de267a7c71
There are changes in the usage of PCI for the user: - new kernel parameter - modification of the way functions are enumerated Let's document these. Signed-off-by: Pierre Morel <pmorel@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
127 lines
3.5 KiB
ReStructuredText
127 lines
3.5 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
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=========
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S/390 PCI
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=========
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Authors:
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- Pierre Morel
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Copyright, IBM Corp. 2020
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command line parameters and debugfs entries
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===========================================
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Command line parameters
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-----------------------
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* nomio
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Do not use MIO instructions.
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* norid
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Ignore the RID field and force use of one PCI domain per PCI function.
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debugfs entries
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---------------
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* /sys/kernel/debug/s390dbf/pci_*/ (S/390 debug feature)
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Some views generated by the debug feature to hold various debug outputs.
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- /sys/kernel/debug/s390dbf/pci_msg/sprintf
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Messages from the processing of PCI events like machine check handling
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and setting of global functionality like UID checking.
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The level of logging can be changed to be more or less verbose by piping to
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/sys/kernel/debug/s390dbf/pci_*/level a number between 0 and 6; see the
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documentation on the S/390 debug feature (Documentation/s390/s390dbf.rst)
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for details.
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Sysfs entries
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=============
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Specific entries, or entries specificities for zPCI functions.
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* /sys/bus/pci/slots/XXXXXXXX
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The slot entries are setup using the FID (Function Identifier) of the
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PCI function.
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- /sys/bus/pci/slots/XXXXXXXX/power
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A physical function currently supporting virtual function can not be
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powered-off until all virtual-function have been removed with
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echo 0 > /sys/bus/pci/devices/XXXX:XX:XX.X/sriov_numvf
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* /sys/bus/pci/devices/XXXX:XX:XX.X/
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- function_id
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zPCI function identifier unique for the complete Z System.
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It define uniquely a function in the system.
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- function_handle
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Low level identifier used for a configured PCI function.
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It may be useful for debuging.
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- pchid
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Model dependent location of the I/O adapter.
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- pfgid
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PCI Function Group ID, functions sharing identical functionality
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are using a common identifier.
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A PCI group defines interrupts, IOMMU, IOTLB and DMA specifics.
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- vfn
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The Virtual Function Number, from 1 to N for virtual functions.
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0 for physical functions.
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- pft
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PCI function type specifies the type of the PCI function.
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- port
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The port correspond to the physical port the function is attached to.
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It also gives an indication on the physical function a virtual function
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is attached to.
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- uid
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The UID, Unique Identifier is defined when configuring a LPAR and is
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unique inside an LPAR.
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- pfip/segmentX
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The segments are used to determine the isolation of a function.
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They corresponds to the physical path to the function.
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The more the segment are different the more the functions are isolated.
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Enumeration and hotplug
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=======================
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The PCI address is made of 4 parts: domain, bus, device and function,
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like in DDDD:BB:dd.f
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* When not using multi-functions (norid is set or firmware does not support
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multi-functions)
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- There is only one function per domain.
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- the domain is set from the zPCI function's UID as defined during the
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LPAR creation.
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- Addresses look like DDDD:00:00.0
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* When using multi-functions (norid parameter is not set), there are some
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change in the way zPCI functions are addressed:
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- There is still only one bus per domain.
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- There can be up to 256 functions per bus.
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- The domain part of the address of all functions of all functions for
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a multi-Function device is set from the zPCI function's UID as defined
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in the LPAR creation for the function zero.
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- New functions will only be ready to be used after the function zero
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(the function with devfn 0) has been enumerated.
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