diff --git a/MAINTAINERS b/MAINTAINERS index 5c9272622033..fb335dc25f43 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -8879,6 +8879,8 @@ S: Supported T: git https://gitlab.freedesktop.org/drm/misc/kernel.git F: drivers/gpu/drm/drm_gpuvm.c F: include/drm/drm_gpuvm.h +F: rust/helpers/drm_gpuvm.c +F: rust/kernel/drm/gpuvm/ DRM LOG M: Jocelyn Falempe diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h index 446dbeaf0866..1124785e210b 100644 --- a/rust/bindings/bindings_helper.h +++ b/rust/bindings/bindings_helper.h @@ -35,6 +35,7 @@ #include #include #include +#include #include #include #include diff --git a/rust/helpers/drm_gpuvm.c b/rust/helpers/drm_gpuvm.c new file mode 100644 index 000000000000..18cf104a8bc7 --- /dev/null +++ b/rust/helpers/drm_gpuvm.c @@ -0,0 +1,20 @@ +// SPDX-License-Identifier: GPL-2.0 or MIT + +#ifdef CONFIG_DRM_GPUVM + +#include + +__rust_helper +struct drm_gpuvm *rust_helper_drm_gpuvm_get(struct drm_gpuvm *obj) +{ + return drm_gpuvm_get(obj); +} + +__rust_helper +bool rust_helper_drm_gpuvm_is_extobj(struct drm_gpuvm *gpuvm, + struct drm_gem_object *obj) +{ + return drm_gpuvm_is_extobj(gpuvm, obj); +} + +#endif // CONFIG_DRM_GPUVM diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c index 625921e27dfb..4488a87223b9 100644 --- a/rust/helpers/helpers.c +++ b/rust/helpers/helpers.c @@ -59,6 +59,7 @@ #include "dma.c" #include "dma-resv.c" #include "drm.c" +#include "drm_gpuvm.c" #include "err.c" #include "irq.c" #include "fs.c" diff --git a/rust/kernel/drm/gpuvm/mod.rs b/rust/kernel/drm/gpuvm/mod.rs new file mode 100644 index 000000000000..1d9138d989b3 --- /dev/null +++ b/rust/kernel/drm/gpuvm/mod.rs @@ -0,0 +1,260 @@ +// SPDX-License-Identifier: GPL-2.0 OR MIT + +#![cfg(CONFIG_DRM_GPUVM = "y")] + +//! DRM GPUVM in immediate mode +//! +//! Rust abstractions for using GPUVM in immediate mode. This is when the GPUVM state is updated +//! during `run_job()`, i.e., in the DMA fence signalling critical path, to ensure that the GPUVM +//! and the GPU's virtual address space has the same state at all times. +//! +//! C header: [`include/drm/drm_gpuvm.h`](srctree/include/drm/drm_gpuvm.h) + +use kernel::{ + alloc::AllocError, + bindings, + drm, + drm::gem::IntoGEMObject, + prelude::*, + sync::aref::{ + ARef, + AlwaysRefCounted, // + }, + types::Opaque, // +}; + +use core::{ + cell::UnsafeCell, + ops::{ + Deref, + Range, // + }, + ptr::NonNull, // +}; + +/// A DRM GPU VA manager. +/// +/// This object is refcounted, but the locations of mapped ranges may only be accessed or changed +/// via the special unique handle [`UniqueRefGpuVm`]. +/// +/// # Invariants +/// +/// * Stored in an allocation managed by the refcount in `self.vm`. +/// * Access to `data` and the gpuvm interval tree is controlled via the [`UniqueRefGpuVm`] type. +/// * Does not contain any sparse `GpuVa` instances. +#[pin_data] +pub struct GpuVm { + #[pin] + vm: Opaque, + /// Accessed only through the [`UniqueRefGpuVm`] reference. + data: UnsafeCell, +} + +// SAFETY: The GPUVM api does not assume that it is tied to a specific thread. The destructor will +// drop the `data` field, which is okay because it is guaranteed `Send` by the `DriverGpuVm` trait. +unsafe impl Send for GpuVm {} +// SAFETY: The GPUVM api is designed to allow &self methods to be called in parallel. +unsafe impl Sync for GpuVm {} + +// SAFETY: By type invariants, the allocation is managed by the refcount in `self.vm`. +unsafe impl AlwaysRefCounted for GpuVm { + fn inc_ref(&self) { + // SAFETY: By type invariants, the allocation is managed by the refcount in `self.vm`. + unsafe { bindings::drm_gpuvm_get(self.vm.get()) }; + } + + unsafe fn dec_ref(obj: NonNull) { + // SAFETY: By type invariants, the allocation is managed by the refcount in `self.vm`. + unsafe { bindings::drm_gpuvm_put((*obj.as_ptr()).vm.get()) }; + } +} + +impl PartialEq for GpuVm { + #[inline] + fn eq(&self, other: &Self) -> bool { + core::ptr::eq(self.as_raw(), other.as_raw()) + } +} +impl Eq for GpuVm {} + +impl GpuVm { + const fn vtable() -> &'static bindings::drm_gpuvm_ops { + &bindings::drm_gpuvm_ops { + vm_free: Some(Self::vm_free), + op_alloc: None, + op_free: None, + vm_bo_alloc: None, + vm_bo_free: None, + vm_bo_validate: None, + sm_step_map: None, + sm_step_unmap: None, + sm_step_remap: None, + } + } + + /// Creates a GPUVM instance. + #[expect(clippy::new_ret_no_self)] + pub fn new( + name: &'static CStr, + dev: &drm::Device, + r_obj: &T::Object, + range: Range, + reserve_range: Range, + data: T, + ) -> Result, E> + where + E: From, + E: From, + { + let obj = KBox::try_pin_init::( + try_pin_init!