/* * Copyright © 2012-2014 Intel Corporation * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice (including the next * paragraph) shall be included in all copies or substantial portions of the * Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS * IN THE SOFTWARE. * */ #include #include #include "i915_drv.h" #include "i915_trace.h" #include "intel_drv.h" #include #include #include #include struct i915_mm_struct { struct mm_struct *mm; struct drm_i915_private *i915; struct i915_mmu_notifier *mn; struct hlist_node node; struct kref kref; struct work_struct work; }; #if defined(CONFIG_MMU_NOTIFIER) #include struct i915_mmu_notifier { spinlock_t lock; struct hlist_node node; struct mmu_notifier mn; struct rb_root objects; struct workqueue_struct *wq; }; struct i915_mmu_object { struct i915_mmu_notifier *mn; struct drm_i915_gem_object *obj; struct interval_tree_node it; struct list_head link; struct work_struct work; bool attached; }; static void cancel_userptr(struct work_struct *work) { struct i915_mmu_object *mo = container_of(work, typeof(*mo), work); struct drm_i915_gem_object *obj = mo->obj; struct drm_device *dev = obj->base.dev; i915_gem_object_wait(obj, I915_WAIT_ALL, MAX_SCHEDULE_TIMEOUT, NULL); mutex_lock(&dev->struct_mutex); /* Cancel any active worker and force us to re-evaluate gup */ obj->userptr.work = NULL; /* We are inside a kthread context and can't be interrupted */ if (i915_gem_object_unbind(obj) == 0) __i915_gem_object_put_pages(obj); WARN_ONCE(obj->mm.pages, "Failed to release pages: bind_count=%d, pages_pin_count=%d, pin_display=%d\n", obj->bind_count, atomic_read(&obj->mm.pages_pin_count), obj->pin_display); i915_gem_object_put(obj); mutex_unlock(&dev->struct_mutex); } static void add_object(struct i915_mmu_object *mo) { if (mo->attached) return; interval_tree_insert(&mo->it, &mo->mn->objects); mo->attached = true; } static void del_object(struct i915_mmu_object *mo) { if (!mo->attached) return; interval_tree_remove(&mo->it, &mo->mn->objects); mo->attached = false; } static void i915_gem_userptr_mn_invalidate_range_start(struct mmu_notifier *_mn, struct mm_struct *mm, unsigned long start, unsigned long end) { struct i915_mmu_notifier *mn = container_of(_mn, struct i915_mmu_notifier, mn); struct i915_mmu_object *mo; struct interval_tree_node *it; LIST_HEAD(cancelled); if (RB_EMPTY_ROOT(&mn->objects)) return; /* interval ranges are inclusive, but invalidate range is exclusive */ end--; spin_lock(&mn->lock); it = interval_tree_iter_first(&mn->objects, start, end); while (it) { /* The mmu_object is released late when destroying the * GEM object so it is entirely possible to gain a * reference on an object in the process of being freed * since our serialisation is via the spinlock and not * the struct_mutex - and consequently use it after it * is freed and then double free it. To prevent that * use-after-free we only acquire a reference on the * object if it is not in the process of being destroyed. */ mo = container_of(it, struct i915_mmu_object, it); if (kref_get_unless_zero(&mo->obj->base.refcount)) queue_work(mn->wq, &mo->work); list_add(&mo->link, &cancelled); it = interval_tree_iter_next(it, start, end); } list_for_each_entry(mo, &cancelled, link) del_object(mo); spin_unlock(&mn->lock); flush_workqueue(mn->wq); } static const struct mmu_notifier_ops i915_gem_userptr_notifier = { .invalidate_range_start = i915_gem_userptr_mn_invalidate_range_start, }; static struct i915_mmu_notifier * i915_mmu_notifier_create(struct mm_struct *mm) { struct i915_mmu_notifier *mn; int ret; mn = kmalloc(sizeof(*mn), GFP_KERNEL); if (mn == NULL) return ERR_PTR(-ENOMEM); spin_lock_init(&mn->lock); mn->mn.ops = &i915_gem_userptr_notifier; mn->objects = RB_ROOT; mn->wq = alloc_workqueue("i915-userptr-release", WQ_UNBOUND, 0); if (mn->wq == NULL) { kfree(mn); return ERR_PTR(-ENOMEM); } /* Protected by mmap_sem (write-lock) */ ret = __mmu_notifier_register(&mn->mn, mm); if (ret) { destroy_workqueue(mn->wq); kfree(mn); return