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2021-04-05s390/pci: expose UID uniqueness guaranteeNiklas Schnelle1-3/+11
On s390 each PCI device has a user-defined ID (UID) exposed under /sys/bus/pci/devices/<dev>/uid. This ID was designed to serve as the PCI device's primary index and to match the device within Linux to the device configured in the hypervisor. To serve as a primary identifier the UID must be unique within the Linux instance, this is guaranteed by the platform if and only if the UID Uniqueness Checking flag is set within the CLP List PCI Functions response. While the UID has been exposed to userspace since commit ac4995b9d570 ("s390/pci: add some new arch specific pci attributes") whether or not the platform guarantees its uniqueness for the lifetime of the Linux instance while defined is not visible from userspace. Remedy this by exposing this as a per device attribute at /sys/bus/pci/devices/<dev>/uid_is_unique Keeping this a per device attribute allows for maximum flexibility if we ever end up with some devices not having a UID or not enjoying the guaranteed uniqueness. Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> Reviewed-by: Viktor Mihajlovski <mihajlov@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2020-05-06s390/pci: Documentation update for s390 PCIPierre Morel1-42/+41
Clarify the documentation. Signed-off-by: Pierre Morel <pmorel@linux.ibm.com> Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2020-04-28s390/pci: Documentation for zPCIPierre Morel1-0/+126
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>