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eb59db53 DDAG |
1 | /* |
2 | * Postcopy migration for RAM | |
3 | * | |
4 | * Copyright 2013-2015 Red Hat, Inc. and/or its affiliates | |
5 | * | |
6 | * Authors: | |
7 | * Dave Gilbert <dgilbert@redhat.com> | |
8 | * | |
9 | * This work is licensed under the terms of the GNU GPL, version 2 or later. | |
10 | * See the COPYING file in the top-level directory. | |
11 | * | |
12 | */ | |
13 | ||
14 | /* | |
15 | * Postcopy is a migration technique where the execution flips from the | |
16 | * source to the destination before all the data has been copied. | |
17 | */ | |
18 | ||
19 | #include <glib.h> | |
20 | #include <stdio.h> | |
21 | #include <unistd.h> | |
22 | ||
23 | #include "qemu-common.h" | |
24 | #include "migration/migration.h" | |
25 | #include "migration/postcopy-ram.h" | |
26 | #include "sysemu/sysemu.h" | |
371ff5a3 | 27 | #include "sysemu/balloon.h" |
eb59db53 DDAG |
28 | #include "qemu/error-report.h" |
29 | #include "trace.h" | |
30 | ||
e0b266f0 DDAG |
31 | /* Arbitrary limit on size of each discard command, |
32 | * keeps them around ~200 bytes | |
33 | */ | |
34 | #define MAX_DISCARDS_PER_COMMAND 12 | |
35 | ||
36 | struct PostcopyDiscardState { | |
37 | const char *ramblock_name; | |
38 | uint64_t offset; /* Bitmap entry for the 1st bit of this RAMBlock */ | |
39 | uint16_t cur_entry; | |
40 | /* | |
41 | * Start and length of a discard range (bytes) | |
42 | */ | |
43 | uint64_t start_list[MAX_DISCARDS_PER_COMMAND]; | |
44 | uint64_t length_list[MAX_DISCARDS_PER_COMMAND]; | |
45 | unsigned int nsentwords; | |
46 | unsigned int nsentcmds; | |
47 | }; | |
48 | ||
eb59db53 DDAG |
49 | /* Postcopy needs to detect accesses to pages that haven't yet been copied |
50 | * across, and efficiently map new pages in, the techniques for doing this | |
51 | * are target OS specific. | |
52 | */ | |
53 | #if defined(__linux__) | |
54 | ||
c4faeed2 DDAG |
55 | #include <poll.h> |
56 | #include <sys/eventfd.h> | |
eb59db53 DDAG |
57 | #include <sys/mman.h> |
58 | #include <sys/ioctl.h> | |
59 | #include <sys/syscall.h> | |
60 | #include <sys/types.h> | |
61 | #include <asm/types.h> /* for __u64 */ | |
62 | #endif | |
63 | ||
64 | #if defined(__linux__) && defined(__NR_userfaultfd) | |
65 | #include <linux/userfaultfd.h> | |
66 | ||
67 | static bool ufd_version_check(int ufd) | |
68 | { | |
69 | struct uffdio_api api_struct; | |
70 | uint64_t ioctl_mask; | |
71 | ||
72 | api_struct.api = UFFD_API; | |
73 | api_struct.features = 0; | |
74 | if (ioctl(ufd, UFFDIO_API, &api_struct)) { | |
75 | error_report("postcopy_ram_supported_by_host: UFFDIO_API failed: %s", | |
76 | strerror(errno)); | |
77 | return false; | |
78 | } | |
79 | ||
80 | ioctl_mask = (__u64)1 << _UFFDIO_REGISTER | | |
81 | (__u64)1 << _UFFDIO_UNREGISTER; | |
82 | if ((api_struct.ioctls & ioctl_mask) != ioctl_mask) { | |
83 | error_report("Missing userfault features: %" PRIx64, | |
84 | (uint64_t)(~api_struct.ioctls & ioctl_mask)); | |
85 | return false; | |
86 | } | |
87 | ||
88 | return true; | |
89 | } | |
90 | ||
58b7c17e DDAG |
91 | /* |
92 | * Note: This has the side effect of munlock'ing all of RAM, that's | |
93 | * normally fine since if the postcopy succeeds it gets turned back on at the | |
94 | * end. | |
95 | */ | |
eb59db53 DDAG |
96 | bool postcopy_ram_supported_by_host(void) |
