debian/patches/pve/0034-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 [FE: split up state_pending for 8.0]
  17 Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
  18 ---
  19  include/migration/misc.h |   3 ++
  20  migration/meson.build    |   2 +
  21  migration/migration.c    |   1 +
  22  migration/pbs-state.c    | 104 +++++++++++++++++++++++++++++++++++++++
  23  pve-backup.c             |   1 +
  24  qapi/block-core.json     |   6 +++
  25  6 files changed, 117 insertions(+)
  26  create mode 100644 migration/pbs-state.c
  27
  28 diff --git a/include/migration/misc.h b/include/migration/misc.h
  29 index 7dcc0b5c2c..4c940b2475 100644
  30 --- a/include/migration/misc.h
  31 +++ b/include/migration/misc.h
  32 @@ -77,4 +77,7 @@ bool migration_in_bg_snapshot(void);
  33  /* migration/block-dirty-bitmap.c */
  34  void dirty_bitmap_mig_init(void);
  35
  36 +/* migration/pbs-state.c */
  37 +void pbs_state_mig_init(void);
  38 +
  39  #endif
  40 diff --git a/migration/meson.build b/migration/meson.build
  41 index 07f6057acc..343994d891 100644
  42 --- a/migration/meson.build
  43 +++ b/migration/meson.build
  44 @@ -7,7 +7,9 @@ migration_files = files(
  45    'vmstate.c',
  46    'qemu-file.c',
  47    'yank_functions.c',
  48 +  'pbs-state.c',
  49  )
  50 +system_ss.add(libproxmox_backup_qemu)
  51
  52  system_ss.add(files(
  53    'block-dirty-bitmap.c',
  54 diff --git a/migration/migration.c b/migration/migration.c
  55 index 7a4c8beb5d..0a955a2a18 100644
  56 --- a/migration/migration.c
  57 +++ b/migration/migration.c
  58 @@ -162,6 +162,7 @@ void migration_object_init(void)
  59      blk_mig_init();
  60      ram_mig_init();
  61      dirty_bitmap_mig_init();
  62 +    pbs_state_mig_init();
  63  }
  64
  65  void migration_cancel(const Error *error)
  66 diff --git a/migration/pbs-state.c b/migration/pbs-state.c
  67 new file mode 100644
  68 index 0000000000..887e998b9e
  69 --- /dev/null
  70 +++ b/migration/pbs-state.c
  71 @@ -0,0 +1,104 @@
  72 +/*
  73 + * PBS (dirty-bitmap) state migration
  74 + */
  75 +
  76 +#include "qemu/osdep.h"
  77 +#include "migration/misc.h"
  78 +#include "qemu-file.h"
  79 +#include "migration/vmstate.h"
  80 +#include "migration/register.h"
  81 +#include "proxmox-backup-qemu.h"
  82 +
  83 +typedef struct PBSState {
  84 +    bool active;
  85 +} PBSState;
  86 +
  87 +/* state is accessed via this static variable directly, 'opaque' is NULL */
  88 +static PBSState pbs_state;
  89 +
  90 +static void pbs_state_pending(void *opaque, uint64_t *must_precopy,
  91 +                              uint64_t *can_postcopy)
  92 +{
  93 +    /* we send everything in save_setup, so nothing is ever pending */
  94 +}
  95 +
  96 +/* receive PBS state via f and deserialize, called on target */
  97 +static int pbs_state_load(QEMUFile *f, void *opaque, int version_id)
  98 +{
  99 +    /* safe cast, we cannot migrate to target with less bits than source */
 100 +    size_t buf_size = (size_t)qemu_get_be64(f);
 101 +
 102 +    uint8_t *buf = (uint8_t *)malloc(buf_size);
 103 +    size_t read = qemu_get_buffer(f, buf, buf_size);
 104 +
 105 +    if (read < buf_size) {
 106 +        fprintf(stderr, "error receiving PBS state: not enough data\n");
 107 +        return -EIO;
 108 +    }
 109 +
 110 +    proxmox_import_state(buf, buf_size);
 111 +
 112 +    free(buf);
 113 +    return 0;
 114 +}
 115 +
 116 +/* serialize PBS state and send to target via f, called on source */
 117 +static int pbs_state_save_setup(QEMUFile *f, void *opaque)
 118 +{
 119 +    size_t buf_size;
 120 +    uint8_t *buf = proxmox_export_state(&buf_size);
