a0d645100e
It is defined and referred to exclusively from a .c file. Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
1773 lines
56 KiB
C
1773 lines
56 KiB
C
/*
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* Postcopy migration for RAM
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*
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* Copyright 2013-2015 Red Hat, Inc. and/or its affiliates
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*
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* Authors:
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* Dave Gilbert <dgilbert@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*
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*/
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/*
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* Postcopy is a migration technique where the execution flips from the
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* source to the destination before all the data has been copied.
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*/
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#include "qemu/osdep.h"
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#include "qemu/madvise.h"
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#include "exec/target_page.h"
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#include "migration.h"
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#include "qemu-file.h"
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#include "savevm.h"
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#include "postcopy-ram.h"
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#include "ram.h"
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#include "qapi/error.h"
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#include "qemu/notify.h"
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#include "qemu/rcu.h"
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#include "sysemu/sysemu.h"
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#include "qemu/error-report.h"
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#include "trace.h"
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#include "hw/boards.h"
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#include "exec/ramblock.h"
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#include "socket.h"
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#include "yank_functions.h"
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#include "tls.h"
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#include "qemu/userfaultfd.h"
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#include "qemu/mmap-alloc.h"
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#include "options.h"
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/* Arbitrary limit on size of each discard command,
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* keeps them around ~200 bytes
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*/
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#define MAX_DISCARDS_PER_COMMAND 12
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typedef struct PostcopyDiscardState {
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const char *ramblock_name;
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uint16_t cur_entry;
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/*
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* Start and length of a discard range (bytes)
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*/
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uint64_t start_list[MAX_DISCARDS_PER_COMMAND];
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uint64_t length_list[MAX_DISCARDS_PER_COMMAND];
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unsigned int nsentwords;
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unsigned int nsentcmds;
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} PostcopyDiscardState;
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static NotifierWithReturnList postcopy_notifier_list;
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void postcopy_infrastructure_init(void)
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{
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notifier_with_return_list_init(&postcopy_notifier_list);
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}
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void postcopy_add_notifier(NotifierWithReturn *nn)
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{
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notifier_with_return_list_add(&postcopy_notifier_list, nn);
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}
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void postcopy_remove_notifier(NotifierWithReturn *n)
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{
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notifier_with_return_remove(n);
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}
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int postcopy_notify(enum PostcopyNotifyReason reason, Error **errp)
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{
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struct PostcopyNotifyData pnd;
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pnd.reason = reason;
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return notifier_with_return_list_notify(&postcopy_notifier_list,
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&pnd, errp);
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}
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/*
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* NOTE: this routine is not thread safe, we can't call it concurrently. But it
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* should be good enough for migration's purposes.
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*/
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void postcopy_thread_create(MigrationIncomingState *mis,
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QemuThread *thread, const char *name,
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void *(*fn)(void *), int joinable)
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{
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qemu_sem_init(&mis->thread_sync_sem, 0);
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qemu_thread_create(thread, name, fn, mis, joinable);
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qemu_sem_wait(&mis->thread_sync_sem);
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qemu_sem_destroy(&mis->thread_sync_sem);
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}
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/* Postcopy needs to detect accesses to pages that haven't yet been copied
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* across, and efficiently map new pages in, the techniques for doing this
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* are target OS specific.
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*/
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#if defined(__linux__)
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#include <poll.h>
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#include <sys/ioctl.h>
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#include <sys/syscall.h>
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#endif
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#if defined(__linux__) && defined(__NR_userfaultfd) && defined(CONFIG_EVENTFD)
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#include <sys/eventfd.h>
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#include <linux/userfaultfd.h>
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typedef struct PostcopyBlocktimeContext {
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/* time when page fault initiated per vCPU */
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uint32_t *page_fault_vcpu_time;
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/* page address per vCPU */
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uintptr_t *vcpu_addr;
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uint32_t total_blocktime;
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/* blocktime per vCPU */
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uint32_t *vcpu_blocktime;
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/* point in time when last page fault was initiated */
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uint32_t last_begin;
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/* number of vCPU are suspended */
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int smp_cpus_down;
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uint64_t start_time;
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/*
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* Handler for exit event, necessary for
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* releasing whole blocktime_ctx
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*/
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Notifier exit_notifier;
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} PostcopyBlocktimeContext;
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static void destroy_blocktime_context(struct PostcopyBlocktimeContext *ctx)
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{
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g_free(ctx->page_fault_vcpu_time);
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g_free(ctx->vcpu_addr);
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g_free(ctx->vcpu_blocktime);
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g_free(ctx);
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}
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static void migration_exit_cb(Notifier *n, void *data)
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{
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PostcopyBlocktimeContext *ctx = container_of(n, PostcopyBlocktimeContext,
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exit_notifier);
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destroy_blocktime_context(ctx);
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}
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static struct PostcopyBlocktimeContext *blocktime_context_new(void)
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{
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MachineState *ms = MACHINE(qdev_get_machine());
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unsigned int smp_cpus = ms->smp.cpus;
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PostcopyBlocktimeContext *ctx = g_new0(PostcopyBlocktimeContext, 1);
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ctx->page_fault_vcpu_time = g_new0(uint32_t, smp_cpus);
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ctx->vcpu_addr = g_new0(uintptr_t, smp_cpus);
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ctx->vcpu_blocktime = g_new0(uint32_t, smp_cpus);
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ctx->exit_notifier.notify = migration_exit_cb;
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ctx->start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
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qemu_add_exit_notifier(&ctx->exit_notifier);
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return ctx;
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}
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static uint32List *get_vcpu_blocktime_list(PostcopyBlocktimeContext *ctx)
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{
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MachineState *ms = MACHINE(qdev_get_machine());
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uint32List *list = NULL;
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int i;
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for (i = ms->smp.cpus - 1; i >= 0; i--) {
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QAPI_LIST_PREPEND(list, ctx->vcpu_blocktime[i]);
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}
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return list;
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}
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/*
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* This function just populates MigrationInfo from postcopy's
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* blocktime context. It will not populate MigrationInfo,
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* unless postcopy-blocktime capability was set.
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*
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* @info: pointer to MigrationInfo to populate
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*/
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void fill_destination_postcopy_migration_info(MigrationInfo *info)
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{
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MigrationIncomingState *mis = migration_incoming_get_current();
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PostcopyBlocktimeContext *bc = mis->blocktime_ctx;
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if (!bc) {
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return;
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}
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info->has_postcopy_blocktime = true;
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info->postcopy_blocktime = bc->total_blocktime;
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info->has_postcopy_vcpu_blocktime = true;
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info->postcopy_vcpu_blocktime = get_vcpu_blocktime_list(bc);
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}
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static uint32_t get_postcopy_total_blocktime(void)
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{
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MigrationIncomingState *mis = migration_incoming_get_current();
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PostcopyBlocktimeContext *bc = mis->blocktime_ctx;
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if (!bc) {
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return 0;
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}
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return bc->total_blocktime;
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}
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/**
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* receive_ufd_features: check userfault fd features, to request only supported
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* features in the future.
