This SaveVMHandler helps device provide its own asynchronous transmission
of the remaining data at the end of a precopy phase via multifd channels,
in parallel with the transfer done by save_live_complete_precopy handlers.
These threads are launched only when multifd device state transfer is
supported.
Management of these threads in done in the multifd migration code,
wrapping them in the generic thread pool.
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/qemu-devel/eac74a4ca7edd8968bbf72aa07b9041c76364a16.1741124640.git.maciej.szmigiero@oracle.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>
Since device state transfer via multifd channels requires multifd
channels with packets and is currently not compatible with multifd
compression add an appropriate query function so device can learn
whether it can actually make use of it.
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Link: https://lore.kernel.org/qemu-devel/1ff0d98b85f470e5a33687406e877583b8fab74e.1741124640.git.maciej.szmigiero@oracle.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>
The newly introduced device state buffer can be used for either storing
VFIO's read() raw data, but already also possible to store generic device
states. After noticing that device states may not easily provide a max
buffer size (also the fact that RAM MultiFDPages_t after all also want to
have flexibility on managing offset[] array), it may not be a good idea to
stick with union on MultiFDSendData.. as it won't play well with such
flexibility.
Switch MultiFDSendData to a struct.
It won't consume a lot more space in reality, after all the real buffers
were already dynamically allocated, so it's so far only about the two
structs (pages, device_state) that will be duplicated, but they're small.
With this, we can remove the pretty hard to understand alloc size logic.
Because now we can allocate offset[] together with the SendData, and
properly free it when the SendData is freed.
[MSS: Make sure to clear possible device state payload before freeing
MultiFDSendData, remove placeholders for other patches not included]
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Acked-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/qemu-devel/7b02baba8e6ddb23ef7c349d312b9b631db09d7e.1741124640.git.maciej.szmigiero@oracle.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>