ERR_PTR(ret); } return mn; } static void i915_gem_userptr_release__mmu_notifier(struct drm_i915_gem_object *obj) { struct i915_mmu_object *mo; mo = obj->userptr.mmu_object; if (mo == NULL) return; spin_lock(&mo->mn->lock); del_object(mo); spin_unlock(&mo->mn->lock); kfree(mo); obj->userptr.mmu_object = NULL; } static struct i915_mmu_notifier * i915_mmu_notifier_find(struct i915_mm_struct *mm) { struct i915_mmu_notifier *mn = mm->mn; mn = mm->mn; if (mn) return mn; down_write(&mm->mm->mmap_sem); mutex_lock(&mm->i915->mm_lock); if ((mn = mm->mn) == NULL) { mn = i915_mmu_notifier_create(mm->mm); if (!IS_ERR(mn)) mm->mn = mn; } mutex_unlock(&mm->i915->mm_lock); up_write(&mm->mm->mmap_sem); return mn; } static int i915_gem_userptr_init__mmu_notifier(struct drm_i915_gem_object *obj, unsigned flags) { struct i915_mmu_notifier *mn; struct i915_mmu_object *mo; if (flags & I915_USERPTR_UNSYNCHRONIZED) return capable(CAP_SYS_ADMIN) ? 0 : -EPERM; if (WARN_ON(obj->userptr.mm == NULL)) return -EINVAL; mn = i915_mmu_notifier_find(obj->userptr.mm); if (IS_ERR(mn)) return PTR_ERR(mn); mo = kzalloc(sizeof(*mo), GFP_KERNEL); if (mo == NULL) return -ENOMEM; mo->mn = mn; mo->obj = obj; mo->it.start = obj->userptr.ptr; mo->it.last = obj->userptr.ptr + obj->base.size - 1; INIT_WORK(&mo->work, cancel_userptr); obj->userptr.mmu_object = mo; return 0; } static void i915_mmu_notifier_free(struct i915_mmu_notifier *mn, struct mm_struct *mm) { if (mn == NULL) return; mmu_notifier_unregister(&mn->mn, mm); destroy_workqueue(mn->wq); kfree(mn); } #else static void i915_gem_userptr_release__mmu_notifier(struct drm_i915_gem_object *obj) { } static int i915_gem_userptr_init__mmu_notifier(struct drm_i915_gem_object *obj, unsigned flags) { if ((flags & I915_USERPTR_UNSYNCHRONIZED) == 0) return -ENODEV; if (!capable(CAP_SYS_ADMIN)) return -EPERM; return 0; } static void i915_mmu_notifier_free(struct i915_mmu_notifier *mn, struct mm_struct *mm) { } #endif static struct i915_mm_struct * __i915_mm_struct_find(struct drm_i915_private *dev_priv, struct mm_struct *real) { struct i915_mm_struct *mm; /* Protected by dev_priv->mm_lock */ hash_for_each_possible(dev_priv->mm_structs, mm, node, (unsigned long)real) if (mm->mm == real) return mm; return NULL; } static int i915_gem_userptr_init__mm_struct(struct drm_i915_gem_object *obj) { struct drm_i915_private *dev_priv = to_i915(obj->base.dev); struct i915_mm_struct *mm; int ret = 0; /* During release of the GEM object we hold the struct_mutex. This * precludes us from calling mmput() at that time as that may be * the last reference and so call exit_mmap(). exit_mmap() will * attempt to reap the vma, and if we were holding a GTT mmap * would then call drm_gem_vm_close() and attempt to reacquire * the struct mutex. So in order to avoid that recursion, we have * to defer releasing the mm reference until after we drop the * struct_mutex, i.e. we need to schedule a worker to do the clean * up. */ mutex_lock(&dev_priv->mm_lock); mm = __i915_mm_struct_find(dev_priv, current->mm); if (mm == NULL) { mm = kmalloc(sizeof(*mm), GFP_KERNEL); if (mm == NULL) { ret = -ENOMEM; goto out; } kref_init(&mm->kref); mm->i915 = to_i915(obj->base.dev); mm->mm = current->mm; atomic_inc(¤t->mm->mm_count); mm->mn = NULL; /* Protected by dev_priv->mm_lock */ hash_add(dev_priv->mm_structs, &mm->node, (unsigned long)mm->mm); } else kref_get(&mm->kref); obj->userptr.mm = mm; out: mutex_unlock(&dev_priv->mm_lock); return ret; } static void __i915_mm_struct_free__worker(struct work_struct *work) { struct i915_mm_struct *mm = container_of(work, typeof(*mm), work); i915_mmu_notifier_free(mm->mn, mm->mm); mmdrop(mm->mm); kfree(mm); } static void __i915_mm_struct_free(struct kref *kref) { struct i915_mm_struct *mm = container_of(kref, typeof(*mm), kref); /* Protected by dev_priv->mm_lock */ hash_del(&mm->node); mutex_unlock(&mm->i915->mm_lock); INIT_WORK(&mm->work, __i915_mm_struct_free__worker); schedule_work(&mm->work); } static