drm/nouveau/gem: attach fences to VMAs to track GPU usage

An upcoming patch will use these to fix issues related to the deferred
unmapping of GEM objects.
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_gem.c

@@ -99,6 +99,7 @@ struct nouveau_gem_object_unmap {
 static void
 nouveau_gem_object_delete(struct nouveau_vma *vma)
 {
+	nouveau_fence_unref(&vma->fence);
 	nouveau_vma_del(&vma);
 }
 
@@ -344,9 +345,20 @@ validate_fini_no_ticket(struct validate_op *op, struct nouveau_fence *fence,
 		nvbo = list_entry(op->list.next, struct nouveau_bo, entry);
 		b = &pbbo[nvbo->pbbo_index];
 
-		if (likely(fence))
+		if (likely(fence)) {
+			struct nouveau_drm *drm = nouveau_bdev(nvbo->bo.bdev);
+			struct nouveau_vma *vma;
+
 			nouveau_bo_fence(nvbo, fence, !!b->write_domains);
 
+			if (drm->client.vmm.vmm.object.oclass >= NVIF_CLASS_VMM_NV50) {
+				vma = (void *)(unsigned long)b->user_priv;
+				nouveau_fence_unref(&vma->fence);
+				dma_fence_get(&fence->base);
+				vma->fence = fence;
+			}
+		}
+
 		if (unlikely(nvbo->validate_mapped)) {
 			ttm_bo_kunmap(&nvbo->kmap);
 			nvbo->validate_mapped = false;

drivers/gpu/drm/nouveau/nouveau_vmm.c

@@ -92,6 +92,7 @@ nouveau_vma_new(struct nouveau_bo *nvbo, struct nouveau_vmm *vmm,
 	vma->refs = 1;
 	vma->addr = ~0ULL;
 	vma->mem = NULL;
+	vma->fence = NULL;
 	list_add_tail(&vma->head, &nvbo->vma_list);
 
 	if (nvbo->bo.mem.mem_type != TTM_PL_SYSTEM &&

drivers/gpu/drm/nouveau/nouveau_vmm.h

@@ -11,6 +11,8 @@ struct nouveau_vma {
 	u64 addr;
 
 	struct nouveau_mem *mem;
+
+	struct nouveau_fence *fence;
 };
 
 struct nouveau_vma *nouveau_vma_find(struct nouveau_bo *, struct nouveau_vmm *);