| /* |
| * Postcopy migration for RAM |
| * |
| * Copyright 2013-2015 Red Hat, Inc. and/or its affiliates |
| * |
| * Authors: |
| * Dave Gilbert <dgilbert@redhat.com> |
| * |
| * This work is licensed under the terms of the GNU GPL, version 2 or later. |
| * See the COPYING file in the top-level directory. |
| * |
| */ |
| |
| /* |
| * Postcopy is a migration technique where the execution flips from the |
| * source to the destination before all the data has been copied. |
| */ |
| |
| #include "qemu/osdep.h" |
| |
| #include "qemu-common.h" |
| #include "exec/target_page.h" |
| #include "migration/migration.h" |
| #include "qemu-file.h" |
| #include "savevm.h" |
| #include "postcopy-ram.h" |
| #include "ram.h" |
| #include "sysemu/sysemu.h" |
| #include "sysemu/balloon.h" |
| #include "qemu/error-report.h" |
| #include "trace.h" |
| |
| /* Arbitrary limit on size of each discard command, |
| * keeps them around ~200 bytes |
| */ |
| #define MAX_DISCARDS_PER_COMMAND 12 |
| |
| struct PostcopyDiscardState { |
| const char *ramblock_name; |
| uint16_t cur_entry; |
| /* |
| * Start and length of a discard range (bytes) |
| */ |
| uint64_t start_list[MAX_DISCARDS_PER_COMMAND]; |
| uint64_t length_list[MAX_DISCARDS_PER_COMMAND]; |
| unsigned int nsentwords; |
| unsigned int nsentcmds; |
| }; |
| |
| /* Postcopy needs to detect accesses to pages that haven't yet been copied |
| * across, and efficiently map new pages in, the techniques for doing this |
| * are target OS specific. |
| */ |
| #if defined(__linux__) |
| |
| #include <poll.h> |
| #include <sys/ioctl.h> |
| #include <sys/syscall.h> |
| #include <asm/types.h> /* for __u64 */ |
| #endif |
| |
| #if defined(__linux__) && defined(__NR_userfaultfd) && defined(CONFIG_EVENTFD) |
| #include <sys/eventfd.h> |
| #include <linux/userfaultfd.h> |
| |
| static bool ufd_version_check(int ufd) |
| { |
| struct uffdio_api api_struct; |
| uint64_t ioctl_mask; |
| |
| api_struct.api = UFFD_API; |
| api_struct.features = 0; |
| if (ioctl(ufd, UFFDIO_API, &api_struct)) { |
| error_report("postcopy_ram_supported_by_host: UFFDIO_API failed: %s", |
| strerror(errno)); |
| return false; |
| } |
| |
| ioctl_mask = (__u64)1 << _UFFDIO_REGISTER | |
| (__u64)1 << _UFFDIO_UNREGISTER; |
| if ((api_struct.ioctls & ioctl_mask) != ioctl_mask) { |
| error_report("Missing userfault features: %" PRIx64, |
| (uint64_t)(~api_struct.ioctls & ioctl_mask)); |
| return false; |
| } |
| |
| if (getpagesize() != ram_pagesize_summary()) { |
| bool have_hp = false; |
| /* We've got a huge page */ |
| #ifdef UFFD_FEATURE_MISSING_HUGETLBFS |
| have_hp = api_struct.features & UFFD_FEATURE_MISSING_HUGETLBFS; |
| #endif |
| if (!have_hp) { |
| error_report("Userfault on this host does not support huge pages"); |
| return false; |
| } |
| } |
| return true; |
| } |
| |
| /* Callback from postcopy_ram_supported_by_host block iterator. |
| */ |
| static int test_ramblock_postcopiable(const char *block_name, void *host_addr, |
| ram_addr_t offset, ram_addr_t length, void *opaque) |
| { |
| RAMBlock *rb = qemu_ram_block_by_name(block_name); |
| size_t pagesize = qemu_ram_pagesize(rb); |
| |
| if (qemu_ram_is_shared(rb)) { |
| error_report("Postcopy on shared RAM (%s) is not yet supported", |
| block_name); |
| return 1; |
| } |
| |
| if (length % pagesize) { |
| error_report("Postcopy requires RAM blocks to be a page size multiple," |