97 | { | |
98 | long pagesize = getpagesize(); | |
99 | int ufd = -1; | |
100 | bool ret = false; /* Error unless we change it */ | |
101 | void *testarea = NULL; | |
102 | struct uffdio_register reg_struct; | |
103 | struct uffdio_range range_struct; | |
104 | uint64_t feature_mask; | |
105 | ||
106 | if ((1ul << qemu_target_page_bits()) > pagesize) { | |
107 | error_report("Target page size bigger than host page size"); | |
108 | goto out; | |
109 | } | |
110 | ||
111 | ufd = syscall(__NR_userfaultfd, O_CLOEXEC); | |
112 | if (ufd == -1) { | |
113 | error_report("%s: userfaultfd not available: %s", __func__, | |
114 | strerror(errno)); | |
115 | goto out; | |
116 | } | |
117 | ||
118 | /* Version and features check */ | |
119 | if (!ufd_version_check(ufd)) { | |
120 | goto out; | |
121 | } | |
122 | ||
58b7c17e DDAG |
123 | /* |
124 | * userfault and mlock don't go together; we'll put it back later if | |
125 | * it was enabled. | |
126 | */ | |
127 | if (munlockall()) { | |
128 | error_report("%s: munlockall: %s", __func__, strerror(errno)); | |
129 | return -1; | |
130 | } | |
131 | ||
eb59db53 DDAG |
132 | /* |
133 | * We need to check that the ops we need are supported on anon memory | |
134 | * To do that we need to register a chunk and see the flags that | |
135 | * are returned. | |
136 | */ | |
137 | testarea = mmap(NULL, pagesize, PROT_READ | PROT_WRITE, MAP_PRIVATE | | |
138 | MAP_ANONYMOUS, -1, 0); | |
139 | if (testarea == MAP_FAILED) { | |
140 | error_report("%s: Failed to map test area: %s", __func__, | |
141 | strerror(errno)); | |
142 | goto out; | |
143 | } | |
144 | g_assert(((size_t)testarea & (pagesize-1)) == 0); | |
145 | ||
146 | reg_struct.range.start = (uintptr_t)testarea; | |
147 | reg_struct.range.len = pagesize; | |
148 | reg_struct.mode = UFFDIO_REGISTER_MODE_MISSING; | |
149 | ||
150 | if (ioctl(ufd, UFFDIO_REGISTER, ®_struct)) { | |
151 | error_report("%s userfault register: %s", __func__, strerror(errno)); | |
152 | goto out; | |
153 | } | |
154 | ||
155 | range_struct.start = (uintptr_t)testarea; | |
156 | range_struct.len = pagesize; | |
157 | if (ioctl(ufd, UFFDIO_UNREGISTER, &range_struct)) { | |
158 | error_report("%s userfault unregister: %s", __func__, strerror(errno)); | |
159 | goto out; | |
160 | } | |
161 | ||
162 | feature_mask = (__u64)1 << _UFFDIO_WAKE | | |
163 | (__u64)1 << _UFFDIO_COPY | | |
164 | (__u64)1 << _UFFDIO_ZEROPAGE; | |
165 | if ((reg_struct.ioctls & feature_mask) != feature_mask) { | |
166 | error_report("Missing userfault map features: %" PRIx64, | |
167 | (uint64_t)(~reg_struct.ioctls & feature_mask)); | |
168 | goto out; | |
169 | } | |
170 | ||
171 | /* Success! */ | |
172 | ret = true; | |
173 | out: | |
174 | if (testarea) { | |
175 | munmap(testarea, pagesize); | |
176 | } | |
177 | if (ufd != -1) { | |
178 | close(ufd); | |
179 | } | |
180 | return ret; | |
181 | } | |
182 | ||
e0b266f0 DDAG |
183 | /** |
184 | * postcopy_ram_discard_range: Discard a range of memory. | |
185 | * We can assume that if we've been called postcopy_ram_hosttest returned true. | |
186 | * | |
187 | * @mis: Current incoming migration state. | |
188 | * @start, @length: range of memory to discard. | |
189 | * | |
190 | * returns: 0 on success. | |
191 | */ | |
192 | int postcopy_ram_discard_range(MigrationIncomingState *mis, uint8_t *start, | |
193 | size_t length) | |
