
1375 int postcopy_ram_incoming_cleanup(MigrationIncomingState
*mis
)
1381 int postcopy_ram_prepare_discard(MigrationIncomingState
*mis
)
1387 int postcopy_request_shared_page(struct PostCopyFD
*pcfd
, RAMBlock
*rb
,
1388 uint64_t client_addr
, uint64_t rb_offset
)
1394 int postcopy_ram_incoming_setup(MigrationIncomingState
*mis
)
1400 int postcopy_place_page(MigrationIncomingState
*mis
, void *host
, void *from
,
1407 int postcopy_place_page_zero(MigrationIncomingState
*mis
, void *host
,
1414 int postcopy_wake_shared(struct PostCopyFD
*pcfd
,
1415 uint64_t client_addr
,
1423 /* ------------------------------------------------------------------------- */
1424 void postcopy_temp_page_reset(PostcopyTmpPage
*tmp_page
)
1426 tmp_page
->target_pages
= 0;
1427 tmp_page
->host_addr
= NULL
;
1429 * This is set to true when reset, and cleared as long as we received any
1430 * of the non-zero small page within this huge page.
1432 tmp_page
->all_zero
= true;
1435 void postcopy_fault_thread_notify(MigrationIncomingState
*mis
)
1440 * Wakeup the fault_thread. It's an eventfd that should currently
1441 * be at 0, we're going to increment it to 1
1443 if (write(mis
->userfault_event_fd
, &tmp64
, 8) != 8) {
1444 /* Not much we can do here, but may as well report it */
1445 error_report("%s: incrementing failed: %s", __func__
,
1451 * postcopy_discard_send_init: Called at the start of each RAMBlock before
1452 * asking to discard individual ranges.
1454 * @ms: The current migration state.
1455 * @offset: the bitmap offset of the named RAMBlock in the migration bitmap.
1456 * @name: RAMBlock that discards will operate on.
1458 static PostcopyDiscardState pds
= {0};
1459 void postcopy_discard_send_init(MigrationState
*ms
, const char *name
)
1461 pds
.ramblock_name
= name
;
1468 * postcopy_discard_send_range: Called by the bitmap code for each chunk to
1469 * discard. May send a discard message, may just leave it queued to
1472 * @ms: Current migration state.
1473 * @start,@length: a range of pages in the migration bitmap in the
1474 * RAM block passed to postcopy_discard_send_init() (length=1 is one page)
1476 void postcopy_discard_send_range(MigrationState
*ms
, unsigned long start
,
1477 unsigned long length
)
1479 size_t tp_size
= qemu_target_page_size();
1480 /* Convert to byte offsets within the RAM block */
1481 pds
.start_list
[pds
.cur_entry
] = start
* tp_size
;
1482 pds
.length_list
[pds
.cur_entry
] = length
* tp_size
;
1483 trace_postcopy_discard_send_range(pds
.ramblock_name
, start
, length
);
1487 if (pds
.cur_entry
== MAX_DISCARDS_PER_COMMAND
) {
1488 /* Full set, ship it! */
1489 qemu_savevm_send_postcopy_ram_discard(ms
->to_dst_file
,
1500 * postcopy_discard_send_finish: Called at the end of each RAMBlock by the
1501 * bitmap code. Sends any outstanding discard messages, frees the PDS
1503 * @ms: Current migration state.
1505 void postcopy_discard_send_finish(MigrationState
*ms
)
1507 /* Anything unsent? */
1508 if (pds
.cur_entry
) {
1509 qemu_savevm_send_postcopy_ram_discard(ms
->to_dst_file
,
1517 trace_postcopy_discard_send_finish(pds
.ramblock_name
, pds
.nsentwords
,
1522 * Current state of incoming postcopy; note this is not part of
1523 * MigrationIncomingState since it's state is used during cleanup
1524 * at the end as MIS is being freed.
1526 static PostcopyState incoming_postcopy_state
;
1528 PostcopyState
postcopy_state_get(void)
1530 return qatomic_load_acquire(&incoming_postcopy_state
);
1533 /* Set the state and return the old state */
1534 PostcopyState
postcopy_state_set(PostcopyState new_state
)
1536 return qatomic_xchg(&incoming_postcopy_state
, new_state
);
1539 /* Register a handler for external shared memory postcopy
1540 * called on the destination.
1542 void postcopy_register_shared_ufd(struct PostCopyFD
*pcfd
)
1544 MigrationIncomingState
*mis
= migration_incoming_get_current();
1546 mis
->postcopy_remote_fds
= g_array_append_val(mis
->postcopy_remote_fds
,
1550 /* Unregister a handler for external shared memory postcopy
1552 void postcopy_unregister_shared_ufd(struct PostCopyFD
*pcfd
)
1555 MigrationIncomingState
*mis
= migration_incoming_get_current();
1556 GArray
*pcrfds
= mis
->postcopy_remote_fds
;
1559 /* migration has already finished and freed the array */
1562 for (i
= 0; i
< pcrfds
->len
; i
++) {
1563 struct PostCopyFD
*cur
= &g_array_index(pcrfds
, struct PostCopyFD
, i
);
1564 if (cur
->fd
== pcfd
->fd
) {
1565 mis
->postcopy_remote_fds
= g_array_remove_index(pcrfds
, i
);
1571 void postcopy_preempt_new_channel(MigrationIncomingState
*mis
, QEMUFile
*file
)
1574 * The new loading channel has its own threads, so it needs to be
1575 * blocked too. It's by default true, just be explicit.
