197 lines
6.3 KiB
Diff
197 lines
6.3 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Stefan Reiter <s.reiter@proxmox.com>
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Date: Thu, 22 Oct 2020 17:34:18 +0200
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Subject: [PATCH] PVE: Migrate dirty bitmap state via savevm
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QEMU provides 'savevm' registrations as a mechanism for arbitrary state
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to be migrated along with a VM. Use this to send a serialized version of
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dirty bitmap state data from proxmox-backup-qemu, and restore it on the
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target node.
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Also add a flag to query-proxmox-support so qemu-server can determine if
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safe migration is possible and makes sense.
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Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
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---
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include/migration/misc.h | 3 ++
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migration/Makefile.objs | 1 +
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migration/pbs-state.c | 97 ++++++++++++++++++++++++++++++++++++++++
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pve-backup.c | 1 +
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qapi/block-core.json | 9 +++-
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softmmu/vl.c | 1 +
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6 files changed, 111 insertions(+), 1 deletion(-)
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create mode 100644 migration/pbs-state.c
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diff --git a/include/migration/misc.h b/include/migration/misc.h
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index 34e7d75713..f83816dd3c 100644
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--- a/include/migration/misc.h
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+++ b/include/migration/misc.h
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@@ -75,4 +75,7 @@ bool migration_in_incoming_postcopy(void);
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/* migration/block-dirty-bitmap.c */
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void dirty_bitmap_mig_init(void);
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+/* migration/pbs-state.c */
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+void pbs_state_mig_init(void);
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+
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#endif
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diff --git a/migration/Makefile.objs b/migration/Makefile.objs
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index 0fc619e380..20b3792599 100644
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--- a/migration/Makefile.objs
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+++ b/migration/Makefile.objs
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@@ -9,6 +9,7 @@ common-obj-y += qjson.o
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common-obj-y += block-dirty-bitmap.o
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common-obj-y += multifd.o
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common-obj-y += multifd-zlib.o
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+common-obj-y += pbs-state.o
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common-obj-$(CONFIG_ZSTD) += multifd-zstd.o
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common-obj-$(CONFIG_RDMA) += rdma.o
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diff --git a/migration/pbs-state.c b/migration/pbs-state.c
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new file mode 100644
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index 0000000000..c711498c3e
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--- /dev/null
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+++ b/migration/pbs-state.c
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@@ -0,0 +1,97 @@
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+/*
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+ * PBS (dirty-bitmap) state migration
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+ */
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+
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+#include "qemu/osdep.h"
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+#include "migration/misc.h"
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+#include "qemu-file.h"
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+#include "migration/vmstate.h"
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+#include "migration/register.h"
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+#include "proxmox-backup-qemu.h"
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+
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+typedef struct PBSState {
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+ bool active;
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+} PBSState;
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+
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+static PBSState pbs_state;
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+
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+static void pbs_state_save_pending(QEMUFile *f, void *opaque,
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+ uint64_t max_size,
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+ uint64_t *res_precopy_only,
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+ uint64_t *res_compatible,
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+ uint64_t *res_postcopy_only)
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+{
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+ /* we send everything in save_setup, so nothing is ever pending */
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+}
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+
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+/* receive PBS state via f and deserialize, called on target */
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+static int pbs_state_load(QEMUFile *f, void *opaque, int version_id)
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+{
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+ /* safe cast, we cannot migrate to target with less bits than source */
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+ size_t buf_size = (size_t)qemu_get_be64(f);
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+
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+ uint8_t *buf = (uint8_t *)malloc(buf_size);
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+ size_t read = qemu_get_buffer(f, buf, buf_size);
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+
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+ if (read < buf_size) {
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+ fprintf(stderr, "error receiving PBS state: not enough data\n");
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+ return -EIO;
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+ }
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+
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+ proxmox_import_state(buf, buf_size);
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+
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+ free(buf);
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+ return 0;
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+}
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+
