debian/patches/pve/0040-PVE-Migrate-dirty-bitmap-state-via-savevm.patch

   1 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
   2 From: Stefan Reiter <s.reiter@proxmox.com>
   3 Date: Thu, 22 Oct 2020 17:34:18 +0200
   4 Subject: [PATCH] PVE: Migrate dirty bitmap state via savevm
   5
   6 QEMU provides 'savevm' registrations as a mechanism for arbitrary state
   7 to be migrated along with a VM. Use this to send a serialized version of
   8 dirty bitmap state data from proxmox-backup-qemu, and restore it on the
   9 target node.
  10
  11 Also add a flag to query-proxmox-support so qemu-server can determine if
  12 safe migration is possible and makes sense.
  13
  14 Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
  15 Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
  16 ---
  17  include/migration/misc.h |   3 ++
  18  migration/meson.build    |   2 +
  19  migration/migration.c    |   1 +
  20  migration/pbs-state.c    | 106 +++++++++++++++++++++++++++++++++++++++
  21  pve-backup.c             |   1 +
  22  qapi/block-core.json     |   6 +++
  23  6 files changed, 119 insertions(+)
  24  create mode 100644 migration/pbs-state.c
  25
  26 diff --git a/include/migration/misc.h b/include/migration/misc.h
  27 index 465906710d..4f0aeceb6f 100644
  28 --- a/include/migration/misc.h
  29 +++ b/include/migration/misc.h
  30 @@ -75,4 +75,7 @@ bool migration_in_bg_snapshot(void);
  31  /* migration/block-dirty-bitmap.c */
  32  void dirty_bitmap_mig_init(void);
  33
  34 +/* migration/pbs-state.c */
  35 +void pbs_state_mig_init(void);
  36 +
  37  #endif
  38 diff --git a/migration/meson.build b/migration/meson.build
  39 index 0842d00cd2..d012f4d8d3 100644
  40 --- a/migration/meson.build
  41 +++ b/migration/meson.build
  42 @@ -6,8 +6,10 @@ migration_files = files(
  43    'vmstate.c',
  44    'qemu-file.c',
  45    'yank_functions.c',
  46 +  'pbs-state.c',
  47  )
  48  softmmu_ss.add(migration_files)
  49 +softmmu_ss.add(libproxmox_backup_qemu)
  50
  51  softmmu_ss.add(files(
  52    'block-dirty-bitmap.c',
  53 diff --git a/migration/migration.c b/migration/migration.c
  54 index f485eea5fb..89b287180f 100644
  55 --- a/migration/migration.c
  56 +++ b/migration/migration.c
  57 @@ -229,6 +229,7 @@ void migration_object_init(void)
  58      blk_mig_init();
  59      ram_mig_init();
  60      dirty_bitmap_mig_init();
  61 +    pbs_state_mig_init();
  62  }
  63
  64  void migration_cancel(const Error *error)
  65 diff --git a/migration/pbs-state.c b/migration/pbs-state.c
  66 new file mode 100644
  67 index 0000000000..29f2b3860d
  68 --- /dev/null
  69 +++ b/migration/pbs-state.c
  70 @@ -0,0 +1,106 @@
  71 +/*
  72 + * PBS (dirty-bitmap) state migration
  73 + */
  74 +
  75 +#include "qemu/osdep.h"
  76 +#include "migration/misc.h"
  77 +#include "qemu-file.h"
  78 +#include "migration/vmstate.h"
  79 +#include "migration/register.h"
  80 +#include "proxmox-backup-qemu.h"
  81 +
  82 +typedef struct PBSState {
  83 +    bool active;
  84 +} PBSState;
  85 +
  86 +/* state is accessed via this static variable directly, 'opaque' is NULL */
  87 +static PBSState pbs_state;
  88 +
  89 +static void pbs_state_save_pending(QEMUFile *f, void *opaque,
  90 +                                      uint64_t max_size,
  91 +                                      uint64_t *res_precopy_only,
  92 +                                      uint64_t *res_compatible,
  93 +                                      uint64_t *res_postcopy_only)
  94 +{
  95 +    /* we send everything in save_setup, so nothing is ever pending */
  96 +}
  97 +
  98 +/* receive PBS state via f and deserialize, called on target */
  99 +static int pbs_state_load(QEMUFile *f, void *opaque, int version_id)
 100 +{
 101 +    /* safe cast, we cannot migrate to target with less bits than source */
 102 +    size_t buf_size = (size_t)qemu_get_be64(f);
 103 +
 104 +    uint8_t *buf = (uint8_t *)malloc(buf_size);