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*
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* Returns: true on success
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*
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* __NR_userfaultfd - should be checked before
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* @features: out parameter will contain uffdio_api.features provided by kernel
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* in case of success
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*/
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static bool receive_ufd_features(uint64_t *features)
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{
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struct uffdio_api api_struct = {0};
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int ufd;
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bool ret = true;
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ufd = uffd_open(O_CLOEXEC);
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if (ufd == -1) {
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error_report("%s: uffd_open() failed: %s", __func__, strerror(errno));
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return false;
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}
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/* ask features */
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api_struct.api = UFFD_API;
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api_struct.features = 0;
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if (ioctl(ufd, UFFDIO_API, &api_struct)) {
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error_report("%s: UFFDIO_API failed: %s", __func__,
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strerror(errno));
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ret = false;
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goto release_ufd;
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}
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*features = api_struct.features;
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release_ufd:
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close(ufd);
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return ret;
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}
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/**
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* request_ufd_features: this function should be called only once on a newly
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* opened ufd, subsequent calls will lead to error.
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*
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* Returns: true on success
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*
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* @ufd: fd obtained from userfaultfd syscall
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* @features: bit mask see UFFD_API_FEATURES
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*/
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static bool request_ufd_features(int ufd, uint64_t features)
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{
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struct uffdio_api api_struct = {0};
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uint64_t ioctl_mask;
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api_struct.api = UFFD_API;
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api_struct.features = features;
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if (ioctl(ufd, UFFDIO_API, &api_struct)) {
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error_report("%s failed: UFFDIO_API failed: %s", __func__,
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strerror(errno));
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return false;
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}
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ioctl_mask = 1ULL << _UFFDIO_REGISTER |
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1ULL << _UFFDIO_UNREGISTER;
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if ((api_struct.ioctls & ioctl_mask) != ioctl_mask) {
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error_report("Missing userfault features: %" PRIx64,
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(uint64_t)(~api_struct.ioctls & ioctl_mask));
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return false;
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}
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return true;
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}
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static bool ufd_check_and_apply(int ufd, MigrationIncomingState *mis,
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Error **errp)
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{
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ERRP_GUARD();
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uint64_t asked_features = 0;
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static uint64_t supported_features;
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/*
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* it's not possible to
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* request UFFD_API twice per one fd
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* userfault fd features is persistent
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*/
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if (!supported_features) {
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if (!receive_ufd_features(&supported_features)) {
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error_setg(errp, "Userfault feature detection failed");
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return false;
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}
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}
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#ifdef UFFD_FEATURE_THREAD_ID
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if (UFFD_FEATURE_THREAD_ID & supported_features) {
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asked_features |= UFFD_FEATURE_THREAD_ID;
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if (migrate_postcopy_blocktime()) {
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if (!mis->blocktime_ctx) {
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mis->blocktime_ctx = blocktime_context_new();
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}
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}
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}
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#endif
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/*
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* request features, even if asked_features is 0, due to
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* kernel expects UFFD_API before UFFDIO_REGISTER, per
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* userfault file descriptor
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*/
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if (!request_ufd_features(ufd, asked_features)) {
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error_setg(errp, "Failed features %" PRIu64, asked_features);
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return false;
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}
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if (qemu_real_host_page_size() != ram_pagesize_summary()) {
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bool have_hp = false;
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/* We've got a huge page */
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#ifdef UFFD_FEATURE_MISSING_HUGETLBFS
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have_hp = supported_features & UFFD_FEATURE_MISSING_HUGETLBFS;
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#endif
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if (!have_hp) {
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error_setg(errp,
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"Userfault on this host does not support huge pages");
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return false;
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}
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}
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return true;
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}
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/* Callback from postcopy_ram_supported_by_host block iterator.
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*/
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static int test_ramblock_postcopiable(RAMBlock *rb, Error **errp)
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{
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const char *block_name = qemu_ram_get_idstr(rb);
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ram_addr_t length = qemu_ram_get_used_length(rb);
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size_t pagesize = qemu_ram_pagesize(rb);
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QemuFsType fs;
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if (length % pagesize) {
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error_setg(errp,
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"Postcopy requires RAM blocks to be a page size multiple,"
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" block %s is 0x" RAM_ADDR_FMT " bytes with a "
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"page size of 0x%zx", block_name, length, pagesize);
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return 1;
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}
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if (rb->fd >= 0) {
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fs = qemu_fd_getfs(rb->fd);
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if (fs != QEMU_FS_TYPE_TMPFS && fs != QEMU_FS_TYPE_HUGETLBFS) {
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error_setg(errp,
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"Host backend files need to be TMPFS or HUGETLBFS only");
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return 1;
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}
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}
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return 0;
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}
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/*
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* Note: This has the side effect of munlock'ing all of RAM, that's
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* normally fine since if the postcopy succeeds it gets turned back on at the
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* end.
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*/
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bool postcopy_ram_supported_by_host(MigrationIncomingState *mis, Error **errp)
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{
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ERRP_GUARD();
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long pagesize = qemu_real_host_page_size();
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int ufd = -1;
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bool ret = false; /* Error unless we change it */
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void *testarea = NULL;
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struct uffdio_register reg_struct;
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struct uffdio_range range_struct;
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uint64_t feature_mask;
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RAMBlock *block;
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if (qemu_target_page_size() > pagesize) {
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error_setg(errp, "Target page size bigger than host page size");
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goto out;
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}
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ufd = uffd_open(O_CLOEXEC);
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if (ufd == -1) {
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error_setg(errp, "Userfaultfd not available: %s", strerror(errno));
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goto out;
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}
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/* Give devices a chance to object */
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if (postcopy_notify(POSTCOPY_NOTIFY_PROBE, errp)) {
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goto out;
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}
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|
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/* Version and features check */
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if (!ufd_check_and_apply(ufd, mis, errp)) {
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goto out;
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}
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|
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/*
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* We don't support postcopy with some type of ramblocks.
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*
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* NOTE: we explicitly ignored migrate_ram_is_ignored() instead we checked
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* all possible ramblocks. This is because this function can be called
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* when creating the migration object, during the phase RAM_MIGRATABLE
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* is not even properly set for all the ramblocks.
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*
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* A side effect of this is we'll also check against RAM_SHARED
|
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* ramblocks even if migrate_ignore_shared() is set (in which case
|
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* we'll never migrate RAM_SHARED at all), but normally this shouldn't
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* affect in reality, or we can revisit.
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*/
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RAMBLOCK_FOREACH(block) {
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if (test_ramblock_postcopiable(block, errp)) {
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goto out;
|
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}
|
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}
|
|
|
|
/*
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* userfault and mlock don't go together; we'll put it back later if
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* it was enabled.
|
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*/
|
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if (munlockall()) {
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error_setg(errp, "munlockall() failed: %s", strerror(errno));
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goto out;
|
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}
|
|
|
|
/*
|
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* We need to check that the ops we need are supported on anon memory
|
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* To do that we need to register a chunk and see the flags that
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* are returned.
