Re: [RFC PATCH v2 0/9] s390x/vfio-ccw: Channel Path Handling

[Cornelia Huck <cohuck@redhat.com>]

On Thu,  6 Feb 2020 22:38:16 +0100
Eric Farman <farman@linux.ibm.com> wrote:

> Here is a new pass at the channel-path handling code for vfio-ccw.
> This was initially developed by Farhan Ali this past summer, and
> picked up by me.  For my own benefit/sanity, I made a small changelog
> in the commit message for each patch, describing the changes I've
> made to his original code beyond just rebasing to master, rather than
> a giant list appended here.
> 
> I had been encountering a host crash which I think was triggered by
> this code rather than existing within it.  I'd sent a potential fix
> for that separately, but need more diagnosis.  So while that is
> outstanding, I think I've gotten most (but probably not all) comments
> from v1 addressed within.
> 
> With this, and the corresponding QEMU series (to be 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.
> 
> For reasons that are hopefully obvious, issuing chchp within the guest
> only works for the logical vary.  Configuring it off/on does not work,
> which I think is fine.

Before I delve into this: While the basic architecture here (and in the
QEMU part) is still similar, you changed things like handling multiple
CRWs? That's at least the impression I got from a very high-level skim.

> 
> v1: https://lore.kernel.org/kvm/20191115025620.19593-1-farman@linux.ibm.com/
> 
> Eric Farman (4):
>   vfio-ccw: Refactor the unregister of the async regions
>   vfio-ccw: Refactor IRQ handlers
>   vfio-ccw: Add trace for CRW event
>   vfio-ccw: Remove inline get_schid() routine
> 
> 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     |  31 ++++-
>  drivers/s390/cio/Makefile           |   2 +-
>  drivers/s390/cio/vfio_ccw_chp.c     | 136 ++++++++++++++++++++
>  drivers/s390/cio/vfio_ccw_drv.c     | 186 ++++++++++++++++++++++++++--
>  drivers/s390/cio/vfio_ccw_fsm.c     |   8 +-
>  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       |  19 +++
>  11 files changed, 463 insertions(+), 34 deletions(-)
>  create mode 100644 drivers/s390/cio/vfio_ccw_chp.c
>