0001 .. SPDX-License-Identifier: GPL-2.0
0002
0003 =========
0004 S/390 PCI
0005 =========
0006
0007 Authors:
0008 - Pierre Morel
0009
0010 Copyright, IBM Corp. 2020
0011
0012
0013 Command line parameters and debugfs entries
0014 ===========================================
0015
0016 Command line parameters
0017 -----------------------
0018
0019 * nomio
0020
0021 Do not use PCI Mapped I/O (MIO) instructions.
0022
0023 * norid
0024
0025 Ignore the RID field and force use of one PCI domain per PCI function.
0026
0027 debugfs entries
0028 ---------------
0029
0030 The S/390 debug feature (s390dbf) generates views to hold various debug results in sysfs directories of the form:
0031
0032 * /sys/kernel/debug/s390dbf/pci_*/
0033
0034 For example:
0035
0036 - /sys/kernel/debug/s390dbf/pci_msg/sprintf
0037 Holds messages from the processing of PCI events, like machine check handling
0038 and setting of global functionality, like UID checking.
0039
0040 Change the level of logging to be more or less verbose by piping
0041 a number between 0 and 6 to /sys/kernel/debug/s390dbf/pci_*/level. For
0042 details, see the documentation on the S/390 debug feature at
0043 Documentation/s390/s390dbf.rst.
0044
0045 Sysfs entries
0046 =============
0047
0048 Entries specific to zPCI functions and entries that hold zPCI information.
0049
0050 * /sys/bus/pci/slots/XXXXXXXX
0051
0052 The slot entries are set up using the function identifier (FID) of the
0053 PCI function. The format depicted as XXXXXXXX above is 8 hexadecimal digits
0054 with 0 padding and lower case hexadecimal digitis.
0055
0056 - /sys/bus/pci/slots/XXXXXXXX/power
0057
0058 A physical function that currently supports a virtual function cannot be
0059 powered off until all virtual functions are removed with:
0060 echo 0 > /sys/bus/pci/devices/XXXX:XX:XX.X/sriov_numvf
0061
0062 * /sys/bus/pci/devices/XXXX:XX:XX.X/
0063
0064 - function_id
0065 A zPCI function identifier that uniquely identifies the function in the Z server.
0066
0067 - function_handle
0068 Low-level identifier used for a configured PCI function.
0069 It might be useful for debuging.
0070
0071 - pchid
0072 Model-dependent location of the I/O adapter.
0073
0074 - pfgid
0075 PCI function group ID, functions that share identical functionality
0076 use a common identifier.
0077 A PCI group defines interrupts, IOMMU, IOTLB, and DMA specifics.
0078
0079 - vfn
0080 The virtual function number, from 1 to N for virtual functions,
0081 0 for physical functions.
0082
0083 - pft
0084 The PCI function type
0085
0086 - port
0087 The port corresponds to the physical port the function is attached to.
0088 It also gives an indication of the physical function a virtual function
0089 is attached to.
0090
0091 - uid
0092 The user identifier (UID) may be defined as part of the machine
0093 configuration or the z/VM or KVM guest configuration. If the accompanying
0094 uid_is_unique attribute is 1 the platform guarantees that the UID is unique
0095 within that instance and no devices with the same UID can be attached
0096 during the lifetime of the system.
0097
0098 - uid_is_unique
0099 Indicates whether the user identifier (UID) is guaranteed to be and remain
0100 unique within this Linux instance.
0101
0102 - pfip/segmentX
0103 The segments determine the isolation of a function.
0104 They correspond to the physical path to the function.
0105 The more the segments are different, the more the functions are isolated.
0106
0107 Enumeration and hotplug
0108 =======================
0109
0110 The PCI address consists of four parts: domain, bus, device and function,
0111 and is of this form: DDDD:BB:dd.f
0112
0113 * When not using multi-functions (norid is set, or the firmware does not
0114 support multi-functions):
0115
0116 - There is only one function per domain.
0117
0118 - The domain is set from the zPCI function's UID as defined during the
0119 LPAR creation.
0120
0121 * When using multi-functions (norid parameter is not set),
0122 zPCI functions are addressed differently:
0123
0124 - There is still only one bus per domain.
0125
0126 - There can be up to 256 functions per bus.
0127
0128 - The domain part of the address of all functions for
0129 a multi-Function device is set from the zPCI function's UID as defined
0130 in the LPAR creation for the function zero.
0131
0132 - New functions will only be ready for use after the function zero
0133 (the function with devfn 0) has been enumerated.
