From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Stefan Reiter Date: Thu, 22 Oct 2020 17:34:18 +0200 Subject: [PATCH] PVE: Migrate dirty bitmap state via savevm QEMU provides 'savevm' registrations as a mechanism for arbitrary state to be migrated along with a VM. Use this to send a serialized version of dirty bitmap state data from proxmox-backup-qemu, and restore it on the target node. Also add a flag to query-proxmox-support so qemu-server can determine if safe migration is possible and makes sense. Signed-off-by: Stefan Reiter --- include/migration/misc.h | 3 ++ migration/meson.build | 2 + migration/pbs-state.c | 106 +++++++++++++++++++++++++++++++++++++++ pve-backup.c | 1 + qapi/block-core.json | 6 +++ softmmu/vl.c | 1 + 6 files changed, 119 insertions(+) create mode 100644 migration/pbs-state.c diff --git a/include/migration/misc.h b/include/migration/misc.h index 34e7d75713..f83816dd3c 100644 --- a/include/migration/misc.h +++ b/include/migration/misc.h @@ -75,4 +75,7 @@ bool migration_in_incoming_postcopy(void); /* migration/block-dirty-bitmap.c */ void dirty_bitmap_mig_init(void); +/* migration/pbs-state.c */ +void pbs_state_mig_init(void); + #endif diff --git a/migration/meson.build b/migration/meson.build index e62b79b60f..b90a04aa75 100644 --- a/migration/meson.build +++ b/migration/meson.build @@ -7,8 +7,10 @@ migration_files = files( 'qemu-file-channel.c', 'qemu-file.c', 'qjson.c', + 'pbs-state.c', ) softmmu_ss.add(migration_files) +softmmu_ss.add(libproxmox_backup_qemu) softmmu_ss.add(files( 'block-dirty-bitmap.c', diff --git a/migration/pbs-state.c b/migration/pbs-state.c new file mode 100644 index 0000000000..29f2b3860d --- /dev/null +++ b/migration/pbs-state.c @@ -0,0 +1,106 @@ +/* + * PBS (dirty-bitmap) state migration + */ + +#include "qemu/osdep.h" +#include "migration/misc.h" +#include "qemu-file.h" +#include "migration/vmstate.h" +#include "migration/register.h" +#include "proxmox-backup-qemu.h" + +typedef struct PBSState { + bool active; +} PBSState; + +/* state is accessed via this static variable directly, 'opaque' is NULL */ +static PBSState pbs_state; + +static void pbs_state_save_pending(QEMUFile *f, void *opaque, + uint64_t max_size, + uint64_t *res_precopy_only, + uint64_t *res_compatible, + uint64_t *res_postcopy_only) +{ + /* we send everything in save_setup, so nothing is ever pending */ +} + +/* receive PBS state via f and deserialize, called on target */ +static int pbs_state_load(QEMUFile *f, void *opaque, int version_id) +{ + /* safe cast, we cannot migrate to target with less bits than source */ + size_t buf_size = (size_t)qemu_get_be64(f); + + uint8_t *buf = (uint8_t *)malloc(buf_size); + size_t read = qemu_get_buffer(f, buf, buf_size); + + if (read < buf_size) { + fprintf(stderr, "error receiving PBS state: not enough data\n"); + return -EIO; + } + + proxmox_import_state(buf, buf_size); + + free(buf); + return 0; +} + +/* serialize PBS state and send to target via f, called on source */ +static int pbs_state_save_setup(QEMUFile *f, void *opaque) +{ + size_t buf_size; + uint8_t *buf = proxmox_export_state(&buf_size); + + /* LV encoding */ + qemu_put_be64(f, buf_size); + qemu_put_buffer(f, buf, buf_size); + + proxmox_free_state_buf(buf); + pbs_state.active = false; + return 0; +} + +static bool pbs_state_is_active(void *opaque) +{ + /* we need to return active exactly once, else .save_setup is never called, + * but if we'd just return true the migration doesn't make progress since + * it'd be waiting for us */ + return pbs_state.active; +} + +static bool pbs_state_is_active_iterate(void *opaque) +{ + /* we don't iterate, everything is sent in save_setup */ + return pbs_state_is_active(opaque); +} + +static bool pbs_state_has_postcopy(void *opaque) +{ + /* PBS state can't change during a migration (since that's blocking any + * potential backups), so we can copy everything before the VM is stopped */ + return false; +} + +static void pbs_state_save_cleanup(void *opaque) +{ + /* reset active after migration succeeds or fails */ + pbs_state.active = false; +} + +static SaveVMHandlers savevm_pbs_state_handlers = { + .save_setup = pbs_state_save_setup, + .has_postcopy = pbs_state_has_postcopy, + .save_live_pending = pbs_state_save_pending, + .is_active_iterate = pbs_state_is_active_iterate, + .load_state = pbs_state_load, + .is_active = pbs_state_is_active, + .save_cleanup = pbs_state_save_cleanup, +}; + +void pbs_state_mig_init(void) +{ + pbs_state.active = true; + register_savevm_live("pbs-state", 0, 1, + &savevm_pbs_state_handlers, + NULL); +} diff --git a/pve-backup.c b/pve-backup.c index ded90cb822..6b25292ba1 100644 --- a/pve-backup.c +++ b/pve-backup.c @@ -1130,5 +1130,6 @@ ProxmoxSupportStatus *qmp_query_proxmox_support(Error **errp) ret->pbs_library_version = g_strdup(proxmox_backup_qemu_version()); ret->pbs_dirty_bitmap = true; ret->query_bitmap_info = true; + ret->pbs_dirty_bitmap_migration = true; return ret; } diff --git a/qapi/block-core.json b/qapi/block-core.json index b90d6abe64..dee3d87efe 100644 --- a/qapi/block-core.json +++ b/qapi/block-core.json @@ -881,12 +881,18 @@ # # @query-bitmap-info: True if the 'query-pbs-bitmap-info' QMP call is supported. # +# @pbs-dirty-bitmap-migration: True if safe migration of dirty-bitmaps including +# PBS state is supported. Enabling 'dirty-bitmaps' +# migration cap if this is false/unset may lead +# to crashes on migration! +# # @pbs-library-version: Running version of libproxmox-backup-qemu0 library. # ## { 'struct': 'ProxmoxSupportStatus', 'data': { 'pbs-dirty-bitmap': 'bool', 'query-bitmap-info': 'bool', + 'pbs-dirty-bitmap-migration': 'bool', 'pbs-library-version': 'str' } } ## diff --git a/softmmu/vl.c b/softmmu/vl.c index 5b5512128e..6721889fee 100644 --- a/softmmu/vl.c +++ b/softmmu/vl.c @@ -4304,6 +4304,7 @@ void qemu_init(int argc, char **argv, char **envp) blk_mig_init(); ram_mig_init(); dirty_bitmap_mig_init(); + pbs_state_mig_init(); qemu_opts_foreach(qemu_find_opts("mon"), mon_init_func, NULL, &error_fatal);