194 | { | |
195 | trace_postcopy_ram_discard_range(start, length); | |
196 | if (madvise(start, length, MADV_DONTNEED)) { | |
197 | error_report("%s MADV_DONTNEED: %s", __func__, strerror(errno)); | |
198 | return -1; | |
199 | } | |
200 | ||
201 | return 0; | |
202 | } | |
203 | ||
1caddf8a DDAG |
204 | /* |
205 | * Setup an area of RAM so that it *can* be used for postcopy later; this | |
206 | * must be done right at the start prior to pre-copy. | |
207 | * opaque should be the MIS. | |
208 | */ | |
209 | static int init_range(const char *block_name, void *host_addr, | |
210 | ram_addr_t offset, ram_addr_t length, void *opaque) | |
211 | { | |
212 | MigrationIncomingState *mis = opaque; | |
213 | ||
214 | trace_postcopy_init_range(block_name, host_addr, offset, length); | |
215 | ||
216 | /* | |
217 | * We need the whole of RAM to be truly empty for postcopy, so things | |
218 | * like ROMs and any data tables built during init must be zero'd | |
219 | * - we're going to get the copy from the source anyway. | |
220 | * (Precopy will just overwrite this data, so doesn't need the discard) | |
221 | */ | |
222 | if (postcopy_ram_discard_range(mis, host_addr, length)) { | |
223 | return -1; | |
224 | } | |
225 | ||
226 | return 0; | |
227 | } | |
228 | ||
229 | /* | |
230 | * At the end of migration, undo the effects of init_range | |
231 | * opaque should be the MIS. | |
232 | */ | |
233 | static int cleanup_range(const char *block_name, void *host_addr, | |
234 | ram_addr_t offset, ram_addr_t length, void *opaque) | |
235 | { | |
236 | MigrationIncomingState *mis = opaque; | |
237 | struct uffdio_range range_struct; | |
238 | trace_postcopy_cleanup_range(block_name, host_addr, offset, length); | |
239 | ||
240 | /* | |
241 | * We turned off hugepage for the precopy stage with postcopy enabled | |
242 | * we can turn it back on now. | |
243 | */ | |
1d741439 | 244 | qemu_madvise(host_addr, length, QEMU_MADV_HUGEPAGE); |
1caddf8a DDAG |
245 | |
246 | /* | |
247 | * We can also turn off userfault now since we should have all the | |
248 | * pages. It can be useful to leave it on to debug postcopy | |
249 | * if you're not sure it's always getting every page. | |
250 | */ | |
251 | range_struct.start = (uintptr_t)host_addr; | |
252 | range_struct.len = length; | |
253 | ||
254 | if (ioctl(mis->userfault_fd, UFFDIO_UNREGISTER, &range_struct)) { | |
255 | error_report("%s: userfault unregister %s", __func__, strerror(errno)); | |
256 | ||
257 | return -1; | |
258 | } | |
259 | ||
260 | return 0; | |
261 | } | |
262 | ||
263 | /* | |
264 | * Initialise postcopy-ram, setting the RAM to a state where we can go into | |
265 | * postcopy later; must be called prior to any precopy. | |
266 | * called from arch_init's similarly named ram_postcopy_incoming_init | |
267 | */ | |
268 | int postcopy_ram_incoming_init(MigrationIncomingState *mis, size_t ram_pages) | |
269 | { | |
270 | if (qemu_ram_foreach_block(init_range, mis)) { | |
271 | return -1; | |
272 | } | |
273 | ||
274 | return 0; | |
275 | } | |
276 | ||
277 | /* | |
278 | * At the end of a migration where postcopy_ram_incoming_init was called. | |
279 | */ | |
280 | int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis) | |
281 | { | |
c4faeed2 DDAG |
282 | trace_postcopy_ram_incoming_cleanup_entry(); |
283 | ||
284 | if (mis->have_fault_thread) { | |
