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Diffstat (limited to 'docs')
| -rw-r--r-- | docs/system/s390x/3270.rst | 32 | ||||
| -rw-r--r-- | docs/system/s390x/css.rst | 86 | ||||
| -rw-r--r-- | docs/system/s390x/vfio-ccw.rst | 77 | ||||
| -rw-r--r-- | docs/system/target-s390x.rst | 3 |
4 files changed, 198 insertions, 0 deletions
diff --git a/docs/system/s390x/3270.rst b/docs/system/s390x/3270.rst new file mode 100644 index 0000000..1774cdc --- /dev/null +++ b/docs/system/s390x/3270.rst @@ -0,0 +1,32 @@ +3270 devices +============ + +QEMU supports connecting an external 3270 terminal emulator (such as +``x3270``) to make a single 3270 device available to a guest. Note that this +supports basic features only. + +To provide a 3270 device to a guest, create a ``x-terminal3270`` linked to +a ``tn3270`` chardev. The guest will see a 3270 channel device. In order +to actually be able to use it, attach the ``x3270`` emulator to the chardev. + +Example configuration +--------------------- + +* Add a ``tn3270`` chardev and a ``x-terminal3270`` to the QEMU command line:: + + -chardev socket,id=char_0,host=0.0.0.0,port=2300,nowait,server,tn3270 + -device x-terminal3270,chardev=char_0,devno=fe.0.000a,id=terminal_0 + +* Start the guest. In the guest, use ``chccwdev -e 0.0.000a`` to enable + the device. + +* On the host, start the ``x3270`` emulator:: + + x3270 <host>:2300 + +* In the guest, locate the 3270 device node under ``/dev/3270/`` (say, + ``tty1``) and start a getty on it:: + + systemctl start serial-getty@3270-tty1.service + +This should get you an addtional tty for logging into the guest. diff --git a/docs/system/s390x/css.rst b/docs/system/s390x/css.rst new file mode 100644 index 0000000..3b40161 --- /dev/null +++ b/docs/system/s390x/css.rst @@ -0,0 +1,86 @@ +The virtual channel subsystem +============================= + +QEMU implements a virtual channel subsystem with subchannels, (mostly +functionless) channel paths, and channel devices (virtio-ccw, 3270, and +devices passed via vfio-ccw). It supports multiple subchannel sets (MSS) and +multiple channel subsystems extended (MCSS-E). + +All channel devices support the ``devno`` property, which takes a parameter +in the form ``<cssid>.<ssid>.<device number>``. + +The default channel subsystem image id (``<cssid>``) is ``0xfe``. Devices in +there will show up in channel subsystem image ``0`` to guests that do not +enable MCSS-E. Note that devices with a different cssid will not be visible +if the guest OS does not enable MCSS-E (which is true for all supported guest +operating systems today). + +Supported values for the subchannel set id (``<ssid>``) range from ``0-3``. +Devices with a ssid that is not ``0`` will not be visible if the guest OS +does not enable MSS (any Linux version that supports virtio also enables MSS). +Any device may be put into any subchannel set, there is no restriction by +device type. + +The device number can range from ``0-0xffff``. + +If the ``devno`` property is not specified for a device, QEMU will choose the +next free device number in subchannel set 0, skipping to the next subchannel +set if no more device numbers are free. + +QEMU places a device at the first free subchannel in the specified subchannel +set. If a device is hotunplugged and later replugged, it may appear at a +different subchannel. (This is similar to how z/VM works.) + + +Examples +-------- + +* a virtio-net device, cssid/ssid/devno automatically assigned:: + + -device virtio-net-ccw + + In a Linux guest (without default devices and no other devices specified + prior to this one), this will show up as ``0.0.0000`` under subchannel + ``0.0.0000``. + + The auto-assigned-properties in QEMU (as seen via e.g. ``info qtree``) + would be ``dev_id = "fe.0.0000"`` and ``subch_id = "fe.0.0000"``. + +* a virtio-rng device in subchannel set ``0``:: + + -device virtio-rng-ccw,devno=fe.0.0042 + + If added to the same Linux guest as above, it would show up as ``0.0.0042`` + under subchannel ``0.0.0001``. + + The properties for the device would be ``dev_id = "fe.0.0042"`` and + ``subch_id = "fe.0.0001"``. + +* a virtio-gpu device in subchannel set ``2``:: + + -device