@@ -3587,6 +3587,8 @@
may put more devices in an IOMMU group.
force_floating [S390] Force usage of floating interrupts.
nomio [S390] Do not use MIO instructions.
+ norid [S390] ignore the RID field and force use of
+ one PCI domain per PCI function
pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
Management.
@@ -15,6 +15,7 @@ s390 Architecture
vfio-ccw
zfcpdump
common_io
+ pci
text_files
new file mode 100644
@@ -0,0 +1,126 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=========
+S/390 PCI
+=========
+
+Authors:
+ - Pierre Morel
+
+Copyright, IBM Corp. 2020
+
+
+command line parameters and debugfs entries
+===========================================
+
+Command line parameters
+-----------------------
+
+* nomio
+
+ Do not use MIO instructions.
+
+* norid
+
+ Ignore the RID field and force use of one PCI domain per PCI function.
+
+debugfs entries
+---------------
+
+* /sys/kernel/debug/s390dbf/pci_*/ (S/390 debug feature)
+
+ Some views generated by the debug feature to hold various debug outputs.
+
+ - /sys/kernel/debug/s390dbf/pci_msg/sprintf
+ Messages from the processing of PCI events like machine check handling
+ and setting of global functionality like UID checking.
+
+ The level of logging can be changed to be more or less verbose by piping to
+ /sys/kernel/debug/s390dbf/pci_*/level a number between 0 and 6; see the
+ documentation on the S/390 debug feature (Documentation/s390/s390dbf.rst)
+ for details.
+
+Sysfs entries
+=============
+
+Specific entries, or entries specificities for zPCI functions.
+
+* /sys/bus/pci/slots/XXXXXXXX
+
+ The slot entries are setup using the FID (Function Identifier) of the
+ PCI function.
+
+ - /sys/bus/pci/slots/XXXXXXXX/power
+
+ A physical function currently supporting virtual function can not be
+ powered-off until all virtual-function have been removed with
+ echo 0 > /sys/bus/pci/devices/XXXX:XX:XX.X/sriov_numvf
+
+* /sys/bus/pci/devices/XXXX:XX:XX.X/
+
+ - function_id
+ zPCI function identifier unique for the complete Z System.
+ It define uniquely a function in the system.
+
+ - function_handle
+ Low level identifier used for a configured PCI function.
+ It may be useful for debuging.
+
+ - pchid
+ Model dependent location of the I/O adapter.
+
+ - pfgid
+ PCI Function Group ID, functions sharing identical functionality
+ are using a common identifier.
+ A PCI group defines interrupts, IOMMU, IOTLB and DMA specifics.
+
+ - vfn
+ The Virtual Function Number, from 1 to N for virtual functions.
+ 0 for physical functions.
+
+ - pft
+ PCI function type specifies the type of the PCI function.
+
+ - port
+ The port correspond to the physical port the function is attached to.
+ It also gives an indication on the physical function a virtual function
+ is attached to.
+
+ - uid
+ The UID, Unique Identifier is defined when configuring a LPAR and is
+ unique inside an LPAR.
+
+ - pfip/segmentX
+ The segments are used to determine the isolation of a function.
+ They corresponds to the physical path to the function.
+ The more the segment are different the more the functions are isolated.
+
+Enumeration and hotplug
+=======================
+
+The PCI address is made of 4 parts: domain, bus, device and function,
+like in DDDD:BB:dd.f
+
+* When not using multi-functions (norid is set or firmware does not support
+ multi-functions)
+
+ - There is only one function per domain.
+
+ - the domain is set from the zPCI function's UID as defined during the
+ LPAR creation.
+
+ - Addresses look like DDDD:00:00.0
+
+* When using multi-functions (norid parameter is not set), there are some
+ change in the way zPCI functions are addressed:
+
+ - There is still only one bus per domain.
+
+ - There can be up to 256 functions per bus.
+
+ - The domain part of the address of all functions of all functions for
+ a multi-Function device is set from the zPCI function's UID as defined
+ in the LPAR creation for the function zero.
+
+ - New functions will only be ready to be used after the function zero
+ (the function with devfn 0) has been enumerated.
@@ -14177,6 +14177,7 @@ W: http://www.ibm.com/developerworks/linux/linux390/
S: Supported
F: arch/s390/pci/
F: drivers/pci/hotplug/s390_pci_hpc.c
+F: Documentation/s390/pci.rst
S390 VFIO-CCW DRIVER
M: Cornelia Huck <cohuck@redhat.com>