/*
 * SPDX-License-Identifier: MIT
 *
 * Copyright © 2011-2012 Intel Corporation
 */

/*
 * This file implements HW context support. On gen5+ a HW context consists of an
 * opaque GPU object which is referenced at times of context saves and restores.
 * With RC6 enabled, the context is also referenced as the GPU enters and exists
 * from RC6 (GPU has it's own internal power context, except on gen5). Though
 * something like a context does exist for the media ring, the code only
 * supports contexts for the render ring.
 *
 * In software, there is a distinction between contexts created by the user,
 * and the default HW context. The default HW context is used by GPU clients
 * that do not request setup of their own hardware context. The default
 * context's state is never restored to help prevent programming errors. This
 * would happen if a client ran and piggy-backed off another clients GPU state.
 * The default context only exists to give the GPU some offset to load as the
 * current to invoke a save of the context we actually care about. In fact, the
 * code could likely be constructed, albeit in a more complicated fashion, to
 * never use the default context, though that limits the driver's ability to
 * swap out, and/or destroy other contexts.
 *
 * All other contexts are created as a request by the GPU client. These contexts
 * store GPU state, and thus allow GPU clients to not re-emit state (and
 * potentially query certain state) at any time. The kernel driver makes
 * certain that the appropriate commands are inserted.
 *
 * The context life cycle is semi-complicated in that context BOs may live
 * longer than the context itself because of the way the hardware, and object
 * tracking works. Below is a very crude representation of the state machine
 * describing the context life.
 *                                         refcount     pincount     active
 * S0: initial state                          0            0           0
 * S1: context created                        1            0           0
 * S2: context is currently running           2            1           X
 * S3: GPU referenced, but not current        2            0           1
 * S4: context is current, but destroyed      1            1           0
 * S5: like S3, but destroyed                 1            0           1
 *
 * The most common (but not all) transitions:
 * S0->S1: client creates a context
 * S1->S2: client submits execbuf with context
 * S2->S3: other clients submits execbuf with context
 * S3->S1: context object was retired
 * S3->S2: clients submits another execbuf
 * S2->S4: context destroy called with current context
 * S3->S5->S0: destroy path
 * S4->S5->S0: destroy path on current context
 *
 * There are two confusing terms used above:
 *  The "current context" means the context which is currently running on the
 *  GPU. The GPU has loaded its state already and has stored away the gtt
 *  offset of the BO. The GPU is not actively referencing the data at this
 *  offset, but it will on the next context switch. The only way to avoid this
 *  is to do a GPU reset.
 *
 *  An "active context' is one which was previously the "current context" and is
 *  on the active list waiting for the next context switch to occur. Until this
 *  happens, the object must remain at the same gtt offset. It is therefore
 *  possible to destroy a context, but it is still active.
 *
 */

#include <linux/log2.h>
#include <linux/nospec.h>

#include <drm/i915_drm.h>

#include "gt/intel_lrc_reg.h"

#include "i915_gem_context.h"
#include "i915_globals.h"
#include "i915_trace.h"
#include "i915_user_extensions.h"

#define ALL_L3_SLICES(dev) (1 << NUM_L3_SLICES(dev)) - 1

static struct i915_global_gem_context {
        struct i915_global base;
        struct kmem_cache *slab_luts;
} global;

struct i915_lut_handle *i915_lut_handle_alloc(void)
{
        return kmem_cache_alloc(global.slab_luts, GFP_KERNEL);
}

void i915_lut_handle_free(struct i915_lut_handle *lut)
{
        return kmem_cache_free(global.slab_luts, lut);
}

static void lut_close(struct i915_gem_context *ctx)
{
        struct radix_tree_iter iter;
        void __rcu **slot;

        lockdep_assert_held(&ctx->mutex);

        rcu_read_lock();
        radix_tree_for_each_slot(slot, &ctx->handles_vma, &iter, 0) {
                struct i915_vma *vma = rcu_dereference_raw(*slot);
                struct drm_i915_gem_object *obj = vma->obj;
                struct i915_lut_handle *lut;

                if (!kref_get_unless_zero(&obj->base.refcount))
                        continue;

                rcu_read_unlock();
                i915_gem_object_lock(obj);
                list_for_each_entry(lut, &obj->lut_list, obj_link) {
                        if (lut->ctx != ctx)
                                continue;

                        if (lut->handle != iter.index)
                                continue;

                        list_del(&lut->obj_link);
                        break;
                }
                i915_gem_object_unlock(obj);
                rcu_read_lock();

                if (&lut->obj_link != &obj->lut_list) {
                        i915_lut_handle_free(lut);
                        radix_tree_iter_delete(&ctx->handles_vma, &iter, slot);
                        if (atomic_dec_and_test(&vma->open_count) &&
                            !i915_vma_is_ggtt(vma))
                                i915_vma_close(vma);
                        i915_gem_object_put(obj);
                }

                i915_gem_object_put(obj);
        }
        rcu_read_unlock();
}

static struct intel_context *
lookup_user_engine(struct i915_gem_context *ctx,
                   unsigned long flags,
                   const struct i915_engine_class_instance *ci)
#define LOOKUP_USER_INDEX BIT(0)
{
        int idx;

        if (!!(flags & LOOKUP_USER_INDEX) != i915_gem_context_user_engines(ctx))
                return ERR_PTR(-EINVAL);

        if (!i915_gem_context_user_engines(ctx)) {
                struct intel_engine_cs *engine;

                engine = intel_engine_lookup_user(ctx->i915,
                                                  ci->engine_class,
                                                  ci->engine_instance);
                if (!engine)
                        return ERR_PTR(-EINVAL);

                idx = engine->id;
        } else {
                idx = ci->engine_instance;
        }