285 | uint64_t tmp64; | |
286 | ||
287 | if (qemu_ram_foreach_block(cleanup_range, mis)) { | |
288 | return -1; | |
289 | } | |
290 | /* | |
291 | * Tell the fault_thread to exit, it's an eventfd that should | |
292 | * currently be at 0, we're going to increment it to 1 | |
293 | */ | |
294 | tmp64 = 1; | |
295 | if (write(mis->userfault_quit_fd, &tmp64, 8) == 8) { | |
296 | trace_postcopy_ram_incoming_cleanup_join(); | |
297 | qemu_thread_join(&mis->fault_thread); | |
298 | } else { | |
299 | /* Not much we can do here, but may as well report it */ | |
300 | error_report("%s: incrementing userfault_quit_fd: %s", __func__, | |
301 | strerror(errno)); | |
302 | } | |
303 | trace_postcopy_ram_incoming_cleanup_closeuf(); | |
304 | close(mis->userfault_fd); | |
305 | close(mis->userfault_quit_fd); | |
306 | mis->have_fault_thread = false; | |
1caddf8a DDAG |
307 | } |
308 | ||
371ff5a3 DDAG |
309 | qemu_balloon_inhibit(false); |
310 | ||
58b7c17e DDAG |
311 | if (enable_mlock) { |
312 | if (os_mlock() < 0) { | |
313 | error_report("mlock: %s", strerror(errno)); | |
314 | /* | |
315 | * It doesn't feel right to fail at this point, we have a valid | |
316 | * VM state. | |
317 | */ | |
318 | } | |
319 | } | |
320 | ||
c4faeed2 DDAG |
321 | postcopy_state_set(POSTCOPY_INCOMING_END); |
322 | migrate_send_rp_shut(mis, qemu_file_get_error(mis->from_src_file) != 0); | |
323 | ||
696ed9a9 DDAG |
324 | if (mis->postcopy_tmp_page) { |
325 | munmap(mis->postcopy_tmp_page, getpagesize()); | |
326 | mis->postcopy_tmp_page = NULL; | |
327 | } | |
c4faeed2 | 328 | trace_postcopy_ram_incoming_cleanup_exit(); |
1caddf8a DDAG |
329 | return 0; |
330 | } | |
331 | ||
f9527107 DDAG |
332 | /* |
333 | * Disable huge pages on an area | |
334 | */ | |
335 | static int nhp_range(const char *block_name, void *host_addr, | |
336 | ram_addr_t offset, ram_addr_t length, void *opaque) | |
337 | { | |
338 | trace_postcopy_nhp_range(block_name, host_addr, offset, length); | |
339 | ||
340 | /* | |
341 | * Before we do discards we need to ensure those discards really | |
342 | * do delete areas of the page, even if THP thinks a hugepage would | |
343 | * be a good idea, so force hugepages off. | |
344 | */ | |
1d741439 | 345 | qemu_madvise(host_addr, length, QEMU_MADV_NOHUGEPAGE); |
f9527107 DDAG |
346 | |
347 | return 0; | |
348 | } | |
349 | ||
350 | /* | |
351 | * Userfault requires us to mark RAM as NOHUGEPAGE prior to discard | |
352 | * however leaving it until after precopy means that most of the precopy | |
353 | * data is still THPd | |
354 | */ | |
355 | int postcopy_ram_prepare_discard(MigrationIncomingState *mis) | |
356 | { | |
357 | if (qemu_ram_foreach_block(nhp_range, mis)) { | |
358 | return -1; | |
359 | } | |
360 | ||
361 | postcopy_state_set(POSTCOPY_INCOMING_DISCARD); | |
362 | ||
363 | return 0; | |
364 | } | |
365 | ||
f0a227ad DDAG |
366 | /* |
367 | * Mark the given area of RAM as requiring notification to unwritten areas | |
368 | * Used as a callback on qemu_ram_foreach_block. | |
369 | * host_addr: Base of area to mark | |
370 | * offset: Offset in the whole ram arena | |
371 | * length: Length of the section | |
372 | * opaque: MigrationIncomingState pointer | |
373 | * Returns 0 on success | |
374 | */ | |
375 | static int ram_block_enable_notify(const char *block_name, void *host_addr, | |
376 | ram_addr_t offset, ram_addr_t length, | |