 105 +    size_t read = qemu_get_buffer(f, buf, buf_size);
 106 +
 107 +    if (read < buf_size) {
 108 +        fprintf(stderr, "error receiving PBS state: not enough data\n");
 109 +        return -EIO;
 110 +    }
 111 +
 112 +    proxmox_import_state(buf, buf_size);
 113 +
 114 +    free(buf);
 115 +    return 0;
 116 +}
 117 +
 118 +/* serialize PBS state and send to target via f, called on source */
 119 +static int pbs_state_save_setup(QEMUFile *f, void *opaque)
 120 +{
 121 +    size_t buf_size;
 122 +    uint8_t *buf = proxmox_export_state(&buf_size);
 123 +
 124 +    /* LV encoding */
 125 +    qemu_put_be64(f, buf_size);
 126 +    qemu_put_buffer(f, buf, buf_size);
 127 +
 128 +    proxmox_free_state_buf(buf);
 129 +    pbs_state.active = false;
 130 +    return 0;
 131 +}
 132 +
 133 +static bool pbs_state_is_active(void *opaque)
 134 +{
 135 +    /* we need to return active exactly once, else .save_setup is never called,
 136 +     * but if we'd just return true the migration doesn't make progress since
 137 +     * it'd be waiting for us */
 138 +    return pbs_state.active;
 139 +}
 140 +
 141 +static bool pbs_state_is_active_iterate(void *opaque)
 142 +{
 143 +    /* we don't iterate, everything is sent in save_setup */
 144 +    return pbs_state_is_active(opaque);
 145 +}
 146 +
 147 +static bool pbs_state_has_postcopy(void *opaque)
 148 +{
 149 +    /* PBS state can't change during a migration (since that's blocking any
 150 +     * potential backups), so we can copy everything before the VM is stopped */
 151 +    return false;
 152 +}
 153 +
 154 +static void pbs_state_save_cleanup(void *opaque)
 155 +{
 156 +    /* reset active after migration succeeds or fails */
 157 +    pbs_state.active = false;
 158 +}
 159 +
 160 +static SaveVMHandlers savevm_pbs_state_handlers = {
 161 +    .save_setup = pbs_state_save_setup,
 162 +    .has_postcopy = pbs_state_has_postcopy,
 163 +    .save_live_pending = pbs_state_save_pending,
 164 +    .is_active_iterate = pbs_state_is_active_iterate,
 165 +    .load_state = pbs_state_load,
 166 +    .is_active = pbs_state_is_active,
 167 +    .save_cleanup = pbs_state_save_cleanup,
 168 +};
 169 +
 170 +void pbs_state_mig_init(void)
 171 +{
 172 +    pbs_state.active = true;
 173 +    register_savevm_live("pbs-state", 0, 1,
 174 +                         &savevm_pbs_state_handlers,
 175 +                         NULL);
 176 +}
 177 diff --git a/pve-backup.c b/pve-backup.c
 178 index 88268bb586..fa9c6c4493 100644
 179 --- a/pve-backup.c
 180 +++ b/pve-backup.c
 181 @@ -1128,6 +1128,7 @@ ProxmoxSupportStatus *qmp_query_proxmox_support(Error **errp)
 182      ret->pbs_library_version = g_strdup(proxmox_backup_qemu_version());
 183      ret->pbs_dirty_bitmap = true;
 184      ret->pbs_dirty_bitmap_savevm = true;
 185 +    ret->pbs_dirty_bitmap_migration = true;
 186      ret->query_bitmap_info = true;
 187      return ret;
 188  }
 189 diff --git a/qapi/block-core.json b/qapi/block-core.json
 190 index bf559c6d52..24f30260c8 100644
 191 --- a/qapi/block-core.json
 192 +++ b/qapi/block-core.json
 193 @@ -879,6 +879,11 @@
 194  # @pbs-dirty-bitmap-savevm: True if 'dirty-bitmaps' migration capability can
 195  #                           safely be set for savevm-async.
 196  #
 197 +# @pbs-dirty-bitmap-migration: True if safe migration of dirty-bitmaps including
 198 +#                              PBS state is supported. Enabling 'dirty-bitmaps'
 199 +#                              migration cap if this is false/unset may lead
 200 +#                              to crashes on migration!
 201 +#
 202  # @pbs-library-version: Running version of libproxmox-backup-qemu0 library.
 203  #
 204  ##
 205 @@ -886,6 +891,7 @@
 206    'data': { 'pbs-dirty-bitmap': 'bool',
 207              'query-bitmap-info': 'bool',
 208              'pbs-dirty-bitmap-savevm': 'bool',
 209 +            'pbs-dirty-bitmap-migration': 'bool',
 210              'pbs-library-version': 'str' } }
 211
 212  ##