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DRM ioctls do not guarantee that the parent bus device is still bound.
However, since DRM device registration is managed through Devres, using
drm_dev_unplug() on unregistration ensures that between drm_dev_enter()
and drm_dev_exit() the parent device must be bound.
Add RegistrationGuard, a guard object representing a drm_dev_enter/exit
SRCU critical section that dereferences to &Device<T, Registered>. The
guard is obtained from Device<T, Ioctl> and proves at runtime that the
device is still registered.
Switch Registration::drop from drm_dev_unregister() to drm_dev_unplug()
to provide the SRCU barrier that RegistrationGuard's safety argument
relies on.
Reviewed-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Tested-by: Deborah Brouwer <deborah.brouwer@collabora.com>
Link: https://patch.msgid.link/20260628145406.2107056-13-dakr@kernel.org
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
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Add the Ioctl DeviceContext for DRM devices that have been registered
with userspace previously.
A Device<T, Ioctl> has been registered at some point, but may be
concurrently unregistering or already unregistered. drm_dev_enter() can
guard against this, ensuring the device remains registered for the
duration of the critical section.
This typestate will be used in ioctl dispatch context where registration
is guaranteed by the DRM core, and RegistrationGuard can safely be
acquired.
Reviewed-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Tested-by: Deborah Brouwer <deborah.brouwer@collabora.com>
Link: https://patch.msgid.link/20260628145406.2107056-12-dakr@kernel.org
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
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Rename the Uninit DeviceContext to Normal to better reflect its purpose
as the general-purpose, reference-counted device context. The Uninit
name was a leftover from when DRM device private data initialization was
planned to split across UnregisteredDevice::new() and
Registration::new(); with the subsequent introduction of
RegistrationData, this distinction is no longer needed.
This also simplifies the DeviceContext documentation, trimming the
multi-stage initialization description that no longer applies.
Subsequent patches will refine the semantics of the Registered context
accordingly.
No functional change.
Reviewed-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Tested-by: Deborah Brouwer <deborah.brouwer@collabora.com>
Link: https://patch.msgid.link/20260628145406.2107056-3-dakr@kernel.org
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
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One of the tricky things about DRM bindings in Rust is the fact that
initialization of a DRM device is a multi-step process. It's quite normal
for a device driver to start making use of its DRM device for tasks like
creating GEM objects before userspace registration happens. This is an
issue in rust though, since prior to userspace registration the device is
only partly initialized. This means there's a plethora of DRM device
operations we can't yet expose without opening up the door to UB if the DRM
device in question isn't yet registered.
Additionally, this isn't something we can reliably check at runtime. And
even if we could, performing an operation which requires the device be
registered when the device isn't actually registered is a programmer bug,
meaning there's no real way to gracefully handle such a mistake at runtime.
And even if that wasn't the case, it would be horrendously annoying and
noisy to have to check if a device is registered constantly throughout a
driver.
In order to solve this, we first take inspiration from
`kernel::device::DeviceContext` and introduce `kernel::drm::DeviceContext`.
This provides us with a ZST type that we can generalize over to represent
contexts where a device is known to have been registered with userspace at
some point in time (`Registered`), along with contexts where we can't make
such a guarantee (`Uninit`).
It's important to note we intentionally do not provide a `DeviceContext`
which represents an unregistered device. This is because there's no
reasonable way to guarantee that a device with long-living references to
itself will not be registered eventually with userspace. Instead, we
provide a new-type for this: `UnregisteredDevice` which can
provide a guarantee that the `Device` has never been registered with
userspace. To ensure this, we modify `Registration` so that creating a new
`Registration` requires passing ownership of an `UnregisteredDevice`.
Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>
Link: https://patch.msgid.link/20260507220044.3204919-2-lyude@redhat.com
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
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Add a GPUVM abstraction to be used by Rust GPU drivers.
GPUVM keeps track of a GPU's virtual address (VA) space and manages the
corresponding virtual mappings represented by "GPU VA" objects. It also
keeps track of the gem::Object<T> used to back the mappings through
GpuVmBo<T>.
This abstraction is only usable by drivers that wish to use GPUVM in
immediate mode. This allows us to build the locking scheme into the API
design. It means that the GEM mutex is used for the GEM gpuva list, and
that the resv lock is used for the extobj list. The evicted list is not
yet used in this version.
This abstraction provides a special handle called the UniqueRefGpuVm,
which is a wrapper around ARef<GpuVm> that provides access to the
interval tree. Generally, all changes to the address space requires
mutable access to this unique handle.