377 | void *opaque) | |
378 | { | |
379 | MigrationIncomingState *mis = opaque; | |
380 | struct uffdio_register reg_struct; | |
381 | ||
382 | reg_struct.range.start = (uintptr_t)host_addr; | |
383 | reg_struct.range.len = length; | |
384 | reg_struct.mode = UFFDIO_REGISTER_MODE_MISSING; | |
385 | ||
386 | /* Now tell our userfault_fd that it's responsible for this area */ | |
387 | if (ioctl(mis->userfault_fd, UFFDIO_REGISTER, ®_struct)) { | |
388 | error_report("%s userfault register: %s", __func__, strerror(errno)); | |
389 | return -1; | |
390 | } | |
391 | ||
392 | return 0; | |
393 | } | |
394 | ||
395 | /* | |
396 | * Handle faults detected by the USERFAULT markings | |
397 | */ | |
398 | static void *postcopy_ram_fault_thread(void *opaque) | |
399 | { | |
400 | MigrationIncomingState *mis = opaque; | |
c4faeed2 DDAG |
401 | struct uffd_msg msg; |
402 | int ret; | |
403 | size_t hostpagesize = getpagesize(); | |
404 | RAMBlock *rb = NULL; | |
405 | RAMBlock *last_rb = NULL; /* last RAMBlock we sent part of */ | |
f0a227ad | 406 | |
c4faeed2 | 407 | trace_postcopy_ram_fault_thread_entry(); |
f0a227ad | 408 | qemu_sem_post(&mis->fault_thread_sem); |
f0a227ad | 409 | |
c4faeed2 DDAG |
410 | while (true) { |
411 | ram_addr_t rb_offset; | |
412 | ram_addr_t in_raspace; | |
413 | struct pollfd pfd[2]; | |
414 | ||
415 | /* | |
416 | * We're mainly waiting for the kernel to give us a faulting HVA, | |
417 | * however we can be told to quit via userfault_quit_fd which is | |
418 | * an eventfd | |
419 | */ | |
420 | pfd[0].fd = mis->userfault_fd; | |
421 | pfd[0].events = POLLIN; | |
422 | pfd[0].revents = 0; | |
423 | pfd[1].fd = mis->userfault_quit_fd; | |
424 | pfd[1].events = POLLIN; /* Waiting for eventfd to go positive */ | |
425 | pfd[1].revents = 0; | |
426 | ||
427 | if (poll(pfd, 2, -1 /* Wait forever */) == -1) { | |
428 | error_report("%s: userfault poll: %s", __func__, strerror(errno)); | |
429 | break; | |
430 | } | |
431 | ||
432 | if (pfd[1].revents) { | |
433 | trace_postcopy_ram_fault_thread_quit(); | |
434 | break; | |
435 | } | |
436 | ||
437 | ret = read(mis->userfault_fd, &msg, sizeof(msg)); | |
438 | if (ret != sizeof(msg)) { | |
439 | if (errno == EAGAIN) { | |
440 | /* | |
441 | * if a wake up happens on the other thread just after | |
442 | * the poll, there is nothing to read. | |
443 | */ | |
444 | continue; | |
445 | } | |
446 | if (ret < 0) { | |
447 | error_report("%s: Failed to read full userfault message: %s", | |
448 | __func__, strerror(errno)); | |
449 | break; | |
450 | } else { | |
451 | error_report("%s: Read %d bytes from userfaultfd expected %zd", | |
452 | __func__, ret, sizeof(msg)); | |
453 | break; /* Lost alignment, don't know what we'd read next */ | |
454 | } | |
455 | } | |
456 | if (msg.event != UFFD_EVENT_PAGEFAULT) { | |
457 | error_report("%s: Read unexpected event %ud from userfaultfd", | |
458 | __func__, msg.event); | |
459 | continue; /* It's not a page fault, shouldn't happen */ | |
460 | } | |
461 | ||
462 | rb = qemu_ram_block_from_host( | |
463 | (void *)(uintptr_t)msg.arg.pagefault.address, | |
464 | true, &in_raspace, &rb_offset); | |
465 | if (!rb) { | |
466 | error_report("postcopy_ram_fault_thread: Fault outside guest: %" | |
467 | PRIx64, (uint64_t)msg.arg.pagefault.address); | |
468 | break; | |
469 | } | |
470 | ||
