On Tue, Oct 29, 2024 at 03:58:12PM +0100, Maciej S. Szmigiero wrote: > From: "Maciej S. Szmigiero" <maciej.szmigi...@oracle.com> > > A new version of the multifd device state transfer support with VFIO consumer > patch set is being prepared, the previous version and the associated > discussion is available here: > https://lore.kernel.org/qemu-devel/cover.1724701542.git.maciej.szmigi...@oracle.com/ > > This new version was originally targeting QEMU 9.2 but such schedule proved > to be too optimistic due to sheer number of invasive changes/rework required, > especially with respect to the VFIO internal threads management and their > synchronization with the migration core. > > In addition to these changes, recently merged commit 3b5948f808e3 > ("vfio/migration: Report only stop-copy size in vfio_state_pending_exact()") > seems to have uncovered a race between multifd RAM and device state transfers: > RAM transfer sender finishes the multifd stream with a SYNC in > ram_save_complete() but the multifd receive channels are only released > from this SYNC after the migration is wholly complete in > process_incoming_migration_bh(). > > The above causes problems if the multifd channels need to still be > running after the RAM transfer is completed, for example because > there is still remaining device state to be transferred. > > Since QEMU 9.2 code freeze is coming I've separated small uncontroversial > commits from that WiP main patch set here, some of which were already > reviewed during previous main patch set iterations. > > This way at least future code conflicts can be reduced and the amount > of patches that need to be carried in the future versions of the main > patch set is reduced. > > > Maciej S. Szmigiero (4): > vfio/migration: Add save_{iterate,complete_precopy}_started trace > events > migration/ram: Add load start trace event > migration/multifd: Zero p->flags before starting filling a packet > migration: Document the BQL behavior of load SaveVMHandlers
I queued patch 2-3. Patch 4 is ok to be merged even after softfreeze if it's a doc only change, but we don't need to rush either.. Thanks, -- Peter Xu
