drm: allow limiting the scatter list size.

Add drm_device argument to drm_prime_pages_to_sg(), so we can
call dma_max_mapping_size() to figure the segment size limit
and call into __sg_alloc_table_from_pages() with the correct
limit.

This fixes virtio-gpu with sev.  Possibly it'll fix other bugs
too given that drm seems to totaly ignore segment size limits
so far ...

v2: place max_segment in drm driver not gem object.
v3: move max_segment next to the other gem fields.
v4: just use dma_max_mapping_size().
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20200907112425.15610-2-kraxel@redhat.com

drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c

@@ -302,7 +302,8 @@ static struct sg_table *amdgpu_dma_buf_map(struct dma_buf_attachment *attach,
 
 	switch (bo->tbo.mem.mem_type) {
 	case TTM_PL_TT:
-		sgt = drm_prime_pages_to_sg(bo->tbo.ttm->pages,
+		sgt = drm_prime_pages_to_sg(obj->dev,
+					    bo->tbo.ttm->pages,
 					    bo->tbo.num_pages);
 		if (IS_ERR(sgt))
 			return sgt;

drivers/gpu/drm/drm_gem_shmem_helper.c

@@ -656,7 +656,7 @@ struct sg_table *drm_gem_shmem_get_sg_table(struct drm_gem_object *obj)
 
 	WARN_ON(shmem->base.import_attach);
 
-	return drm_prime_pages_to_sg(shmem->pages, obj->size >> PAGE_SHIFT);
+	return drm_prime_pages_to_sg(obj->dev, shmem->pages, obj->size >> PAGE_SHIFT);
 }
 EXPORT_SYMBOL_GPL(drm_gem_shmem_get_sg_table);
 

drivers/gpu/drm/drm_prime.c

@@ -802,9 +802,11 @@ static const struct dma_buf_ops drm_gem_prime_dmabuf_ops =  {
  *
  * This is useful for implementing &drm_gem_object_funcs.get_sg_table.
  */
-struct sg_table *drm_prime_pages_to_sg(struct page **pages, unsigned int nr_pages)
+struct sg_table *drm_prime_pages_to_sg(struct drm_device *dev,
+				       struct page **pages, unsigned int nr_pages)
 {
 	struct sg_table *sg = NULL;
+	size_t max_segment = 0;
 	int ret;
 
 	sg = kmalloc(sizeof(struct sg_table), GFP_KERNEL);
@@ -813,8 +815,13 @@ struct sg_table *drm_prime_pages_to_sg(struct page **pages, unsigned int nr_page
 		goto out;
 	}
 
-	ret = sg_alloc_table_from_pages(sg, pages, nr_pages, 0,
-				nr_pages << PAGE_SHIFT, GFP_KERNEL);
+	if (dev)
+		max_segment = dma_max_mapping_size(dev->dev);
+	if (max_segment == 0 || max_segment > SCATTERLIST_MAX_SEGMENT)
+		max_segment = SCATTERLIST_MAX_SEGMENT;
+	ret = __sg_alloc_table_from_pages(sg, pages, nr_pages, 0,
+					  nr_pages << PAGE_SHIFT,
+					  max_segment, GFP_KERNEL);
 	if (ret)
 		goto out;
 

drivers/gpu/drm/etnaviv/etnaviv_gem.c

@@ -103,7 +103,8 @@ struct page **etnaviv_gem_get_pages(struct etnaviv_gem_object *etnaviv_obj)
 		int npages = etnaviv_obj->base.size >> PAGE_SHIFT;
 		struct sg_table *sgt;
 
-		sgt = drm_prime_pages_to_sg(etnaviv_obj->pages, npages);
+		sgt = drm_prime_pages_to_sg(etnaviv_obj->base.dev,
+					    etnaviv_obj->pages, npages);
 		if (IS_ERR(sgt)) {
 			dev_err(dev->dev, "failed to allocate sgt: %ld\n",
 				PTR_ERR(sgt));

drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c

@@ -19,7 +19,7 @@ struct sg_table *etnaviv_gem_prime_get_sg_table(struct drm_gem_object *obj)
 	if (WARN_ON(!etnaviv_obj->pages))  /* should have already pinned! */
 		return ERR_PTR(-EINVAL);
 
-	return drm_prime_pages_to_sg(etnaviv_obj->pages, npages);
+	return drm_prime_pages_to_sg(obj->dev, etnaviv_obj->pages, npages);
 }
 
 void *etnaviv_gem_prime_vmap(struct drm_gem_object *obj)

drivers/gpu/drm/msm/msm_gem.c

@@ -126,7 +126,7 @@ static struct page **get_pages(struct drm_gem_object *obj)
 
 		msm_obj->pages = p;
 
-		msm_obj->sgt = drm_prime_pages_to_sg(p, npages);
+		msm_obj->sgt = drm_prime_pages_to_sg(obj->dev, p, npages);
 		if (IS_ERR(msm_obj->sgt)) {
 			void *ptr = ERR_CAST(msm_obj->sgt);
 

drivers/gpu/drm/msm/msm_gem_prime.c

@@ -19,7 +19,7 @@ struct sg_table *msm_gem_prime_get_sg_table(struct drm_gem_object *obj)
 	if (WARN_ON(!msm_obj->pages))  /* should have already pinned! */
 		return NULL;
 