| " block %s is 0x" RAM_ADDR_FMT " bytes with a " |
| "page size of 0x%zx", block_name, length, pagesize); |
| return 1; |
| } |
| return 0; |
| } |
| |
| /* |
| * Note: This has the side effect of munlock'ing all of RAM, that's |
| * normally fine since if the postcopy succeeds it gets turned back on at the |
| * end. |
| */ |
| bool postcopy_ram_supported_by_host(void) |
| { |
| long pagesize = getpagesize(); |
| int ufd = -1; |
| bool ret = false; /* Error unless we change it */ |
| void *testarea = NULL; |
| struct uffdio_register reg_struct; |
| struct uffdio_range range_struct; |
| uint64_t feature_mask; |
| |
| if (qemu_target_page_size() > pagesize) { |
| error_report("Target page size bigger than host page size"); |
| goto out; |
| } |
| |
| ufd = syscall(__NR_userfaultfd, O_CLOEXEC); |
| if (ufd == -1) { |
| error_report("%s: userfaultfd not available: %s", __func__, |
| strerror(errno)); |
| goto out; |
| } |
| |
| /* Version and features check */ |
| if (!ufd_version_check(ufd)) { |
| goto out; |
| } |
| |
| /* We don't support postcopy with shared RAM yet */ |
| if (qemu_ram_foreach_block(test_ramblock_postcopiable, NULL)) { |
| goto out; |
| } |
| |
| /* |
| * userfault and mlock don't go together; we'll put it back later if |
| * it was enabled. |
| */ |
| if (munlockall()) { |
| error_report("%s: munlockall: %s", __func__, strerror(errno)); |
| return -1; |
| } |
| |
| /* |
| * We need to check that the ops we need are supported on anon memory |
| * To do that we need to register a chunk and see the flags that |
| * are returned. |
| */ |
| testarea = mmap(NULL, pagesize, PROT_READ | PROT_WRITE, MAP_PRIVATE | |
| MAP_ANONYMOUS, -1, 0); |
| if (testarea == MAP_FAILED) { |
| error_report("%s: Failed to map test area: %s", __func__, |
| strerror(errno)); |
| goto out; |
| } |
| g_assert(((size_t)testarea & (pagesize-1)) == 0); |
| |
| reg_struct.range.start = (uintptr_t)testarea; |
| reg_struct.range.len = pagesize; |
| reg_struct.mode = UFFDIO_REGISTER_MODE_MISSING; |
| |
| if (ioctl(ufd, UFFDIO_REGISTER, ®_struct)) { |
| error_report("%s userfault register: %s", __func__, strerror(errno)); |
| goto out; |
| } |
| |
| range_struct.start = (uintptr_t)testarea; |
| range_struct.len = pagesize; |
| if (ioctl(ufd, UFFDIO_UNREGISTER, &range_struct)) { |
| error_report("%s userfault unregister: %s", __func__, strerror(errno)); |
| goto out; |
| } |
| |
| feature_mask = (__u64)1 << _UFFDIO_WAKE | |
| (__u64)1 << _UFFDIO_COPY | |
| (__u64)1 << _UFFDIO_ZEROPAGE; |
| if ((reg_struct.ioctls & feature_mask) != feature_mask) { |
| error_report("Missing userfault map features: %" PRIx64, |
| (uint64_t)(~reg_struct.ioctls & feature_mask)); |
| goto out; |
| } |
| |
| /* Success! */ |
| ret = true; |
| out: |
| if (testarea) { |
| munmap(testarea, pagesize); |
| } |
| if (ufd != -1) { |
| close(ufd); |
| } |
| return ret; |
| } |
| |
| /* |
| * Setup an area of RAM so that it *can* be used for postcopy later; this |
| * must be done right at the start prior to pre-copy. |
| * opaque should be the MIS. |
| */ |
| static int init_range(const char *block_name, void *host_addr, |
| ram_addr_t offset, ram_addr_t length, void *opaque) |
| { |
| trace_postcopy_init_range(block_name, host_addr, offset, length); |
| |
| /* |
| * We need the whole of RAM to be truly empty for postcopy, so things |
| * like ROMs and any data tables built during init must be zero'd |
