[25.04 FEAT] [VS2214] KVM: Enable dynamic update of vfio-ap mediated devices for management applications - s390-tools part

[bugproxy]

Feature Description:

The configuration of a vfio-ap matrix device can be updated while being in use, e.g. by a running KVM guest. However, presently this configuration change can't be performed using the higher level management interfaces and tools, like mdevctl and the libvirt nodedev API. Neither it is possible to observe the dynamic updates at the higher levels. This can lead to confusion and hard-to-debug problems in the field.
We want to enable mdevctl and libvirt to be used to perform dynamic updates of vfio-ap matrix devices. To achieve this, it will be necessary to enable mdevctl to support dynamic updates in principle, but also requires support in the vfio-ap driver to support bulk updates in sysfs (of multiple APQNs in one operation), enhancements to the ap-check callout of s390-tools to exploit the vfio-ap specific sysfs interfaces and perform the actual update. Finally, the libvirt nodedev API must be extended to support a modify operation.

[bugproxy (bugproxy)]

------- Comment From <email address hidden> 2025-02-05 18:45 EDT-------
This is included in s390-tools v2.34.0

The related upstream commits are:

5806c4e1f ap_tools/ap-check: implement get capabilities callout
9d199e06c ap_tools/ap-check: implement dynamic config during live modify
f7425a08d ap_tools/ap-check: refactor active config checking
f6a97902c libap: handle reading ap_config attribute
962af1a90 libap: add routines to generate masks for vfio_ap_device
46dadc8cc libap: add routine to check for dynamic config support
9c8d117cc zdev: remove duplicate ap_node structure

git tag --contains 5806c4e1f
v2.34.0
...

[Frank Heimes (fheimes)]

Many thanks for the detailed list of commits.
Since plucky includes s390-tools v2.36.0-0ubuntu1,
I'm updating this ticket to "Fix Released" (hence closing as done).