-	return drm_prime_pages_to_sg(msm_obj->pages, npages);
+	return drm_prime_pages_to_sg(obj->dev, msm_obj->pages, npages);
 }
 
 void *msm_gem_prime_vmap(struct drm_gem_object *obj)

drivers/gpu/drm/nouveau/nouveau_prime.c

@@ -32,7 +32,7 @@ struct sg_table *nouveau_gem_prime_get_sg_table(struct drm_gem_object *obj)
 	struct nouveau_bo *nvbo = nouveau_gem_object(obj);
 	int npages = nvbo->bo.num_pages;
 
-	return drm_prime_pages_to_sg(nvbo->bo.ttm->pages, npages);
+	return drm_prime_pages_to_sg(obj->dev, nvbo->bo.ttm->pages, npages);
 }
 
 void *nouveau_gem_prime_vmap(struct drm_gem_object *obj)

drivers/gpu/drm/radeon/radeon_prime.c

@@ -36,7 +36,7 @@ struct sg_table *radeon_gem_prime_get_sg_table(struct drm_gem_object *obj)
 	struct radeon_bo *bo = gem_to_radeon_bo(obj);
 	int npages = bo->tbo.num_pages;
 
-	return drm_prime_pages_to_sg(bo->tbo.ttm->pages, npages);
+	return drm_prime_pages_to_sg(obj->dev, bo->tbo.ttm->pages, npages);
 }
 
 void *radeon_gem_prime_vmap(struct drm_gem_object *obj)

drivers/gpu/drm/rockchip/rockchip_drm_gem.c

@@ -85,7 +85,8 @@ static int rockchip_gem_get_pages(struct rockchip_gem_object *rk_obj)
 
 	rk_obj->num_pages = rk_obj->base.size >> PAGE_SHIFT;
 
-	rk_obj->sgt = drm_prime_pages_to_sg(rk_obj->pages, rk_obj->num_pages);
+	rk_obj->sgt = drm_prime_pages_to_sg(rk_obj->base.dev,
+					    rk_obj->pages, rk_obj->num_pages);
 	if (IS_ERR(rk_obj->sgt)) {
 		ret = PTR_ERR(rk_obj->sgt);
 		goto err_put_pages;
@@ -442,7 +443,7 @@ struct sg_table *rockchip_gem_prime_get_sg_table(struct drm_gem_object *obj)
 	int ret;
 
 	if (rk_obj->pages)
-		return drm_prime_pages_to_sg(rk_obj->pages, rk_obj->num_pages);
+		return drm_prime_pages_to_sg(obj->dev, rk_obj->pages, rk_obj->num_pages);
 
 	sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
 	if (!sgt)

drivers/gpu/drm/tegra/gem.c

@@ -284,7 +284,7 @@ static int tegra_bo_get_pages(struct drm_device *drm, struct tegra_bo *bo)
 
 	bo->num_pages = bo->gem.size >> PAGE_SHIFT;
 
-	bo->sgt = drm_prime_pages_to_sg(bo->pages, bo->num_pages);
+	bo->sgt = drm_prime_pages_to_sg(bo->gem.dev, bo->pages, bo->num_pages);
 	if (IS_ERR(bo->sgt)) {
 		err = PTR_ERR(bo->sgt);
 		goto put_pages;

drivers/gpu/drm/vgem/vgem_drv.c

@@ -321,7 +321,7 @@ static struct sg_table *vgem_prime_get_sg_table(struct drm_gem_object *obj)
 {
 	struct drm_vgem_gem_object *bo = to_vgem_bo(obj);
 
-	return drm_prime_pages_to_sg(bo->pages, bo->base.size >> PAGE_SHIFT);
+	return drm_prime_pages_to_sg(obj->dev, bo->pages, bo->base.size >> PAGE_SHIFT);
 }
 
 static struct drm_gem_object* vgem_prime_import(struct drm_device *dev,

drivers/gpu/drm/xen/xen_drm_front_gem.c

@@ -179,7 +179,8 @@ struct sg_table *xen_drm_front_gem_get_sg_table(struct drm_gem_object *gem_obj)
 	if (!xen_obj->pages)
 		return ERR_PTR(-ENOMEM);
 
-	return drm_prime_pages_to_sg(xen_obj->pages, xen_obj->num_pages);
+	return drm_prime_pages_to_sg(gem_obj->dev,
+				     xen_obj->pages, xen_obj->num_pages);
 }
 
 struct drm_gem_object *

include/drm/drm_prime.h

@@ -88,7 +88,8 @@ void drm_gem_dmabuf_vunmap(struct dma_buf *dma_buf, void *vaddr);
 int drm_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma);
 int drm_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *vma);
 
-struct sg_table *drm_prime_pages_to_sg(struct page **pages, unsigned int nr_pages);
+struct sg_table *drm_prime_pages_to_sg(struct drm_device *dev,
+				       struct page **pages, unsigned int nr_pages);
 struct dma_buf *drm_gem_prime_export(struct drm_gem_object *obj,
 				     int flags);