        return i915_gem_context_get_engine(ctx, idx);
}

static inline int new_hw_id(struct drm_i915_private *i915, gfp_t gfp)
{
        unsigned int max;

        lockdep_assert_held(&i915->contexts.mutex);

        if (INTEL_GEN(i915) >= 11)
                max = GEN11_MAX_CONTEXT_HW_ID;
        else if (USES_GUC_SUBMISSION(i915))
                /*
                 * When using GuC in proxy submission, GuC consumes the
                 * highest bit in the context id to indicate proxy submission.
                 */
                max = MAX_GUC_CONTEXT_HW_ID;
        else
                max = MAX_CONTEXT_HW_ID;

        return ida_simple_get(&i915->contexts.hw_ida, 0, max, gfp);
}

static int steal_hw_id(struct drm_i915_private *i915)
{
        struct i915_gem_context *ctx, *cn;
        LIST_HEAD(pinned);
        int id = -ENOSPC;

        lockdep_assert_held(&i915->contexts.mutex);

        list_for_each_entry_safe(ctx, cn,
                                 &i915->contexts.hw_id_list, hw_id_link) {
                if (atomic_read(&ctx->hw_id_pin_count)) {
                        list_move_tail(&ctx->hw_id_link, &pinned);
                        continue;
                }

                GEM_BUG_ON(!ctx->hw_id); /* perma-pinned kernel context */
                list_del_init(&ctx->hw_id_link);
                id = ctx->hw_id;
                break;
        }

        /*
         * Remember how far we got up on the last repossesion scan, so the
         * list is kept in a "least recently scanned" order.
         */
        list_splice_tail(&pinned, &i915->contexts.hw_id_list);
        return id;
}

static int assign_hw_id(struct drm_i915_private *i915, unsigned int *out)
{
        int ret;

        lockdep_assert_held(&i915->contexts.mutex);

        /*
         * We prefer to steal/stall ourselves and our users over that of the
         * entire system. That may be a little unfair to our users, and
         * even hurt high priority clients. The choice is whether to oomkill
         * something else, or steal a context id.
         */
        ret = new_hw_id(i915, GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_NOWARN);
        if (unlikely(ret < 0)) {
                ret = steal_hw_id(i915);
                if (ret < 0) /* once again for the correct errno code */
                        ret = new_hw_id(i915, GFP_KERNEL);
                if (ret < 0)
                        return ret;
        }

        *out = ret;
        return 0;
}

static void release_hw_id(struct i915_gem_context *ctx)
{
        struct drm_i915_private *i915 = ctx->i915;

        if (list_empty(&ctx->hw_id_link))
                return;

        mutex_lock(&i915->contexts.mutex);
        if (!list_empty(&ctx->hw_id_link)) {
                ida_simple_remove(&i915->contexts.hw_ida, ctx->hw_id);
                list_del_init(&ctx->hw_id_link);
        }
        mutex_unlock(&i915->contexts.mutex);
}

static void __free_engines(struct i915_gem_engines *e, unsigned int count)
{
        while (count--) {
                if (!e->engines[count])
                        continue;

                intel_context_put(e->engines[count]);
        }
        kfree(e);
}

static void free_engines(struct i915_gem_engines *e)
{
        __free_engines(e, e->num_engines);
}

static void free_engines_rcu(struct rcu_head *rcu)
{
        free_engines(container_of(rcu, struct i915_gem_engines, rcu));
}

static struct i915_gem_engines *default_engines(struct i915_gem_context *ctx)
{
        struct intel_engine_cs *engine;
        struct i915_gem_engines *e;
        enum intel_engine_id id;

        e = kzalloc(struct_size(e, engines, I915_NUM_ENGINES), GFP_KERNEL);
        if (!e)
                return ERR_PTR(-ENOMEM);

        init_rcu_head(&e->rcu);
        for_each_engine(engine, ctx->i915, id) {
                struct intel_context *ce;

                ce = intel_context_create(ctx, engine);
                if (IS_ERR(ce)) {
                        __free_engines(e, id);
                        return ERR_CAST(ce);
                }

                e->engines[id] = ce;
        }
        e->num_engines = id;

        return e;
}

static void i915_gem_context_free(struct i915_gem_context *ctx)
{
        lockdep_assert_held(&ctx->i915->drm.struct_mutex);
        GEM_BUG_ON(!i915_gem_context_is_closed(ctx));

        release_hw_id(ctx);
        if (ctx->vm)
                i915_vm_put(ctx->vm);

        free_engines(rcu_access_pointer(ctx->engines));
        mutex_destroy(&ctx->engines_mutex);

        if (ctx->timeline)
                i915_timeline_put(ctx->timeline);

        kfree(ctx->name);
        put_pid(ctx->pid);

        list_del(&ctx->link);
        mutex_destroy(&ctx->mutex);

        kfree_rcu(ctx, rcu);
}

static void contexts_free(struct drm_i915_private *i915)
{
        struct llist_node *freed = llist_del_all(&i915->contexts.free_list);
        struct i915_gem_context *ctx, *cn;

        lockdep_assert_held(&i915->drm.struct_mutex);

        llist_for_each_entry_safe(ctx, cn, freed, free_link)
                i915_gem_context_free(ctx);
}

static void contexts_free_first(struct drm_i915_private *i915)
{
        struct i915_gem_context *ctx;
        struct llist_node *freed;

        lockdep_assert_held(&i915->drm.struct_mutex);

        freed = llist_del_first(&i915->contexts.free_list);
        if (!freed)
                return;

        ctx = container_of(freed, typeof(*ctx), free_link);
        i915_gem_context_free(ctx);
}

static void contexts_free_worker(struct work_struct *work)
{
        struct drm_i915_private *i915 =
                container_of(work, typeof(*i915), contexts.free_work);

        mutex_lock(&i915->drm.struct_mutex);
        contexts_free(i915);
        mutex_unlock(&i915->drm.struct_mutex);
}

void i915_gem_context_release(struct kref *ref)
{
        struct i915_gem_context *ctx = container_of(ref, typeof(*ctx), ref);
        struct drm_i915_private *i915 = ctx->i915;

        trace_i915_context_free(ctx);
        if (llist_add(&ctx->free_link, &i915->contexts.free_list))
                queue_work(i915->wq, &i915->contexts.free_work);
}

static void context_close(struct i915_gem_context *ctx)
{
        mutex_lock(&ctx->mutex);

        i915_gem_context_set_closed(ctx);
        ctx->file_priv = ERR_PTR(-EBADF);

