On Sun, Feb 09, 2025 at 11:20:00PM +0100, Stefano Brivio wrote:Introduce facilities for guest migration on top of vhost-user infrastructure. Add migration facilities based on top of the current vhost-user infrastructure, moving vu_migrate() and related functions to migrate.c. Versioned migration stages define function pointers to be called on source or target, or data sections that need to be transferred. The migration header consists of a magic number, a version number for the encoding, and a "compat_version" which represents the oldest version which is compatible with the current one. We don't use it yet, but that allows for the future possibility of backwards compatible protocol extensions. Co-authored-by: David Gibson <david(a)gibson.dropbear.id.au> Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio(a)redhat.com>Reviewed-by: David Gibson <david(a)gibson.dropbear.id.au> with the exception of one nit, which I hope to send a fixup patch for today: [snip]+/** + * struct migrate_stage - Callbacks and parameters for one stage of migration + * @name: Stage name (for debugging) + * @source: Callback to implement this stage on the source + * @target: Callback to implement this stage on the target + * @iov: Optional data section to transfer + */ +struct migrate_stage { + const char *name; + int (*source)(struct ctx *c, const struct migrate_stage *stage, int fd); + int (*target)(struct ctx *c, const struct migrate_stage *stage, int fd); + + /* Add here separate rollback callbacks if needed */ + + struct iovec iov;We're no longer using this @iov field, and it can be removed. -- David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson