Commit c488a94e authored by Mary Guillemard's avatar Mary Guillemard Committed by Lyude Paul
Browse files

drm/nouveau/uvmm: Allow larger pages 



Now that everything in UVMM knows about the variable page shift, we can
select larger values.

The proposed approach relies on nouveau_bo::page unless if it would cause
alignment issues (in which case we fall back to searching for an
appropriate shift)

Signed-off-by: default avatarMary Guillemard <mary@mary.zone>
Co-developed-by: default avatarMohamed Ahmed <mohamedahmedegypt2001@gmail.com>
Signed-off-by: default avatarMohamed Ahmed <mohamedahmedegypt2001@gmail.com>
Reviewed-by: default avatarLyude Paul <lyude@redhat.com>
Reviewed-by: default avatarJames Jones <jajones@nvidia.com>
Signed-off-by: default avatarLyude Paul <lyude@redhat.com>
Link: https://patch.msgid.link/20251110-nouveau-compv6-v6-2-83b05475f57c@mary.zone
parent 6d134953

drivers/gpu/drm/nouveau/nouveau_uvmm.c

+58 −2
Original line number Diff line number Diff line
@@ -454,6 +454,62 @@ 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 non_page_bits = (1ULL << page_shift) - 1;



	return (op->va.addr & non_page_bits) == 0 &&

	       (op->va.range & non_page_bits) == 0 &&

	       (op->gem.offset & non_page_bits) == 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);



	/* nouveau_bo_fixup_align() guarantees that the page size will be aligned

	 * for most cases, but it can't handle cases where userspace allocates with

	 * a size and then binds with a smaller granularity. So in order to avoid

	 * breaking old userspace, we need to ensure that the VA is actually

	 * aligned before using it, and if it isn't, then we downgrade to the first

	 * granularity that will fit, which is optimal from a correctness and

	 * performance perspective.

	 */

	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;



	/* If the given granularity doesn't fit, let's find one that will fit. */

	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.

	 */

	drm_WARN_ONCE(op->gem.obj->dev, 1, "Could not find an appropriate page size.\n");



	return PAGE_SHIFT;

}



static void

nouveau_uvmm_sm_prepare_unwind(struct nouveau_uvmm *uvmm,

			       struct nouveau_uvma_prealloc *new,
@@ -506,7 +562,7 @@ 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: {
@@ -599,7 +655,7 @@ op_map_prepare(struct nouveau_uvmm *uvmm, 


	uvma->region = args->region;

	uvma->kind = args->kind;

	uvma->page_shift = PAGE_SHIFT;

	uvma->page_shift = select_page_shift(uvmm, op);



	drm_gpuva_map(&uvmm->base, &uvma->va, op);