void i915_gem_userptr_release__mm_struct(struct drm_i915_gem_object *obj) { if (obj->userptr.mm == NULL) return; kref_put_mutex(&obj->userptr.mm->kref, __i915_mm_struct_free, &to_i915(obj->base.dev)->mm_lock); obj->userptr.mm = NULL; } struct get_pages_work { struct work_struct work; struct drm_i915_gem_object *obj; struct task_struct *task; }; #if IS_ENABLED(CONFIG_SWIOTLB) #define swiotlb_active() swiotlb_nr_tbl() #else #define swiotlb_active() 0 #endif static int st_set_pages(struct sg_table **st, struct page **pvec, int num_pages) { struct scatterlist *sg; int ret, n; *st = kmalloc(sizeof(**st), GFP_KERNEL); if (*st == NULL) return -ENOMEM; if (swiotlb_active()) { ret = sg_alloc_table(*st, num_pages, GFP_KERNEL); if (ret) goto err; for_each_sg((*st)->sgl, sg, num_pages, n) sg_set_page(sg, pvec[n], PAGE_SIZE, 0); } else { ret = sg_alloc_table_from_pages(*st, pvec, num_pages, 0, num_pages << PAGE_SHIFT, GFP_KERNEL); if (ret) goto err; } return 0; err: kfree(*st); *st = NULL; return ret; } static struct sg_table * __i915_gem_userptr_set_pages(struct drm_i915_gem_object *obj, struct page **pvec, int num_pages) { struct sg_table *pages; int ret; ret = st_set_pages(&pages, pvec, num_pages); if (ret) return ERR_PTR(ret); ret = i915_gem_gtt_prepare_pages(obj, pages); if (ret) { sg_free_table(pages); kfree(pages); return ERR_PTR(ret); } return pages; } static int __i915_gem_userptr_set_active(struct drm_i915_gem_object *obj, bool value) { int ret = 0; /* During mm_invalidate_range we need to cancel any userptr that * overlaps the range being invalidated. Doing so requires the * struct_mutex, and that risks recursion. In order to cause * recursion, the user must alias the userptr address space with * a GTT mmapping (possible with a MAP_FIXED) - then when we have * to invalidate that mmaping, mm_invalidate_range is called with * the userptr address *and* the struct_mutex held. To prevent that * we set a flag under the i915_mmu_notifier spinlock to indicate * whether this object is valid. */ #if defined(CONFIG_MMU_NOTIFIER) if (obj->userptr.mmu_object == NULL) return 0; spin_lock(&obj->userptr.mmu_object->mn->lock); /* In order to serialise get_pages with an outstanding * cancel_userptr, we must drop the struct_mutex and try again. */ if (!value) del_object(obj->userptr.mmu_object); else if (!work_pending(&obj->userptr.mmu_object->work)) add_object(obj->userptr.mmu_object); else ret = -EAGAIN; spin_unlock(&obj->userptr.mmu_object->mn->lock); #endif return ret; } static void __i915_gem_userptr_get_pages_worker(struct work_struct *_work) { struct get_pages_work *work = container_of(_work, typeof(*work), work); struct drm_i915_gem_object *obj = work->obj; const int npages = obj->base.size >> PAGE_SHIFT; struct page **pvec; int pinned, ret; ret = -ENOMEM; pinned = 0; pvec = drm_malloc_gfp(npages, sizeof(struct page *), GFP_TEMPORARY); if (pvec != NULL) { struct mm_struct *mm = obj->userptr.mm->mm; unsigned int flags = 0; if (!obj->userptr.read_only) flags |= FOLL_WRITE; ret = -EFAULT; if (atomic_inc_not_zero(&mm->mm_users)) { down_read(&mm->mmap_sem); while (pinned < npages) { ret = get_user_pages_remote (work->task, mm, obj->userptr.ptr + pinned * PAGE_SIZE, npages - pinned, flags, pvec + pinned, NULL); if (ret < 0) break; pinned += ret; } up_read(&mm->mmap_sem); mmput(mm); } } mutex_lock(&obj->mm.lock); if (obj->userptr.work == &work->work) { struct sg_table *pages = ERR_PTR(ret); if (pinned == npages) { pages = __i915_gem_userptr_set_pages(obj, pvec, npages); if (!IS_ERR(pages)) { __i915_gem_object_set_pages(obj, pages); pinned = 0; pages = NULL; } } obj->userptr.work = ERR_CAST(pages); } mutex_unlock(&obj->mm.lock); release_pages(pvec, pinned, 0); drm_free_large(pvec); i915_gem_object_put_unlocked(obj); put_task_struct(work->task); kfree(work); } static struct sg_table * __i915_gem_userptr_get_pages_schedule(struct drm_i915_gem_object *obj, bool *active) { struct get_pages_work *work; /* Spawn a worker so that