|
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*/
|
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testarea = mmap(NULL, pagesize, PROT_READ | PROT_WRITE, MAP_PRIVATE |
|
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MAP_ANONYMOUS, -1, 0);
|
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if (testarea == MAP_FAILED) {
|
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error_setg(errp, "Failed to map test area: %s", strerror(errno));
|
|
goto out;
|
|
}
|
|
g_assert(QEMU_PTR_IS_ALIGNED(testarea, pagesize));
|
|
|
|
reg_struct.range.start = (uintptr_t)testarea;
|
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reg_struct.range.len = pagesize;
|
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reg_struct.mode = UFFDIO_REGISTER_MODE_MISSING;
|
|
|
|
if (ioctl(ufd, UFFDIO_REGISTER, ®_struct)) {
|
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error_setg(errp, "UFFDIO_REGISTER failed: %s", strerror(errno));
|
|
goto out;
|
|
}
|
|
|
|
range_struct.start = (uintptr_t)testarea;
|
|
range_struct.len = pagesize;
|
|
if (ioctl(ufd, UFFDIO_UNREGISTER, &range_struct)) {
|
|
error_setg(errp, "UFFDIO_UNREGISTER failed: %s", strerror(errno));
|
|
goto out;
|
|
}
|
|
|
|
feature_mask = 1ULL << _UFFDIO_WAKE |
|
|
1ULL << _UFFDIO_COPY |
|
|
1ULL << _UFFDIO_ZEROPAGE;
|
|
if ((reg_struct.ioctls & feature_mask) != feature_mask) {
|
|
error_setg(errp, "Missing userfault map features: %" PRIx64,
|
|
(uint64_t)(~reg_struct.ioctls & feature_mask));
|
|
goto out;
|
|
}
|
|
|
|
/* Success! */
|
|
ret = true;
|
|
out:
|
|
if (testarea) {
|
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munmap(testarea, pagesize);
|
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}
|
|
if (ufd != -1) {
|
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close(ufd);
|
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}
|
|
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(RAMBlock *rb, void *opaque)
|
|
{
|
|
const char *block_name = qemu_ram_get_idstr(rb);
|
|
void *host_addr = qemu_ram_get_host_addr(rb);
|
|
ram_addr_t offset = qemu_ram_get_offset(rb);
|
|
ram_addr_t length = qemu_ram_get_used_length(rb);
|
|
trace_postcopy_init_range(block_name, host_addr, offset, length);
|
|
|
|
/*
|
|
* Save the used_length before running the guest. In case we have to
|
|
* resize RAM blocks when syncing RAM block sizes from the source during
|
|
* precopy, we'll update it manually via the ram block notifier.
|
|
*/
|
|
rb->postcopy_length = 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(RAMBlock *rb, void *opaque)
|
|
{
|
|
const char *block_name = qemu_ram_get_idstr(rb);
|
|
void *host_addr = qemu_ram_get_host_addr(rb);
|
|
ram_addr_t offset = qemu_ram_get_offset(rb);
|
|
ram_addr_t length = rb->postcopy_length;
|
|
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)
|
|
{
|
|
if (foreach_not_ignored_block(init_range, NULL)) {
|
|
return -1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void postcopy_temp_pages_cleanup(MigrationIncomingState *mis)
|
|
{
|
|
int i;
|
|
|
|
if (mis->postcopy_tmp_pages) {
|
|
for (i = 0; i < mis->postcopy_channels; i++) {
|
|
if (mis->postcopy_tmp_pages[i].tmp_huge_page) {
|
|
munmap(mis->postcopy_tmp_pages[i].tmp_huge_page,
|
|
mis->largest_page_size);
|
|
mis->postcopy_tmp_pages[i].tmp_huge_page = NULL;
|
|
}
|
|
}
|
|
g_free(mis->postcopy_tmp_pages);
|
|
mis->postcopy_tmp_pages = NULL;
|
|
}
|
|
|
|
if (mis->postcopy_tmp_zero_page) {
|
|
munmap(mis->postcopy_tmp_zero_page, mis->largest_page_size);
|
|
mis->postcopy_tmp_zero_page = NULL;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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->preempt_thread_status == PREEMPT_THREAD_CREATED) {
|
|
/* Notify the fast load thread to quit */
|
|
mis->preempt_thread_status = PREEMPT_THREAD_QUIT;
|
|
/*
|
|
* Update preempt_thread_status before reading count. Note: mutex
|
|
* lock only provide ACQUIRE semantic, and it doesn't stops this
|
|
* write to be reordered after reading the count.
|
|
*/
|
|
smp_mb();
|
|
/*
|
|
* It's possible that the preempt thread is still handling the last
|
|
* pages to arrive which were requested by guest page faults.
|
|
* Making sure nothing is left behind by waiting on the condvar if
|
|
* that unlikely case happened.
|
|
*/
|
|
WITH_QEMU_LOCK_GUARD(&mis->page_request_mutex) {
|
|
if (qatomic_read(&mis->page_requested_count)) {
|
|
/*
|
|
* It is guaranteed to receive a signal later, because the
|
|
* count>0 now, so it's destined to be decreased to zero
|
|
* very soon by the preempt thread.
|
|
*/
|
|
qemu_cond_wait(&mis->page_request_cond,
|
|
&mis->page_request_mutex);
|
|
}
|
|
}
|
|
/* Notify the fast load thread to quit */
|
|
if (mis->postcopy_qemufile_dst) {
|
|
qemu_file_shutdown(mis->postcopy_qemufile_dst);
|
|
}
|
|
qemu_thread_join(&mis->postcopy_prio_thread);
|
|
mis->preempt_thread_status = PREEMPT_THREAD_NONE;
|
|
}
|
|
|
|
if (mis->have_fault_thread) {
|
|
Error *local_err = NULL;
|
|
|
|
/* Let the fault thread quit */
|
|
qatomic_set(&mis->fault_thread_quit, 1);
|
|
postcopy_fault_thread_notify(mis);
|
|
trace_postcopy_ram_incoming_cleanup_join();
|
|
qemu_thread_join(&mis->fault_thread);
|
|
|
|
if (postcopy_notify(POSTCOPY_NOTIFY_INBOUND_END, &local_err)) {
|
|
error_report_err(local_err);
|
|
return -1;
|
|
}
|
|
|
|
if (foreach_not_ignored_block(cleanup_range, mis)) {
|
|
return -1;
|
|
}
|
|
|
|
trace_postcopy_ram_incoming_cleanup_closeuf();
|
|
close(mis->userfault_fd);
|
|
close(mis->userfault_event_fd);
|
|
mis->have_fault_thread = 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_temp_pages_cleanup(mis);
|
|
|
|
trace_postcopy_ram_incoming_cleanup_blocktime(
|
|
get_postcopy_total_blocktime());
|
|
|
|
trace_postcopy_ram_incoming_cleanup_exit();
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Disable huge pages on an area
|
|
*/
|
|
static int nhp_range(RAMBlock *rb, void *opaque)
|
|
{
|
|
const char *block_name = qemu_ram_get_idstr(rb);
|
|
void *host_addr = qemu_ram_get_host_addr(rb);
|
|
ram_addr_t offset = qemu_ram_get_offset(rb);
|
|
ram_addr_t length = rb->postcopy_length;
|
|
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 (foreach_not_ignored_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 foreach_not_ignored_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(RAMBlock *rb, void *opaque)
|
|
{
|
|
MigrationIncomingState *mis = opaque;
|
|
struct uffdio_register reg_struct;
|
|
|
|
reg_struct.range.start = (uintptr_t)qemu_ram_get_host_addr(rb);
|
|
reg_struct.range.len = rb->postcopy_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 & (1ULL << _UFFDIO_COPY))) {
|
|
error_report("%s userfault: Region doesn't support COPY", __func__);
|
|
return -1;
|
|
}
|
|
if (reg_struct.ioctls & (1ULL << _UFFDIO_ZEROPAGE)) {
|
|
qemu_ram_set_uf_zeroable(rb);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
int postcopy_wake_shared(struct PostCopyFD *pcfd,
|
|
uint64_t client_addr,
|
|
RAMBlock *rb)
|
|
{
|
|
size_t pagesize = qemu_ram_pagesize(rb);
|
|
struct uffdio_range range;
|
|
int ret;
|
|
trace_postcopy_wake_shared(client_addr, qemu_ram_get_idstr(rb));
|
|
range.start = ROUND_DOWN(client_addr, pagesize);
|
|
range.len = pagesize;
|
|
ret = ioctl(pcfd->fd, UFFDIO_WAKE, &range);
|
|
if (ret) {
|
|
error_report("%s: Failed to wake: %zx in %s (%s)",
|
|
__func__, (size_t)client_addr, qemu_ram_get_idstr(rb),
|
|
strerror(errno));
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
static int postcopy_request_page(MigrationIncomingState *mis, RAMBlock *rb,
|
|
ram_addr_t start, uint64_t haddr)
|
|
{
|
|
void *aligned = (void *)(uintptr_t)ROUND_DOWN(haddr, qemu_ram_pagesize(rb));
|
|
|
|
/*
|
|
* Discarded pages (via RamDiscardManager) are never migrated. On unlikely
|
|
* access, place a zeropage, which will also set the relevant bits in the
|
|
* recv_bitmap accordingly, so we won't try placing a zeropage twice.
