This patch series was ultimately created to fix a bug reported via BZ203687. Halil did some problem determination and concluded that the problem was due to the fact that all queues removed from the guest's AP configuration are not reset. For example, when an adapter or domain is assigned to the mdev matrix, if a queue device associated with the adapter or domain is not bound to the vfio_ap device driver, the adapter to which the queue is attached will be removed from the guest's configuration. The problem is, removing the adapter also implicitly removes all queues attached to that adapter. Those queues also need to be reset to avert leaking crypto data should any of those queues get assigned to another guest or back to the host.
The original intent was to ensure that all queues removed from a guest's AP configuration get reset. The testing included permutations of various scenarios involving the binding/unbinding of queues either manually, or due to dynamic host AP configuration changes initiated via an SE or HMC attached to a DPM-enabled LPAR. This testing revealed several issues that are also addressed via this patch series.
Note that several of the patches has a 'Fixes:' tag as well as a Cc: stable@vger.kernel.org tag. I'm not sure whether this is necessary because the patches not related to the reset issue are probably rarely if ever encountered, so I'd like an opinion on that also.
Tony Krowiak (7): s390/vfio-ap: always filter entire AP matrix s390/vfio-ap: circumvent filtering for adapters/domains not in host config s390/vfio-ap: do not reset queue removed from host config s390/vfio-ap: let 'on_scan_complete' callback filter matrix and update guest's APCB s390/vfio-ap: allow reset of subset of queues assigned to matrix mdev s390/vfio-ap: reset queues filtered from the guest's AP config s390/vfio-ap: reset queues associated with adapter for queue unbound from driver
drivers/s390/crypto/vfio_ap_ops.c | 294 +++++++++++++++++++------- drivers/s390/crypto/vfio_ap_private.h | 25 ++- 2 files changed, 234 insertions(+), 85 deletions(-)