[PATCH v3] docs/s390x: document vfio-ccw

[PATCH v3] docs/s390x: document vfio-ccw

[Cornelia Huck]

Add a basic example for passing a dasd via vfio-ccw.

Signed-off-by: Cornelia Huck <cohuck@redhat.com>
---

v2->v3: moved uuid generation (Thomas)

---
 docs/system/s390x/vfio-ccw.rst | 77 ++++++++++++++++++++++++++++++++++
 docs/system/target-s390x.rst   |  1 +
 2 files changed, 78 insertions(+)
 create mode 100644 docs/system/s390x/vfio-ccw.rst

diff --git a/docs/system/s390x/vfio-ccw.rst b/docs/system/s390x/vfio-ccw.rst
new file mode 100644
index 000000000000..fff23d9afff7
--- /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 2592a05303ef..644e404ef9fd 100644
--- a/docs/system/target-s390x.rst
+++ b/docs/system/target-s390x.rst
@@ -25,6 +25,7 @@ or vfio-ap is also available.
    s390x/vfio-ap
    s390x/css
    s390x/3270
+   s390x/vfio-ccw
 
 Architectural features
 ======================
-- 
2.25.4

Re: [PATCH v3] docs/s390x: document vfio-ccw

[Thomas Huth]

On 18/05/2020 09.55, Cornelia Huck wrote:
> Add a basic example for passing a dasd via vfio-ccw.
> 
> Signed-off-by: Cornelia Huck <cohuck@redhat.com>
> ---
> 
> v2->v3: moved uuid generation (Thomas)
> 
> ---
>  docs/system/s390x/vfio-ccw.rst | 77 ++++++++++++++++++++++++++++++++++
>  docs/system/target-s390x.rst   |  1 +
>  2 files changed, 78 insertions(+)
>  create mode 100644 docs/system/s390x/vfio-ccw.rst
> 
> diff --git a/docs/system/s390x/vfio-ccw.rst b/docs/system/s390x/vfio-ccw.rst
> new file mode 100644
> index 000000000000..fff23d9afff7
> --- /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\

Maybe add a space before the backslash?

> +                  -p 0.0.0313 -t vfio-ccw_io -a
> +
> +If using ``mdevctl``  is not possible or wanted, follow the manual procedure
> +below.

Nit: Doubled whitespaces after mdevctl. With that fixed:
Reviewed-by: Thomas Huth <thuth@redhat.com>

Re: [PATCH v3] docs/s390x: document vfio-ccw

[Cornelia Huck]

On Tue, 19 May 2020 15:19:21 +0200
Thomas Huth <thuth@redhat.com> wrote:

> On 18/05/2020 09.55, Cornelia Huck wrote:
> > Add a basic example for passing a dasd via vfio-ccw.
> > 
> > Signed-off-by: Cornelia Huck <cohuck@redhat.com>
> > ---
> > 
> > v2->v3: moved uuid generation (Thomas)
> > 
> > ---
> >  docs/system/s390x/vfio-ccw.rst | 77 ++++++++++++++++++++++++++++++++++
> >  docs/system/target-s390x.rst   |  1 +
> >  2 files changed, 78 insertions(+)
> >  create mode 100644 docs/system/s390x/vfio-ccw.rst
> > 
> > diff --git a/docs/system/s390x/vfio-ccw.rst b/docs/system/s390x/vfio-ccw.rst
> > new file mode 100644
> > index 000000000000..fff23d9afff7
> > --- /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\  
> 
> Maybe add a space before the backslash?
> 
> > +                  -p 0.0.0313 -t vfio-ccw_io -a
> > +
> > +If using ``mdevctl``  is not possible or wanted, follow the manual procedure
> > +below.  
> 
> Nit: Doubled whitespaces after mdevctl. With that fixed:
> Reviewed-by: Thomas Huth <thuth@redhat.com>

Thanks!

Fixed the nits and queued to s390-next.