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62c9917d9c
Below warnings are fixed:
Documentation/ABI/testing/sysfs-kernel-iommu_groups:38: WARNING: Unexpected indentation.
Documentation/ABI/testing/sysfs-kernel-iommu_groups:38: WARNING: Block quote ends without a blank line; unexpected unindent.
Documentation/ABI/testing/sysfs-kernel-iommu_groups:38: WARNING: Enumerated list ends without a blank line; unexpected unindent.
Documentation/ABI/testing/sysfs-kernel-iommu_groups:38: WARNING: Unexpected indentation.
Documentation/ABI/testing/sysfs-kernel-iommu_groups:38: WARNING: Block quote ends without a blank line; unexpected unindent.
Fixes: 63a816749d ("iommu: Document usage of "/sys/kernel/iommu_groups/<grp_id>/type" file")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Link: https://lore.kernel.org/linux-next/20201126174851.200e0e58@canb.auug.org.au/
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20201126090603.1511589-1-baolu.lu@linux.intel.com
Signed-off-by: Will Deacon <will@kernel.org>
66 lines
2.9 KiB
Plaintext
66 lines
2.9 KiB
Plaintext
What: /sys/kernel/iommu_groups/
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Date: May 2012
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KernelVersion: v3.5
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Contact: Alex Williamson <alex.williamson@redhat.com>
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Description: /sys/kernel/iommu_groups/ contains a number of sub-
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directories, each representing an IOMMU group. The
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name of the sub-directory matches the iommu_group_id()
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for the group, which is an integer value. Within each
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subdirectory is another directory named "devices" with
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links to the sysfs devices contained in this group.
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The group directory also optionally contains a "name"
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file if the IOMMU driver has chosen to register a more
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common name for the group.
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Users:
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What: /sys/kernel/iommu_groups/reserved_regions
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Date: January 2017
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KernelVersion: v4.11
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Contact: Eric Auger <eric.auger@redhat.com>
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Description: /sys/kernel/iommu_groups/reserved_regions list IOVA
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regions that are reserved. Not necessarily all
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reserved regions are listed. This is typically used to
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output direct-mapped, MSI, non mappable regions. Each
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region is described on a single line: the 1st field is
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the base IOVA, the second is the end IOVA and the third
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field describes the type of the region.
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What: /sys/kernel/iommu_groups/reserved_regions
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Date: June 2019
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KernelVersion: v5.3
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Contact: Eric Auger <eric.auger@redhat.com>
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Description: In case an RMRR is used only by graphics or USB devices
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it is now exposed as "direct-relaxable" instead of "direct".
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In device assignment use case, for instance, those RMRR
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are considered to be relaxable and safe.
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What: /sys/kernel/iommu_groups/<grp_id>/type
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Date: November 2020
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KernelVersion: v5.11
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Contact: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
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Description: /sys/kernel/iommu_groups/<grp_id>/type shows the type of default
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domain in use by iommu for this group. See include/linux/iommu.h
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for possible read values. A privileged user could request kernel to
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change the group type by writing to this file. Valid write values:
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======== ======================================================
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DMA All the DMA transactions from the device in this group
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are translated by the iommu.
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identity All the DMA transactions from the device in this group
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are not translated by the iommu.
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auto Change to the type the device was booted with.
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======== ======================================================
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The default domain type of a group may be modified only when
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- The group has only one device.
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- The device in the group is not bound to any device driver.
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So, the users must unbind the appropriate driver before
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changing the default domain type.
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Unbinding a device driver will take away the driver's control
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over the device and if done on devices that host root file
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system could lead to catastrophic effects (the users might
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need to reboot the machine to get it to normal state). So, it's
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expected that the users understand what they're doing.
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