| * - we're going to get the copy from the source anyway. |
| * (Precopy will just overwrite this data, so doesn't need the discard) |
| */ |
| if (ram_discard_range(block_name, 0, length)) { |
| return -1; |
| } |
| |
| return 0; |
| } |
| |
| /* |
| * At the end of migration, undo the effects of init_range |
| * opaque should be the MIS. |
| */ |
| static int cleanup_range(const char *block_name, void *host_addr, |
| ram_addr_t offset, ram_addr_t length, void *opaque) |
| { |
| MigrationIncomingState *mis = opaque; |
| struct uffdio_range range_struct; |
| trace_postcopy_cleanup_range(block_name, host_addr, offset, length); |
| |
| /* |
| * We turned off hugepage for the precopy stage with postcopy enabled |
| * we can turn it back on now. |
| */ |
| qemu_madvise(host_addr, length, QEMU_MADV_HUGEPAGE); |
| |
| /* |
| * We can also turn off userfault now since we should have all the |
| * pages. It can be useful to leave it on to debug postcopy |
| * if you're not sure it's always getting every page. |
| */ |
| range_struct.start = (uintptr_t)host_addr; |
| range_struct.len = length; |
| |
| if (ioctl(mis->userfault_fd, UFFDIO_UNREGISTER, &range_struct)) { |
| error_report("%s: userfault unregister %s", __func__, strerror(errno)); |
| |
| return -1; |
| } |
| |
| return 0; |
| } |
| |
| /* |
| * Initialise postcopy-ram, setting the RAM to a state where we can go into |
| * postcopy later; must be called prior to any precopy. |
| * called from arch_init's similarly named ram_postcopy_incoming_init |
| */ |
| int postcopy_ram_incoming_init(MigrationIncomingState *mis, size_t ram_pages) |
| { |
| if (qemu_ram_foreach_block(init_range, NULL)) { |
| return -1; |
| } |
| |
| return 0; |
| } |
| |
| /* |
| * At the end of a migration where postcopy_ram_incoming_init was called. |
| */ |
| int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis) |
| { |
| trace_postcopy_ram_incoming_cleanup_entry(); |
| |
| if (mis->have_fault_thread) { |
| uint64_t tmp64; |
| |
| if (qemu_ram_foreach_block(cleanup_range, mis)) { |
| return -1; |
| } |
| /* |
| * Tell the fault_thread to exit, it's an eventfd that should |
| * currently be at 0, we're going to increment it to 1 |
| */ |
| tmp64 = 1; |
| if (write(mis->userfault_quit_fd, &tmp64, 8) == 8) { |
| trace_postcopy_ram_incoming_cleanup_join(); |
| qemu_thread_join(&mis->fault_thread); |
| } else { |
| /* Not much we can do here, but may as well report it */ |
| error_report("%s: incrementing userfault_quit_fd: %s", __func__, |
| strerror(errno)); |
| } |
| trace_postcopy_ram_incoming_cleanup_closeuf(); |
| close(mis->userfault_fd); |
| close(mis->userfault_quit_fd); |
| mis->have_fault_thread = false; |
| } |
| |
| qemu_balloon_inhibit(false); |
| |
| if (enable_mlock) { |
| if (os_mlock() < 0) { |
| error_report("mlock: %s", strerror(errno)); |
| /* |
| * It doesn't feel right to fail at this point, we have a valid |
| * VM state. |
| */ |
| } |
| } |
| |
| postcopy_state_set(POSTCOPY_INCOMING_END); |
| |
| if (mis->postcopy_tmp_page) { |
| munmap(mis->postcopy_tmp_page, mis->largest_page_size); |
| mis->postcopy_tmp_page = NULL; |
| } |
| if (mis->postcopy_tmp_zero_page) { |
| munmap(mis->postcopy_tmp_zero_page, mis->largest_page_size); |
| mis->postcopy_tmp_zero_page = NULL; |
| } |
| trace_postcopy_ram_incoming_cleanup_exit(); |
| return 0; |
| } |
| |
| /* |