        /*
         * This context will never again be assinged to HW, so we can
         * reuse its ID for the next context.
         */
        release_hw_id(ctx);

        /*
         * The LUT uses the VMA as a backpointer to unref the object,
         * so we need to clear the LUT before we close all the VMA (inside
         * the ppgtt).
         */
        lut_close(ctx);

        mutex_unlock(&ctx->mutex);
        i915_gem_context_put(ctx);
}

static u32 default_desc_template(const struct drm_i915_private *i915,
                                 const struct i915_address_space *vm)
{
        u32 address_mode;
        u32 desc;

        desc = GEN8_CTX_VALID | GEN8_CTX_PRIVILEGE;

        address_mode = INTEL_LEGACY_32B_CONTEXT;
        if (vm && i915_vm_is_4lvl(vm))
                address_mode = INTEL_LEGACY_64B_CONTEXT;
        desc |= address_mode << GEN8_CTX_ADDRESSING_MODE_SHIFT;

        if (IS_GEN(i915, 8))
                desc |= GEN8_CTX_L3LLC_COHERENT;

        /* TODO: WaDisableLiteRestore when we start using semaphore
         * signalling between Command Streamers
         * ring->ctx_desc_template |= GEN8_CTX_FORCE_RESTORE;
         */

        return desc;
}

static struct i915_gem_context *
__create_context(struct drm_i915_private *i915)
{
        struct i915_gem_context *ctx;
        struct i915_gem_engines *e;
        int err;
        int i;

        ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
        if (!ctx)
                return ERR_PTR(-ENOMEM);

        kref_init(&ctx->ref);
        list_add_tail(&ctx->link, &i915->contexts.list);
        ctx->i915 = i915;
        ctx->sched.priority = I915_USER_PRIORITY(I915_PRIORITY_NORMAL);
        mutex_init(&ctx->mutex);

        mutex_init(&ctx->engines_mutex);
        e = default_engines(ctx);
        if (IS_ERR(e)) {
                err = PTR_ERR(e);
                goto err_free;
        }
        RCU_INIT_POINTER(ctx->engines, e);

        INIT_RADIX_TREE(&ctx->handles_vma, GFP_KERNEL);
        INIT_LIST_HEAD(&ctx->hw_id_link);

        /* NB: Mark all slices as needing a remap so that when the context first
         * loads it will restore whatever remap state already exists. If there
         * is no remap info, it will be a NOP. */
        ctx->remap_slice = ALL_L3_SLICES(i915);

        i915_gem_context_set_bannable(ctx);
        i915_gem_context_set_recoverable(ctx);

        ctx->ring_size = 4 * PAGE_SIZE;
        ctx->desc_template =
                default_desc_template(i915, &i915->mm.aliasing_ppgtt->vm);

        for (i = 0; i < ARRAY_SIZE(ctx->hang_timestamp); i++)
                ctx->hang_timestamp[i] = jiffies - CONTEXT_FAST_HANG_JIFFIES;

        return ctx;

err_free:
        kfree(ctx);
        return ERR_PTR(err);
}

static struct i915_address_space *
__set_ppgtt(struct i915_gem_context *ctx, struct i915_address_space *vm)
{
        struct i915_address_space *old = ctx->vm;

        ctx->vm = i915_vm_get(vm);
        ctx->desc_template = default_desc_template(ctx->i915, vm);

        return old;
}

static void __assign_ppgtt(struct i915_gem_context *ctx,
                           struct i915_address_space *vm)
{
        if (vm == ctx->vm)
                return;

        vm = __set_ppgtt(ctx, vm);
        if (vm)
                i915_vm_put(vm);
}

static struct i915_gem_context *
i915_gem_create_context(struct drm_i915_private *dev_priv, unsigned int flags)
{
        struct i915_gem_context *ctx;

        lockdep_assert_held(&dev_priv->drm.struct_mutex);

        if (flags & I915_CONTEXT_CREATE_FLAGS_SINGLE_TIMELINE &&
            !HAS_EXECLISTS(dev_priv))
                return ERR_PTR(-EINVAL);

        /* Reap the most stale context */
        contexts_free_first(dev_priv);

        ctx = __create_context(dev_priv);
        if (IS_ERR(ctx))
                return ctx;

        if (HAS_FULL_PPGTT(dev_priv)) {
                struct i915_ppgtt *ppgtt;

                ppgtt = i915_ppgtt_create(dev_priv);
                if (IS_ERR(ppgtt)) {
                        DRM_DEBUG_DRIVER("PPGTT setup failed (%ld)\n",
                                         PTR_ERR(ppgtt));
                        context_close(ctx);
                        return ERR_CAST(ppgtt);
                }

