unassign_domain_store(9)

💅 unassign_domain_store(9) 💅

okay so bestie, welcome to the Kernel API Manual 🫶 this page is lowkey a tiny kernel helper with a very specific job, and it's giving focused-icon energy. let's go 💖

✨ NAME ✨

unassign_domain_store parses the APQI from @buf and clears the corresponding bit in the mediated matrix device's AQM. that's it, that's the whole assignment — APQI in, matching bit cleared, periodt 💅

✨ SYNOPSIS ✨

ssize_t unassign_domain_store (struct device *dev , struct
       device_attribute *attr , const char *buf , size_t count );

🎀 ARGUMENTS 🎀

• dev — the matrix device. main character device energy 👑
• attr — the mediated matrix device's unassign_domain attribute. yes, that exact attribute bestie 💅
• buf — a buffer containing the AP queue index (APQI) of the domain to be unassigned. it's literally carrying the APQI 🫶
• count — the number of bytes in buf. keep count cute and correct 📏

🔥 RETURN 🔥

if the APQI is valid, it returns the number of bytes processed. slay ✅

otherwise, it returns one of the following errors:

• -EINVAL if the APQI is not a number. not a number? blocked 😭
• -ENODEV if the APQI exceeds the maximum value configured for the system. too big? also blocked 💀

🦋 SEE ALSO 🦋

Kernel file: ./drivers/s390/crypto/vfio_ap_ops.c — go read the source bestie, it's right there 👀

the whole friend group is here too:

• get_update_locks_for_kvm(9)
• release_update_locks_for_kvm(9)
• get_update_locks_for_mdev(9)
• release_update_locks_for_mdev(9)
• get_update_locks_by_apqn(9)
• get_update_locks_for_queue(9)
• vfio_ap_mdev_get_queue(9)
• vfio_ap_wait_for_irqclear(9)
• vfio_ap_free_aqic_resources(9)
• vfio_ap_irq_disable(9)
• vfio_ap_validate_nib(9)
• ensure_nib_shared(9)
• vfio_ap_irq_enable(9)
• vfio_ap_le_guid_to_be_uuid(9)
• handle_pqap(9)
• vfio_ap_mdev_verify_no_sharing(9)
• vfio_ap_mdev_validate_masks(9)
• assign_adapter_store(9)
• vfio_ap_mdev_unlink_adapter(9)
• unassign_adapter_store(9)
• assign_domain_store(9)
• assign_control_domain_store(9)
• unassign_control_domain_store(9)
• vfio_ap_mdev_set_kvm(9)
• vfio_ap_mdev_unset_kvm(9)
• vfio_ap_mdev_resource_in_use(9)
• vfio_ap_mdev_hot_unplug_cfg(9)
• vfio_ap_mdev_cfg_remove(9)
• vfio_ap_mdev_on_cfg_remove(9)
• vfio_ap_filter_apid_by_qtype(9)
• vfio_ap_mdev_cfg_add(9)
• vfio_ap_mdev_on_cfg_add(9)
• vfio_ap_on_cfg_changed(9)

mwah 💋 this page comes from ./drivers/s390/crypto and is dated October 2026 — unassign_domain_store(9), signing off like the icon it is 🫶✨