debian/patches/pve/0039-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 ---
  16  include/migration/misc.h |   3 ++
  17  migration/meson.build    |   2 +
  18  migration/pbs-state.c    | 106 +++++++++++++++++++++++++++++++++++++++
  19  pve-backup.c             |   1 +
  20  qapi/block-core.json     |   6 +++
  21  softmmu/vl.c             |   1 +
  22  6 files changed, 119 insertions(+)
  23  create mode 100644 migration/pbs-state.c
  24
  25 diff --git a/include/migration/misc.h b/include/migration/misc.h
  26 index 34e7d75713..f83816dd3c 100644
  27 --- a/include/migration/misc.h
  28 +++ b/include/migration/misc.h
  29 @@ -75,4 +75,7 @@ bool migration_in_incoming_postcopy(void);
  30  /* migration/block-dirty-bitmap.c */
  31  void dirty_bitmap_mig_init(void);
  32
  33 +/* migration/pbs-state.c */
  34 +void pbs_state_mig_init(void);
  35 +
  36  #endif
  37 diff --git a/migration/meson.build b/migration/meson.build
  38 index e62b79b60f..b90a04aa75 100644
  39 --- a/migration/meson.build
  40 +++ b/migration/meson.build
  41 @@ -7,8 +7,10 @@ migration_files = files(
  42    'qemu-file-channel.c',
  43    'qemu-file.c',
  44    'qjson.c',
  45 +  'pbs-state.c',
  46  )
  47  softmmu_ss.add(migration_files)
  48 +softmmu_ss.add(libproxmox_backup_qemu)
  49
  50  softmmu_ss.add(files(
  51    'block-dirty-bitmap.c',
  52 diff --git a/migration/pbs-state.c b/migration/pbs-state.c
  53 new file mode 100644
  54 index 0000000000..29f2b3860d
  55 --- /dev/null
  56 +++ b/migration/pbs-state.c
  57 @@ -0,0 +1,106 @@
  58 +/*
  59 + * PBS (dirty-bitmap) state migration
  60 + */
  61 +
  62 +#include "qemu/osdep.h"
  63 +#include "migration/misc.h"
  64 +#include "qemu-file.h"
  65 +#include "migration/vmstate.h"
  66 +#include "migration/register.h"
  67 +#include "proxmox-backup-qemu.h"
  68 +
  69 +typedef struct PBSState {
  70 +    bool active;
  71 +} PBSState;
  72 +
  73 +/* state is accessed via this static variable directly, 'opaque' is NULL */
  74 +static PBSState pbs_state;
  75 +
  76 +static void pbs_state_save_pending(QEMUFile *f, void *opaque,
  77 +                                      uint64_t max_size,
  78 +                                      uint64_t *res_precopy_only,
  79 +                                      uint64_t *res_compatible,
  80 +                                      uint64_t *res_postcopy_only)
  81 +{
  82 +    /* we send everything in save_setup, so nothing is ever pending */
  83 +}
  84 +
  85 +/* receive PBS state via f and deserialize, called on target */
  86 +static int pbs_state_load(QEMUFile *f, void *opaque, int version_id)
  87 +{
  88 +    /* safe cast, we cannot migrate to target with less bits than source */
  89 +    size_t buf_size = (size_t)qemu_get_be64(f);
  90 +
  91 +    uint8_t *buf = (uint8_t *)malloc(buf_size);
  92 +    size_t read = qemu_get_buffer(f, buf, buf_size);
  93 +
  94 +    if (read < buf_size) {
  95 +        fprintf(stderr, "error receiving PBS state: not enough data\n");
  96 +        return -EIO;
  97 +    }
  98 +
  99 +    proxmox_import_state(buf, buf_size);
 100 +
 101 +    free(buf);
 102 +    return 0;
 103 +}
 104 +
 105 +/* serialize PBS state and send to target via f, called on source */
 106 +static int pbs_state_save_setup(QEMUFile *f, void *opaque)
 107 +{
 108 +    size_t buf_size;
 109 +    uint8_t *buf = proxmox_export_state(&buf_size);
 110 +
 111 +    /* LV encoding */
 112 +    qemu_put_be64(f, buf_size);
 113 +    qemu_put_buffer(f, buf, buf_size);
 114 +
 115 +    proxmox_free_state_buf(buf);
