[Nouveau] [PATCH 4/6] drm: enable big page mapping for small pages when IOMMU is available

[Vince Hsu]

Some platforms have IOMMU to map non-contiguous physical memory into
contiguous GPU virtual address. We can use this feature to enable big pages
mapping on scattered small pages. To achieve that, we also need changes in
subdev/mmu as well.

Signed-off-by: Vince Hsu <vinceh at nvidia.com>
---
 drm/nouveau/nouveau_bo.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drm/nouveau/nouveau_bo.c b/drm/nouveau/nouveau_bo.c
index 77326e344dad..da76ee1121e4 100644
--- a/drm/nouveau/nouveau_bo.c
+++ b/drm/nouveau/nouveau_bo.c
@@ -221,6 +221,11 @@ nouveau_bo_new(struct drm_device *dev, int size, int align,
 	if (drm->client.vm) {
 		if (!(flags & TTM_PL_FLAG_TT) && size > 256 * 1024)
 			nvbo->page_shift = drm->client.vm->mmu->lpg_shift;
+
+		if ((flags & TTM_PL_FLAG_TT) &&
+				drm->client.vm->mmu->iommu_capable &&
+				(size % (1 << drm->client.vm->mmu->lpg_shift)) == 0)
+			nvbo->page_shift = drm->client.vm->mmu->lpg_shift;
 	}
 
 	nouveau_bo_fixup_align(nvbo, flags, &align, &size);
@@ -1641,6 +1646,10 @@ nouveau_bo_vma_add(struct nouveau_bo *nvbo, struct nvkm_vm *vm,
 	    (nvbo->bo.mem.mem_type == TTM_PL_VRAM ||
 	     nvbo->page_shift != vma->vm->mmu->lpg_shift))
 		nvkm_vm_map(vma, nvbo->bo.mem.mm_node);
+	else if (nvbo->bo.mem.mem_type == TTM_PL_TT &&
+		vma->vm->mmu->iommu_capable &&
+		nvbo->page_shift == vma->vm->mmu->lpg_shift)
+		nvkm_vm_map(vma, nvbo->bo.mem.mm_node);
 
 	list_add_tail(&vma->head, &nvbo->vma_list);
 	vma->refcount = 1;
-- 
2.1.4