vfio-ccw: support hsch/csch (kernel part)

[This is the Linux kernel part, git tree is available at
https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/vfio-ccw.git vfio-ccw-caps

The companion QEMU patches are available at
https://github.com/cohuck/qemu vfio-ccw-caps]

Currently, vfio-ccw only relays START SUBCHANNEL requests to the real device. This tends to work well for the most common 'good path' scenarios; however, as we emulate {HALT,CLEAR} SUBCHANNEL in QEMU, things like clearing pending requests at the device is currently not supported. This may be a problem for e.g. error recovery.

This patch series introduces capabilities (similar to what vfio-pci uses) and exposes a new async region for handling hsch/csch.

Very lightly tested (I can interact with a dasd as before; I have not found a reliable way to trigger hsch/csch in the Linux dasd guest driver.)

Cornelia Huck (3):
vfio-ccw: add capabilities chain
s390/cio: export hsch to modules
vfio-ccw: add handling for asnyc channel instructions

 drivers/s390/cio/Makefile           |   3 +-
 drivers/s390/cio/ioasm.c            |   1 +
 drivers/s390/cio/vfio_ccw_async.c   |  88 +++++++++++++
 drivers/s390/cio/vfio_ccw_drv.c     |  48 +++++--
 drivers/s390/cio/vfio_ccw_fsm.c     | 158 +++++++++++++++++++++-
 drivers/s390/cio/vfio_ccw_ops.c     | 195 ++++++++++++++++++++++++----
 drivers/s390/cio/vfio_ccw_private.h |  44 +++++++
 include/uapi/linux/vfio.h           |   5 +
 include/uapi/linux/vfio_ccw.h       |  12 ++
 9 files changed, 509 insertions(+), 45 deletions(-)
 create mode 100644 drivers/s390/cio/vfio_ccw_async.c

2.17.2