Allow capping the maximum total size of in-flight VFIO device state buffers
queued at the destination, otherwise a malicious QEMU source could
theoretically cause the target QEMU to allocate unlimited amounts of memory
for buffers-in-flight.
Since this is not expected to be a realistic threat in most of VFIO live
migration use cases and the right value depends on the particular setup
disable this limit by default by setting it to UINT64_MAX.
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Avihai Horon <avihaih@nvidia.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Link: https://lore.kernel.org/qemu-devel/4f7cad490988288f58e36b162d7a888ed7e7fd17.1752589295.git.maciej.szmigiero@oracle.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>
This property allows configuring whether to start the config load only
after all iterables were loaded, during non-iterables loading phase.
Such interlocking is required for ARM64 due to this platform VFIO
dependency on interrupt controller being loaded first.
The property defaults to AUTO, which means ON for ARM, OFF for other
platforms.
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Avihai Horon <avihaih@nvidia.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Link: https://lore.kernel.org/qemu-devel/0e03c60dbc91f9a9ba2516929574df605b7dfcb4.1752589295.git.maciej.szmigiero@oracle.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>
Restrict "exec/tswap.h" to the tswap*() methods,
move the load/store helpers with the other ones
declared in "qemu/bswap.h".
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Message-Id: <20250708215320.70426-8-philmd@linaro.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Recent patch [1] renames the save_live_complete_precopy handler to
save_complete, as the machine is not live in most cases when this
handler is executed. The same is true also for
save_live_complete_precopy_thread, therefore this patch removes the
"live" keyword from the handler itself and related types to keep the
naming unified.
In contrast to save_complete, this handler is only executed at the end
of precopy, therefore the "precopy" keyword is retained.
[1]: https://lore.kernel.org/all/20250613140801.474264-7-peterx@redhat.com/
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Juraj Marcin <jmarcin@redhat.com>
Link: https://lore.kernel.org/r/20250626085235.294690-1-jmarcin@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
"hw/vfio/vfio-common.h" has been emptied of most of its declarations
by the previous changes and the only declarations left are related to
VFIODevice. Rename it to "hw/vfio/vfio-device.h" and make the
necessary adjustments.
Reviewed-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Link: https://lore.kernel.org/qemu-devel/20250326075122.1299361-36-clg@redhat.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>
The migration core subsystem makes use of the VFIO migration API to
collect statistics on the number of bytes transferred. These services
are declared in "hw/vfio/vfio-common.h" which also contains VFIO
internal declarations. Move the migration declarations into a new
header file "hw/vfio/vfio-migration.h" to reduce the exposure of VFIO
internals.
While at it, use a 'vfio_migration_' prefix for these services.
To be noted, vfio_migration_add_bytes_transferred() is a VFIO
migration internal service which we will be moved in the subsequent
patches.
Cc: Kirti Wankhede <kwankhede@nvidia.com>
Cc: Avihai Horon <avihaih@nvidia.com>
Reviewed-by: Prasad Pandit <pjp@fedoraproject.org>
Reviewed-by: John Levon <john.levon@nutanix.com>
Reviewed-by: Avihai Horon <avihaih@nvidia.com>
Link: https://lore.kernel.org/qemu-devel/20250326075122.1299361-4-clg@redhat.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>
Wire data commonly use BE byte order (including in the existing migration
protocol), use it also for for VFIO device state packets.
This will allow VFIO multifd device state transfer between hosts with
different endianness.
Although currently there is no such use case, it's good to have it now
for completeness.
Reviewed-by: Avihai Horon <avihaih@nvidia.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Link: https://lore.kernel.org/qemu-devel/dcfc04cc1a50655650dbac8398e2742ada84ee39.1741611079.git.maciej.szmigiero@oracle.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>
DEFINE_PROP_ON_OFF_AUTO() property isn't runtime-mutable so using it
would mean that the source VM would need to decide upfront at startup
time whether it wants to do a multifd device state transfer at some
point.
Source VM can run for a long time before being migrated so it is
desirable to have a fallback mechanism to the old way of transferring
VFIO device state if it turns to be necessary.
This brings this property to the same mutability level as ordinary
migration parameters, which too can be adjusted at the run time.
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/qemu-devel/f2f2d66bda477da3e6cb8c0311006cff36e8651d.1741124640.git.maciej.szmigiero@oracle.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>
This property allows configuring whether to transfer the particular device
state via multifd channels when live migrating that device.
It defaults to AUTO, which means that VFIO device state transfer via
multifd channels is attempted in configurations that otherwise support it.
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/qemu-devel/d6dbb326e3d53c7104d62c96c9e3dd64e1c7b940.1741124640.git.maciej.szmigiero@oracle.com
[ clg: Added documentation ]
Signed-off-by: Cédric Le Goater <clg@redhat.com>
Implement the multifd device state transfer via additional per-device
thread inside save_live_complete_precopy_thread handler.
Switch between doing the data transfer in the new handler and doing it
in the old save_state handler depending if VFIO multifd transfer is enabled
or not.
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/qemu-devel/4d727e2e0435e0022d50004e474077632830e08d.1741124640.git.maciej.szmigiero@oracle.com
[ clg: - Reordered savevm_vfio_handlers
- Updated save_live_complete_precopy* documentation ]
Signed-off-by: Cédric Le Goater <clg@redhat.com>
Add a thread which loads the VFIO device state buffers that were received
via multifd.
Each VFIO device that has multifd device state transfer enabled has one
such thread, which is created using migration core API
qemu_loadvm_start_load_thread().
Since it's important to finish loading device state transferred via the
main migration channel (via save_live_iterate SaveVMHandler) before
starting loading the data asynchronously transferred via multifd the thread
doing the actual loading of the multifd transferred data is only started
from switchover_start SaveVMHandler.
switchover_start handler is called when MIG_CMD_SWITCHOVER_START
sub-command of QEMU_VM_COMMAND is received via the main migration channel.
This sub-command is only sent after all save_live_iterate data have already
been posted so it is safe to commence loading of the multifd-transferred
device state upon receiving it - loading of save_live_iterate data happens
synchronously in the main migration thread (much like the processing of
MIG_CMD_SWITCHOVER_START) so by the time MIG_CMD_SWITCHOVER_START is
processed all the proceeding data must have already been loaded.
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/qemu-devel/9abe612d775aaf42e31646796acd2363c723a57a.1741124640.git.maciej.szmigiero@oracle.com
[ clg: - Reordered savevm_vfio_handlers
- Added switchover_start documentation ]
Signed-off-by: Cédric Le Goater <clg@redhat.com>
The multifd received data needs to be reassembled since device state
packets sent via different multifd channels can arrive out-of-order.
Therefore, each VFIO device state packet carries a header indicating its
position in the stream.
The raw device state data is saved into a VFIOStateBuffer for later
in-order loading into the device.
The last such VFIO device state packet should have
VFIO_DEVICE_STATE_CONFIG_STATE flag set and carry the device config state.
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/qemu-devel/e3bff515a8d61c582b94b409eb12a45b1a143a69.1741124640.git.maciej.szmigiero@oracle.com
[ clg: - Reordered savevm_vfio_handlers
- Added load_state_buffer documentation ]
Signed-off-by: Cédric Le Goater <clg@redhat.com>
Add basic types and flags used by VFIO multifd device state transfer
support.
Since we'll be introducing a lot of multifd transfer specific code,
add a new file migration-multifd.c to home it, wired into main VFIO
migration code (migration.c) via migration-multifd.h header file.
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/qemu-devel/4eedd529e6617f80f3d6a66d7268a0db2bc173fa.1741124640.git.maciej.szmigiero@oracle.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>