                __assign_ppgtt(ctx, &ppgtt->vm);
                i915_vm_put(&ppgtt->vm);
        }

        if (flags & I915_CONTEXT_CREATE_FLAGS_SINGLE_TIMELINE) {
                struct i915_timeline *timeline;

                timeline = i915_timeline_create(dev_priv, NULL);
                if (IS_ERR(timeline)) {
                        context_close(ctx);
                        return ERR_CAST(timeline);
                }

                ctx->timeline = timeline;
        }

        trace_i915_context_create(ctx);

        return ctx;
}

/**
 * i915_gem_context_create_gvt - create a GVT GEM context
 * @dev: drm device *
 *
 * This function is used to create a GVT specific GEM context.
 *
 * Returns:
 * pointer to i915_gem_context on success, error pointer if failed
 *
 */
struct i915_gem_context *
i915_gem_context_create_gvt(struct drm_device *dev)
{
        struct i915_gem_context *ctx;
        int ret;

        if (!IS_ENABLED(CONFIG_DRM_I915_GVT))
                return ERR_PTR(-ENODEV);

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ERR_PTR(ret);

        ctx = i915_gem_create_context(to_i915(dev), 0);
        if (IS_ERR(ctx))
                goto out;

        ret = i915_gem_context_pin_hw_id(ctx);
        if (ret) {
                context_close(ctx);
                ctx = ERR_PTR(ret);
                goto out;
        }

        ctx->file_priv = ERR_PTR(-EBADF);
        i915_gem_context_set_closed(ctx); /* not user accessible */
        i915_gem_context_clear_bannable(ctx);
        i915_gem_context_set_force_single_submission(ctx);
        if (!USES_GUC_SUBMISSION(to_i915(dev)))
                ctx->ring_size = 512 * PAGE_SIZE; /* Max ring buffer size */

        GEM_BUG_ON(i915_gem_context_is_kernel(ctx));
out:
        mutex_unlock(&dev->struct_mutex);
        return ctx;
}

static void
destroy_kernel_context(struct i915_gem_context **ctxp)
{
        struct i915_gem_context *ctx;

        /* Keep the context ref so that we can free it immediately ourselves */
        ctx = i915_gem_context_get(fetch_and_zero(ctxp));
        GEM_BUG_ON(!i915_gem_context_is_kernel(ctx));

        context_close(ctx);
        i915_gem_context_free(ctx);
}

struct i915_gem_context *
i915_gem_context_create_kernel(struct drm_i915_private *i915, int prio)
{
        struct i915_gem_context *ctx;
        int err;

        ctx = i915_gem_create_context(i915, 0);
        if (IS_ERR(ctx))
                return ctx;

        err = i915_gem_context_pin_hw_id(ctx);
        if (err) {
                destroy_kernel_context(&ctx);
                return ERR_PTR(err);
        }

        i915_gem_context_clear_bannable(ctx);
        ctx->sched.priority = I915_USER_PRIORITY(prio);
        ctx->ring_size = PAGE_SIZE;

        GEM_BUG_ON(!i915_gem_context_is_kernel(ctx));

        return ctx;
}

static void init_contexts(struct drm_i915_private *i915)
{
        mutex_init(&i915->contexts.mutex);
        INIT_LIST_HEAD(&i915->contexts.list);

        /* Using the simple ida interface, the max is limited by sizeof(int) */
        BUILD_BUG_ON(MAX_CONTEXT_HW_ID > INT_MAX);
        BUILD_BUG_ON(GEN11_MAX_CONTEXT_HW_ID > INT_MAX);
        ida_init(&i915->contexts.hw_ida);
        INIT_LIST_HEAD(&i915->contexts.hw_id_list);

        INIT_WORK(&i915->contexts.free_work, contexts_free_worker);
        init_llist_head(&i915->contexts.free_list);
}

static bool needs_preempt_context(struct drm_i915_private *i915)
{
        return HAS_EXECLISTS(i915);
}

int i915_gem_contexts_init(struct drm_i915_private *dev_priv)
{
        struct i915_gem_context *ctx;

        /* Reassure ourselves we are only called once */
        GEM_BUG_ON(dev_priv->kernel_context);
        GEM_BUG_ON(dev_priv->preempt_context);

        intel_engine_init_ctx_wa(dev_priv->engine[RCS0]);
        init_contexts(dev_priv);

        /* lowest priority; idle task */
        ctx = i915_gem_context_create_kernel(dev_priv, I915_PRIORITY_MIN);
        if (IS_ERR(ctx)) {
                DRM_ERROR("Failed to create default global context\n");
                return PTR_ERR(ctx);
        }
        /*
         * For easy recognisablity, we want the kernel context to be 0 and then
         * all user contexts will have non-zero hw_id. Kernel contexts are
         * permanently pinned, so that we never suffer a stall and can
         * use them from any allocation context (e.g. for evicting other
         * contexts and from inside the shrinker).
         */
        GEM_BUG_ON(ctx->hw_id);
        GEM_BUG_ON(!atomic_read(&ctx->hw_id_pin_count));
        dev_priv->kernel_context = ctx;

        /* highest priority; preempting task */
        if (needs_preempt_context(dev_priv)) {
                ctx = i915_gem_context_create_kernel(dev_priv, INT_MAX);
                if (!IS_ERR(ctx))
                        dev_priv->preempt_context = ctx;
                else
                        DRM_ERROR("Failed to create preempt context; disabling preemption\n");
        }

        DRM_DEBUG_DRIVER("%s context support initialized\n",
                         DRIVER_CAPS(dev_priv)->has_logical_contexts ?
                         "logical" : "fake");
        return 0;
}

void i915_gem_contexts_fini(struct drm_i915_private *i915)
{
        lockdep_assert_held(&i915->drm.struct_mutex);

        if (i915->preempt_context)
                destroy_kernel_context(&i915->preempt_context);
        destroy_kernel_context(&i915->kernel_context);

