Add some documentation about the zpci device and how to use it with pci devices on s390x.
Used source: Cornelia Huck's blog post https://people.redhat.com/~cohuck/2018/02/19/notes-on-pci-on-s390x.html Signed-off-by: Sebastian Mitterle <smitt...@redhat.com> --- v2: move section below 'Device support' --- docs/system/s390x/pcidevices.rst | 34 ++++++++++++++++++++++++++++++++ docs/system/target-s390x.rst | 1 + 2 files changed, 35 insertions(+) create mode 100644 docs/system/s390x/pcidevices.rst diff --git a/docs/system/s390x/pcidevices.rst b/docs/system/s390x/pcidevices.rst new file mode 100644 index 0000000000..fec905d6e6 --- /dev/null +++ b/docs/system/s390x/pcidevices.rst @@ -0,0 +1,34 @@ +PCI devices on s390x +==================== + +PCI devices on s390x work differently than on other architectures. + +To start with, using a PCI device requires the additional ``zpci`` device. For example, +in order to pass a PCI device ``0000:00:00.0`` through you'd specify:: + + qemu-system-s390x ... \ + -device zpci,uid=1,fid=0,target=hostdev0,id=zpci1 \ + -device vfio-pci,host=0000:00:00.0,id=hostdev0 + +Here, the zpci device is joined with the PCI device via the ``target`` property. + +Note that we don't set bus, slot or function here for the guest as is common in other +PCI implementations. Topology information is not available on s390x. Instead, ``uid`` +and ``fid`` determine how the device is presented to the guest operating system. + +In case of Linux, ``uid`` will be used in the ``domain`` part of the PCI identifier, and +``fid`` identifies the physical slot, i.e.:: + + qemu-system-s390x ... \ + -device zpci,uid=7,fid=8,target=hostdev0,id=zpci1 \ + ... + +will be presented in the guest as:: + + # lspci -v + 0007:00:00.0 ... + Physical Slot: 00000008 + ... + +Finally, note that you might have to enable the ``zpci`` feature in the cpu model in oder to use +it. diff --git a/docs/system/target-s390x.rst b/docs/system/target-s390x.rst index c636f64113..f6f11433c7 100644 --- a/docs/system/target-s390x.rst +++ b/docs/system/target-s390x.rst @@ -26,6 +26,7 @@ or vfio-ap is also available. s390x/css s390x/3270 s390x/vfio-ccw + s390x/pcidevices Architectural features ====================== -- 2.37.3
