[RFC 0/7] s390/vfio-ap: reset queues removed from guest's AP configuration

[Tony Krowiak <akrowiak@linux.ibm.com>]

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(-)

-- 
2.41.0