        /* Must free all deferred contexts (via flush_workqueue) first */
        GEM_BUG_ON(!list_empty(&i915->contexts.hw_id_list));
        ida_destroy(&i915->contexts.hw_ida);
}

static int context_idr_cleanup(int id, void *p, void *data)
{
        context_close(p);
        return 0;
}

static int vm_idr_cleanup(int id, void *p, void *data)
{
        i915_vm_put(p);
        return 0;
}

static int gem_context_register(struct i915_gem_context *ctx,
                                struct drm_i915_file_private *fpriv)
{
        int ret;

        ctx->file_priv = fpriv;
        if (ctx->vm)
                ctx->vm->file = fpriv;

        ctx->pid = get_task_pid(current, PIDTYPE_PID);
        ctx->name = kasprintf(GFP_KERNEL, "%s[%d]",
                              current->comm, pid_nr(ctx->pid));
        if (!ctx->name) {
                ret = -ENOMEM;
                goto err_pid;
        }

        /* And finally expose ourselves to userspace via the idr */
        mutex_lock(&fpriv->context_idr_lock);
        ret = idr_alloc(&fpriv->context_idr, ctx, 0, 0, GFP_KERNEL);
        mutex_unlock(&fpriv->context_idr_lock);
        if (ret >= 0)
                goto out;

        kfree(fetch_and_zero(&ctx->name));
err_pid:
        put_pid(fetch_and_zero(&ctx->pid));
out:
        return ret;
}

int i915_gem_context_open(struct drm_i915_private *i915,
                          struct drm_file *file)
{
        struct drm_i915_file_private *file_priv = file->driver_priv;
        struct i915_gem_context *ctx;
        int err;

        mutex_init(&file_priv->context_idr_lock);
        mutex_init(&file_priv->vm_idr_lock);

        idr_init(&file_priv->context_idr);
        idr_init_base(&file_priv->vm_idr, 1);

        mutex_lock(&i915->drm.struct_mutex);
        ctx = i915_gem_create_context(i915, 0);
        mutex_unlock(&i915->drm.struct_mutex);
        if (IS_ERR(ctx)) {
                err = PTR_ERR(ctx);
                goto err;
        }

        err = gem_context_register(ctx, file_priv);
        if (err < 0)
                goto err_ctx;

        GEM_BUG_ON(i915_gem_context_is_kernel(ctx));
        GEM_BUG_ON(err > 0);

        return 0;

err_ctx:
        context_close(ctx);
err:
        idr_destroy(&file_priv->vm_idr);
        idr_destroy(&file_priv->context_idr);
        mutex_destroy(&file_priv->vm_idr_lock);
        mutex_destroy(&file_priv->context_idr_lock);
        return err;
}

void i915_gem_context_close(struct drm_file *file)
{
        struct drm_i915_file_private *file_priv = file->driver_priv;

        idr_for_each(&file_priv->context_idr, context_idr_cleanup, NULL);
        idr_destroy(&file_priv->context_idr);
        mutex_destroy(&file_priv->context_idr_lock);

        idr_for_each(&file_priv->vm_idr, vm_idr_cleanup, NULL);
        idr_destroy(&file_priv->vm_idr);
        mutex_destroy(&file_priv->vm_idr_lock);
}

int i915_gem_vm_create_ioctl(struct drm_device *dev, void *data,
                             struct drm_file *file)
{
        struct drm_i915_private *i915 = to_i915(dev);
        struct drm_i915_gem_vm_control *args = data;
        struct drm_i915_file_private *file_priv = file->driver_priv;
        struct i915_ppgtt *ppgtt;
        int err;

        if (!HAS_FULL_PPGTT(i915))
                return -ENODEV;

        if (args->flags)
                return -EINVAL;

        ppgtt = i915_ppgtt_create(i915);
        if (IS_ERR(ppgtt))
                return PTR_ERR(ppgtt);

        ppgtt->vm.file = file_priv;

        if (args->extensions) {
                err = i915_user_extensions(u64_to_user_ptr(args->extensions),
                                           NULL, 0,
                                           ppgtt);
                if (err)
                        goto err_put;
        }

        err = mutex_lock_interruptible(&file_priv->vm_idr_lock);
        if (err)
                goto err_put;

        err = idr_alloc(&file_priv->vm_idr, &ppgtt->vm, 0, 0, GFP_KERNEL);
        if (err < 0)
                goto err_unlock;

        GEM_BUG_ON(err == 0); /* reserved for invalid/unassigned ppgtt */

        mutex_unlock(&file_priv->vm_idr_lock);

        args->vm_id = err;
        return 0;

err_unlock:
        mutex_unlock(&file_priv->vm_idr_lock);
err_put:
        i915_vm_put(&ppgtt->vm);
        return err;
}

int i915_gem_vm_destroy_ioctl(struct drm_device *dev, void *data,
                              struct drm_file *file)
{
        struct drm_i915_file_private *file_priv = file->driver_priv;
        struct drm_i915_gem_vm_control *args = data;
        struct i915_address_space *vm;
        int err;
        u32 id;

        if (args->flags)
                return -EINVAL;

        if (args->extensions)
                return -EINVAL;

        id = args->vm_id;
        if (!id)
                return -ENOENT;

        err = mutex_lock_interruptible(&file_priv->vm_idr_lock);
        if (err)
                return err;

        vm = idr_remove(&file_priv->vm_idr, id);

        mutex_unlock(&file_priv->vm_idr_lock);
        if (!vm)
                return -ENOENT;

        i915_vm_put(vm);
        return 0;
}

struct context_barrier_task {
        struct i915_active base;
        void (*task)(void *data);
        void *data;
};

static void cb_retire(struct i915_active *base)
{
        struct context_barrier_task *cb = container_of(base, typeof(*cb), base);

        if (cb->task)
                cb->task(cb->data);

        i915_active_fini(&cb->base);
        kfree(cb);
}

I915_SELFTEST_DECLARE(static intel_engine_mask_t context_barrier_inject_fault);
static int context_barrier_task(struct i915_gem_context *ctx,
                                intel_engine_mask_t engines,
                                bool (*skip)(struct intel_context *ce, void *data),
                                int (*emit)(struct i915_request *rq, void *data),
                                void (*task)(void *data),
                                void *data)
{
        struct drm_i915_private *i915 = ctx->i915;
        struct context_barrier_task *cb;
        struct i915_gem_engines_iter it;
        struct intel_context *ce;
        int err = 0;