|
|
*
|
|
* Checking a single bit is sufficient to handle pagesize > TPS as either
|
|
* all relevant bits are set or not.
|
|
*/
|
|
assert(QEMU_IS_ALIGNED(start, qemu_ram_pagesize(rb)));
|
|
if (ramblock_page_is_discarded(rb, start)) {
|
|
bool received = ramblock_recv_bitmap_test_byte_offset(rb, start);
|
|
|
|
return received ? 0 : postcopy_place_page_zero(mis, aligned, rb);
|
|
}
|
|
|
|
return migrate_send_rp_req_pages(mis, rb, start, haddr);
|
|
}
|
|
|
|
/*
|
|
* Callback from shared fault handlers to ask for a page,
|
|
* the page must be specified by a RAMBlock and an offset in that rb
|
|
* Note: Only for use by shared fault handlers (in fault thread)
|
|
*/
|
|
int postcopy_request_shared_page(struct PostCopyFD *pcfd, RAMBlock *rb,
|
|
uint64_t client_addr, uint64_t rb_offset)
|
|
{
|
|
uint64_t aligned_rbo = ROUND_DOWN(rb_offset, qemu_ram_pagesize(rb));
|
|
MigrationIncomingState *mis = migration_incoming_get_current();
|
|
|
|
trace_postcopy_request_shared_page(pcfd->idstr, qemu_ram_get_idstr(rb),
|
|
rb_offset);
|
|
if (ramblock_recv_bitmap_test_byte_offset(rb, aligned_rbo)) {
|
|
trace_postcopy_request_shared_page_present(pcfd->idstr,
|
|
qemu_ram_get_idstr(rb), rb_offset);
|
|
return postcopy_wake_shared(pcfd, client_addr, rb);
|
|
}
|
|
postcopy_request_page(mis, rb, aligned_rbo, client_addr);
|
|
return 0;
|
|
}
|
|
|
|
static int get_mem_fault_cpu_index(uint32_t pid)
|
|
{
|
|
CPUState *cpu_iter;
|
|
|
|
CPU_FOREACH(cpu_iter) {
|
|
if (cpu_iter->thread_id == pid) {
|
|
trace_get_mem_fault_cpu_index(cpu_iter->cpu_index, pid);
|
|
return cpu_iter->cpu_index;
|
|
}
|
|
}
|
|
trace_get_mem_fault_cpu_index(-1, pid);
|
|
return -1;
|
|
}
|
|
|
|
static uint32_t get_low_time_offset(PostcopyBlocktimeContext *dc)
|
|
{
|
|
int64_t start_time_offset = qemu_clock_get_ms(QEMU_CLOCK_REALTIME) -
|
|
dc->start_time;
|
|
return start_time_offset < 1 ? 1 : start_time_offset & UINT32_MAX;
|
|
}
|
|
|
|
/*
|
|
* This function is being called when pagefault occurs. It
|
|
* tracks down vCPU blocking time.
|
|
*
|
|
* @addr: faulted host virtual address
|
|
* @ptid: faulted process thread id
|
|
* @rb: ramblock appropriate to addr
|
|
*/
|
|
static void mark_postcopy_blocktime_begin(uintptr_t addr, uint32_t ptid,
|
|
RAMBlock *rb)
|
|
{
|
|
int cpu, already_received;
|
|
MigrationIncomingState *mis = migration_incoming_get_current();
|
|
PostcopyBlocktimeContext *dc = mis->blocktime_ctx;
|
|
uint32_t low_time_offset;
|
|
|
|
if (!dc || ptid == 0) {
|
|
return;
|
|
}
|
|
cpu = get_mem_fault_cpu_index(ptid);
|
|
if (cpu < 0) {
|
|
return;
|
|
}
|
|
|
|
low_time_offset = get_low_time_offset(dc);
|
|
if (dc->vcpu_addr[cpu] == 0) {
|
|
qatomic_inc(&dc->smp_cpus_down);
|
|
}
|
|
|
|
qatomic_xchg(&dc->last_begin, low_time_offset);
|
|
qatomic_xchg(&dc->page_fault_vcpu_time[cpu], low_time_offset);
|
|
qatomic_xchg(&dc->vcpu_addr[cpu], addr);
|
|
|
|
/*
|
|
* check it here, not at the beginning of the function,
|
|
* due to, check could occur early than bitmap_set in
|
|
* qemu_ufd_copy_ioctl
|
|
*/
|
|
already_received = ramblock_recv_bitmap_test(rb, (void *)addr);
|
|
if (already_received) {
|
|
qatomic_xchg(&dc->vcpu_addr[cpu], 0);
|
|
qatomic_xchg(&dc->page_fault_vcpu_time[cpu], 0);
|
|
qatomic_dec(&dc->smp_cpus_down);
|
|
}
|
|
trace_mark_postcopy_blocktime_begin(addr, dc, dc->page_fault_vcpu_time[cpu],
|
|
cpu, already_received);
|
|
}
|
|
|
|
/*
|
|
* This function just provide calculated blocktime per cpu and trace it.
|
|
* Total blocktime is calculated in mark_postcopy_blocktime_end.
|
|
*
|
|
*
|
|
* Assume we have 3 CPU
|
|
*
|
|
* S1 E1 S1 E1
|
|
* -----***********------------xxx***************------------------------> CPU1
|
|
*
|
|
* S2 E2
|
|
* ------------****************xxx---------------------------------------> CPU2
|
|
*
|
|
* S3 E3
|
|
* ------------------------****xxx********-------------------------------> CPU3
|
|
*
|
|
* We have sequence S1,S2,E1,S3,S1,E2,E3,E1
|
|
* S2,E1 - doesn't match condition due to sequence S1,S2,E1 doesn't include CPU3
|
|
* S3,S1,E2 - sequence includes all CPUs, in this case overlap will be S1,E2 -
|
|
* it's a part of total blocktime.
