18e75b835SCornelia HuckSubchannel passthrough via vfio-ccw 28e75b835SCornelia Huck=================================== 38e75b835SCornelia Huck 48e75b835SCornelia Huckvfio-ccw (based upon the mediated vfio device infrastructure) allows to 58e75b835SCornelia Huckmake certain I/O subchannels and their devices available to a guest. The 68e75b835SCornelia Huckhost will not interact with those subchannels/devices any more. 78e75b835SCornelia Huck 88e75b835SCornelia HuckNote that while vfio-ccw should work with most non-QDIO devices, only ECKD 98e75b835SCornelia HuckDASDs have really been tested. 108e75b835SCornelia Huck 118e75b835SCornelia HuckExample configuration 128e75b835SCornelia Huck--------------------- 138e75b835SCornelia Huck 148e75b835SCornelia HuckStep 1: configure the host device 158e75b835SCornelia Huck~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 168e75b835SCornelia Huck 178e75b835SCornelia HuckAs every mdev is identified by a uuid, the first step is to obtain one:: 188e75b835SCornelia Huck 198e75b835SCornelia Huck [root@host ~]# uuidgen 208e75b835SCornelia Huck 7e270a25-e163-4922-af60-757fc8ed48c6 218e75b835SCornelia Huck 228e75b835SCornelia HuckNote: it is recommended to use the ``mdevctl`` tool for actually configuring 238e75b835SCornelia Huckthe host device. 248e75b835SCornelia Huck 258e75b835SCornelia HuckTo define the same device as configured below to be started 268e75b835SCornelia Huckautomatically, use 278e75b835SCornelia Huck 288e75b835SCornelia Huck:: 298e75b835SCornelia Huck 308e75b835SCornelia Huck [root@host ~]# driverctl -b css set-override 0.0.0313 vfio_ccw 318e75b835SCornelia Huck [root@host ~]# mdevctl define -u 7e270a25-e163-4922-af60-757fc8ed48c6 \ 32*9ece07d7SCornelia Huck -p 0.0.0313 -t vfio_ccw-io -a 338e75b835SCornelia Huck 348e75b835SCornelia HuckIf using ``mdevctl`` is not possible or wanted, follow the manual procedure 358e75b835SCornelia Huckbelow. 368e75b835SCornelia Huck 378e75b835SCornelia Huck* Locate the subchannel for the device (in this example, ``0.0.2b09``):: 388e75b835SCornelia Huck 398e75b835SCornelia Huck [root@host ~]# lscss | grep 0.0.2b09 | awk '{print $2}' 408e75b835SCornelia Huck 0.0.0313 418e75b835SCornelia Huck 428e75b835SCornelia Huck* Unbind the subchannel (in this example, ``0.0.0313``) from the standard 438e75b835SCornelia Huck I/O subchannel driver and bind it to the vfio-ccw driver:: 448e75b835SCornelia Huck 458e75b835SCornelia Huck [root@host ~]# echo 0.0.0313 > /sys/bus/css/devices/0.0.0313/driver/unbind 468e75b835SCornelia Huck [root@host ~]# echo 0.0.0313 > /sys/bus/css/drivers/vfio_ccw/bind 478e75b835SCornelia Huck 488e75b835SCornelia Huck* Create the mediated device (identified by the uuid):: 498e75b835SCornelia Huck 508e75b835SCornelia Huck [root@host ~]# echo "7e270a25-e163-4922-af60-757fc8ed48c6" > \ 518e75b835SCornelia Huck /sys/bus/css/devices/0.0.0313/mdev_supported_types/vfio_ccw-io/create 528e75b835SCornelia Huck 538e75b835SCornelia HuckStep 2: configure QEMU 548e75b835SCornelia Huck~~~~~~~~~~~~~~~~~~~~~~ 558e75b835SCornelia Huck 568e75b835SCornelia Huck* Reference the created mediated device and (optionally) pick a device id to 578e75b835SCornelia Huck be presented in the guest (here, ``fe.0.1234``, which will end up visible 588e75b835SCornelia Huck in the guest as ``0.0.1234``:: 598e75b835SCornelia Huck 608e75b835SCornelia Huck -device vfio-ccw,devno=fe.0.1234,sysfsdev=\ 618e75b835SCornelia Huck /sys/bus/mdev/devices/7e270a25-e163-4922-af60-757fc8ed48c6 628e75b835SCornelia Huck 638e75b835SCornelia Huck* Start the guest. The device (here, ``0.0.1234``) should now be usable:: 648e75b835SCornelia Huck 658e75b835SCornelia Huck [root@guest ~]# lscss -d 0.0.1234 668e75b835SCornelia Huck Device Subchan. DevType CU Type Use PIM PAM POM CHPID 678e75b835SCornelia Huck ---------------------------------------------------------------------- 688e75b835SCornelia Huck 0.0.1234 0.0.0007 3390/0e 3990/e9 f0 f0 ff 1a2a3a0a 00000000 698e75b835SCornelia Huck [root@guest ~]# chccwdev -e 0.0.1234 708e75b835SCornelia Huck Setting device 0.0.1234 online 718e75b835SCornelia Huck Done 728e75b835SCornelia Huck [root@guest ~]# dmesg -t 738e75b835SCornelia Huck (...) 748e75b835SCornelia Huck dasd-eckd 0.0.1234: A channel path to the device has become operational 758e75b835SCornelia Huck dasd-eckd 0.0.1234: New DASD 3390/0E (CU 3990/01) with 10017 cylinders, 15 heads, 224 sectors 768e75b835SCornelia Huck dasd-eckd 0.0.1234: DASD with 4 KB/block, 7212240 KB total size, 48 KB/track, compatible disk layout 778e75b835SCornelia Huck dasda:VOL1/ 0X2B09: dasda1 78