Signed-off-by: Asahi Lina <lina+kernel@asahilina.net>
Co-developed-by: Daniel Almeida <daniel.almeida@collabora.com>
Signed-off-by: Daniel Almeida <daniel.almeida@collabora.com>
Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>
Co-developed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://patch.msgid.link/20260409-gpuvm-rust-v6-1-b16e6ada7261@google.com
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
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DRM GEM is the DRM memory management subsystem used by most modern
drivers; add a Rust abstraction for DRM GEM.
This includes the BaseObject trait, which contains operations shared by
all GEM object classes.
Signed-off-by: Asahi Lina <lina@asahilina.net>
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Link: https://lore.kernel.org/r/20250410235546.43736-8-dakr@kernel.org
[ Rework of GEM object abstractions
* switch to the Opaque<T> type
* fix (mutable) references to struct drm_gem_object (which in this
context is UB)
* drop all custom reference types in favor of AlwaysRefCounted
* bunch of minor changes and simplifications (e.g. IntoGEMObject
trait)
* write and fix safety and invariant comments
* remove necessity for and convert 'as' casts
* original source archive: https://archive.is/dD5SL
- Danilo ]
[ Fix missing CONFIG_DRM guards in rust/helpers/drm.c. - Danilo ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
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A DRM File is the DRM counterpart to a kernel file structure,
representing an open DRM file descriptor.
Add a Rust abstraction to allow drivers to implement their own File types
that implement the DriverFile trait.
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Asahi Lina <lina@asahilina.net>
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Link: https://lore.kernel.org/r/20250410235546.43736-7-dakr@kernel.org
[ Rework of drm::File
* switch to the Opaque<T> type
* fix (mutable) references to struct drm_file (which in this context
is UB)
* restructure and rename functions to align with common kernel
schemes
* write and fix safety and invariant comments
* remove necessity for and convert 'as' casts
* original source archive: https://archive.is/GH8oy
- Danilo ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
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Implement the DRM driver `Registration`.
The `Registration` structure is responsible to register and unregister a
DRM driver. It makes use of the `Devres` container in order to allow the
`Registration` to be owned by devres, such that it is automatically
dropped (and the DRM driver unregistered) once the parent device is
unbound.
Signed-off-by: Asahi Lina <lina@asahilina.net>
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Link: https://lore.kernel.org/r/20250410235546.43736-6-dakr@kernel.org
[ Rework of drm::Registration
* move VTABLE to drm::Device to prevent use-after-free bugs; VTABLE
needs to be bound to the lifetime of drm::Device, not the
drm::Registration
* combine new() and register() to get rid of the registered boolean
* remove file_operations
* move struct drm_device creation to drm::Device
* introduce Devres
* original source archive: https://archive.is/Pl9ys
- Danilo ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
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Implement the abstraction for a `struct drm_device`.
A `drm::Device` creates a static const `struct drm_driver` filled with
the data from the `drm::Driver` trait implementation of the actual
driver creating the `drm::Device`.
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Asahi Lina <lina@asahilina.net>
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Link: https://lore.kernel.org/r/20250410235546.43736-5-dakr@kernel.org
[ Rewrite of drm::Device
* full rewrite of the drm::Device abstraction using the subclassing
pattern
* original source archive: http://archive.today/5NxBo
- Danilo ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
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Implement the DRM driver abstractions.
The `Driver` trait provides the interface to the actual driver to fill
in the driver specific data, such as the `DriverInfo`, driver features
and IOCTLs.
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Asahi Lina <lina@asahilina.net>
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Link: https://lore.kernel.org/r/20250410235546.43736-4-dakr@kernel.org
[ MISC changes
* remove unnecessary DRM features; make remaining ones crate private
* add #[expect(unused)] to avoid warnings
* add sealed trait
* remove shmem::Object references
* original source archive: https://archive.is/Pl9ys
- Danilo ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
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DRM drivers need to be able to declare which driver-specific ioctls they
support. Add an abstraction implementing the required types and a helper
macro to generate the ioctl definition inside the DRM driver.
Note that this macro is not usable until further bits of the abstraction
are in place (but it will not fail to compile on its own, if not called).
Signed-off-by: Asahi Lina <lina@asahilina.net>
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Link: https://lore.kernel.org/r/20250410235546.43736-3-dakr@kernel.org
[ MISC fixes
* wrap raw_data in Opaque to avoid UB when creating a reference
* fix IOCTL sample declaration
* fix safety comment of IOCTL argument
* original source archive: https://archive.is/LqHDQ
- Danilo ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
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