| * Disable huge pages on an area |
| */ |
| static int nhp_range(const char *block_name, void *host_addr, |
| ram_addr_t offset, ram_addr_t length, void *opaque) |
| { |
| trace_postcopy_nhp_range(block_name, host_addr, offset, length); |
| |
| /* |
| * Before we do discards we need to ensure those discards really |
| * do delete areas of the page, even if THP thinks a hugepage would |
| * be a good idea, so force hugepages off. |
| */ |
| qemu_madvise(host_addr, length, QEMU_MADV_NOHUGEPAGE); |
| |
| return 0; |
| } |
| |
| /* |
| * Userfault requires us to mark RAM as NOHUGEPAGE prior to discard |
| * however leaving it until after precopy means that most of the precopy |
| * data is still THPd |
| */ |
| int postcopy_ram_prepare_discard(MigrationIncomingState *mis) |
| { |
| if (qemu_ram_foreach_block(nhp_range, mis)) { |
| return -1; |
| } |
| |
| postcopy_state_set(POSTCOPY_INCOMING_DISCARD); |
| |
| return 0; |
| } |
| |
| /* |
| * Mark the given area of RAM as requiring notification to unwritten areas |
| * Used as a callback on qemu_ram_foreach_block. |
| * host_addr: Base of area to mark |
| * offset: Offset in the whole ram arena |
| * length: Length of the section |
| * opaque: MigrationIncomingState pointer |
| * Returns 0 on success |
| */ |
| static int ram_block_enable_notify(const char *block_name, void *host_addr, |
| ram_addr_t offset, ram_addr_t length, |
| void *opaque) |
| { |
| MigrationIncomingState *mis = opaque; |
| struct uffdio_register reg_struct; |
| |
| reg_struct.range.start = (uintptr_t)host_addr; |
| reg_struct.range.len = length; |
| reg_struct.mode = UFFDIO_REGISTER_MODE_MISSING; |
| |
| /* Now tell our userfault_fd that it's responsible for this area */ |
| if (ioctl(mis->userfault_fd, UFFDIO_REGISTER, ®_struct)) { |
| error_report("%s userfault register: %s", __func__, strerror(errno)); |
| return -1; |
| } |
| if (!(reg_struct.ioctls & ((__u64)1 << _UFFDIO_COPY))) { |
| error_report("%s userfault: Region doesn't support COPY", __func__); |
| return -1; |
| } |
| |
| return 0; |
| } |
| |
| /* |
| * Handle faults detected by the USERFAULT markings |
| */ |
| static void *postcopy_ram_fault_thread(void *opaque) |
| { |
| MigrationIncomingState *mis = opaque; |
| struct uffd_msg msg; |
| int ret; |
| RAMBlock *rb = NULL; |
| RAMBlock *last_rb = NULL; /* last RAMBlock we sent part of */ |
| |
| trace_postcopy_ram_fault_thread_entry(); |
| qemu_sem_post(&mis->fault_thread_sem); |
| |
| while (true) { |
| ram_addr_t rb_offset; |
| struct pollfd pfd[2]; |
| |
| /* |
| * We're mainly waiting for the kernel to give us a faulting HVA, |
| * however we can be told to quit via userfault_quit_fd which is |
| * an eventfd |
| */ |
| pfd[0].fd = mis->userfault_fd; |
| pfd[0].events = POLLIN; |
| pfd[0].revents = 0; |
| pfd[1].fd = mis->userfault_quit_fd; |
| pfd[1].events = POLLIN; /* Waiting for eventfd to go positive */ |
| pfd[1].revents = 0; |
| |
| if (poll(pfd, 2, -1 /* Wait forever */) == -1) { |
| error_report("%s: userfault poll: %s", __func__, strerror(errno)); |
| break; |
| } |
| |
| if (pfd[1].revents) { |
| trace_postcopy_ram_fault_thread_quit(); |
| break; |
| } |
| |
| ret = read(mis->userfault_fd, &msg, sizeof(msg)); |
| if (ret != sizeof(msg)) { |
| if (errno == EAGAIN) { |
| /* |
| * if a wake up happens on the other thread just after |
| * the poll, there is nothing to read. |
| */ |
| continue; |
