[v7,0/4] vfio: ap: AP Queue Interrupt Control

Message

Pierre Morel April 26, 2019, 1:01 p.m. UTC

This patch series implements PQAP/AQIC interception in KVM.

1) Data to handle GISA interrupt for AQIC

To implement this we need to add a new structure, vfio_ap_queue,
to be able to retrieve the mediated device associated with a queue
and specific values needed to register/unregister the interrupt
structures:
  - APQN: to be able to issue the commands and search for queue
    structures
  - NIB and old NIB : to unpin the NIB on clear IRQ
  - ISC and old ISC : to unregister with the GIB interface
  - matrix_mdev: to retrieve the associate matrix and mediated device

Specific handling bei keeping old values when re-registering is
needed because the guest could unregister interrupt in a invisble
manner bei issuing an un-interceptible RESET command.

Reset commands issued directly by the guest and indirectly when
removing the guest unpin the memory and deregister the ISC.

The vfio_ap_queue is associated to the ap_device during the probe
of the device and dissociated during the remove of the ap_device.

The vfio_ap_queue is associated to the matrix mediated device during
each interception of the AQIC command, so it do not need to be
dissociated until the guest is terminated.

The life of the vfio_ap_queue will be protected by the matrix_dev lock
to guaranty that no change can occur to the CRYCB or that devices can
not be removed when a vfio_ap_queue is in use.

2) KVM destroy race conditions

To make sure that KVM do not vanish and GISA is still available
when the VFIO_AP driver is in used we take a reference to KVM
during the opening of the mediated device and release it on
releasing the mediated device.

3) Interception of PQAP

The driver registers a hook structure to KVM providing:
- a pointer to a function implementing PQAP(AQIC) handling
- the reference to the module owner of the hook

On interception by KVM we do not change the behavior, returning
 -EOPNOTSUPP to the user in the case AP instructions are not
supported by the host or by the guest.
Otherwise we verify the exceptions cases before trying to call 
the vfio_ap hook.

In the case we do not find a hook we assume that the CRYCB has not
been setup for the guest and is empty.


4) Removing the AP device

Removing the AP device without having unassign it is clearly
discourage by the documentation.
The patch series does not check if the queue is used by a
guest and simply free the vfio_ap_queue.

5) Associated QEMU patch

There is a QEMU patch which is needed to enable the PQAP/AQIC
facility in the guest.

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Pierre Morel (4):
  s390: ap: kvm: add PQAP interception for AQIC
  vfio: ap: register IOMMU VFIO notifier
  s390: ap: implement PAPQ AQIC interception in kernel
  s390: ap: kvm: Enable PQAP/AQIC facility for the guest

 arch/s390/include/asm/kvm_host.h      |   7 +
 arch/s390/kvm/priv.c                  |  86 +++++++++
 arch/s390/tools/gen_facilities.c      |   1 +
 drivers/s390/crypto/ap_bus.h          |   1 +
 drivers/s390/crypto/vfio_ap_drv.c     |  30 ++-
 drivers/s390/crypto/vfio_ap_ops.c     | 336 +++++++++++++++++++++++++++++++++-
 drivers/s390/crypto/vfio_ap_private.h |  15 ++
 7 files changed, 468 insertions(+), 8 deletions(-)