[PATCH v4 0/8] s390x/vfio-ccw: Channel Path Handling [KVM]

[Eric Farman <farman@linux.ibm.com>]

Here is a new pass at the channel-path handling code for vfio-ccw.
Changes from previous versions are recorded in git notes for each patch.
Patches 5 through 7 got swizzled a little bit, in order to better
compartmentalize the code they define. Basically, the IRQ definitions
were moved from patch 7 to 5, and then patch 6 was placed ahead of
patch 5.

I have put Conny's r-b's on patches 1, 3, 4, (new) 5, and 8, and believe
I have addressed all comments from v3, with two exceptions:

> I'm wondering if we should make this [vfio_ccw_schib_region_{write,release}]
> callback optional (not in this patch).

I have that implemented on top of this series, and will send later as part
of a larger cleanup series.

> One thing though that keeps coming up: do we need any kind of
> serialization? Can there be any confusion from concurrent reads from
> userspace, or are we sure that we always provide consistent data?

I _think_ this is in good shape, though as suggested another set of
eyeballs would be nice. There is still a problem on the main
interrupt/FSM path, which I'm not attempting to address here.

With this code plus the corresponding QEMU series (posted momentarily)
applied I am able to configure off/on a CHPID (for example, by issuing
"chchp -c 0/1 xx" on the host), and the guest is able to see both the
events and reflect the updated path masks in its structures.

v3: https://lore.kernel.org/kvm/20200417023001.65006-1-farman@linux.ibm.com/
v2: https://lore.kernel.org/kvm/20200206213825.11444-1-farman@linux.ibm.com/
v1: https://lore.kernel.org/kvm/20191115025620.19593-1-farman@linux.ibm.com/

Eric Farman (3):
  vfio-ccw: Refactor the unregister of the async regions
  vfio-ccw: Refactor IRQ handlers
  vfio-ccw: Add trace for CRW event

Farhan Ali (5):
  vfio-ccw: Introduce new helper functions to free/destroy regions
  vfio-ccw: Register a chp_event callback for vfio-ccw
  vfio-ccw: Introduce a new schib region
  vfio-ccw: Introduce a new CRW region
  vfio-ccw: Wire up the CRW irq and CRW region

 Documentation/s390/vfio-ccw.rst     |  38 ++++++-
 drivers/s390/cio/Makefile           |   2 +-
 drivers/s390/cio/vfio_ccw_chp.c     | 148 +++++++++++++++++++++++++
 drivers/s390/cio/vfio_ccw_drv.c     | 165 ++++++++++++++++++++++++++--
 drivers/s390/cio/vfio_ccw_ops.c     |  65 ++++++++---
 drivers/s390/cio/vfio_ccw_private.h |  16 +++
 drivers/s390/cio/vfio_ccw_trace.c   |   1 +
 drivers/s390/cio/vfio_ccw_trace.h   |  30 +++++
 include/uapi/linux/vfio.h           |   3 +
 include/uapi/linux/vfio_ccw.h       |  18 +++
 10 files changed, 458 insertions(+), 28 deletions(-)
 create mode 100644 drivers/s390/cio/vfio_ccw_chp.c

-- 
2.17.1