471 | rb_offset &= ~(hostpagesize - 1); | |
472 | trace_postcopy_ram_fault_thread_request(msg.arg.pagefault.address, | |
473 | qemu_ram_get_idstr(rb), | |
474 | rb_offset); | |
475 | ||
476 | /* | |
477 | * Send the request to the source - we want to request one | |
478 | * of our host page sizes (which is >= TPS) | |
479 | */ | |
480 | if (rb != last_rb) { | |
481 | last_rb = rb; | |
482 | migrate_send_rp_req_pages(mis, qemu_ram_get_idstr(rb), | |
483 | rb_offset, hostpagesize); | |
484 | } else { | |
485 | /* Save some space */ | |
486 | migrate_send_rp_req_pages(mis, NULL, | |
487 | rb_offset, hostpagesize); | |
488 | } | |
489 | } | |
490 | trace_postcopy_ram_fault_thread_exit(); | |
f0a227ad DDAG |
491 | return NULL; |
492 | } | |
493 | ||
494 | int postcopy_ram_enable_notify(MigrationIncomingState *mis) | |
495 | { | |
c4faeed2 DDAG |
496 | /* Open the fd for the kernel to give us userfaults */ |
497 | mis->userfault_fd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK); | |
498 | if (mis->userfault_fd == -1) { | |
499 | error_report("%s: Failed to open userfault fd: %s", __func__, | |
500 | strerror(errno)); | |
501 | return -1; | |
502 | } | |
503 | ||
504 | /* | |
505 | * Although the host check already tested the API, we need to | |
506 | * do the check again as an ABI handshake on the new fd. | |
507 | */ | |
508 | if (!ufd_version_check(mis->userfault_fd)) { | |
509 | return -1; | |
510 | } | |
511 | ||
512 | /* Now an eventfd we use to tell the fault-thread to quit */ | |
513 | mis->userfault_quit_fd = eventfd(0, EFD_CLOEXEC); | |
514 | if (mis->userfault_quit_fd == -1) { | |
515 | error_report("%s: Opening userfault_quit_fd: %s", __func__, | |
516 | strerror(errno)); | |
517 | close(mis->userfault_fd); | |
518 | return -1; | |
519 | } | |
520 | ||
f0a227ad DDAG |
521 | qemu_sem_init(&mis->fault_thread_sem, 0); |
522 | qemu_thread_create(&mis->fault_thread, "postcopy/fault", | |
523 | postcopy_ram_fault_thread, mis, QEMU_THREAD_JOINABLE); | |
524 | qemu_sem_wait(&mis->fault_thread_sem); | |
525 | qemu_sem_destroy(&mis->fault_thread_sem); | |
c4faeed2 | 526 | mis->have_fault_thread = true; |
f0a227ad DDAG |
527 | |
528 | /* Mark so that we get notified of accesses to unwritten areas */ | |
529 | if (qemu_ram_foreach_block(ram_block_enable_notify, mis)) { | |
530 | return -1; | |
531 | } | |
532 | ||
371ff5a3 DDAG |
533 | /* |
534 | * Ballooning can mark pages as absent while we're postcopying | |
535 | * that would cause false userfaults. | |
536 | */ | |
537 | qemu_balloon_inhibit(true); | |
538 | ||
c4faeed2 DDAG |
539 | trace_postcopy_ram_enable_notify(); |
540 | ||
f0a227ad DDAG |
541 | return 0; |
542 | } | |
543 | ||
696ed9a9 DDAG |
544 | /* |
545 | * Place a host page (from) at (host) atomically | |
546 | * returns 0 on success | |
547 | */ | |
548 | int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from) | |
549 | { | |
550 | struct uffdio_copy copy_struct; | |
551 | ||
552 | copy_struct.dst = (uint64_t)(uintptr_t)host; | |
553 | copy_struct.src = (uint64_t)(uintptr_t)from; | |
554 | copy_struct.len = getpagesize(); | |
555 | copy_struct.mode = 0; | |
556 | ||
557 | /* copy also acks to the kernel waking the stalled thread up | |
558 | * TODO: We can inhibit that ack and only do it if it was requested | |
559 | * which would be slightly cheaper, but we'd have to be careful | |
560 | * of the order of updating our page state. | |
