Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi...

[deliverable/linux.git] / drivers / gpu / drm / i915 / i915_gem_userptr.c

/*
 * 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 "drmP.h"
#include "i915_drm.h"
#include "i915_drv.h"
#include "i915_trace.h"
#include "intel_drv.h"
#include <linux/mmu_context.h>
#include <linux/mmu_notifier.h>
#include <linux/mempolicy.h>
#include <linux/swap.h>

#if defined(CONFIG_MMU_NOTIFIER)
#include <linux/interval_tree.h>

struct i915_mmu_notifier {
        spinlock_t lock;
        struct hlist_node node;
        struct mmu_notifier mn;
        struct rb_root objects;
        struct drm_device *dev;
        struct mm_struct *mm;
        struct work_struct work;
        unsigned long count;
        unsigned long serial;
};

struct i915_mmu_object {
        struct i915_mmu_notifier *mmu;
        struct interval_tree_node it;
        struct drm_i915_gem_object *obj;
};

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 interval_tree_node *it = NULL;
        unsigned long serial = 0;

        end--; /* interval ranges are inclusive, but invalidate range is exclusive */
        while (start < end) {
                struct drm_i915_gem_object *obj;

                obj = NULL;
                spin_lock(&mn->lock);
                if (serial == mn->serial)
                        it = interval_tree_iter_next(it, start, end);
                else
                        it = interval_tree_iter_first(&mn->objects, start, end);
                if (it != NULL) {
                        obj = container_of(it, struct i915_mmu_object, it)->obj;
                        drm_gem_object_reference(&obj->base);
                        serial = mn->serial;
                }
                spin_unlock(&mn->lock);
                if (obj == NULL)
                        return;

                mutex_lock(&mn->dev->struct_mutex);
                /* Cancel any active worker and force us to re-evaluate gup */
                obj->userptr.work = NULL;

                if (obj->pages != NULL) {
                        struct drm_i915_private *dev_priv = to_i915(mn->dev);
                        struct i915_vma *vma, *tmp;
                        bool was_interruptible;

                        was_interruptible = dev_priv->mm.interruptible;
                        dev_priv->mm.interruptible = false;

                        list_for_each_entry_safe(vma, tmp, &obj->vma_list, vma_link) {
                                int ret = i915_vma_unbind(vma);
                                WARN_ON(ret && ret != -EIO);
                        }
                        WARN_ON(i915_gem_object_put_pages(obj));

                        dev_priv->mm.interruptible = was_interruptible;
                }

                start = obj->userptr.ptr + obj->base.size;

                drm_gem_object_unreference(&obj->base);
                mutex_unlock(&mn->dev->struct_mutex);
        }
}

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_lookup(struct drm_device *dev, struct mm_struct *mm)
{
        struct drm_i915_private *dev_priv = to_i915(dev);
        struct i915_mmu_notifier *mmu;

        /* Protected by dev->struct_mutex */
        hash_for_each_possible(dev_priv->mmu_notifiers, mmu, node, (unsigned long)mm)
                if (mmu->mm == mm)
                        return mmu;

        return NULL;
}

static struct i915_mmu_notifier *
i915_mmu_notifier_get(struct drm_device *dev, struct mm_struct *mm)
{
        struct drm_i915_private *dev_priv = to_i915(dev);
        struct i915_mmu_notifier *mmu;
        int ret;

        lockdep_assert_held(&dev->struct_mutex);

        mmu = __i915_mmu_notifier_lookup(dev, mm);
        if (mmu)
                return mmu;

        mmu = kmalloc(sizeof(*mmu), GFP_KERNEL);
        if (mmu == NULL)
                return ERR_PTR(-ENOMEM);

        spin_lock_init(&mmu->lock);
        mmu->dev = dev;
        mmu->mn.ops = &i915_gem_userptr_notifier;
        mmu->mm = mm;
        mmu->objects = RB_ROOT;
        mmu->count = 0;
        mmu->serial = 0;