        lockdep_assert_held(&i915->drm.struct_mutex);
        GEM_BUG_ON(!task);

        cb = kmalloc(sizeof(*cb), GFP_KERNEL);
        if (!cb)
                return -ENOMEM;

        i915_active_init(i915, &cb->base, cb_retire);
        i915_active_acquire(&cb->base);

        for_each_gem_engine(ce, i915_gem_context_lock_engines(ctx), it) {
                struct i915_request *rq;

                if (I915_SELFTEST_ONLY(context_barrier_inject_fault &
                                       ce->engine->mask)) {
                        err = -ENXIO;
                        break;
                }

                if (!(ce->engine->mask & engines))
                        continue;

                if (skip && skip(ce, data))
                        continue;

                rq = intel_context_create_request(ce);
                if (IS_ERR(rq)) {
                        err = PTR_ERR(rq);
                        break;
                }

                err = 0;
                if (emit)
                        err = emit(rq, data);
                if (err == 0)
                        err = i915_active_ref(&cb->base, rq->fence.context, rq);

                i915_request_add(rq);
                if (err)
                        break;
        }
        i915_gem_context_unlock_engines(ctx);

        cb->task = err ? NULL : task; /* caller needs to unwind instead */
        cb->data = data;

        i915_active_release(&cb->base);

        return err;
}

static int get_ppgtt(struct drm_i915_file_private *file_priv,
                     struct i915_gem_context *ctx,
                     struct drm_i915_gem_context_param *args)
{
        struct i915_address_space *vm;
        int ret;

        if (!ctx->vm)
                return -ENODEV;

        /* XXX rcu acquire? */
        ret = mutex_lock_interruptible(&ctx->i915->drm.struct_mutex);
        if (ret)
                return ret;

        vm = i915_vm_get(ctx->vm);
        mutex_unlock(&ctx->i915->drm.struct_mutex);

        ret = mutex_lock_interruptible(&file_priv->vm_idr_lock);
        if (ret)
                goto err_put;

        ret = idr_alloc(&file_priv->vm_idr, vm, 0, 0, GFP_KERNEL);
        GEM_BUG_ON(!ret);
        if (ret < 0)
                goto err_unlock;

        i915_vm_get(vm);

        args->size = 0;
        args->value = ret;

        ret = 0;
err_unlock:
        mutex_unlock(&file_priv->vm_idr_lock);
err_put:
        i915_vm_put(vm);
        return ret;
}

static void set_ppgtt_barrier(void *data)
{
        struct i915_address_space *old = data;

        if (INTEL_GEN(old->i915) < 8)
                gen6_ppgtt_unpin_all(i915_vm_to_ppgtt(old));

        i915_vm_put(old);
}

static int emit_ppgtt_update(struct i915_request *rq, void *data)
{
        struct i915_address_space *vm = rq->gem_context->vm;
        struct intel_engine_cs *engine = rq->engine;
        u32 base = engine->mmio_base;
        u32 *cs;
        int i;

        if (i915_vm_is_4lvl(vm)) {
                struct i915_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
                const dma_addr_t pd_daddr = px_dma(ppgtt->pd);

                cs = intel_ring_begin(rq, 6);
                if (IS_ERR(cs))
                        return PTR_ERR(cs);

                *cs++ = MI_LOAD_REGISTER_IMM(2);

                *cs++ = i915_mmio_reg_offset(GEN8_RING_PDP_UDW(base, 0));
                *cs++ = upper_32_bits(pd_daddr);
                *cs++ = i915_mmio_reg_offset(GEN8_RING_PDP_LDW(base, 0));
                *cs++ = lower_32_bits(pd_daddr);

                *cs++ = MI_NOOP;
                intel_ring_advance(rq, cs);
        } else if (HAS_LOGICAL_RING_CONTEXTS(engine->i915)) {
                struct i915_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);

                cs = intel_ring_begin(rq, 4 * GEN8_3LVL_PDPES + 2);
                if (IS_ERR(cs))
                        return PTR_ERR(cs);

                *cs++ = MI_LOAD_REGISTER_IMM(2 * GEN8_3LVL_PDPES);
                for (i = GEN8_3LVL_PDPES; i--; ) {
                        const dma_addr_t pd_daddr = i915_page_dir_dma_addr(ppgtt, i);

                        *cs++ = i915_mmio_reg_offset(GEN8_RING_PDP_UDW(base, i));
                        *cs++ = upper_32_bits(pd_daddr);
                        *cs++ = i915_mmio_reg_offset(GEN8_RING_PDP_LDW(base, i));
                        *cs++ = lower_32_bits(pd_daddr);
                }
                *cs++ = MI_NOOP;
                intel_ring_advance(rq, cs);
        } else {
                /* ppGTT is not part of the legacy context image */
                gen6_ppgtt_pin(i915_vm_to_ppgtt(vm));
        }

        return 0;
}

static bool skip_ppgtt_update(struct intel_context *ce, void *data)
{
        if (HAS_LOGICAL_RING_CONTEXTS(ce->engine->i915))
                return !ce->state;
        else
                return !atomic_read(&ce->pin_count);
}

static int set_ppgtt(struct drm_i915_file_private *file_priv,
                     struct i915_gem_context *ctx,
                     struct drm_i915_gem_context_param *args)
{
        struct i915_address_space *vm, *old;
        int err;

        if (args->size)
                return -EINVAL;

        if (!ctx->vm)
                return -ENODEV;

        if (upper_32_bits(args->value))
                return -ENOENT;

        err = mutex_lock_interruptible(&file_priv->vm_idr_lock);
        if (err)
                return err;

        vm = idr_find(&file_priv->vm_idr, args->value);
        if (vm)
                i915_vm_get(vm);
        mutex_unlock(&file_priv->vm_idr_lock);
        if (!vm)
                return -ENOENT;

        err = mutex_lock_interruptible(&ctx->i915->drm.struct_mutex);
        if (err)
                goto out;

        if (vm == ctx->vm)
                goto unlock;

