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The sysfs interface for default domain types exists primarily so users
can choose the performance/security tradeoff relevant to their own
workload. As such, the choice between the policies for DMA domains fits
perfectly as an additional point on that scale - downgrading a
particular device from a strict default to non-strict may be enough to
let it reach the desired level of performance, while still retaining
more peace of mind than with a wide-open identity domain. Now that we've
abstracted non-strict mode as a distinct type of DMA domain, allow it to
be chosen through the user interface as well.
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: John Garry <john.garry@huawei.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/0e08da5ed4069fd3473cfbadda758ca983becdbf.1628682049.git.robin.murphy@arm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
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./scripts/get_abi.pl is reporting a duplicated definition for
/sys/kernel/iommu_groups/reserved_regions, both at the same
file:
Warning: /sys/kernel/iommu_groups/reserved_regions is defined 2 times: Documentation/ABI/testing/sysfs-kernel-iommu_groups:15 Documentation/ABI/testing/sysfs-kernel-iommu_groups:27
Fix it by merging those into an unified entry.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/ec33e8e9b8f120232ffb3b9fcc99c97b87f242e3.1621413933.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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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: 63a816749d86 ("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>
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The default domain type of an iommu group can be changed by writing to
"/sys/kernel/iommu_groups/<grp_id>/type" file. Hence, document it's usage
and more importantly spell out its limitations.
Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Sohil Mehta <sohil.mehta@intel.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Link: https://lore.kernel.org/r/20201124130604.2912899-5-baolu.lu@linux.intel.com
Signed-off-by: Will Deacon <will@kernel.org>
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Introduce a new type for reserved region. This corresponds
to directly mapped regions which are known to be relaxable
in some specific conditions, such as device assignment use
case. Well known examples are those used by USB controllers
providing PS/2 keyboard emulation for pre-boot BIOS and
early BOOT or RMRRs associated to IGD working in legacy mode.
Since commit c875d2c1b808 ("iommu/vt-d: Exclude devices using RMRRs
from IOMMU API domains") and commit 18436afdc11a ("iommu/vt-d: Allow
RMRR on graphics devices too"), those regions are currently
considered "safe" with respect to device assignment use case
which requires a non direct mapping at IOMMU physical level
(RAM GPA -> HPA mapping).
Those RMRRs currently exist and sometimes the device is
attempting to access it but this has not been considered
an issue until now.
However at the moment, iommu_get_group_resv_regions() is
not able to make any difference between directly mapped
regions: those which must be absolutely enforced and those
like above ones which are known as relaxable.
This is a blocker for reporting severe conflicts between
non relaxable RMRRs (like MSI doorbells) and guest GPA space.
With this new reserved region type we will be able to use
iommu_get_group_resv_regions() to enumerate the IOVA space
that is usable through the IOMMU API without introducing
regressions with respect to existing device assignment
use cases (USB and IGD).
Signed-off-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
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A new iommu-group sysfs attribute file is introduced. It contains
the list of reserved regions for the iommu-group. Each reserved
region is described on a separate line:
- first field is the start IOVA address,
- second is the end IOVA address,
- third is the type.
Signed-off-by: Eric Auger <eric.auger@redhat.com>
Tested-by: Tomasz Nowicki <tomasz.nowicki@caviumnetworks.com>
Tested-by: Bharat Bhushan <bharat.bhushan@nxp.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
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IOMMU device groups are currently a rather vague associative notion
with assembly required by the user or user level driver provider to
do anything useful. This patch intends to grow the IOMMU group concept
into something a bit more consumable.
To do this, we first create an object representing the group, struct
iommu_group. This structure is allocated (iommu_group_alloc) and
filled (iommu_group_add_device) by the iommu driver. The iommu driver
is free to add devices to the group using it's own set of policies.
This allows inclusion of devices based on physical hardware or topology
limitations of the platform, as well as soft requirements, such as
multi-function trust levels or peer-to-peer protection of the
interconnects. Each device may only belong to a single iommu group,
which is linked from struct device.iommu_group. IOMMU groups are
maintained using kobject reference counting, allowing for automatic
removal of empty, unreferenced groups. It is the responsibility of
the iommu driver to remove devices from the group
(iommu_group_remove_device).
IOMMU groups also include a userspace representation in sysfs under
/sys/kernel/iommu_groups. When allocated, each group is given a
dynamically assign ID (int). The ID is managed by the core IOMMU group
code to support multiple heterogeneous iommu drivers, which could
potentially collide in group naming/numbering. This also keeps group
IDs to small, easily managed values. A directory is created under
/sys/kernel/iommu_groups for each group. A further subdirectory named
"devices" contains links to each device within the group. The iommu_group
file in the device's sysfs directory, which formerly contained a group
number when read, is now a link to the iommu group. Example:
$ ls -l /sys/kernel/iommu_groups/26/devices/
total 0
lrwxrwxrwx. 1 root root 0 Apr 17 12:57 0000:00:1e.0 ->
../../../../devices/pci0000:00/0000:00:1e.0
lrwxrwxrwx. 1 root root 0 Apr 17 12:57 0000:06:0d.0 ->
../../../../devices/pci0000:00/0000:00:1e.0/0000:06:0d.0
lrwxrwxrwx. 1 root root 0 Apr 17 12:57 0000:06:0d.1 ->
../../../../devices/pci0000:00/0000:00:1e.0/0000:06:0d.1
$ ls -l /sys/kernel/iommu_groups/26/devices/*/iommu_group
[truncating perms/owner/timestamp]
/sys/kernel/iommu_groups/26/devices/0000:00:1e.0/iommu_group ->
../../../kernel/iommu_groups/26
/sys/kernel/iommu_groups/26/devices/0000:06:0d.0/iommu_group ->
../../../../kernel/iommu_groups/26
/sys/kernel/iommu_groups/26/devices/0000:06:0d.1/iommu_group ->
../../../../kernel/iommu_groups/26
Groups also include several exported functions for use by user level
driver providers, for example VFIO. These include:
iommu_group_get(): Acquires a reference to a group from a device
iommu_group_put(): Releases reference
iommu_group_for_each_dev(): Iterates over group devices using callback
iommu_group_[un]register_notifier(): Allows notification of device add
and remove operations relevant to the group
iommu_group_id(): Return the group number
This patch also extends the IOMMU API to allow attaching groups to
domains. This is currently a simple wrapper for iterating through
devices within a group, but it's expected that the IOMMU API may
eventually make groups a more integral part of domains.
Groups intentionally do not try to manage group ownership. A user
level driver provider must independently acquire ownership for each
device within a group before making use of the group as a whole.
This may change in the future if group usage becomes more pervasive
across both DMA and IOMMU ops.
Groups intentionally do not provide a mechanism for driver locking
or otherwise manipulating driver matching/probing of devices within
the group. Such interfaces are generic to devices and beyond the
scope of IOMMU groups. If implemented, user level providers have
ready access via iommu_group_for_each_dev and group notifiers.
iommu_device_group() is removed here as it has no users. The
replacement is:
group = iommu_group_get(dev);
id = iommu_group_id(group);
iommu_group_put(group);
AMD-Vi & Intel VT-d support re-added in following patches.
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
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Robin Murphy
Mauro Carvalho Chehab
Lu Baolu
Sai Praneeth Prakhya
Eric Auger
Alex Williamson