        /* Protected by mmap_sem (write-lock) */
        ret = __mmu_notifier_register(&mmu->mn, mm);
        if (ret) {
                kfree(mmu);
                return ERR_PTR(ret);
        }

        /* Protected by dev->struct_mutex */
        hash_add(dev_priv->mmu_notifiers, &mmu->node, (unsigned long)mm);
        return mmu;
}

static void
__i915_mmu_notifier_destroy_worker(struct work_struct *work)
{
        struct i915_mmu_notifier *mmu = container_of(work, typeof(*mmu), work);
        mmu_notifier_unregister(&mmu->mn, mmu->mm);
        kfree(mmu);
}

static void
__i915_mmu_notifier_destroy(struct i915_mmu_notifier *mmu)
{
        lockdep_assert_held(&mmu->dev->struct_mutex);

        /* Protected by dev->struct_mutex */
        hash_del(&mmu->node);

        /* Our lock ordering is: mmap_sem, mmu_notifier_scru, struct_mutex.
         * We enter the function holding struct_mutex, therefore we need
         * to drop our mutex prior to calling mmu_notifier_unregister in
         * order to prevent lock inversion (and system-wide deadlock)
         * between the mmap_sem and struct-mutex. Hence we defer the
         * unregistration to a workqueue where we hold no locks.
         */
        INIT_WORK(&mmu->work, __i915_mmu_notifier_destroy_worker);
        schedule_work(&mmu->work);
}

static void __i915_mmu_notifier_update_serial(struct i915_mmu_notifier *mmu)
{
        if (++mmu->serial == 0)
                mmu->serial = 1;
}

static void
i915_mmu_notifier_del(struct i915_mmu_notifier *mmu,
                      struct i915_mmu_object *mn)
{
        lockdep_assert_held(&mmu->dev->struct_mutex);

        spin_lock(&mmu->lock);
        interval_tree_remove(&mn->it, &mmu->objects);
        __i915_mmu_notifier_update_serial(mmu);
        spin_unlock(&mmu->lock);

        /* Protected against _add() by dev->struct_mutex */
        if (--mmu->count == 0)
                __i915_mmu_notifier_destroy(mmu);
}

static int
i915_mmu_notifier_add(struct i915_mmu_notifier *mmu,
                      struct i915_mmu_object *mn)
{
        struct interval_tree_node *it;
        int ret;

        ret = i915_mutex_lock_interruptible(mmu->dev);
        if (ret)
                return ret;

        /* Make sure we drop the final active reference (and thereby
         * remove the objects from the interval tree) before we do
         * the check for overlapping objects.
         */
        i915_gem_retire_requests(mmu->dev);

        /* Disallow overlapping userptr objects */
        spin_lock(&mmu->lock);
        it = interval_tree_iter_first(&mmu->objects,
                                      mn->it.start, mn->it.last);
        if (it) {
                struct drm_i915_gem_object *obj;

                /* We only need to check the first object in the range as it
                 * either has cancelled gup work queued and we need to
                 * return back to the user to give time for the gup-workers
                 * to flush their object references upon which the object will
                 * be removed from the interval-tree, or the the range is
                 * still in use by another client and the overlap is invalid.
                 */

                obj = container_of(it, struct i915_mmu_object, it)->obj;
                ret = obj->userptr.workers ? -EAGAIN : -EINVAL;
        } else {
                interval_tree_insert(&mn->it, &mmu->objects);
                __i915_mmu_notifier_update_serial(mmu);
                ret = 0;
        }
        spin_unlock(&mmu->lock);
        mutex_unlock(&mmu->dev->struct_mutex);

        return ret;
}

static void
i915_gem_userptr_release__mmu_notifier(struct drm_i915_gem_object *obj)
{
        struct i915_mmu_object *mn;

        mn = obj->userptr.mn;
        if (mn == NULL)
                return;

        i915_mmu_notifier_del(mn->mmu, mn);
        obj->userptr.mn = NULL;
}

static int
i915_gem_userptr_init__mmu_notifier(struct drm_i915_gem_object *obj,
                                    unsigned flags)
{
        struct i915_mmu_notifier *mmu;
        struct i915_mmu_object *mn;
        int ret;