561 | */ | |
562 | if (ioctl(mis->userfault_fd, UFFDIO_COPY, ©_struct)) { | |
563 | int e = errno; | |
564 | error_report("%s: %s copy host: %p from: %p", | |
565 | __func__, strerror(e), host, from); | |
566 | ||
567 | return -e; | |
568 | } | |
569 | ||
570 | trace_postcopy_place_page(host); | |
571 | return 0; | |
572 | } | |
573 | ||
574 | /* | |
575 | * Place a zero page at (host) atomically | |
576 | * returns 0 on success | |
577 | */ | |
578 | int postcopy_place_page_zero(MigrationIncomingState *mis, void *host) | |
579 | { | |
580 | struct uffdio_zeropage zero_struct; | |
581 | ||
582 | zero_struct.range.start = (uint64_t)(uintptr_t)host; | |
583 | zero_struct.range.len = getpagesize(); | |
584 | zero_struct.mode = 0; | |
585 | ||
586 | if (ioctl(mis->userfault_fd, UFFDIO_ZEROPAGE, &zero_struct)) { | |
587 | int e = errno; | |
588 | error_report("%s: %s zero host: %p", | |
589 | __func__, strerror(e), host); | |
590 | ||
591 | return -e; | |
592 | } | |
593 | ||
594 | trace_postcopy_place_page_zero(host); | |
595 | return 0; | |
596 | } | |
597 | ||
598 | /* | |
599 | * Returns a target page of memory that can be mapped at a later point in time | |
600 | * using postcopy_place_page | |
601 | * The same address is used repeatedly, postcopy_place_page just takes the | |
602 | * backing page away. | |
603 | * Returns: Pointer to allocated page | |
604 | * | |
605 | */ | |
606 | void *postcopy_get_tmp_page(MigrationIncomingState *mis) | |
607 | { | |
608 | if (!mis->postcopy_tmp_page) { | |
609 | mis->postcopy_tmp_page = mmap(NULL, getpagesize(), | |
610 | PROT_READ | PROT_WRITE, MAP_PRIVATE | | |
611 | MAP_ANONYMOUS, -1, 0); | |
612 | if (!mis->postcopy_tmp_page) { | |
613 | error_report("%s: %s", __func__, strerror(errno)); | |
614 | return NULL; | |
615 | } | |
616 | } | |
617 | ||
618 | return mis->postcopy_tmp_page; | |
619 | } | |
620 | ||
eb59db53 DDAG |
621 | #else |
622 | /* No target OS support, stubs just fail */ | |
623 | bool postcopy_ram_supported_by_host(void) | |
624 | { | |
625 | error_report("%s: No OS support", __func__); | |
626 | return false; | |
627 | } | |
628 | ||
1caddf8a DDAG |
629 | int postcopy_ram_incoming_init(MigrationIncomingState *mis, size_t ram_pages) |
630 | { | |
631 | error_report("postcopy_ram_incoming_init: No OS support"); | |
632 | return -1; | |
633 | } | |
634 | ||
635 | int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis) | |
636 | { | |
637 | assert(0); | |
638 | return -1; | |
639 | } | |
640 | ||
e0b266f0 DDAG |
641 | int postcopy_ram_discard_range(MigrationIncomingState *mis, uint8_t *start, |
642 | size_t length) | |
643 | { | |
644 | assert(0); | |
1caddf8a | 645 | return -1; |
e0b266f0 | 646 | } |
f0a227ad | 647 | |
f9527107 DDAG |
648 | int postcopy_ram_prepare_discard(MigrationIncomingState *mis) |
649 | { | |
650 | assert(0); | |
651 | return -1; | |
652 | } | |
653 | ||
f0a227ad DDAG |
654 | int postcopy_ram_enable_notify(MigrationIncomingState *mis) |
655 | { | |
656 | assert(0); | |
657 | return -1; | |
658 | } | |
696ed9a9 DDAG |
659 | |
660 | int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from) | |
661 | { | |
662 | assert(0); | |
663 | return -1; | |
664 | } | |
665 | ||
666 | int postcopy_place_page_zero(MigrationIncomingState *mis, void *host) | |
667 | { | |
668 | assert(0); | |
669 | return -1; | |
