Re: [PATCH v10 4/7] drm/tyr: add GPU virtual memory (VM) support

[Alice Ryhl]

On Tue, Jul 28, 2026 at 8:39 PM Deborah Brouwer
<deborah.brouwer@xxxxxxxxxxxxx> wrote:
>
> From: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
>
> Add GPU virtual address space management using the DRM GPUVM framework.
> Each virtual memory (VM) space is backed by ARM64 LPAE Stage 1 page tables
> and can be mapped into hardware address space (AS) slots for GPU execution.
>
> The implementation provides memory isolation and virtual address
> allocation. VMs support mapping GEM buffer objects with configurable
> protection flags (readonly, noexec, uncached) and handle both 4KB and 2MB
> page sizes. A new_dummy_object() helper is provided to create a dummy GEM
> object for use as a GPUVM root.
>
> The vm module integrates with the MMU for address space activation and
> provides map/unmap/remap operations with page table synchronization.
>
> Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
> Co-developed-by: Daniel Almeida <daniel.almeida@xxxxxxxxxxxxx>
> Signed-off-by: Daniel Almeida <daniel.almeida@xxxxxxxxxxxxx>
> Co-developed-by: Deborah Brouwer <deborah.brouwer@xxxxxxxxxxxxx>
> Signed-off-by: Deborah Brouwer <deborah.brouwer@xxxxxxxxxxxxx>

There's a 32-bit build failure :(

error[E0308]: mismatched types
   --> /home/runner/work/linux/linux/linux/drivers/gpu/drm/tyr/vm.rs:873:17
    |
871 |             pt.map_pages(
    |                --------- arguments to this method are incorrect
872 |                 curr_iova,
873 |                 curr_paddr,
    |                 ^^^^^^^^^^ expected `u32`, found `u64`
    |
note: method defined here
   --> /home/runner/work/linux/linux/linux/rust/kernel/iommu/pgtable.rs:152:19
    |
152 |     pub unsafe fn map_pages(
    |                   ^^^^^^^^^
help: you can convert a `u64` to a `u32` and panic if the converted
value doesn't fit
    |
873 |                 curr_paddr.try_into().unwrap(),
    |                           ++++++++++++++++++++