Changes from v5:
* Add bql_locked() assertion to migration_incoming_state_destroy()
with a
comment describing why holding BQL there is necessary.
* Add SPDX-License-Identifier to newly added files.
* Move consistency of multfd transfer settings check to the patch adding
x-migration-multifd-transfer property.
* Change packet->idx == UINT32_MAX message to the suggested one.
* Use WITH_QEMU_LOCK_GUARD() in vfio_load_state_buffer().
* Add vfio_load_bufs_thread_{start,end} trace events.
* Invert "ret" value computation logic in vfio_load_bufs_thread() and
  vfio_multifd_save_complete_precopy_thread() - initialize "ret" to
false
  at definition, remove "ret = false" at every failure/early exit
block and
  add "ret = true" just before the early exit jump label.
* Make vfio_load_bufs_thread_load_config() return a bool and take an
  "Error **" parameter.
* Make vfio_multifd_setup() (previously called
vfio_multifd_transfer_setup())
  allocate struct VFIOMultifd if requested by "alloc_multifd"
parameter.
* Add vfio_multifd_cleanup() call to vfio_save_cleanup() (for
consistency
  with the load code), with a comment describing that it is
currently a NOP
  there.
* Move vfio_multifd_cleanup() to migration-multifd.c.
* Move general multifd migration description in
docs/devel/migration/vfio.rst
  from the top section to new "Multifd" section at the bottom.
* Add comment describing why x-migration-multifd-transfer needs to be
  a custom property above the variable containing that custom
property type
  in register_vfio_pci_dev_type().
* Add object_class_property_set_description() description for all 3
newly
  added parameters: x-migration-multifd-transfer,
  x-migration-load-config-after-iter and
x-migration-max-queued-buffers.
* Split out wiring vfio_multifd_setup() and vfio_multifd_cleanup() into
  general VFIO load/save setup and cleanup methods into a brand new
  patch/commit.
* Squash the patch introducing VFIOStateBuffer(s) into the "received
buffers
  queuing" commit to fix building the interim code form at the time
of this
  patch with "-Werror".
* Change device state packet "idstr" field to NULL-terminated and drop
  QEMU_NONSTRING marking from its definition.
* Add vbasedev->name to VFIO error messages to know which device caused
  that error.
* Move BQL lock ordering assert closer to the other lock in the lock
order
  in vfio_load_state_buffer().
* Drop orphan "QemuThread load_bufs_thread" VFIOMultifd member leftover
  from the days of the version 2 of this patch set.
* Change "guint" into an "unsigned int" where it was present in this
  patch set.
* Use g_autoptr() for QEMUFile also in
vfio_load_bufs_thread_load_config().
* Call multifd_abort_device_state_save_threads() if a migration error is
  already set in the save path to avoid needlessly waiting for the
remaining
  threads to do all of their normal work.
* Other minor changes that should not have functional impact, like:
  renamed functions/labels, moved code lines between patches contained
  in this patch set, added review tags, code formatting, rebased on top
  of the latest QEMU git master, etc.
========================================================================
This patch set is targeting QEMU 10.0.
It is also exported as a git tree:
https://gitlab.com/maciejsszmigiero/qemu/-/commits/multifd-device-state-transfer-vfio
========================================================================
Maciej S. Szmigiero (35):
  migration: Clarify that {load,save}_cleanup handlers can run without
    setup
  thread-pool: Remove thread_pool_submit() function
  thread-pool: Rename AIO pool functions to *_aio() and data types to
    *Aio
  thread-pool: Implement generic (non-AIO) pool support
  migration: Add MIG_CMD_SWITCHOVER_START and its load handler
  migration: Add qemu_loadvm_load_state_buffer() and its handler
  migration: postcopy_ram_listen_thread() should take BQL for some
calls
  error: define g_autoptr() cleanup function for the Error type
  migration: Add thread pool of optional load threads
  migration/multifd: Split packet into header and RAM data
  migration/multifd: Device state transfer support - receive side
  migration/multifd: Make multifd_send() thread safe
  migration/multifd: Add an explicit MultiFDSendData destructor
  migration/multifd: Device state transfer support - send side
  migration/multifd: Add multifd_device_state_supported()
  migration: Add save_live_complete_precopy_thread handler
  vfio/migration: Add load_device_config_state_start trace event
  vfio/migration: Convert bytes_transferred counter to atomic
  vfio/migration: Add vfio_add_bytes_transferred()
  vfio/migration: Move migration channel flags to vfio-common.h header
    file
  vfio/migration: Multifd device state transfer support - basic types
  vfio/migration: Multifd device state transfer - add support checking
    function
  vfio/migration: Multifd setup/cleanup functions and associated
    VFIOMultifd
  vfio/migration: Setup and cleanup multifd transfer in these general
    methods
  vfio/migration: Multifd device state transfer support - received
    buffers queuing
  vfio/migration: Multifd device state transfer support - load thread
  migration/qemu-file: Define g_autoptr() cleanup function for QEMUFile
  vfio/migration: Multifd device state transfer support - config
loading
    support
  vfio/migration: Multifd device state transfer support - send side
  vfio/migration: Add x-migration-multifd-transfer VFIO property
  vfio/migration: Make x-migration-multifd-transfer VFIO property
    mutable
  hw/core/machine: Add compat for x-migration-multifd-transfer VFIO
    property
  vfio/migration: Max in-flight VFIO device state buffer count limit
  vfio/migration: Add x-migration-load-config-after-iter VFIO property
  vfio/migration: Update VFIO migration documentation
Peter Xu (1):
  migration/multifd: Make MultiFDSendData a struct
 docs/devel/migration/vfio.rst     | 79 ++-
 hw/core/machine.c                 |  2 +
 hw/vfio/meson.build               |  1 +
 hw/vfio/migration-multifd.c       | 786 +++++++++++++++++++++++++++++
 hw/vfio/migration-multifd.h       | 37 ++
 hw/vfio/migration.c               | 111 ++--
 hw/vfio/pci.c                     | 40 ++
 hw/vfio/trace-events              | 13 +-
 include/block/aio.h               |  8 +-
 include/block/thread-pool.h       | 62 ++-
 include/hw/vfio/vfio-common.h     | 34 ++
 include/migration/client-options.h |  4 +
 include/migration/misc.h          | 25 +
 include/migration/register.h      | 52 +-
 include/qapi/error.h              |  2 +
 include/qemu/typedefs.h           |  5 +
 migration/colo.c                  |  3 +
 migration/meson.build             |  1 +
 migration/migration-hmp-cmds.c    |  2 +
 migration/migration.c             | 20 +-
 migration/migration.h             |  7 +
 migration/multifd-device-state.c  | 212 ++++++++
 migration/multifd-nocomp.c        | 30 +-
 migration/multifd.c               | 248 +++++++--
 migration/multifd.h               | 74 ++-
 migration/options.c               |  9 +
 migration/qemu-file.h             |  2 +
 migration/savevm.c                | 201 +++++++-
 migration/savevm.h                |  6 +-
 migration/trace-events            |  1 +
 scripts/analyze-migration.py      | 11 +
 tests/unit/test-thread-pool.c     |  6 +-
 util/async.c                      |  6 +-
 util/thread-pool.c                | 184 +++++--
 util/trace-events                 |  6 +-
 35 files changed, 2125 insertions(+), 165 deletions(-)
 create mode 100644 hw/vfio/migration-multifd.c
 create mode 100644 hw/vfio/migration-multifd.h
 create mode 100644 migration/multifd-device-state.c