we can acquire the * user pages without holding our mutex. Access * to the user pages requires mmap_sem, and we have * a strict lock ordering of mmap_sem, struct_mutex - * we already hold struct_mutex here and so cannot * call gup without encountering a lock inversion. * * Userspace will keep on repeating the operation * (thanks to EAGAIN) until either we hit the fast * path or the worker completes. If the worker is * cancelled or superseded, the task is still run * but the results ignored. (This leads to * complications that we may have a stray object * refcount that we need to be wary of when * checking for existing objects during creation.) * If the worker encounters an error, it reports * that error back to this function through * obj->userptr.work = ERR_PTR. */ work = kmalloc(sizeof(*work), GFP_KERNEL); if (work == NULL) return ERR_PTR(-ENOMEM); obj->userptr.work = &work->work; work->obj = i915_gem_object_get(obj); work->task = current; get_task_struct(work->task); INIT_WORK(&work->work, __i915_gem_userptr_get_pages_worker); schedule_work(&work->work); *active = true; return ERR_PTR(-EAGAIN); } static struct sg_table * i915_gem_userptr_get_pages(struct drm_i915_gem_object *obj) { const int num_pages = obj->base.size >> PAGE_SHIFT; struct page **pvec; struct sg_table *pages; int pinned, ret; bool active; /* If userspace should engineer that these pages are replaced in * the vma between us binding this page into the GTT and completion * of rendering... Their loss. If they change the mapping of their * pages they need to create a new bo to point to the new vma. * * However, that still leaves open the possibility of the vma * being copied upon fork. Which falls under the same userspace * synchronisation issue as a regular bo, except that this time * the process may not be expecting that a particular piece of * memory is tied to the GPU. * * Fortunately, we can hook into the mmu_notifier in order to * discard the page references prior to anything nasty happening * to the vma (discard or cloning) which should prevent the more * egregious cases from causing harm. */ if (obj->userptr.work) { /* active flag should still be held for the pending work */ if (IS_ERR(obj->userptr.work)) return ERR_CAST(obj->userptr.work); else return ERR_PTR(-EAGAIN); } /* Let the mmu-notifier know that we have begun and need cancellation */ ret = __i915_gem_userptr_set_active(obj, true); if (ret) return ERR_PTR(ret); pvec = NULL; pinned = 0; if (obj->userptr.mm->mm == current->mm) { pvec = drm_malloc_gfp(num_pages, sizeof(struct page *), GFP_TEMPORARY); if (pvec == NULL) { __i915_gem_userptr_set_active(obj, false); return ERR_PTR(-ENOMEM); } pinned = __get_user_pages_fast(obj->userptr.ptr, num_pages, !obj->userptr.read_only, pvec); } active = false; if (pinned < 0) pages = ERR_PTR(pinned), pinned = 0; else if (pinned < num_pages) pages = __i915_gem_userptr_get_pages_schedule(obj, &active); else pages = __i915_gem_userptr_set_pages(obj, pvec, num_pages); if (IS_ERR(pages)) { __i915_gem_userptr_set_active(obj, active); release_pages(pvec, pinned, 0); } drm_free_large(pvec); return pages; } static void i915_gem_userptr_put_pages(struct drm_i915_gem_object *obj, struct sg_table *pages) { struct sgt_iter sgt_iter; struct page *page; BUG_ON(obj->userptr.work != NULL); __i915_gem_userptr_set_active(obj, false); if (obj->mm.madv != I915_MADV_WILLNEED) obj->mm.dirty = false; i915_gem_gtt_finish_pages(obj, pages); for_each_sgt_page(page, sgt_iter, pages) { if (obj->mm.dirty) set_page_dirty(page); mark_page_accessed(page); put_page(page); } obj->mm.dirty = false; sg_free_table(pages); kfree(pages); } static void i915_gem_userptr_release(struct drm_i915_gem_object *obj) { i915_gem_userptr_release__mmu_notifier(obj); i915_gem_userptr_release__mm_struct(obj); } static int i915_gem_userptr_dmabuf_export(struct drm_i915_gem_object *obj) { if (obj->userptr.mmu_object) return 0; return i915_gem_userptr_init__mmu_notifier(obj, 0); } static const struct