|
|
* S1 - here is last_begin
|
|
* Legend of the picture is following:
|
|
* * - means blocktime per vCPU
|
|
* x - means overlapped blocktime (total blocktime)
|
|
*
|
|
* @addr: host virtual address
|
|
*/
|
|
static void mark_postcopy_blocktime_end(uintptr_t addr)
|
|
{
|
|
MigrationIncomingState *mis = migration_incoming_get_current();
|
|
PostcopyBlocktimeContext *dc = mis->blocktime_ctx;
|
|
MachineState *ms = MACHINE(qdev_get_machine());
|
|
unsigned int smp_cpus = ms->smp.cpus;
|
|
int i, affected_cpu = 0;
|
|
bool vcpu_total_blocktime = false;
|
|
uint32_t read_vcpu_time, low_time_offset;
|
|
|
|
if (!dc) {
|
|
return;
|
|
}
|
|
|
|
low_time_offset = get_low_time_offset(dc);
|
|
/* lookup cpu, to clear it,
|
|
* that algorithm looks straightforward, but it's not
|
|
* optimal, more optimal algorithm is keeping tree or hash
|
|
* where key is address value is a list of */
|
|
for (i = 0; i < smp_cpus; i++) {
|
|
uint32_t vcpu_blocktime = 0;
|
|
|
|
read_vcpu_time = qatomic_fetch_add(&dc->page_fault_vcpu_time[i], 0);
|
|
if (qatomic_fetch_add(&dc->vcpu_addr[i], 0) != addr ||
|
|
read_vcpu_time == 0) {
|
|
continue;
|
|
}
|
|
qatomic_xchg(&dc->vcpu_addr[i], 0);
|
|
vcpu_blocktime = low_time_offset - read_vcpu_time;
|
|
affected_cpu += 1;
|
|
/* we need to know is that mark_postcopy_end was due to
|
|
* faulted page, another possible case it's prefetched
|
|
* page and in that case we shouldn't be here */
|
|
if (!vcpu_total_blocktime &&
|
|
qatomic_fetch_add(&dc->smp_cpus_down, 0) == smp_cpus) {
|
|
vcpu_total_blocktime = true;
|
|
}
|
|
/* continue cycle, due to one page could affect several vCPUs */
|
|
dc->vcpu_blocktime[i] += vcpu_blocktime;
|
|
}
|
|
|
|
qatomic_sub(&dc->smp_cpus_down, affected_cpu);
|
|
if (vcpu_total_blocktime) {
|
|
dc->total_blocktime += low_time_offset - qatomic_fetch_add(
|
|
&dc->last_begin, 0);
|
|
}
|
|
trace_mark_postcopy_blocktime_end(addr, dc, dc->total_blocktime,
|
|
affected_cpu);
|
|
}
|
|
|
|
static void postcopy_pause_fault_thread(MigrationIncomingState *mis)
|
|
{
|
|
trace_postcopy_pause_fault_thread();
|
|
qemu_sem_wait(&mis->postcopy_pause_sem_fault);
|
|
trace_postcopy_pause_fault_thread_continued();
|
|
}
|
|
|
|
/*
|
|
* Handle faults detected by the USERFAULT markings
|
|
*/
|
|
static void *postcopy_ram_fault_thread(void *opaque)
|
|
{
|
|
MigrationIncomingState *mis = opaque;
|
|
struct uffd_msg msg;
|
|
int ret;
|
|
size_t index;
|
|
RAMBlock *rb = NULL;
|
|
|
|
trace_postcopy_ram_fault_thread_entry();
|
|
rcu_register_thread();
|
|
mis->last_rb = NULL; /* last RAMBlock we sent part of */
|
|
qemu_sem_post(&mis->thread_sync_sem);
|
|
|
|
struct pollfd *pfd;
|
|
size_t pfd_len = 2 + mis->postcopy_remote_fds->len;
|
|
|
|
pfd = g_new0(struct pollfd, pfd_len);
|
|
|
|
pfd[0].fd = mis->userfault_fd;
|
|
pfd[0].events = POLLIN;
|
|
pfd[1].fd = mis->userfault_event_fd;
|
|
pfd[1].events = POLLIN; /* Waiting for eventfd to go positive */
|
|
trace_postcopy_ram_fault_thread_fds_core(pfd[0].fd, pfd[1].fd);
|
|
for (index = 0; index < mis->postcopy_remote_fds->len; index++) {
|
|
struct PostCopyFD *pcfd = &g_array_index(mis->postcopy_remote_fds,
|
|
struct PostCopyFD, index);
|
|
pfd[2 + index].fd = pcfd->fd;
|
|
pfd[2 + index].events = POLLIN;
|
|
trace_postcopy_ram_fault_thread_fds_extra(2 + index, pcfd->idstr,
|
|
pcfd->fd);
|
|
}
|
|
|
|
while (true) {
|
|
ram_addr_t rb_offset;
|
|
int poll_result;
|
|
|
|
/*
|
|
* 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
|
|
*/
|
|
|
|
poll_result = poll(pfd, pfd_len, -1 /* Wait forever */);
|
|
if (poll_result == -1) {
|
|
error_report("%s: userfault poll: %s", __func__, strerror(errno));
|
|
break;
|
|
}
|
|
|
|
if (!mis->to_src_file) {
|
|
/*
|
|
* Possibly someone tells us that the return path is
|
|
* broken already using the event. We should hold until
|
|
* the channel is rebuilt.