670 | } | |
671 | ||
672 | void *postcopy_get_tmp_page(MigrationIncomingState *mis) | |
673 | { | |
674 | assert(0); | |
675 | return NULL; | |
676 | } | |
677 | ||
eb59db53 DDAG |
678 | #endif |
679 | ||
e0b266f0 DDAG |
680 | /* ------------------------------------------------------------------------- */ |
681 | ||
682 | /** | |
683 | * postcopy_discard_send_init: Called at the start of each RAMBlock before | |
684 | * asking to discard individual ranges. | |
685 | * | |
686 | * @ms: The current migration state. | |
687 | * @offset: the bitmap offset of the named RAMBlock in the migration | |
688 | * bitmap. | |
689 | * @name: RAMBlock that discards will operate on. | |
690 | * | |
691 | * returns: a new PDS. | |
692 | */ | |
693 | PostcopyDiscardState *postcopy_discard_send_init(MigrationState *ms, | |
694 | unsigned long offset, | |
695 | const char *name) | |
696 | { | |
697 | PostcopyDiscardState *res = g_malloc0(sizeof(PostcopyDiscardState)); | |
698 | ||
699 | if (res) { | |
700 | res->ramblock_name = name; | |
701 | res->offset = offset; | |
702 | } | |
703 | ||
704 | return res; | |
705 | } | |
706 | ||
707 | /** | |
708 | * postcopy_discard_send_range: Called by the bitmap code for each chunk to | |
709 | * discard. May send a discard message, may just leave it queued to | |
710 | * be sent later. | |
711 | * | |
712 | * @ms: Current migration state. | |
713 | * @pds: Structure initialised by postcopy_discard_send_init(). | |
714 | * @start,@length: a range of pages in the migration bitmap in the | |
715 | * RAM block passed to postcopy_discard_send_init() (length=1 is one page) | |
716 | */ | |
717 | void postcopy_discard_send_range(MigrationState *ms, PostcopyDiscardState *pds, | |
718 | unsigned long start, unsigned long length) | |
719 | { | |
720 | size_t tp_bits = qemu_target_page_bits(); | |
721 | /* Convert to byte offsets within the RAM block */ | |
722 | pds->start_list[pds->cur_entry] = (start - pds->offset) << tp_bits; | |
723 | pds->length_list[pds->cur_entry] = length << tp_bits; | |
724 | trace_postcopy_discard_send_range(pds->ramblock_name, start, length); | |
725 | pds->cur_entry++; | |
726 | pds->nsentwords++; | |
727 | ||
728 | if (pds->cur_entry == MAX_DISCARDS_PER_COMMAND) { | |
729 | /* Full set, ship it! */ | |
730 | qemu_savevm_send_postcopy_ram_discard(ms->file, pds->ramblock_name, | |
731 | pds->cur_entry, | |
732 | pds->start_list, | |
733 | pds->length_list); | |
734 | pds->nsentcmds++; | |
735 | pds->cur_entry = 0; | |
736 | } | |
737 | } | |
738 | ||
739 | /** | |
740 | * postcopy_discard_send_finish: Called at the end of each RAMBlock by the | |
741 | * bitmap code. Sends any outstanding discard messages, frees the PDS | |
742 | * | |
743 | * @ms: Current migration state. | |
744 | * @pds: Structure initialised by postcopy_discard_send_init(). | |
745 | */ | |
746 | void postcopy_discard_send_finish(MigrationState *ms, PostcopyDiscardState *pds) | |
747 | { | |
748 | /* Anything unsent? */ | |
749 | if (pds->cur_entry) { | |
750 | qemu_savevm_send_postcopy_ram_discard(ms->file, pds->ramblock_name, | |
751 | pds->cur_entry, | |
752 | pds->start_list, | |
753 | pds->length_list); | |
754 | pds->nsentcmds++; | |
755 | } | |
756 | ||
757 | trace_postcopy_discard_send_finish(pds->ramblock_name, pds->nsentwords, | |
758 | pds->nsentcmds); | |
759 | ||
760 | g_free(pds); | |
761 | } |