drm_i915_gem_object_ops i915_gem_userptr_ops = { .flags = I915_GEM_OBJECT_HAS_STRUCT_PAGE, .get_pages = i915_gem_userptr_get_pages, .put_pages = i915_gem_userptr_put_pages, .dmabuf_export = i915_gem_userptr_dmabuf_export, .release = i915_gem_userptr_release, }; /** * Creates a new mm object that wraps some normal memory from the process * context - user memory. * * We impose several restrictions upon the memory being mapped * into the GPU. * 1. It must be page aligned (both start/end addresses, i.e ptr and size). * 2. It must be normal system memory, not a pointer into another map of IO * space (e.g. it must not be a GTT mmapping of another object). * 3. We only allow a bo as large as we could in theory map into the GTT, * that is we limit the size to the total size of the GTT. * 4. The bo is marked as being snoopable. The backing pages are left * accessible directly by the CPU, but reads and writes by the GPU may * incur the cost of a snoop (unless you have an LLC architecture). * * Synchronisation between multiple users and the GPU is left to userspace * through the normal set-domain-ioctl. The kernel will enforce that the * GPU relinquishes the VMA before it is returned back to the system * i.e. upon free(), munmap() or process termination. However, the userspace * malloc() library may not immediately relinquish the VMA after free() and * instead reuse it whilst the GPU is still reading and writing to the VMA. * Caveat emptor. * * Also note, that the object created here is not currently a "first class" * object, in that several ioctls are banned. These are the CPU access * ioctls: mmap(), pwrite and pread. In practice, you are expected to use * direct access via your pointer rather than use those ioctls. Another * restriction is that we do not allow userptr surfaces to be pinned to the * hardware and so we reject any attempt to create a framebuffer out of a * userptr. * * If you think this is a good interface to use to pass GPU memory between * drivers, please use dma-buf instead. In fact, wherever possible use * dma-buf instead. */ int i915_gem_userptr_ioctl(struct drm_device *dev, void *data, struct drm_file *file) { struct drm_i915_gem_userptr *args = data; struct drm_i915_gem_object *obj; int ret; u32 handle; if (!HAS_LLC(dev) && !HAS_SNOOP(dev)) { /* We cannot support coherent userptr objects on hw without * LLC and broken snooping. */ return -ENODEV; } if (args->flags & ~(I915_USERPTR_READ_ONLY | I915_USERPTR_UNSYNCHRONIZED)) return -EINVAL; if (offset_in_page(args->user_ptr | args->user_size)) return -EINVAL; if (!access_ok(args->flags & I915_USERPTR_READ_ONLY ? VERIFY_READ : VERIFY_WRITE, (char __user *)(unsigned long)args->user_ptr, args->user_size)) return -EFAULT; if (args->flags & I915_USERPTR_READ_ONLY) { /* On almost all of the current hw, we cannot tell the GPU that a * page is readonly, so this is just a placeholder in the uAPI. */ return -ENODEV; } obj = i915_gem_object_alloc(dev); if (obj == NULL) return -ENOMEM; drm_gem_private_object_init(dev, &obj->base, args->user_size); i915_gem_object_init(obj, &i915_gem_userptr_ops); obj->cache_level = I915_CACHE_LLC; obj->base.write_domain = I915_GEM_DOMAIN_CPU; obj->base.read_domains = I915_GEM_DOMAIN_CPU; obj->userptr.ptr = args->user_ptr; obj->userptr.read_only = !!(args->flags & I915_USERPTR_READ_ONLY); /* And keep a pointer to the current->mm for resolving the user pages * at binding. This means that we need to hook into the mmu_notifier * in order to detect if the mmu is destroyed. */ ret = i915_gem_userptr_init__mm_struct(obj); if (ret == 0) ret = i915_gem_userptr_init__mmu_notifier(obj, args->flags); if (ret == 0) ret = drm_gem_handle_create(file, &obj->base, &handle); /* drop reference from allocate - handle holds it now */ i915_gem_object_put_unlocked(obj); if (ret) return ret; args->handle = handle; return 0; } void i915_gem_init_userptr(struct drm_i915_private *dev_priv) { mutex_init(&dev_priv->mm_lock); hash_init(dev_priv->mm_structs); }