        if (flags & I915_USERPTR_UNSYNCHRONIZED)
                return capable(CAP_SYS_ADMIN) ? 0 : -EPERM;

        down_write(&obj->userptr.mm->mmap_sem);
        ret = i915_mutex_lock_interruptible(obj->base.dev);
        if (ret == 0) {
                mmu = i915_mmu_notifier_get(obj->base.dev, obj->userptr.mm);
                if (!IS_ERR(mmu))
                        mmu->count++; /* preemptive add to act as a refcount */
                else
                        ret = PTR_ERR(mmu);
                mutex_unlock(&obj->base.dev->struct_mutex);
        }
        up_write(&obj->userptr.mm->mmap_sem);
        if (ret)
                return ret;

        mn = kzalloc(sizeof(*mn), GFP_KERNEL);
        if (mn == NULL) {
                ret = -ENOMEM;
                goto destroy_mmu;
        }

        mn->mmu = mmu;
        mn->it.start = obj->userptr.ptr;
        mn->it.last = mn->it.start + obj->base.size - 1;
        mn->obj = obj;

        ret = i915_mmu_notifier_add(mmu, mn);
        if (ret)
                goto free_mn;

        obj->userptr.mn = mn;
        return 0;

free_mn:
        kfree(mn);
destroy_mmu:
        mutex_lock(&obj->base.dev->struct_mutex);
        if (--mmu->count == 0)
                __i915_mmu_notifier_destroy(mmu);
        mutex_unlock(&obj->base.dev->struct_mutex);
        return ret;
}

#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;
}
#endif

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 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;
        struct drm_device *dev = obj->base.dev;
        const int num_pages = obj->base.size >> PAGE_SHIFT;
        struct page **pvec;
        int pinned, ret;

        ret = -ENOMEM;
        pinned = 0;

        pvec = kmalloc(num_pages*sizeof(struct page *),
                       GFP_TEMPORARY | __GFP_NOWARN | __GFP_NORETRY);
        if (pvec == NULL)
                pvec = drm_malloc_ab(num_pages, sizeof(struct page *));
        if (pvec != NULL) {
                struct mm_struct *mm = obj->userptr.mm;

                down_read(&mm->mmap_sem);
                while (pinned < num_pages) {
                        ret = get_user_pages(work->task, mm,
                                             obj->userptr.ptr + pinned * PAGE_SIZE,
                                             num_pages - pinned,
                                             !obj->userptr.read_only, 0,
                                             pvec + pinned, NULL);
                        if (ret < 0)
                                break;

                        pinned += ret;
                }
                up_read(&mm->mmap_sem);
        }

        mutex_lock(&dev->struct_mutex);
        if (obj->userptr.work != &work->work) {
                ret = 0;
        } else if (pinned == num_pages) {
                ret = st_set_pages(&obj->pages, pvec, num_pages);
                if (ret == 0) {
                        list_add_tail(&obj->global_list, &to_i915(dev)->mm.unbound_list);
                        pinned = 0;
                }
        }

        obj->userptr.work = ERR_PTR(ret);
        obj->userptr.workers--;
        drm_gem_object_unreference(&obj->base);
        mutex_unlock(&dev->struct_mutex);

        release_pages(pvec, pinned, 0);
        drm_free_large(pvec);

        put_task_struct(work->task);
        kfree(work);
}

static int
i915_gem_userptr_get_pages(struct drm_i915_gem_object *obj)
{
        const int num_pages = obj->base.size >> PAGE_SHIFT;
        struct page **pvec;
        int pinned, ret;