(Self { + data: UnsafeCell::new(data), + vm <- Opaque::ffi_init(|vm| { + // SAFETY: These arguments are valid. `vm` is valid until refcount drops to + // zero. The `vm` is zeroed before calling this method by `__GFP_ZERO` flag + // below. + unsafe { + bindings::drm_gpuvm_init( + vm, + name.as_char_ptr(), + bindings::drm_gpuvm_flags_DRM_GPUVM_IMMEDIATE_MODE + | bindings::drm_gpuvm_flags_DRM_GPUVM_RESV_PROTECTED, + dev.as_raw(), + r_obj.as_raw(), + range.start, + range.end - range.start, + reserve_range.start, + reserve_range.end - reserve_range.start, + const { Self::vtable() }, + ) + } + }), + }? E), + GFP_KERNEL | __GFP_ZERO, + )?; + // SAFETY: This transfers the initial refcount to the ARef. + let aref = unsafe { + ARef::from_raw(NonNull::new_unchecked(KBox::into_raw( + Pin::into_inner_unchecked(obj), + ))) + }; + // INVARIANT: This reference is unique. + Ok(UniqueRefGpuVm(aref)) + } + + /// Access this [`GpuVm`] from a raw pointer. + /// + /// # Safety + /// + /// The pointer must reference the `struct drm_gpuvm` in a valid [`GpuVm`] that remains + /// valid for at least `'a`. + #[inline] + pub unsafe fn from_raw<'a>(ptr: *mut bindings::drm_gpuvm) -> &'a Self { + // SAFETY: Caller passes a pointer to the `drm_gpuvm` in a `GpuVm`. Caller ensures the + // pointer is valid for 'a. + unsafe { &*kernel::container_of!(Opaque::cast_from(ptr), Self, vm) } + } + + /// Returns a raw pointer to the embedded `struct drm_gpuvm`. + #[inline] + pub fn as_raw(&self) -> *mut bindings::drm_gpuvm { + self.vm.get() + } + + /// The start of the VA space. + #[inline] + pub fn va_start(&self) -> u64 { + // SAFETY: The `mm_start` field is immutable. + unsafe { (*self.as_raw()).mm_start } + } + + /// The length of the GPU's virtual address space. + #[inline] + pub fn va_length(&self) -> u64 { + // SAFETY: The `mm_range` field is immutable. + unsafe { (*self.as_raw()).mm_range } + } + + /// Returns the range of the GPU virtual address space. + #[inline] + pub fn va_range(&self) -> Range { + let start = self.va_start(); + // OVERFLOW: This reconstructs the Range passed to the constructor, so it won't fail. + let end = start + self.va_length(); + Range { start, end } + } + + /// Clean up buffer objects that are no longer used. + #[inline] + pub fn deferred_cleanup(&self) { + // SAFETY: This GPUVM uses immediate mode. + unsafe { bindings::drm_gpuvm_bo_deferred_cleanup(self.as_raw()) } + } + + /// Check if this GEM object is an external object for this GPUVM. + #[inline] + pub fn is_extobj(&self, obj: &T::Object) -> bool { + // SAFETY: We may call this with any GPUVM and GEM object. + unsafe { bindings::drm_gpuvm_is_extobj(self.as_raw(), obj.as_raw()) } + } + + /// Free this GPUVM. + /// + /// # Safety + /// + /// Called when refcount hits zero. + unsafe extern "C" fn vm_free(me: *mut bindings::drm_gpuvm) { + // SAFETY: Caller passes a pointer to the `drm_gpuvm` in a `GpuVm`. + let me = unsafe { kernel::container_of!(Opaque::cast_from(me), Self, vm).cast_mut() }; + // SAFETY: By type invariants we can free it when refcount hits zero. + drop(unsafe { KBox::from_raw(me) }) + } +} + +/// The manager for a GPUVM. +pub trait DriverGpuVm: Sized + Send { + /// Parent `Driver` for this object. + type Driver: drm::Driver; + + /// The kind of GEM object stored in this GPUVM. + type Object: IntoGEMObject; +} + +/// The core of the DRM GPU VA manager. +/// +/// This object is a unique reference to the VM that can access the interval tree and the Rust +/// `data` field. +/// +/// # Invariants +/// +/// Each `GpuVm` instance has at most one `UniqueRefGpuVm` reference. +pub struct UniqueRefGpuVm(ARef>); + +// SAFETY: The GPUVM api is designed to allow &self methods to be called in parallel, and +// concurrent access to `data` is safe due to the `T: Sync` requirement. +unsafe impl Sync for UniqueRefGpuVm {} + +impl UniqueRefGpuVm { + /// Access the data owned by this `UniqueRefGpuVm` immutably. + #[inline] + pub fn data_ref(&self) -> &T { + // SAFETY: By the type invariants we may access `data`. + unsafe { &*self.0.data.get() } + } + + /// Access the data owned by this `UniqueRefGpuVm` mutably. + #[inline] + pub fn data(&mut self) -> &mut T { + // SAFETY: By the type invariants we may access `data`. + unsafe { &mut *self.0.data.get() } + } +} + +impl Deref for UniqueRefGpuVm { + type Target = GpuVm; + + #[inline] + fn deref(&self) -> &GpuVm { + &self.0 + } +} diff --git a/rust/kernel/drm/mod.rs b/rust/kernel/drm/mod.rs index 1b82b6945edf..a4b6c5430198 100644 --- a/rust/kernel/drm/mod.rs +++ b/rust/kernel/drm/mod.rs @@ -6,6 +6,7 @@ pub mod driver; pub mod file; pub mod gem; +pub mod gpuvm; pub mod ioctl; pub use self::device::Device;