        /* Teardown the existing obj:vma cache, it will have to be rebuilt. */
        mutex_lock(&ctx->mutex);
        lut_close(ctx);
        mutex_unlock(&ctx->mutex);

        old = __set_ppgtt(ctx, vm);

        /*
         * We need to flush any requests using the current ppgtt before
         * we release it as the requests do not hold a reference themselves,
         * only indirectly through the context.
         */
        err = context_barrier_task(ctx, ALL_ENGINES,
                                   skip_ppgtt_update,
                                   emit_ppgtt_update,
                                   set_ppgtt_barrier,
                                   old);
        if (err) {
                ctx->vm = old;
                ctx->desc_template = default_desc_template(ctx->i915, old);
                i915_vm_put(vm);
        }

unlock:
        mutex_unlock(&ctx->i915->drm.struct_mutex);

out:
        i915_vm_put(vm);
        return err;
}

static int gen8_emit_rpcs_config(struct i915_request *rq,
                                 struct intel_context *ce,
                                 struct intel_sseu sseu)
{
        u64 offset;
        u32 *cs;

        cs = intel_ring_begin(rq, 4);
        if (IS_ERR(cs))
                return PTR_ERR(cs);

        offset = i915_ggtt_offset(ce->state) +
                 LRC_STATE_PN * PAGE_SIZE +
                 (CTX_R_PWR_CLK_STATE + 1) * 4;

        *cs++ = MI_STORE_DWORD_IMM_GEN4 | MI_USE_GGTT;
        *cs++ = lower_32_bits(offset);
        *cs++ = upper_32_bits(offset);
        *cs++ = intel_sseu_make_rpcs(rq->i915, &sseu);

        intel_ring_advance(rq, cs);

        return 0;
}

static int
gen8_modify_rpcs(struct intel_context *ce, struct intel_sseu sseu)
{
        struct i915_request *rq;
        int ret;

        lockdep_assert_held(&ce->pin_mutex);

        /*
         * If the context is not idle, we have to submit an ordered request to
         * modify its context image via the kernel context (writing to our own
         * image, or into the registers directory, does not stick). Pristine
         * and idle contexts will be configured on pinning.
         */
        if (!intel_context_is_pinned(ce))
                return 0;

        rq = i915_request_create(ce->engine->kernel_context);
        if (IS_ERR(rq))
                return PTR_ERR(rq);

        /* Queue this switch after all other activity by this context. */
        ret = i915_active_request_set(&ce->ring->timeline->last_request, rq);
        if (ret)
                goto out_add;

        /*
         * Guarantee context image and the timeline remains pinned until the
         * modifying request is retired by setting the ce activity tracker.
         *
         * But we only need to take one pin on the account of it. Or in other
         * words transfer the pinned ce object to tracked active request.
         */
        GEM_BUG_ON(i915_active_is_idle(&ce->active));
        ret = i915_active_ref(&ce->active, rq->fence.context, rq);
        if (ret)
                goto out_add;

        ret = gen8_emit_rpcs_config(rq, ce, sseu);

out_add:
        i915_request_add(rq);
        return ret;
}

static int
__intel_context_reconfigure_sseu(struct intel_context *ce,
                                 struct intel_sseu sseu)
{
        int ret;

        GEM_BUG_ON(INTEL_GEN(ce->gem_context->i915) < 8);

        ret = intel_context_lock_pinned(ce);
        if (ret)
                return ret;

        /* Nothing to do if unmodified. */
        if (!memcmp(&ce->sseu, &sseu, sizeof(sseu)))
                goto unlock;

        ret = gen8_modify_rpcs(ce, sseu);
        if (!ret)
                ce->sseu = sseu;

unlock:
        intel_context_unlock_pinned(ce);
        return ret;
}

static int
intel_context_reconfigure_sseu(struct intel_context *ce, struct intel_sseu sseu)
{
        struct drm_i915_private *i915 = ce->gem_context->i915;
        int ret;

        ret = mutex_lock_interruptible(&i915->drm.struct_mutex);
        if (ret)
                return ret;

        ret = __intel_context_reconfigure_sseu(ce, sseu);

        mutex_unlock(&i915->drm.struct_mutex);

        return ret;
}

static int
user_to_context_sseu(struct drm_i915_private *i915,
                     const struct drm_i915_gem_context_param_sseu *user,
                     struct intel_sseu *context)
{
        const struct sseu_dev_info *device = &RUNTIME_INFO(i915)->sseu;

        /* No zeros in any field. */
        if (!user->slice_mask || !user->subslice_mask ||
            !user->min_eus_per_subslice || !user->max_eus_per_subslice)
                return -EINVAL;

        /* Max > min. */
        if (user->max_eus_per_subslice < user->min_eus_per_subslice)
                return -EINVAL;

        /*
         * Some future proofing on the types since the uAPI is wider than the
         * current internal implementation.
         */
        if (overflows_type(user->slice_mask, context->slice_mask) ||
            overflows_type(user->subslice_mask, context->subslice_mask) ||
            overflows_type(user->min_eus_per_subslice,
                           context->min_eus_per_subslice) ||
            overflows_type(user->max_eus_per_subslice,
                           context->max_eus_per_subslice))
                return -EINVAL;