        /* 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.
         */

        pvec = NULL;
        pinned = 0;
        if (obj->userptr.mm == current->mm) {
                pvec = kmalloc(num_pages*sizeof(struct page *),
                               GFP_TEMPORARY | __GFP_NOWARN | __GFP_NORETRY);
                if (pvec == NULL) {
                        pvec = drm_malloc_ab(num_pages, sizeof(struct page *));
                        if (pvec == NULL)
                                return -ENOMEM;
                }

                pinned = __get_user_pages_fast(obj->userptr.ptr, num_pages,
                                               !obj->userptr.read_only, pvec);
        }
        if (pinned < num_pages) {
                if (pinned < 0) {
                        ret = pinned;
                        pinned = 0;
                } else {
                        /* 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.
                         */
                        ret = -EAGAIN;
                        if (obj->userptr.work == NULL &&
                            obj->userptr.workers < I915_GEM_USERPTR_MAX_WORKERS) {
                                struct get_pages_work *work;

                                work = kmalloc(sizeof(*work), GFP_KERNEL);
                                if (work != NULL) {
                                        obj->userptr.work = &work->work;
                                        obj->userptr.workers++;

                                        work->obj = obj;
                                        drm_gem_object_reference(&obj->base);

                                        work->task = current;
                                        get_task_struct(work->task);

                                        INIT_WORK(&work->work, __i915_gem_userptr_get_pages_worker);
                                        schedule_work(&work->work);
                                } else
                                        ret = -ENOMEM;
                        } else {
                                if (IS_ERR(obj->userptr.work)) {
                                        ret = PTR_ERR(obj->userptr.work);
                                        obj->userptr.work = NULL;
                                }
                        }
                }
        } else {
                ret = st_set_pages(&obj->pages, pvec, num_pages);
                if (ret == 0) {
                        obj->userptr.work = NULL;
                        pinned = 0;
                }
        }

        release_pages(pvec, pinned, 0);
        drm_free_large(pvec);
        return ret;
}

static void
i915_gem_userptr_put_pages(struct drm_i915_gem_object *obj)
{
        struct scatterlist *sg;
        int i;

        BUG_ON(obj->userptr.work != NULL);

        if (obj->madv != I915_MADV_WILLNEED)
                obj->dirty = 0;

        for_each_sg(obj->pages->sgl, sg, obj->pages->nents, i) {
                struct page *page = sg_page(sg);

                if (obj->dirty)
                        set_page_dirty(page);

                mark_page_accessed(page);
                page_cache_release(page);
        }
        obj->dirty = 0;

        sg_free_table(obj->pages);
        kfree(obj->pages);
}

static void
i915_gem_userptr_release(struct drm_i915_gem_object *obj)
{
        i915_gem_userptr_release__mmu_notifier(obj);

        if (obj->userptr.mm) {
                mmput(obj->userptr.mm);
                obj->userptr.mm = NULL;
        }
}

static int
i915_gem_userptr_dmabuf_export(struct drm_i915_gem_object *obj)
{
        if (obj->userptr.mn)
                return 0;

        return i915_gem_userptr_init__mmu_notifier(obj, 0);
}

static const struct drm_i915_gem_object_ops i915_gem_userptr_ops = {
        .dmabuf_export = i915_gem_userptr_dmabuf_export,
        .get_pages = i915_gem_userptr_get_pages,
        .put_pages = i915_gem_userptr_put_pages,
        .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 cannot overlap any other userptr object in the same address space.
 * 3. 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).
 * 4. 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.
 * 5. 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.
 *
 * 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_private *dev_priv = dev->dev_private;
        struct drm_i915_gem_userptr *args = data;
        struct drm_i915_gem_object *obj;
        int ret;
        u32 handle;

        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 (args->user_size > dev_priv->gtt.base.total)
                return -E2BIG;

        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;
        }

        /* Allocate the new object */
        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 = -ENOMEM;
        if ((obj->userptr.mm = get_task_mm(current)))
                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 */
        drm_gem_object_unreference_unlocked(&obj->base);
        if (ret)
                return ret;

        args->handle = handle;
        return 0;
}

int
i915_gem_init_userptr(struct drm_device *dev)
{
#if defined(CONFIG_MMU_NOTIFIER)
        struct drm_i915_private *dev_priv = to_i915(dev);
        hash_init(dev_priv->mmu_notifiers);
#endif
        return 0;
}