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+/* serialize PBS state and send to target via f, called on source */
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+static int pbs_state_save_setup(QEMUFile *f, void *opaque)
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+{
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+ size_t buf_size;
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+ uint8_t *buf = proxmox_export_state(&buf_size);
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+
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+ /* LV encoding */
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+ qemu_put_be64(f, buf_size);
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+ qemu_put_buffer(f, buf, buf_size);
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+
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+ proxmox_free_state_buf(buf);
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+ pbs_state.active = false;
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+ return 0;
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+}
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+
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+static bool pbs_state_is_active(void *opaque)
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+{
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+ // we need to be return active once, else .save_setup is never called, but,
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+ // if we'd just would return true, we'd freeze the migration for ~ 5 - 10s
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+ return pbs_state.active;
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+}
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+
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+static bool pbs_state_is_active_iterate(void *opaque)
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+{
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+ /* we don't iterate, everything is sent in save_setup */
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+ return pbs_state_is_active(opaque);
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+}
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+
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+static bool pbs_state_has_postcopy(void *opaque)
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+{
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+ /* PBS state can't change during a migration (since that's blocking any
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+ * potential backups), so we can copy everything before the VM is stopped */
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+ return false;
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+}
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+
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+static SaveVMHandlers savevm_pbs_state_handlers = {
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+ .save_setup = pbs_state_save_setup,
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+ .has_postcopy = pbs_state_has_postcopy,
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+ .save_live_pending = pbs_state_save_pending,
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+ .is_active_iterate = pbs_state_is_active_iterate,
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+ .load_state = pbs_state_load,
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+ .is_active = pbs_state_is_active,
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+};
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+
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+void pbs_state_mig_init(void)
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+{
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+ pbs_state.active = true;
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+ register_savevm_live("pbs-state", 0, 1,
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+ &savevm_pbs_state_handlers,
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+ &pbs_state);
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+}
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diff --git a/pve-backup.c b/pve-backup.c
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index 1a2647e7a5..c12ff8bb61 100644
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--- a/pve-backup.c
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+++ b/pve-backup.c
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@@ -1129,5 +1129,6 @@ ProxmoxSupportStatus *qmp_query_proxmox_support(Error **errp)
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ProxmoxSupportStatus *ret = g_malloc0(sizeof(*ret));
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ret->pbs_dirty_bitmap = true;
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ret->query_bitmap_info = true;
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+ ret->pbs_dirty_bitmap_migration = true;
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return ret;
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}
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diff --git a/qapi/block-core.json b/qapi/block-core.json
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index b31ad8d989..00c9e12fcc 100644
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--- a/qapi/block-core.json
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+++ b/qapi/block-core.json
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@@ -890,9 +890,16 @@
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#
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# @query-bitmap-info: True if the 'query-pbs-bitmap-info' QMP call is supported.
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#
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+# @pbs-dirty-bitmap-migration: True if safe migration of dirty-bitmaps including
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+# PBS state is supported. Enabling 'dirty-bitmaps'
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+# migration cap if this is false/unset may lead
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+# to crashes on migration!
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+#
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##
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{ 'struct': 'ProxmoxSupportStatus',
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- 'data': { 'pbs-dirty-bitmap': 'bool', 'query-bitmap-info': 'bool' } }
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+ 'data': { 'pbs-dirty-bitmap': 'bool',
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+ 'query-bitmap-info': 'bool',
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+ 'pbs-dirty-bitmap-migration': 'bool' } }
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##
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# @query-proxmox-support:
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diff --git a/softmmu/vl.c b/softmmu/vl.c
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index 16aa2186b0..88b13871fd 100644
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--- a/softmmu/vl.c
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+++ b/softmmu/vl.c
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@@ -4288,6 +4288,7 @@ void qemu_init(int argc, char **argv, char **envp)
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blk_mig_init();
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ram_mig_init();
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dirty_bitmap_mig_init();
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+ pbs_state_mig_init();
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qemu_opts_foreach(qemu_find_opts("mon"),
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mon_init_func, NULL, &error_fatal);
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