 116 +    pbs_state.active = false;
 117 +    return 0;
 118 +}
 119 +
 120 +static bool pbs_state_is_active(void *opaque)
 121 +{
 122 +    /* we need to return active exactly once, else .save_setup is never called,
 123 +     * but if we'd just return true the migration doesn't make progress since
 124 +     * it'd be waiting for us */
 125 +    return pbs_state.active;
 126 +}
 127 +
 128 +static bool pbs_state_is_active_iterate(void *opaque)
 129 +{
 130 +    /* we don't iterate, everything is sent in save_setup */
 131 +    return pbs_state_is_active(opaque);
 132 +}
 133 +
 134 +static bool pbs_state_has_postcopy(void *opaque)
 135 +{
 136 +    /* PBS state can't change during a migration (since that's blocking any
 137 +     * potential backups), so we can copy everything before the VM is stopped */
 138 +    return false;
 139 +}
 140 +
 141 +static void pbs_state_save_cleanup(void *opaque)
 142 +{
 143 +    /* reset active after migration succeeds or fails */
 144 +    pbs_state.active = false;
 145 +}
 146 +
 147 +static SaveVMHandlers savevm_pbs_state_handlers = {
 148 +    .save_setup = pbs_state_save_setup,
 149 +    .has_postcopy = pbs_state_has_postcopy,
 150 +    .save_live_pending = pbs_state_save_pending,
 151 +    .is_active_iterate = pbs_state_is_active_iterate,
 152 +    .load_state = pbs_state_load,
 153 +    .is_active = pbs_state_is_active,
 154 +    .save_cleanup = pbs_state_save_cleanup,
 155 +};
 156 +
 157 +void pbs_state_mig_init(void)
 158 +{
 159 +    pbs_state.active = true;
 160 +    register_savevm_live("pbs-state", 0, 1,
 161 +                         &savevm_pbs_state_handlers,
 162 +                         NULL);
 163 +}
 164 diff --git a/pve-backup.c b/pve-backup.c
 165 index ded90cb822..6b25292ba1 100644
 166 --- a/pve-backup.c
 167 +++ b/pve-backup.c
 168 @@ -1130,5 +1130,6 @@ ProxmoxSupportStatus *qmp_query_proxmox_support(Error **errp)
 169      ret->pbs_library_version = g_strdup(proxmox_backup_qemu_version());
 170      ret->pbs_dirty_bitmap = true;
 171      ret->query_bitmap_info = true;
 172 +    ret->pbs_dirty_bitmap_migration = true;
 173      return ret;
 174  }
 175 diff --git a/qapi/block-core.json b/qapi/block-core.json
 176 index b90d6abe64..dee3d87efe 100644
 177 --- a/qapi/block-core.json
 178 +++ b/qapi/block-core.json
 179 @@ -881,12 +881,18 @@
 180  #
 181  # @query-bitmap-info: True if the 'query-pbs-bitmap-info' QMP call is supported.
 182  #
 183 +# @pbs-dirty-bitmap-migration: True if safe migration of dirty-bitmaps including
 184 +#                              PBS state is supported. Enabling 'dirty-bitmaps'
 185 +#                              migration cap if this is false/unset may lead
 186 +#                              to crashes on migration!
 187 +#
 188  # @pbs-library-version: Running version of libproxmox-backup-qemu0 library.
 189  #
 190  ##
 191  { 'struct': 'ProxmoxSupportStatus',
 192    'data': { 'pbs-dirty-bitmap': 'bool',
 193              'query-bitmap-info': 'bool',
 194 +            'pbs-dirty-bitmap-migration': 'bool',
 195              'pbs-library-version': 'str' } }
 196
 197  ##
 198 diff --git a/softmmu/vl.c b/softmmu/vl.c
 199 index 5b5512128e..6721889fee 100644
 200 --- a/softmmu/vl.c
 201 +++ b/softmmu/vl.c
 202 @@ -4304,6 +4304,7 @@ void qemu_init(int argc, char **argv, char **envp)
 203      blk_mig_init();
 204      ram_mig_init();
 205      dirty_bitmap_mig_init();
 206 +    pbs_state_mig_init();
 207
 208      qemu_opts_foreach(qemu_find_opts("mon"),
 209                        mon_init_func, NULL, &error_fatal);