[SRU][Disco][Cosmic][Bionic][Patch 0/1] Fixes for 1818854

[frank.heimes at canonical.com]

Buglink: https://bugs.launchpad.net/bugs/1818854

SRU Justification:

[Impact]

* The vfio-ap driver will create a matrix device in sysfs without a subsystem link.

* This causes failures in libudev that might also lead to libvirt errors.

* A fix is upstream in master branch for kernel 5.1

[Fix]

* 36360658eb5a6cf04bb9f2704d1e4ce54037ec99 3636065 "s390: vfio_ap: link the vfio_ap devices to the vfio_ap bus subsystem"

[Test Case]

* An s390x machine with at least one CryptoExpress card,
  where at least one AP and one 'Domain' is assigned to a particular LPAR.

* Now running virsh nodedev-list before (and later after) construction the matrix device should expose the issue.

* For details about how to setup a vfio-ap matrix device see: http://kvmonz.blogspot.com/2018/12/qemu-v31-released.html
  (see 2nd bullet: virtio-ap)

[Regression Potential] 

* The regression potential can be considered as low since it only affects the s390x platform

* and there it only affects the usage of AP (CryptoExpress) cards and it's driver/module

* and again only affects the recently introduced virtual IO function of AP (vfio-ap).

[Other Info]

* It was already briefly discussed here:
  https://www.redhat.com/archives/libvir-list/2019-February/msg00837.html
  as well as reviewed and pushed.

* Commit 3636065 from v5.1-rc1

* This affects ccw cards and their vf only, NOT vf of PCI/PCIe cards!

* * For details on virtio-ap/vfio-ap see bullet #2 here: http://kvmonz.blogspot.com/2018/12/qemu-v31-released.html

Pierre Morel (1):
   s390: vfio_ap: link the vfio_ap devices to the vfio_ap bus subsystem
---
 drivers/s390/crypto/vfio_ap_drv.c     | 44 ++++++++++++++++++++++++++++-------
 drivers/s390/crypto/vfio_ap_ops.c     |  4 ++--
 drivers/s390/crypto/vfio_ap_private.h |  1 +
 3 files changed, 38 insertions(+), 11 deletions(-)