| } |
| if (ret < 0) { |
| error_report("%s: Failed to read full userfault message: %s", |
| __func__, strerror(errno)); |
| break; |
| } else { |
| error_report("%s: Read %d bytes from userfaultfd expected %zd", |
| __func__, ret, sizeof(msg)); |
| break; /* Lost alignment, don't know what we'd read next */ |
| } |
| } |
| if (msg.event != UFFD_EVENT_PAGEFAULT) { |
| error_report("%s: Read unexpected event %ud from userfaultfd", |
| __func__, msg.event); |
| continue; /* It's not a page fault, shouldn't happen */ |
| } |
| |
| rb = qemu_ram_block_from_host( |
| (void *)(uintptr_t)msg.arg.pagefault.address, |
| true, &rb_offset); |
| if (!rb) { |
| error_report("postcopy_ram_fault_thread: Fault outside guest: %" |
| PRIx64, (uint64_t)msg.arg.pagefault.address); |
| break; |
| } |
| |
| rb_offset &= ~(qemu_ram_pagesize(rb) - 1); |
| trace_postcopy_ram_fault_thread_request(msg.arg.pagefault.address, |
| qemu_ram_get_idstr(rb), |
| rb_offset); |
| |
| /* |
| * Send the request to the source - we want to request one |
| * of our host page sizes (which is >= TPS) |
| */ |
| if (rb != last_rb) { |
| last_rb = rb; |
| migrate_send_rp_req_pages(mis, qemu_ram_get_idstr(rb), |
| rb_offset, qemu_ram_pagesize(rb)); |
| } else { |
| /* Save some space */ |
| migrate_send_rp_req_pages(mis, NULL, |
| rb_offset, qemu_ram_pagesize(rb)); |
| } |
| } |
| trace_postcopy_ram_fault_thread_exit(); |
| return NULL; |
| } |
| |
| int postcopy_ram_enable_notify(MigrationIncomingState *mis) |
| { |
| /* Open the fd for the kernel to give us userfaults */ |
| mis->userfault_fd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK); |
| if (mis->userfault_fd == -1) { |
| error_report("%s: Failed to open userfault fd: %s", __func__, |
| strerror(errno)); |
| return -1; |
| } |
| |
| /* |
| * Although the host check already tested the API, we need to |
| * do the check again as an ABI handshake on the new fd. |
| */ |
| if (!ufd_version_check(mis->userfault_fd)) { |
| return -1; |
| } |
| |
| /* Now an eventfd we use to tell the fault-thread to quit */ |
| mis->userfault_quit_fd = eventfd(0, EFD_CLOEXEC); |
| if (mis->userfault_quit_fd == -1) { |
| error_report("%s: Opening userfault_quit_fd: %s", __func__, |
| strerror(errno)); |
| close(mis->userfault_fd); |
| return -1; |
| } |
| |
| qemu_sem_init(&mis->fault_thread_sem, 0); |
| qemu_thread_create(&mis->fault_thread, "postcopy/fault", |
| postcopy_ram_fault_thread, mis, QEMU_THREAD_JOINABLE); |
| qemu_sem_wait(&mis->fault_thread_sem); |
| qemu_sem_destroy(&mis->fault_thread_sem); |
| mis->have_fault_thread = true; |
| |
| /* Mark so that we get notified of accesses to unwritten areas */ |
| if (qemu_ram_foreach_block(ram_block_enable_notify, mis)) { |
| return -1; |
| } |
| |
| /* |
| * Ballooning can mark pages as absent while we're postcopying |
| * that would cause false userfaults. |
| */ |
| qemu_balloon_inhibit(true); |
| |
| trace_postcopy_ram_enable_notify(); |
| |
| return 0; |
| } |
| |
| /* |
| * Place a host page (from) at (host) atomically |
| * returns 0 on success |
| */ |
| int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from, |
| size_t pagesize) |
| { |
| struct uffdio_copy copy_struct; |
| |
| copy_struct.dst = (uint64_t)(uintptr_t)host; |
| copy_struct.src = (uint64_t)(uintptr_t)from; |
| copy_struct.len = pagesize; |
| copy_struct.mode = 0; |
| |
| /* copy also acks to the kernel waking the stalled thread up |