virtio-gpu-ccw,devno=fe.2.1111 + + If added to the same Linux guest as above, it would show up as ``0.2.1111`` + under subchannel ``0.2.0000``. + + The properties for the device would be ``dev_id = "fe.2.1111"`` and + ``subch_id = "fe.2.0000"``. + +* a virtio-mouse device in a non-standard channel subsystem image:: + + -device virtio-mouse-ccw,devno=2.0.2222 + + This would not show up in a standard Linux guest. + + The properties for the device would be ``dev_id = "2.0.2222"`` and + ``subch_id = "2.0.0000"``. + +* a virtio-keyboard device in another non-standard channel subsystem image:: + + -device virtio-keyboard-ccw,devno=0.0.1234 + + This would not show up in a standard Linux guest, either, as ``0`` is not + the standard channel subsystem image id. + + The properties for the device would be ``dev_id = "0.0.1234"`` and + ``subch_id = "0.0.0000"``. diff --git a/docs/system/s390x/vfio-ccw.rst b/docs/system/s390x/vfio-ccw.rst new file mode 100644 index 0000000..8f65442 --- /dev/null +++ b/docs/system/s390x/vfio-ccw.rst @@ -0,0 +1,77 @@ +Subchannel passthrough via vfio-ccw +=================================== + +vfio-ccw (based upon the mediated vfio device infrastructure) allows to +make certain I/O subchannels and their devices available to a guest. The +host will not interact with those subchannels/devices any more. + +Note that while vfio-ccw should work with most non-QDIO devices, only ECKD +DASDs have really been tested. + +Example configuration +--------------------- + +Step 1: configure the host device +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +As every mdev is identified by a uuid, the first step is to obtain one:: + + [root@host ~]# uuidgen + 7e270a25-e163-4922-af60-757fc8ed48c6 + +Note: it is recommended to use the ``mdevctl`` tool for actually configuring +the host device. + +To define the same device as configured below to be started +automatically, use + +:: + + [root@host ~]# driverctl -b css set-override 0.0.0313 vfio_ccw + [root@host ~]# mdevctl define -u 7e270a25-e163-4922-af60-757fc8ed48c6 \ + -p 0.0.0313 -t vfio-ccw_io -a + +If using ``mdevctl`` is not possible or wanted, follow the manual procedure +below. + +* Locate the subchannel for the device (in this example, ``0.0.2b09``):: + + [root@host ~]# lscss | grep 0.0.2b09 | awk '{print $2}' + 0.0.0313 + +* Unbind the subchannel (in this example, ``0.0.0313``) from the standard + I/O subchannel driver and bind it to the vfio-ccw driver:: + + [root@host ~]# echo 0.0.0313 > /sys/bus/css/devices/0.0.0313/driver/unbind + [root@host ~]# echo 0.0.0313 > /sys/bus/css/drivers/vfio_ccw/bind + +* Create the mediated device (identified by the uuid):: + + [root@host ~]# echo "7e270a25-e163-4922-af60-757fc8ed48c6" > \ + /sys/bus/css/devices/0.0.0313/mdev_supported_types/vfio_ccw-io/create + +Step 2: configure QEMU +~~~~~~~~~~~~~~~~~~~~~~ + +* Reference the created mediated device and (optionally) pick a device id to + be presented in the guest (here, ``fe.0.1234``, which will end up visible + in the guest as ``0.0.1234``:: + + -device vfio-ccw,devno=fe.0.1234,sysfsdev=\ + /sys/bus/mdev/devices/7e270a25-e163-4922-af60-757fc8ed48c6 + +* Start the guest. The device (here, ``0.0.1234``) should now be usable:: + + [root@guest ~]# lscss -d 0.0.1234 + Device Subchan. DevType CU Type Use PIM PAM POM CHPID + ---------------------------------------------------------------------- + 0.0.1234 0.0.0007 3390/0e 3990/e9 f0 f0 ff 1a2a3a0a 00000000 + [root@guest ~]# chccwdev -e 0.0.1234 + Setting device 0.0.1234 online + Done + [root@guest ~]# dmesg -t + (...) + dasd-eckd 0.0.1234: A channel path to the device has become operational + dasd-eckd 0.0.1234: New DASD 3390/0E (CU 3990/01) with 10017 cylinders, 15 heads, 224 sectors + dasd-eckd 0.0.1234: DASD with 4 KB/block, 7212240 KB total size, 48 KB/track, compatible disk layout + dasda:VOL1/ 0X2B09: dasda1 diff --git a/docs/system/target-s390x.rst b/docs/system/target-s390x.rst index 7d76ae9..644e404 100644 --- a/docs/system/target-s390x.rst +++ b/docs/system/target-s390x.rst @@ -23,6 +23,9 @@ or vfio-ap is also available. .. toctree:: s390x/vfio-ap + s390x/css + s390x/3270 + s390x/vfio-ccw Architectural features ====================== |