From e227330223a7721b4284c3921651bd9ca8f3581a Mon Sep 17 00:00:00 2001 From: Imre Deak Date: Thu, 9 Jul 2015 12:59:05 +0300 Subject: [PATCH] drm/i915: avoid leaking DMA mappings We have 3 types of DMA mappings for GEM objects: 1. physically contiguous for stolen and for objects needing contiguous memory 2. DMA-buf mappings imported via a DMA-buf attach operation 3. SG DMA mappings for shmem backed and userptr objects For 1. and 2. the lifetime of the DMA mapping matches the lifetime of the corresponding backing pages and so in practice we create/release the mapping in the object's get_pages/put_pages callback. For 3. the lifetime of the mapping matches that of any existing GPU binding of the object, so we'll create the mapping when the object is bound to the first vma and release the mapping when the object is unbound from its last vma. Since the object can be bound to multiple vmas, we can end up creating a new DMA mapping in the 3. case even if the object already had one. This is not allowed by the DMA API and can lead to leaked mapping data and IOMMU memory space starvation in certain cases. For example HW IOMMU drivers (intel_iommu) allocate a new range from their memory space whenever a mapping is created, silently overriding a pre-existing mapping. Fix this by moving the creation/removal of DMA mappings to the object's get_pages/put_pages callbacks. These callbacks already check for and do an early return in case of any nested calls. This way objects of the 3. case also become more like the other object types. I noticed this issue by enabling DMA debugging, which got disabled after a while due to its internal mapping tables getting full. It also reported errors in connection to random other drivers that did a DMA mapping for an address that was previously mapped by i915 but was never released. Besides these diagnostic messages and the memory space starvation problem for IOMMUs, I'm not aware of this causing a real issue. The fix is based on a patch from Chris. v2: - move the DMA mapping create/remove calls to the get_pages/put_pages callbacks instead of adding new callbacks for these (Chris) v3: - also fix the get_page cache logic on the userptr async path (Chris) Signed-off-by: Imre Deak Reviewed-by: Chris Wilson Cc: stable@vger.kernel.org Signed-off-by: Daniel Vetter --- drivers/gpu/drm/i915/i915_gem.c | 31 +++++++++++++------------ drivers/gpu/drm/i915/i915_gem_userptr.c | 29 +++++++++++++++++++++-- 2 files changed, 43 insertions(+), 17 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 716e5acc3bb0..95b92ad1f2b5 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -2139,6 +2139,8 @@ i915_gem_object_put_pages_gtt(struct drm_i915_gem_object *obj) obj->base.read_domains = obj->base.write_domain = I915_GEM_DOMAIN_CPU; } + i915_gem_gtt_finish_object(obj); + if (i915_gem_object_needs_bit17_swizzle(obj)) i915_gem_object_save_bit_17_swizzle(obj); @@ -2199,6 +2201,7 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj) struct sg_page_iter sg_iter; struct page *page; unsigned long last_pfn = 0; /* suppress gcc warning */ + int ret; gfp_t gfp; /* Assert that the object is not currently in any GPU domain. As it @@ -2246,8 +2249,10 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj) */ i915_gem_shrink_all(dev_priv); page = shmem_read_mapping_page(mapping, i); - if (IS_ERR(page)) + if (IS_ERR(page)) { + ret = PTR_ERR(page); goto err_pages; + } } #ifdef CONFIG_SWIOTLB if (swiotlb_nr_tbl()) { @@ -2276,6 +2281,10 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj) sg_mark_end(sg); obj->pages = st; + ret = i915_gem_gtt_prepare_object(obj); + if (ret) + goto err_pages; + if (i915_gem_object_needs_bit17_swizzle(obj)) i915_gem_object_do_bit_17_swizzle(obj); @@ -2300,10 +2309,10 @@ err_pages: * space and so want to translate the error from shmemfs back to our * usual understanding of ENOMEM. */ - if (PTR_ERR(page) == -ENOSPC) - return -ENOMEM; - else - return PTR_ERR(page); + if (ret == -ENOSPC) + ret = -ENOMEM; + + return ret; } /* Ensure that the associated pages are gathered from the backing storage @@ -3248,10 +3257,8 @@ int i915_vma_unbind(struct i915_vma *vma) /* Since the unbound list is global, only move to that list if * no more VMAs exist. */ - if (list_empty(&obj->vma_list)) { - i915_gem_gtt_finish_object(obj); + if (list_empty(&obj->vma_list)) list_move_tail(&obj->global_list, &dev_priv->mm.unbound_list); - } /* And finally now the object is completely decoupled from this vma, * we can drop its hold on the backing storage and allow it to be @@ -3769,22 +3776,16 @@ search_free: goto err_remove_node; } - ret = i915_gem_gtt_prepare_object(obj); - if (ret) - goto err_remove_node; - trace_i915_vma_bind(vma, flags); ret = i915_vma_bind(vma, obj->cache_level, flags); if (ret) - goto err_finish_gtt; + goto err_remove_node; list_move_tail(&obj->global_list, &dev_priv->mm.bound_list); list_add_tail(&vma->mm_list, &vm->inactive_list); return vma; -err_finish_gtt: - i915_gem_gtt_finish_object(obj); err_remove_node: drm_mm_remove_node(&vma->node); err_free_vma: diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c index 1f4e5a32a16e..8fd431bcdfd3 100644 --- a/drivers/gpu/drm/i915/i915_gem_userptr.c +++ b/drivers/gpu/drm/i915/i915_gem_userptr.c @@ -545,6 +545,26 @@ err: return ret; } +static int +__i915_gem_userptr_set_pages(struct drm_i915_gem_object *obj, + struct page **pvec, int num_pages) +{ + int ret; + + ret = st_set_pages(&obj->pages, pvec, num_pages); + if (ret) + return ret; + + ret = i915_gem_gtt_prepare_object(obj); + if (ret) { + sg_free_table(obj->pages); + kfree(obj->pages); + obj->pages = NULL; + } + + return ret; +} + static void __i915_gem_userptr_get_pages_worker(struct work_struct *_work) { @@ -584,9 +604,12 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work) if (obj->userptr.work != &work->work) { ret = 0; } else if (pinned == num_pages) { - ret = st_set_pages(&obj->pages, pvec, num_pages); + ret = __i915_gem_userptr_set_pages(obj, pvec, num_pages); if (ret == 0) { list_add_tail(&obj->global_list, &to_i915(dev)->mm.unbound_list); + obj->get_page.sg = obj->pages->sgl; + obj->get_page.last = 0; + pinned = 0; } } @@ -693,7 +716,7 @@ i915_gem_userptr_get_pages(struct drm_i915_gem_object *obj) } } } else { - ret = st_set_pages(&obj->pages, pvec, num_pages); + ret = __i915_gem_userptr_set_pages(obj, pvec, num_pages); if (ret == 0) { obj->userptr.work = NULL; pinned = 0; @@ -715,6 +738,8 @@ i915_gem_userptr_put_pages(struct drm_i915_gem_object *obj) if (obj->madv != I915_MADV_WILLNEED) obj->dirty = 0; + i915_gem_gtt_finish_object(obj); + for_each_sg_page(obj->pages->sgl, &sg_iter, obj->pages->nents, 0) { struct page *page = sg_page_iter_page(&sg_iter); -- 2.20.1