| * TODO: We can inhibit that ack and only do it if it was requested |
| * which would be slightly cheaper, but we'd have to be careful |
| * of the order of updating our page state. |
| */ |
| if (ioctl(mis->userfault_fd, UFFDIO_COPY, ©_struct)) { |
| int e = errno; |
| error_report("%s: %s copy host: %p from: %p (size: %zd)", |
| __func__, strerror(e), host, from, pagesize); |
| |
| return -e; |
| } |
| |
| trace_postcopy_place_page(host); |
| return 0; |
| } |
| |
| /* |
| * Place a zero page at (host) atomically |
| * returns 0 on success |
| */ |
| int postcopy_place_page_zero(MigrationIncomingState *mis, void *host, |
| size_t pagesize) |
| { |
| trace_postcopy_place_page_zero(host); |
| |
| if (pagesize == getpagesize()) { |
| struct uffdio_zeropage zero_struct; |
| zero_struct.range.start = (uint64_t)(uintptr_t)host; |
| zero_struct.range.len = getpagesize(); |
| zero_struct.mode = 0; |
| |
| if (ioctl(mis->userfault_fd, UFFDIO_ZEROPAGE, &zero_struct)) { |
| int e = errno; |
| error_report("%s: %s zero host: %p", |
| __func__, strerror(e), host); |
| |
| return -e; |
| } |
| } else { |
| /* The kernel can't use UFFDIO_ZEROPAGE for hugepages */ |
| if (!mis->postcopy_tmp_zero_page) { |
| mis->postcopy_tmp_zero_page = mmap(NULL, mis->largest_page_size, |
| PROT_READ | PROT_WRITE, |
| MAP_PRIVATE | MAP_ANONYMOUS, |
| -1, 0); |
| if (mis->postcopy_tmp_zero_page == MAP_FAILED) { |
| int e = errno; |
| mis->postcopy_tmp_zero_page = NULL; |
| error_report("%s: %s mapping large zero page", |
| __func__, strerror(e)); |
| return -e; |
| } |
| memset(mis->postcopy_tmp_zero_page, '\0', mis->largest_page_size); |
| } |
| return postcopy_place_page(mis, host, mis->postcopy_tmp_zero_page, |
| pagesize); |
| } |
| |
| return 0; |
| } |
| |
| /* |
| * Returns a target page of memory that can be mapped at a later point in time |
| * using postcopy_place_page |
| * The same address is used repeatedly, postcopy_place_page just takes the |
| * backing page away. |
| * Returns: Pointer to allocated page |
| * |
| */ |
| void *postcopy_get_tmp_page(MigrationIncomingState *mis) |
| { |
| if (!mis->postcopy_tmp_page) { |
| mis->postcopy_tmp_page = mmap(NULL, mis->largest_page_size, |
| PROT_READ | PROT_WRITE, MAP_PRIVATE | |
| MAP_ANONYMOUS, -1, 0); |
| if (mis->postcopy_tmp_page == MAP_FAILED) { |
| mis->postcopy_tmp_page = NULL; |
| error_report("%s: %s", __func__, strerror(errno)); |
| return NULL; |
| } |
| } |
| |
| return mis->postcopy_tmp_page; |
| } |
| |
| #else |
| /* No target OS support, stubs just fail */ |
| bool postcopy_ram_supported_by_host(void) |
| { |
| error_report("%s: No OS support", __func__); |
| return false; |
| } |
| |
| int postcopy_ram_incoming_init(MigrationIncomingState *mis, size_t ram_pages) |
| { |
| error_report("postcopy_ram_incoming_init: No OS support"); |
| return -1; |
| } |
| |
| int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis) |
| { |
| assert(0); |
| return -1; |
| } |
| |
| int postcopy_ram_prepare_discard(MigrationIncomingState *mis) |
| { |
| assert(0); |
| return -1; |
| } |
| |
| int postcopy_ram_enable_notify(MigrationIncomingState *mis) |
| { |
| assert(0); |
| return -1; |
| } |
| |
| int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from, |
| size_t pagesize) |
| { |
| assert(0); |
| return -1; |
| } |
| |
| int postcopy_place_page_zero(MigrationIncomingState *mis, void *host, |