|
|
*/
|
|
postcopy_pause_fault_thread(mis);
|
|
}
|
|
|
|
if (pfd[1].revents) {
|
|
uint64_t tmp64 = 0;
|
|
|
|
/* Consume the signal */
|
|
if (read(mis->userfault_event_fd, &tmp64, 8) != 8) {
|
|
/* Nothing obviously nicer than posting this error. */
|
|
error_report("%s: read() failed", __func__);
|
|
}
|
|
|
|
if (qatomic_read(&mis->fault_thread_quit)) {
|
|
trace_postcopy_ram_fault_thread_quit();
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (pfd[0].revents) {
|
|
poll_result--;
|
|
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 = ROUND_DOWN(rb_offset, qemu_ram_pagesize(rb));
|
|
trace_postcopy_ram_fault_thread_request(msg.arg.pagefault.address,
|
|
qemu_ram_get_idstr(rb),
|
|
rb_offset,
|
|
msg.arg.pagefault.feat.ptid);
|
|
mark_postcopy_blocktime_begin(
|
|
(uintptr_t)(msg.arg.pagefault.address),
|
|
msg.arg.pagefault.feat.ptid, rb);
|
|
|
|
retry:
|
|
/*
|
|
* Send the request to the source - we want to request one
|
|
* of our host page sizes (which is >= TPS)
|
|
*/
|
|
ret = postcopy_request_page(mis, rb, rb_offset,
|
|
msg.arg.pagefault.address);
|
|
if (ret) {
|
|
/* May be network failure, try to wait for recovery */
|
|
postcopy_pause_fault_thread(mis);
|
|
goto retry;
|
|
}
|
|
}
|
|
|
|
/* Now handle any requests from external processes on shared memory */
|
|
/* TODO: May need to handle devices deregistering during postcopy */
|
|
for (index = 2; index < pfd_len && poll_result; index++) {
|
|
if (pfd[index].revents) {
|
|
struct PostCopyFD *pcfd =
|
|
&g_array_index(mis->postcopy_remote_fds,
|
|
struct PostCopyFD, index - 2);
|
|
|
|
poll_result--;
|
|
if (pfd[index].revents & POLLERR) {
|
|
error_report("%s: POLLERR on poll %zd fd=%d",
|
|
__func__, index, pcfd->fd);
|
|
pfd[index].events = 0;
|
|
continue;
|
|
}
|
|
|
|
ret = read(pcfd->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 (shared) revents=%d",
|
|
__func__, strerror(errno),
|
|
pfd[index].revents);
|
|
/*TODO: Could just disable this sharer */
|
|
break;
|
|
} else {
|
|
error_report("%s: Read %d bytes from userfaultfd "
|
|
"expected %zd (shared)",
|
|
__func__, ret, sizeof(msg));
|
|
/*TODO: Could just disable this sharer */
|
|
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 (shared)",
|
|
__func__, msg.event);
|
|
continue; /* It's not a page fault, shouldn't happen */
|
|
}
|
|
/* Call the device handler registered with us */
|
|
ret = pcfd->handler(pcfd, &msg);
|
|
if (ret) {
|
|
error_report("%s: Failed to resolve shared fault on %zd/%s",
|
|
__func__, index, pcfd->idstr);
|
|
/* TODO: Fail? Disable this sharer? */
|
|
}
|
|
}
|
|
}
|
|
}
|
|
rcu_unregister_thread();
|
|
trace_postcopy_ram_fault_thread_exit();
|
|
g_free(pfd);
|
|
return NULL;
|
|
}
|
|
|
|
static int postcopy_temp_pages_setup(MigrationIncomingState *mis)
|
|
{
|
|
PostcopyTmpPage *tmp_page;
|
|
int err, i, channels;
|
|
void *temp_page;
|
|
|
|
if (migrate_postcopy_preempt()) {
|
|
/* If preemption enabled, need extra channel for urgent requests */
|
|
mis->postcopy_channels = RAM_CHANNEL_MAX;
|
|
} else {
|
|
/* Both precopy/postcopy on the same channel */
|
|
mis->postcopy_channels = 1;
|
|
}
|
|
|
|
channels = mis->postcopy_channels;
|
|
mis->postcopy_tmp_pages = g_malloc0_n(sizeof(PostcopyTmpPage), channels);
|
|
|
|
for (i = 0; i < channels; i++) {
|
|
tmp_page = &mis->postcopy_tmp_pages[i];
|
|
temp_page = mmap(NULL, mis->largest_page_size, PROT_READ | PROT_WRITE,
|
|
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
|
|
if (temp_page == MAP_FAILED) {
|
|
err = errno;
|
|
error_report("%s: Failed to map postcopy_tmp_pages[%d]: %s",
|
|
__func__, i, strerror(err));
|
|
/* Clean up will be done later */
|
|
return -err;
|
|
}
|
|
tmp_page->tmp_huge_page = temp_page;
|
|
/* Initialize default states for each tmp page */
|
|
postcopy_temp_page_reset(tmp_page);
|
|
}
|
|
|
|
/*
|
|
* Map large zero page when kernel can't use UFFDIO_ZEROPAGE for hugepages
|
|
*/
|
|
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) {
|
|
err = errno;
|
|
mis->postcopy_tmp_zero_page = NULL;
|
|
error_report("%s: Failed to map large zero page %s",
|
|
__func__, strerror(err));
|
|
return -err;
|
|
}
|
|
|
|
memset(mis->postcopy_tmp_zero_page, '\0', mis->largest_page_size);
|
|
|
|
return 0;
|
|
}
|
|
|
|
int postcopy_ram_incoming_setup(MigrationIncomingState *mis)
|
|
{
|
|
Error *local_err = NULL;
|
|
|
|
/* Open the fd for the kernel to give us userfaults */
|
|
mis->userfault_fd = uffd_open(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_check_and_apply(mis->userfault_fd, mis, &local_err)) {
|
|
error_report_err(local_err);
|
|
return -1;
|
|
}
|
|
|
|
/* Now an eventfd we use to tell the fault-thread to quit */
|
|
mis->userfault_event_fd = eventfd(0, EFD_CLOEXEC);
|
|
if (mis->userfault_event_fd == -1) {
|
|
error_report("%s: Opening userfault_event_fd: %s", __func__,
|
|
strerror(errno));
|
|
close(mis->userfault_fd);
|
|
return -1;
|
|
}
|
|
|
|
postcopy_thread_create(mis, &mis->fault_thread, "fault-default",
|
|
postcopy_ram_fault_thread, QEMU_THREAD_JOINABLE);
|
|
mis->have_fault_thread = true;
|
|
|
|
/* Mark so that we get notified of accesses to unwritten areas */
|
|
if (foreach_not_ignored_block(ram_block_enable_notify, mis)) {
|
|
error_report("ram_block_enable_notify failed");
|
|
return -1;
|
|
}
|
|
|
|
if (postcopy_temp_pages_setup(mis)) {
|
|
/* Error dumped in the sub-function */
|
|
return -1;
|
|
}
|
|
|
|
if (migrate_postcopy_preempt()) {
|
|
/*
|
|
* This thread needs to be created after the temp pages because
|
|
* it'll fetch RAM_CHANNEL_POSTCOPY PostcopyTmpPage immediately.
|
|
*/
|
|
postcopy_thread_create(mis, &mis->postcopy_prio_thread, "fault-fast",
|
|
postcopy_preempt_thread, QEMU_THREAD_JOINABLE);
|
|
mis->preempt_thread_status = PREEMPT_THREAD_CREATED;
|
|
}
|
|
|
|
trace_postcopy_ram_enable_notify();
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int qemu_ufd_copy_ioctl(MigrationIncomingState *mis, void *host_addr,
|
|
void *from_addr, uint64_t pagesize, RAMBlock *rb)
|
|
{
|
|
int userfault_fd = mis->userfault_fd;
|
|
int ret;
|
|
|
|
if (from_addr) {
|
|
struct uffdio_copy copy_struct;
|
|
copy_struct.dst = (uint64_t)(uintptr_t)host_addr;
|
|
copy_struct.src = (uint64_t)(uintptr_t)from_addr;
|
|
copy_struct.len = pagesize;
|
|
copy_struct.mode = 0;
|
|
ret = ioctl(userfault_fd, UFFDIO_COPY, ©_struct);
|
|
} else {
|
|
struct uffdio_zeropage zero_struct;
|
|
zero_struct.range.start = (uint64_t)(uintptr_t)host_addr;
|
|
zero_struct.range.len = pagesize;
|
|
zero_struct.mode = 0;
|
|
ret = ioctl(userfault_fd, UFFDIO_ZEROPAGE, &zero_struct);
|
|
}
|
|
if (!ret) {
|
|
qemu_mutex_lock(&mis->page_request_mutex);
|
|
ramblock_recv_bitmap_set_range(rb, host_addr,
|
|
pagesize / qemu_target_page_size());
|
|
/*
|
|
* If this page resolves a page fault for a previous recorded faulted
|
|
* address, take a special note to maintain the requested page list.
