STRUCT VFIO_MIGRATION_OPS(9)

✨ struct vfio_migration_ops(9) ✨

okay bestie, welcome to the Kernel API Manual 💖 this little page is all about struct vfio_migration_ops and honestly? it's giving "backstage pass to migration" energy 🎀

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💅 NAME

struct vfio_migration_ops — the VFIO bus device driver migration callbacks 👑 like, these are the lil functions your driver hands over so migration can actually happen.

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🌸 SYNOPSIS

struct vfio_migration_ops {
    struct file *(*migration_set_state)( struct vfio_device *device,
enum vfio_device_mig_state new_state);
    int (*migration_get_state)(struct vfio_device *device, enum
vfio_device_mig_state *curr_state);
    int (*migration_get_data_size)(struct vfio_device *device, unsigned
long *stop_copy_length);
 };

no cap, that's the whole struct 🫶 three function pointers, each one optional-but-actually-mandatory-if-you-want-migration (more on that in a sec 👀).

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🦋 Members

• migration_set_state — an optional callback that changes the migration state for devices that support migration ✨. it is mandatory for VFIO_DEVICE_FEATURE_MIGRATION migration support, so like… optional in theory, required in practice, iykyk 💀. the returned FD is used for data transfer according to the FSM definition 📨. and the driver is responsible for making sure that FD reaches end of stream or error whenever the migration FSM leaves a data transfer state, or before close_device returns 🚨 — yes, that's on you, bestie, no dodging it.
• migration_get_state — an optional callback that gets the migration state for devices that support migration 🌈. also mandatory for VFIO_DEVICE_FEATURE_MIGRATION migration support. the way it just peeks at where you're at, iconic.
• migration_get_data_size — an optional callback that gets the estimated data length that will be required to complete stop copy 📏. and yup, you guessed it: mandatory for VFIO_DEVICE_FEATURE_MIGRATION migration support 🔥.

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🎀 SEE ALSO

• Kernel file ./include/linux/vfio.h
• struct vfio_device_ops(9)
• struct vfio_log_ops(9)
• vfio_check_feature(9)
• vfio_check_precopy_ioctl(9)

go read those too, they're lowkey the whole friend group 💜

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fr fr, remember the vibe check: all three callbacks say "Optional" in the description, but every single one is mandatory for VFIO_DEVICE_FEATURE_MIGRATION migration support. don't let the word "optional" gaslight you 🙈

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okay that's the page!! tysm for reading, mwah 💋 this one came from ./include/linux, dated October 2026 — literally a little time capsule, slay ⭐🧚‍♀️