| size_t pagesize) |
| { |
| assert(0); |
| return -1; |
| } |
| |
| void *postcopy_get_tmp_page(MigrationIncomingState *mis) |
| { |
| assert(0); |
| return NULL; |
| } |
| |
| #endif |
| |
| /* ------------------------------------------------------------------------- */ |
| |
| /** |
| * postcopy_discard_send_init: Called at the start of each RAMBlock before |
| * asking to discard individual ranges. |
| * |
| * @ms: The current migration state. |
| * @offset: the bitmap offset of the named RAMBlock in the migration |
| * bitmap. |
| * @name: RAMBlock that discards will operate on. |
| * |
| * returns: a new PDS. |
| */ |
| PostcopyDiscardState *postcopy_discard_send_init(MigrationState *ms, |
| const char *name) |
| { |
| PostcopyDiscardState *res = g_malloc0(sizeof(PostcopyDiscardState)); |
| |
| if (res) { |
| res->ramblock_name = name; |
| } |
| |
| return res; |
| } |
| |
| /** |
| * postcopy_discard_send_range: Called by the bitmap code for each chunk to |
| * discard. May send a discard message, may just leave it queued to |
| * be sent later. |
| * |
| * @ms: Current migration state. |
| * @pds: Structure initialised by postcopy_discard_send_init(). |
| * @start,@length: a range of pages in the migration bitmap in the |
| * RAM block passed to postcopy_discard_send_init() (length=1 is one page) |
| */ |
| void postcopy_discard_send_range(MigrationState *ms, PostcopyDiscardState *pds, |
| unsigned long start, unsigned long length) |
| { |
| size_t tp_size = qemu_target_page_size(); |
| /* Convert to byte offsets within the RAM block */ |
| pds->start_list[pds->cur_entry] = start * tp_size; |
| pds->length_list[pds->cur_entry] = length * tp_size; |
| trace_postcopy_discard_send_range(pds->ramblock_name, start, length); |
| pds->cur_entry++; |
| pds->nsentwords++; |
| |
| if (pds->cur_entry == MAX_DISCARDS_PER_COMMAND) { |
| /* Full set, ship it! */ |
| qemu_savevm_send_postcopy_ram_discard(ms->to_dst_file, |
| pds->ramblock_name, |
| pds->cur_entry, |
| pds->start_list, |
| pds->length_list); |
| pds->nsentcmds++; |
| pds->cur_entry = 0; |
| } |
| } |
| |
| /** |
| * postcopy_discard_send_finish: Called at the end of each RAMBlock by the |
| * bitmap code. Sends any outstanding discard messages, frees the PDS |
| * |
| * @ms: Current migration state. |
| * @pds: Structure initialised by postcopy_discard_send_init(). |
| */ |
| void postcopy_discard_send_finish(MigrationState *ms, PostcopyDiscardState *pds) |
| { |
| /* Anything unsent? */ |
| if (pds->cur_entry) { |
| qemu_savevm_send_postcopy_ram_discard(ms->to_dst_file, |
| pds->ramblock_name, |
| pds->cur_entry, |
| pds->start_list, |
| pds->length_list); |
| pds->nsentcmds++; |
| } |
| |
| trace_postcopy_discard_send_finish(pds->ramblock_name, pds->nsentwords, |
| pds->nsentcmds); |
| |
| g_free(pds); |
| } |
| |
| /* |
| * Current state of incoming postcopy; note this is not part of |
| * MigrationIncomingState since it's state is used during cleanup |
| * at the end as MIS is being freed. |
| */ |
| static PostcopyState incoming_postcopy_state; |
| |
| PostcopyState postcopy_state_get(void) |
| { |
| return atomic_mb_read(&incoming_postcopy_state); |
| } |
| |
| /* Set the state and return the old state */ |
| PostcopyState postcopy_state_set(PostcopyState new_state) |
| { |
| return atomic_xchg(&incoming_postcopy_state, new_state); |
| } |