|
|
*/
|
|
if (g_tree_lookup(mis->page_requested, host_addr)) {
|
|
g_tree_remove(mis->page_requested, host_addr);
|
|
int left_pages = qatomic_dec_fetch(&mis->page_requested_count);
|
|
|
|
trace_postcopy_page_req_del(host_addr, mis->page_requested_count);
|
|
/* Order the update of count and read of preempt status */
|
|
smp_mb();
|
|
if (mis->preempt_thread_status == PREEMPT_THREAD_QUIT &&
|
|
left_pages == 0) {
|
|
/*
|
|
* This probably means the main thread is waiting for us.
|
|
* Notify that we've finished receiving the last requested
|
|
* page.
|
|
*/
|
|
qemu_cond_signal(&mis->page_request_cond);
|
|
}
|
|
}
|
|
qemu_mutex_unlock(&mis->page_request_mutex);
|
|
mark_postcopy_blocktime_end((uintptr_t)host_addr);
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
int postcopy_notify_shared_wake(RAMBlock *rb, uint64_t offset)
|
|
{
|
|
int i;
|
|
MigrationIncomingState *mis = migration_incoming_get_current();
|
|
GArray *pcrfds = mis->postcopy_remote_fds;
|
|
|
|
for (i = 0; i < pcrfds->len; i++) {
|
|
struct PostCopyFD *cur = &g_array_index(pcrfds, struct PostCopyFD, i);
|
|
int ret = cur->waker(cur, rb, offset);
|
|
if (ret) {
|
|
return ret;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Place a host page (from) at (host) atomically
|
|
* returns 0 on success
|
|
*/
|
|
int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from,
|
|
RAMBlock *rb)
|
|
{
|
|
size_t pagesize = qemu_ram_pagesize(rb);
|
|
|
|
/* 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 (qemu_ufd_copy_ioctl(mis, host, from, pagesize, rb)) {
|
|
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 postcopy_notify_shared_wake(rb,
|
|
qemu_ram_block_host_offset(rb, host));
|
|
}
|
|
|
|
/*
|
|
* Place a zero page at (host) atomically
|
|
* returns 0 on success
|
|
*/
|
|
int postcopy_place_page_zero(MigrationIncomingState *mis, void *host,
|
|
RAMBlock *rb)
|
|
{
|
|
size_t pagesize = qemu_ram_pagesize(rb);
|
|
trace_postcopy_place_page_zero(host);
|
|
|
|
/* Normal RAMBlocks can zero a page using UFFDIO_ZEROPAGE
|
|
* but it's not available for everything (e.g. hugetlbpages)
|
|
*/
|
|
if (qemu_ram_is_uf_zeroable(rb)) {
|
|
if (qemu_ufd_copy_ioctl(mis, host, NULL, pagesize, rb)) {
|
|
int e = errno;
|
|
error_report("%s: %s zero host: %p",
|
|
__func__, strerror(e), host);
|
|
|
|
return -e;
|
|
}
|
|
return postcopy_notify_shared_wake(rb,
|
|
qemu_ram_block_host_offset(rb,
|
|
host));
|
|
} else {
|
|
return postcopy_place_page(mis, host, mis->postcopy_tmp_zero_page, rb);
|
|
}
|
|
}
|
|
|
|
#else
|
|
/* No target OS support, stubs just fail */
|
|
void fill_destination_postcopy_migration_info(MigrationInfo *info)
|
|
{
|
|
}
|
|
|
|
bool postcopy_ram_supported_by_host(MigrationIncomingState *mis, Error **errp)
|
|
{
|
|
error_report("%s: No OS support", __func__);
|
|
return false;
|
|
}
|
|
|
|
int postcopy_ram_incoming_init(MigrationIncomingState *mis)
|
|
{
|
|
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_request_shared_page(struct PostCopyFD *pcfd, RAMBlock *rb,
|
|
uint64_t client_addr, uint64_t rb_offset)
|
|
{
|
|
assert(0);
|
|
return -1;
|
|
}
|
|
|
|
int postcopy_ram_incoming_setup(MigrationIncomingState *mis)
|
|
{
|
|
assert(0);
|
|
return -1;
|
|
}
|
|
|
|
int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from,
|
|
RAMBlock *rb)
|
|
{
|
|
assert(0);
|
|
return -1;
|
|
}
|
|
|
|
int postcopy_place_page_zero(MigrationIncomingState *mis, void *host,
|
|
RAMBlock *rb)
|
|
{
|
|
assert(0);
|
|
return -1;
|
|
}
|
|
|
|
int postcopy_wake_shared(struct PostCopyFD *pcfd,
|
|
uint64_t client_addr,
|
|
RAMBlock *rb)
|
|
{
|
|
assert(0);
|
|
return -1;
|
|
}
|
|
#endif
|
|
|
|
/* ------------------------------------------------------------------------- */
|
|
void postcopy_temp_page_reset(PostcopyTmpPage *tmp_page)
|
|
{
|
|
tmp_page->target_pages = 0;
|
|
tmp_page->host_addr = NULL;
|
|
/*
|
|
* This is set to true when reset, and cleared as long as we received any
|
|
* of the non-zero small page within this huge page.
|
|
*/
|
|
tmp_page->all_zero = true;
|
|
}
|
|
|
|
void postcopy_fault_thread_notify(MigrationIncomingState *mis)
|
|
{
|
|
uint64_t tmp64 = 1;
|
|
|
|
/*
|
|
* Wakeup the fault_thread. It's an eventfd that should currently
|
|
* be at 0, we're going to increment it to 1
|
|
*/
|
|
if (write(mis->userfault_event_fd, &tmp64, 8) != 8) {
|
|
/* Not much we can do here, but may as well report it */
|
|
error_report("%s: incrementing failed: %s", __func__,
|
|
strerror(errno));
|
|
}
|
|
}
|
|
|
|
/**
|
|
* 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.
|
|
*/
|
|
static PostcopyDiscardState pds = {0};
|
|
void postcopy_discard_send_init(MigrationState *ms, const char *name)
|
|
{
|
|
pds.ramblock_name = name;
|
|
pds.cur_entry = 0;
|
|
pds.nsentwords = 0;
|
|
pds.nsentcmds = 0;
|
|
}
|
|
|
|
/**
|
|
* 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.
|
|
* @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, 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.
|
|
*/
|
|
void postcopy_discard_send_finish(MigrationState *ms)
|
|
{
|
|
/* 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);
|
|
}
|
|
|
|
/*
|
|
* 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 qatomic_load_acquire(&incoming_postcopy_state);
|
|
}
|
|
|
|
/* Set the state and return the old state */
|
|
PostcopyState postcopy_state_set(PostcopyState new_state)
|
|
{
|
|
return qatomic_xchg(&incoming_postcopy_state, new_state);
|
|
}
|
|
|
|
/* Register a handler for external shared memory postcopy
|
|
* called on the destination.
