On Mon Oct 6, 2025 at 9:13 PM CEST, Mohamed Ahmed wrote:
> From: Mary Guillemard <[email protected]>
>
> Now that everything in UVMM knows about the variable page shift, we can
> select larger values.
>
> The proposed approach rely on nouveau_bo::page unless it would cause
> alignment issues (in which case we fall back to searching an appropriate
> shift)
>
> Co-developed-by: Mohamed Ahmed <[email protected]>
> Signed-off-by: Mohamed Ahmed <[email protected]>
> Signed-off-by: Mary Guillemard <[email protected]>
NIT: Both of your tags should come after Mary's tag. The same applied to some of
the other patches.
> ---
> drivers/gpu/drm/nouveau/nouveau_uvmm.c | 55 +++++++++++++++++++++++++-
> 1 file changed, 53 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/nouveau/nouveau_uvmm.c
> b/drivers/gpu/drm/nouveau/nouveau_uvmm.c
> index a92c729600d6..c336a121e320 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_uvmm.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_uvmm.c
> @@ -454,6 +454,56 @@ op_unmap_prepare_unwind(struct drm_gpuva *va)
> drm_gpuva_insert(va->vm, va);
> }
>
> +static bool
> +op_map_aligned_to_page_shift(const struct drm_gpuva_op_map *op, u8
> page_shift)
> +{
> + u64 page_size = 1ULL << page_shift;
> +
> + return op->va.addr % page_size == 0 && op->va.range % page_size == 0 &&
> + op->gem.offset % page_size == 0;
> +}
> +
> +static u8
> +select_page_shift(struct nouveau_uvmm *uvmm, struct drm_gpuva_op_map *op)
> +{
> + struct nouveau_bo *nvbo = nouveau_gem_object(op->gem.obj);
> +
> + if (nvbo) {
In nouveau a struct drm_gpuva_op_map always has a valid GEM object set; we bail
out if userspace gives us an invalid GEM handle.
> + /* If the BO preferred page shift already fits, use it. */
> + if (op_map_aligned_to_page_shift(op, nvbo->page))
> + return nvbo->page;
> +
> + struct nouveau_mem *mem = nouveau_mem(nvbo->bo.resource);
> + struct nvif_vmm *vmm = &uvmm->vmm.vmm;
> + int i;
> +
> + /* Otherwise let's find a granuality that will fit. */
Do we ever run into the "otherwise" case? nouveau_bo_fixup_align() seems to
already ensure that your previous call will never fail?
> + for (i = 0; i < vmm->page_nr; i++) {
> + /* Ignore anything that is bigger or identical to the
> BO preference. */
> + if (vmm->page[i].shift >= nvbo->page)
> + continue;
> +
> + /* Skip incompatible domains. */
> + if ((mem->mem.type & NVIF_MEM_VRAM) &&
> !vmm->page[i].vram)
> + continue;
> + if ((mem->mem.type & NVIF_MEM_HOST) &&
> + (!vmm->page[i].host || vmm->page[i].shift >
> PAGE_SHIFT))
> + continue;
> +
> + /* If it fits, return the proposed shift. */
> + if (op_map_aligned_to_page_shift(op,
> vmm->page[i].shift))
> + return vmm->page[i].shift;
> + }
> +
> + /* If we get here then nothing can reconcile the requirements.
> This should never
> + * happen.
> + */
> + WARN_ON(1);
> + }
> +
> + return PAGE_SHIFT;
> +}
> +
> static void
> nouveau_uvmm_sm_prepare_unwind(struct nouveau_uvmm *uvmm,
> struct nouveau_uvma_prealloc *new,
> @@ -506,7 +556,7 @@ nouveau_uvmm_sm_prepare_unwind(struct nouveau_uvmm *uvmm,
> if (vmm_get_range)
> nouveau_uvmm_vmm_put(uvmm, vmm_get_start,
> vmm_get_range,
> - PAGE_SHIFT);
> + select_page_shift(uvmm,
> &op->map));
> break;
> }
> case DRM_GPUVA_OP_REMAP: {
> @@ -636,7 +686,8 @@ nouveau_uvmm_sm_prepare(struct nouveau_uvmm *uvmm,
> case DRM_GPUVA_OP_MAP: {
> u64 vmm_get_range = vmm_get_end - vmm_get_start;
>
> - ret = op_map_prepare(uvmm, &new->map, &op->map, args,
> PAGE_SHIFT);
> + ret = op_map_prepare(uvmm, &new->map, &op->map, args,
> + select_page_shift(uvmm, &op->map));
Let's move the call to select_page_shift() into op_map_prepare().
> if (ret)
> goto unwind;
>
> --
> 2.51.0