1577 qemu_file_set_blocking(file
, true);
1578 mis
->postcopy_qemufile_dst
= file
;
1579 qemu_sem_post(&mis
->postcopy_qemufile_dst_done
);
1580 trace_postcopy_preempt_new_channel();
1584 * Setup the postcopy preempt channel with the IOC. If ERROR is specified,
1585 * setup the error instead. This helper will free the ERROR if specified.
1588 postcopy_preempt_send_channel_done(MigrationState
*s
,
1589 QIOChannel
*ioc
, Error
*local_err
)
1592 migrate_set_error(s
, local_err
);
1593 error_free(local_err
);
1595 migration_ioc_register_yank(ioc
);
1596 s
->postcopy_qemufile_src
= qemu_file_new_output(ioc
);
1597 trace_postcopy_preempt_new_channel();
1601 * Kick the waiter in all cases. The waiter should check upon
1602 * postcopy_qemufile_src to know whether it failed or not.
1604 qemu_sem_post(&s
->postcopy_qemufile_src_sem
);
1608 postcopy_preempt_tls_handshake(QIOTask
*task
, gpointer opaque
)
1610 g_autoptr(QIOChannel
) ioc
= QIO_CHANNEL(qio_task_get_source(task
));
1611 MigrationState
*s
= opaque
;
1612 Error
*local_err
= NULL
;
1614 qio_task_propagate_error(task
, &local_err
);
1615 postcopy_preempt_send_channel_done(s
, ioc
, local_err
);
1619 postcopy_preempt_send_channel_new(QIOTask
*task
, gpointer opaque
)
1621 g_autoptr(QIOChannel
) ioc
= QIO_CHANNEL(qio_task_get_source(task
));
1622 MigrationState
*s
= opaque
;
1623 QIOChannelTLS
*tioc
;
1624 Error
*local_err
= NULL
;
1626 if (qio_task_propagate_error(task
, &local_err
)) {
1630 if (migrate_channel_requires_tls_upgrade(ioc
)) {
1631 tioc
= migration_tls_client_create(s
, ioc
, s
->hostname
, &local_err
);
1635 trace_postcopy_preempt_tls_handshake();
1636 qio_channel_set_name(QIO_CHANNEL(tioc
), "migration-tls-preempt");
1637 qio_channel_tls_handshake(tioc
, postcopy_preempt_tls_handshake
,
1639 /* Setup the channel until TLS handshake finished */
1644 /* This handles both good and error cases */
1645 postcopy_preempt_send_channel_done(s
, ioc
, local_err
);
1649 * This function will kick off an async task to establish the preempt
1650 * channel, and wait until the connection setup completed. Returns 0 if
1651 * channel established, -1 for error.
1653 int postcopy_preempt_establish_channel(MigrationState
*s
)
1655 /* If preempt not enabled, no need to wait */
1656 if (!migrate_postcopy_preempt()) {
1661 * Kick off async task to establish preempt channel. Only do so with
1662 * 8.0+ machines, because 7.1/7.2 require the channel to be created in
1663 * setup phase of migration (even if racy in an unreliable network).
1665 if (!s
->preempt_pre_7_2
) {
1666 postcopy_preempt_setup(s
);
1670 * We need the postcopy preempt channel to be established before
1671 * starting doing anything.
1673 qemu_sem_wait(&s
->postcopy_qemufile_src_sem
);
1675 return s
->postcopy_qemufile_src
? 0 : -1;
1678 void postcopy_preempt_setup(MigrationState
*s
)
1680 /* Kick an async task to connect */
1681 socket_send_channel_create(postcopy_preempt_send_channel_new
, s
);
1684 static void postcopy_pause_ram_fast_load(MigrationIncomingState
*mis
)
1686 trace_postcopy_pause_fast_load();
1687 qemu_mutex_unlock(&mis
->postcopy_prio_thread_mutex
);
1688 qemu_sem_wait(&mis
->postcopy_pause_sem_fast_load
);
1689 qemu_mutex_lock(&mis
->postcopy_prio_thread_mutex
);
1690 trace_postcopy_pause_fast_load_continued();
1693 static bool preempt_thread_should_run(MigrationIncomingState
*mis
)
1695 return mis
->preempt_thread_status
!= PREEMPT_THREAD_QUIT
;
1698 void *postcopy_preempt_thread(void *opaque
)
1700 MigrationIncomingState
*mis
= opaque
;
1703 trace_postcopy_preempt_thread_entry();
1705 rcu_register_thread();
1707 qemu_sem_post(&mis
->thread_sync_sem
);
1710 * The preempt channel is established in asynchronous way. Wait
1711 * for its completion.
1713 qemu_sem_wait(&mis
->postcopy_qemufile_dst_done
);
1715 /* Sending RAM_SAVE_FLAG_EOS to terminate this thread */
1716 qemu_mutex_lock(&mis
->postcopy_prio_thread_mutex
);
1717 while (preempt_thread_should_run(mis
)) {
1718 ret
= ram_load_postcopy(mis
->postcopy_qemufile_dst
,
1719 RAM_CHANNEL_POSTCOPY
);
1720 /* If error happened, go into recovery routine */
1721 if (ret
&& preempt_thread_should_run(mis
)) {
1722 postcopy_pause_ram_fast_load(mis
);
1728 qemu_mutex_unlock(&mis
->postcopy_prio_thread_mutex
);
1730 rcu_unregister_thread();
1732 trace_postcopy_preempt_thread_exit();