Re: [PATCH v7 00/13] basic channel IO passthrough infrastructure based on vfio

Cornelia Huck
2017-05-05T12:22:34Z

On Fri, 5 May 2017 04:03:39 +0200
Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com> wrote:

> The patch series introduce a basic channel I/O passthrough
> infrastructure based on vfio.
> - Focus on supporting dasd-eckd(cu_type/dev_type = 0x3990/0x3390) as
> the target device.
> - Support new qemu parameters in the style of:
> -machine s390-ccw-virtio(,s390-squash-mcss=on|off) \
> -device vfio-ccw,sysfsdev=$MDEV_PATH
> We want to support real (i.e. not virtual) channel devices even for
> guests that do not support MCSS-E (where guests may see devices from
> any channel subsystem image at once). As all virtio-ccw devices are in
> css 0xfe (and show up in the default css 0 for guests not activating
> MCSS-E), we need an option to squash e.g. passed-through channel devices
> from their real css (0-3, or 0 for hosts not activating MCSS-E) into
> the default css, that is what the new machine option s390-squash-css is
> added.

Basically looks good, some small nitpicking and the virtual vs. virtio
issue I noticed.

Let's wait if others have more comments. Hopefully, the 3270 changes
will by then be in master and you can rebase on top of them :)