drm/nouveau: Fix fallout from reservation object rework

Commit 019cbd4a ("drm/nouveau: Initialize GEM object before TTM
object") introduced a subtle change in how the buffer allocation size is
handled. Prior to that change, the size would get aligned to at least a
page, whereas after that change a non-page-aligned size would get passed
through unmodified. This ultimately causes a BUG_ON() to trigger in
drm_gem_private_object_init() and crashes the system.

Fix this by restoring the code that align the allocation size.

Fixes: 019cbd4a ("drm/nouveau: Initialize GEM object before TTM object")
Reported-by: Ilia Mirkin <imirkin@alum.mit.edu>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_bo.c

@@ -186,8 +186,8 @@ nouveau_bo_fixup_align(struct nouveau_bo *nvbo, u32 flags,
 }
 
 struct nouveau_bo *
-nouveau_bo_alloc(struct nouveau_cli *cli, u64 size, u32 flags, u32 tile_mode,
-		 u32 tile_flags)
+nouveau_bo_alloc(struct nouveau_cli *cli, u64 *size, int *align, u32 flags,
+		 u32 tile_mode, u32 tile_flags)
 {
 	struct nouveau_drm *drm = cli->drm;
 	struct nouveau_bo *nvbo;
@@ -195,8 +195,8 @@ nouveau_bo_alloc(struct nouveau_cli *cli, u64 size, u32 flags, u32 tile_mode,
 	struct nvif_vmm *vmm = cli->svm.cli ? &cli->svm.vmm : &cli->vmm.vmm;
 	int i, pi = -1;
 
-	if (!size) {
-		NV_WARN(drm, "skipped size %016llx\n", size);
+	if (!*size) {
+		NV_WARN(drm, "skipped size %016llx\n", *size);
 		return ERR_PTR(-EINVAL);
 	}
 
@@ -266,7 +266,7 @@ nouveau_bo_alloc(struct nouveau_cli *cli, u64 size, u32 flags, u32 tile_mode,
 			pi = i;
 
 		/* Stop once the buffer is larger than the current page size. */
-		if (size >= 1ULL << vmm->page[i].shift)
+		if (*size >= 1ULL << vmm->page[i].shift)
 			break;
 	}
 
@@ -281,6 +281,8 @@ nouveau_bo_alloc(struct nouveau_cli *cli, u64 size, u32 flags, u32 tile_mode,
 	}
 	nvbo->page = vmm->page[pi].shift;
 
+	nouveau_bo_fixup_align(nvbo, flags, align, size);
+
 	return nvbo;
 }
 
@@ -294,7 +296,6 @@ nouveau_bo_init(struct nouveau_bo *nvbo, u64 size, int align, u32 flags,
 
 	acc_size = ttm_bo_dma_acc_size(nvbo->bo.bdev, size, sizeof(*nvbo));
 
-	nouveau_bo_fixup_align(nvbo, flags, &align, &size);
 	nvbo->bo.mem.num_pages = size >> PAGE_SHIFT;
 	nouveau_bo_placement_set(nvbo, flags, 0);
 
@@ -318,7 +319,8 @@ nouveau_bo_new(struct nouveau_cli *cli, u64 size, int align,
 	struct nouveau_bo *nvbo;
 	int ret;
 
-	nvbo = nouveau_bo_alloc(cli, size, flags, tile_mode, tile_flags);
+	nvbo = nouveau_bo_alloc(cli, &size, &align, flags, tile_mode,
+				tile_flags);
 	if (IS_ERR(nvbo))
 		return PTR_ERR(nvbo);
 

drivers/gpu/drm/nouveau/nouveau_bo.h

@@ -71,8 +71,8 @@ nouveau_bo_ref(struct nouveau_bo *ref, struct nouveau_bo **pnvbo)
 extern struct ttm_bo_driver nouveau_bo_driver;
 
 void nouveau_bo_move_init(struct nouveau_drm *);
-struct nouveau_bo *nouveau_bo_alloc(struct nouveau_cli *, u64 size, u32 flags,
-				    u32 tile_mode, u32 tile_flags);
+struct nouveau_bo *nouveau_bo_alloc(struct nouveau_cli *, u64 *size, int *align,
+				    u32 flags, u32 tile_mode, u32 tile_flags);
 int  nouveau_bo_init(struct nouveau_bo *, u64 size, int align, u32 flags,
 		     struct sg_table *sg, struct dma_resv *robj);
 int  nouveau_bo_new(struct nouveau_cli *, u64 size, int align, u32 flags,

drivers/gpu/drm/nouveau/nouveau_gem.c

@@ -188,7 +188,8 @@ nouveau_gem_new(struct nouveau_cli *cli, u64 size, int align, uint32_t domain,
 	if (domain & NOUVEAU_GEM_DOMAIN_COHERENT)
 		flags |= TTM_PL_FLAG_UNCACHED;
 
-	nvbo = nouveau_bo_alloc(cli, size, flags, tile_mode, tile_flags);
+	nvbo = nouveau_bo_alloc(cli, &size, &align, flags, tile_mode,
+				tile_flags);
 	if (IS_ERR(nvbo))
 		return PTR_ERR(nvbo);
 

drivers/gpu/drm/nouveau/nouveau_prime.c

@@ -62,14 +62,15 @@ struct drm_gem_object *nouveau_gem_prime_import_sg_table(struct drm_device *dev,
 	struct nouveau_drm *drm = nouveau_drm(dev);
 	struct nouveau_bo *nvbo;
 	struct dma_resv *robj = attach->dmabuf->resv;
-	size_t size = attach->dmabuf->size;
+	u64 size = attach->dmabuf->size;
 	u32 flags = 0;
+	int align = 0;
 	int ret;
 
 	flags = TTM_PL_FLAG_TT;
 
 	dma_resv_lock(robj, NULL);
-	nvbo = nouveau_bo_alloc(&drm->client, size, flags, 0, 0);
+	nvbo = nouveau_bo_alloc(&drm->client, &size, &align, flags, 0, 0);
 	dma_resv_unlock(robj);
 	if (IS_ERR(nvbo))
 		return ERR_CAST(nvbo);
@@ -84,7 +85,7 @@ struct drm_gem_object *nouveau_gem_prime_import_sg_table(struct drm_device *dev,
 		return ERR_PTR(-ENOMEM);
 	}
 
-	ret = nouveau_bo_init(nvbo, size, 0, flags, sg, robj);
+	ret = nouveau_bo_init(nvbo, size, align, flags, sg, robj);
 	if (ret) {
 		nouveau_bo_ref(NULL, &nvbo);
 		return ERR_PTR(ret);