Re: [Qemu-devel] [PATCH v8 00/13] basic channel IO passthrough infrastructure based on vfio

[Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>]

* Cornelia Huck <cornelia.huck@de.ibm.com> [2017-05-18 15:13:56 +0200]:

Hi Conny,

> On Wed, 17 May 2017 02:48:00 +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.
> 
> Patches queued, with minor changes (see my comments).
> 
> I'll push out to s390-next once this passes some of my tests.
> 
:-D

> > 
> > Build and install:
> > 1. kernel configuration
> >   CONFIG_S390_CCW_IOMMU=m
> >   CONFIG_VFIO=m
> >   CONFIG_VFIO_MDEV=m
> >   CONFIG_VFIO_MDEV_DEVICE=m
> >   CONFIG_VFIO_CCW=m
> > 2. modules required
> >   modprobe vfio.ko
> >   modprobe mdev.ko
> >   modprobe vfio_mdev.ko
> >   modprobe vfio_iommu_type1.ko
> >   modprobe vfio_ccw.ko
> > 3. find a subchannel(0.0."%schid") of a DASD-ECKD device and bind it to
> >   vfio_ccw driver
> >   #find the dasd you can use with lsdasd on your host. e.g.:
> >   devno="7e52"
> >   schid="16ca"
> >   #unbind the ccw device from the subchannel
> >   echo 0.0."$devno" > /sys/bus/ccw/devices/0.0."$devno"/driver/unbind
> >   #unbind the subchannel from io_subchannel driver
> >   echo 0.0."$schid" > /sys/bus/css/devices/0.0."$schid"/driver/unbind
> >   #bind the subchannel with vfio_ccw driver
> >   echo 0.0."$schid" > /sys/bus/css/drivers/vfio_ccw/bind
> > 4. create a mediated device
> >   #generate a uuid with uuidgen. e.g.:
> >   uuid="6dfd3ec5-e8b3-4e18-a6fe-57bc9eceb920"
> >   echo "$uuid" > \
> >   /sys/bus/css/devices/0.0."$schid"/mdev_supported_types/vfio_ccw-io/create
> > 5. pass-through this device to a vm
> >   -M s390-ccw-virtio,s390-squash-css=on \
> >   -device vfio-ccw,sysfsdev=/sys/bus/mdev/devices/$uuid \
> >   ... ...
> 
> These instructions would be helpful to preserve in the qemu wiki and
> could even be expanded upon.
Nod.

> Ping me if you need an account (hint, hint ;)
(uh...)
Dear Frau, could you please kindly get me an account? Then I can try to
add a new page for vfio-ccw in the qemu wiki. ;)

I will ping you when you online.

Thanks!

-- 
Dong Jia Shi