|
|
*/
|
|
void postcopy_register_shared_ufd(struct PostCopyFD *pcfd)
|
|
{
|
|
MigrationIncomingState *mis = migration_incoming_get_current();
|
|
|
|
mis->postcopy_remote_fds = g_array_append_val(mis->postcopy_remote_fds,
|
|
*pcfd);
|
|
}
|
|
|
|
/* Unregister a handler for external shared memory postcopy
|
|
*/
|
|
void postcopy_unregister_shared_ufd(struct PostCopyFD *pcfd)
|
|
{
|
|
guint i;
|
|
MigrationIncomingState *mis = migration_incoming_get_current();
|
|
GArray *pcrfds = mis->postcopy_remote_fds;
|
|
|
|
if (!pcrfds) {
|
|
/* migration has already finished and freed the array */
|
|
return;
|
|
}
|
|
for (i = 0; i < pcrfds->len; i++) {
|
|
struct PostCopyFD *cur = &g_array_index(pcrfds, struct PostCopyFD, i);
|
|
if (cur->fd == pcfd->fd) {
|
|
mis->postcopy_remote_fds = g_array_remove_index(pcrfds, i);
|
|
return;
|
|
}
|
|
}
|
|
}
|
|
|
|
void postcopy_preempt_new_channel(MigrationIncomingState *mis, QEMUFile *file)
|
|
{
|
|
/*
|
|
* The new loading channel has its own threads, so it needs to be
|
|
* blocked too. It's by default true, just be explicit.
|
|
*/
|
|
qemu_file_set_blocking(file, true);
|
|
mis->postcopy_qemufile_dst = file;
|
|
qemu_sem_post(&mis->postcopy_qemufile_dst_done);
|
|
trace_postcopy_preempt_new_channel();
|
|
}
|
|
|
|
/*
|
|
* Setup the postcopy preempt channel with the IOC. If ERROR is specified,
|
|
* setup the error instead. This helper will free the ERROR if specified.
|
|
*/
|
|
static void
|
|
postcopy_preempt_send_channel_done(MigrationState *s,
|
|
QIOChannel *ioc, Error *local_err)
|
|
{
|
|
if (local_err) {
|
|
migrate_set_error(s, local_err);
|
|
error_free(local_err);
|
|
} else {
|
|
migration_ioc_register_yank(ioc);
|
|
s->postcopy_qemufile_src = qemu_file_new_output(ioc);
|
|
trace_postcopy_preempt_new_channel();
|
|
}
|
|
|
|
/*
|
|
* Kick the waiter in all cases. The waiter should check upon
|
|
* postcopy_qemufile_src to know whether it failed or not.
|
|
*/
|
|
qemu_sem_post(&s->postcopy_qemufile_src_sem);
|
|
}
|
|
|
|
static void
|
|
postcopy_preempt_tls_handshake(QIOTask *task, gpointer opaque)
|
|
{
|
|
g_autoptr(QIOChannel) ioc = QIO_CHANNEL(qio_task_get_source(task));
|
|
MigrationState *s = opaque;
|
|
Error *local_err = NULL;
|
|
|
|
qio_task_propagate_error(task, &local_err);
|
|
postcopy_preempt_send_channel_done(s, ioc, local_err);
|
|
}
|
|
|
|
static void
|
|
postcopy_preempt_send_channel_new(QIOTask *task, gpointer opaque)
|
|
{
|
|
g_autoptr(QIOChannel) ioc = QIO_CHANNEL(qio_task_get_source(task));
|
|
MigrationState *s = opaque;
|
|
QIOChannelTLS *tioc;
|
|
Error *local_err = NULL;
|
|
|
|
if (qio_task_propagate_error(task, &local_err)) {
|
|
goto out;
|
|
}
|
|
|
|
if (migrate_channel_requires_tls_upgrade(ioc)) {
|
|
tioc = migration_tls_client_create(ioc, s->hostname, &local_err);
|
|
if (!tioc) {
|
|
goto out;
|
|
}
|
|
trace_postcopy_preempt_tls_handshake();
|
|
qio_channel_set_name(QIO_CHANNEL(tioc), "migration-tls-preempt");
|
|
qio_channel_tls_handshake(tioc, postcopy_preempt_tls_handshake,
|
|
s, NULL, NULL);
|
|
/* Setup the channel until TLS handshake finished */
|
|
return;
|
|
}
|
|
|
|
out:
|
|
/* This handles both good and error cases */
|
|
postcopy_preempt_send_channel_done(s, ioc, local_err);
|
|
}
|
|
|
|
/*
|
|
* This function will kick off an async task to establish the preempt
|
|
* channel, and wait until the connection setup completed. Returns 0 if
|
|
* channel established, -1 for error.
|
|
*/
|
|
int postcopy_preempt_establish_channel(MigrationState *s)
|
|
{
|
|
/* If preempt not enabled, no need to wait */
|
|
if (!migrate_postcopy_preempt()) {
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Kick off async task to establish preempt channel. Only do so with
|
|
* 8.0+ machines, because 7.1/7.2 require the channel to be created in
|
|
* setup phase of migration (even if racy in an unreliable network).
|
|
*/
|
|
if (!s->preempt_pre_7_2) {
|
|
postcopy_preempt_setup(s);
|
|
}
|
|
|
|
/*
|
|
* We need the postcopy preempt channel to be established before
|
|
* starting doing anything.
|
|
*/
|
|
qemu_sem_wait(&s->postcopy_qemufile_src_sem);
|
|
|
|
return s->postcopy_qemufile_src ? 0 : -1;
|
|
}
|
|
|
|
void postcopy_preempt_setup(MigrationState *s)
|
|
{
|
|
/* Kick an async task to connect */
|
|
socket_send_channel_create(postcopy_preempt_send_channel_new, s);
|
|
}
|
|
|
|
static void postcopy_pause_ram_fast_load(MigrationIncomingState *mis)
|
|
{
|
|
trace_postcopy_pause_fast_load();
|
|
qemu_mutex_unlock(&mis->postcopy_prio_thread_mutex);
|
|
qemu_sem_wait(&mis->postcopy_pause_sem_fast_load);
|
|
qemu_mutex_lock(&mis->postcopy_prio_thread_mutex);
|
|
trace_postcopy_pause_fast_load_continued();
|
|
}
|
|
|
|
static bool preempt_thread_should_run(MigrationIncomingState *mis)
|
|
{
|
|
return mis->preempt_thread_status != PREEMPT_THREAD_QUIT;
|
|
}
|
|
|
|
void *postcopy_preempt_thread(void *opaque)
|
|
{
|
|
MigrationIncomingState *mis = opaque;
|
|
int ret;
|
|
|
|
trace_postcopy_preempt_thread_entry();
|
|
|
|
rcu_register_thread();
|
|
|
|
qemu_sem_post(&mis->thread_sync_sem);
|
|
|
|
/*
|
|
* The preempt channel is established in asynchronous way. Wait
|
|
* for its completion.
|
|
*/
|
|
qemu_sem_wait(&mis->postcopy_qemufile_dst_done);
|
|
|
|
/* Sending RAM_SAVE_FLAG_EOS to terminate this thread */
|
|
qemu_mutex_lock(&mis->postcopy_prio_thread_mutex);
|
|
while (preempt_thread_should_run(mis)) {
|
|
ret = ram_load_postcopy(mis->postcopy_qemufile_dst,
|
|
RAM_CHANNEL_POSTCOPY);
|
|
/* If error happened, go into recovery routine */
|
|
if (ret && preempt_thread_should_run(mis)) {
|
|
postcopy_pause_ram_fast_load(mis);
|
|
} else {
|
|
/* We're done */
|
|
break;
|
|
}
|
|
}
|
|
qemu_mutex_unlock(&mis->postcopy_prio_thread_mutex);
|
|
|
|
rcu_unregister_thread();
|
|
|
|
trace_postcopy_preempt_thread_exit();
|
|
|
|
return NULL;
|
|
}
|