 121 +
 122 +    /* LV encoding */
 123 +    qemu_put_be64(f, buf_size);
 124 +    qemu_put_buffer(f, buf, buf_size);
 125 +
 126 +    proxmox_free_state_buf(buf);
 127 +    pbs_state.active = false;
 128 +    return 0;
 129 +}
 130 +
 131 +static bool pbs_state_is_active(void *opaque)
 132 +{
 133 +    /* we need to return active exactly once, else .save_setup is never called,
 134 +     * but if we'd just return true the migration doesn't make progress since
 135 +     * it'd be waiting for us */
 136 +    return pbs_state.active;
 137 +}
 138 +
 139 +static bool pbs_state_is_active_iterate(void *opaque)
 140 +{
 141 +    /* we don't iterate, everything is sent in save_setup */
 142 +    return pbs_state_is_active(opaque);
 143 +}
 144 +
 145 +static bool pbs_state_has_postcopy(void *opaque)
 146 +{
 147 +    /* PBS state can't change during a migration (since that's blocking any
 148 +     * potential backups), so we can copy everything before the VM is stopped */
 149 +    return false;
 150 +}
 151 +
 152 +static void pbs_state_save_cleanup(void *opaque)
 153 +{
 154 +    /* reset active after migration succeeds or fails */
 155 +    pbs_state.active = false;
 156 +}
 157 +
 158 +static SaveVMHandlers savevm_pbs_state_handlers = {
 159 +    .save_setup = pbs_state_save_setup,
 160 +    .has_postcopy = pbs_state_has_postcopy,
 161 +    .state_pending_exact = pbs_state_pending,
 162 +    .state_pending_estimate = pbs_state_pending,
 163 +    .is_active_iterate = pbs_state_is_active_iterate,
 164 +    .load_state = pbs_state_load,
 165 +    .is_active = pbs_state_is_active,
 166 +    .save_cleanup = pbs_state_save_cleanup,
 167 +};
 168 +
 169 +void pbs_state_mig_init(void)
 170 +{
 171 +    pbs_state.active = true;
 172 +    register_savevm_live("pbs-state", 0, 1,
 173 +                         &savevm_pbs_state_handlers,
 174 +                         NULL);
 175 +}
 176 diff --git a/pve-backup.c b/pve-backup.c
 177 index ae3d137e12..e6b17b797e 100644
 178 --- a/pve-backup.c
 179 +++ b/pve-backup.c
 180 @@ -1082,6 +1082,7 @@ ProxmoxSupportStatus *qmp_query_proxmox_support(Error **errp)
 181      ret->pbs_library_version = g_strdup(proxmox_backup_qemu_version());
 182      ret->pbs_dirty_bitmap = true;
 183      ret->pbs_dirty_bitmap_savevm = true;
 184 +    ret->pbs_dirty_bitmap_migration = true;
 185      ret->query_bitmap_info = true;
 186      ret->pbs_masterkey = true;
 187      ret->backup_max_workers = true;
 188 diff --git a/qapi/block-core.json b/qapi/block-core.json
 189 index d67a6d448a..09de550c95 100644
 190 --- a/qapi/block-core.json
 191 +++ b/qapi/block-core.json
 192 @@ -991,6 +991,11 @@
 193  # @pbs-dirty-bitmap-savevm: True if 'dirty-bitmaps' migration capability can
 194  #                           safely be set for savevm-async.
 195  #
 196 +# @pbs-dirty-bitmap-migration: True if safe migration of dirty-bitmaps including
 197 +#                              PBS state is supported. Enabling 'dirty-bitmaps'
 198 +#                              migration cap if this is false/unset may lead
 199 +#                              to crashes on migration!
 200 +#
 201  # @pbs-masterkey: True if the QMP backup call supports the 'master_keyfile'
 202  #                 parameter.
 203  #
 204 @@ -1001,6 +1006,7 @@
 205    'data': { 'pbs-dirty-bitmap': 'bool',
 206              'query-bitmap-info': 'bool',
 207              'pbs-dirty-bitmap-savevm': 'bool',
 208 +            'pbs-dirty-bitmap-migration': 'bool',
 209              'pbs-masterkey': 'bool',
 210              'pbs-library-version': 'str',
 211              'backup-max-workers': 'bool' } }