        /* Check validity against hardware. */
        if (user->slice_mask & ~device->slice_mask)
                return -EINVAL;

        if (user->subslice_mask & ~device->subslice_mask[0])
                return -EINVAL;

        if (user->max_eus_per_subslice > device->max_eus_per_subslice)
                return -EINVAL;

        context->slice_mask = user->slice_mask;
        context->subslice_mask = user->subslice_mask;
        context->min_eus_per_subslice = user->min_eus_per_subslice;
        context->max_eus_per_subslice = user->max_eus_per_subslice;

        /* Part specific restrictions. */
        if (IS_GEN(i915, 11)) {
                unsigned int hw_s = hweight8(device->slice_mask);
                unsigned int hw_ss_per_s = hweight8(device->subslice_mask[0]);
                unsigned int req_s = hweight8(context->slice_mask);
                unsigned int req_ss = hweight8(context->subslice_mask);

                /*
                 * Only full subslice enablement is possible if more than one
                 * slice is turned on.
                 */
                if (req_s > 1 && req_ss != hw_ss_per_s)
                        return -EINVAL;

                /*
                 * If more than four (SScount bitfield limit) subslices are
                 * requested then the number has to be even.
                 */
                if (req_ss > 4 && (req_ss & 1))
                        return -EINVAL;

                /*
                 * If only one slice is enabled and subslice count is below the
                 * device full enablement, it must be at most half of the all
                 * available subslices.
                 */
                if (req_s == 1 && req_ss < hw_ss_per_s &&
                    req_ss > (hw_ss_per_s / 2))
                        return -EINVAL;

                /* ABI restriction - VME use case only. */

                /* All slices or one slice only. */
                if (req_s != 1 && req_s != hw_s)
                        return -EINVAL;

                /*
                 * Half subslices or full enablement only when one slice is
                 * enabled.
                 */
                if (req_s == 1 &&
                    (req_ss != hw_ss_per_s && req_ss != (hw_ss_per_s / 2)))
                        return -EINVAL;

                /* No EU configuration changes. */
                if ((user->min_eus_per_subslice !=
                     device->max_eus_per_subslice) ||
                    (user->max_eus_per_subslice !=
                     device->max_eus_per_subslice))
                        return -EINVAL;
        }

        return 0;
}

static int set_sseu(struct i915_gem_context *ctx,
                    struct drm_i915_gem_context_param *args)
{
        struct drm_i915_private *i915 = ctx->i915;
        struct drm_i915_gem_context_param_sseu user_sseu;
        struct intel_context *ce;
        struct intel_sseu sseu;
        unsigned long lookup;
        int ret;

        if (args->size < sizeof(user_sseu))
                return -EINVAL;

        if (!IS_GEN(i915, 11))
                return -ENODEV;

        if (copy_from_user(&user_sseu, u64_to_user_ptr(args->value),
                           sizeof(user_sseu)))
                return -EFAULT;

        if (user_sseu.rsvd)
                return -EINVAL;

        if (user_sseu.flags & ~(I915_CONTEXT_SSEU_FLAG_ENGINE_INDEX))
                return -EINVAL;

        lookup = 0;
        if (user_sseu.flags & I915_CONTEXT_SSEU_FLAG_ENGINE_INDEX)
                lookup |= LOOKUP_USER_INDEX;

        ce = lookup_user_engine(ctx, lookup, &user_sseu.engine);
        if (IS_ERR(ce))
                return PTR_ERR(ce);

        /* Only render engine supports RPCS configuration. */
        if (ce->engine->class != RENDER_CLASS) {
                ret = -ENODEV;
                goto out_ce;
        }

        ret = user_to_context_sseu(i915, &user_sseu, &sseu);
        if (ret)
                goto out_ce;

        ret = intel_context_reconfigure_sseu(ce, sseu);
        if (ret)
                goto out_ce;

        args->size = sizeof(user_sseu);

out_ce:
        intel_context_put(ce);
        return ret;
}

struct set_engines {
        struct i915_gem_context *ctx;
        struct i915_gem_engines *engines;
};

static int
set_engines__load_balance(struct i915_user_extension __user *base, void *data)
{
        struct i915_context_engines_load_balance __user *ext =
                container_of_user(base, typeof(*ext), base);
        const struct set_engines *set = data;
        struct intel_engine_cs *stack[16];
        struct intel_engine_cs **siblings;
        struct intel_context *ce;
        u16 num_siblings, idx;
        unsigned int n;
        int err;

        if (!HAS_EXECLISTS(set->ctx->i915))
                return -ENODEV;

        if (USES_GUC_SUBMISSION(set->ctx->i915))
                return -ENODEV; /* not implement yet */

        if (get_user(idx, &ext->engine_index))
                return -EFAULT;

        if (idx >= set->engines->num_engines) {
                DRM_DEBUG("Invalid placement value, %d >= %d\n",
                          idx, set->engines->num_engines);
                return -EINVAL;
        }

        idx = array_index_nospec(idx, set->engines->num_engines);
        if (set->engines->engines[idx]) {
                DRM_DEBUG("Invalid placement[%d], already occupied\n", idx);
                return -EEXIST;
        }

        if (get_user(num_siblings, &ext->num_siblings))
                return -EFAULT;

        err = check_user_mbz(&ext->flags);
        if (err)
                return err;

        err = check_user_mbz(&ext->mbz64);
        if (err)
                return err;

        siblings = stack;
        if (num_siblings > ARRAY_SIZE(stack)) {
                siblings = kmalloc_array(num_siblings,
                                         sizeof(*siblings),
                                         GFP_KERNEL);
                if (!siblings)
                        return -ENOMEM;
        }

        for (n = 0; n < num_siblings; n++) {
                struct i915_engine_class_instance ci;

                if (copy_from_user(&ci, &ext->engines[n], sizeof(ci))) {
                        err = -EFAULT;
                        goto out_siblings;
                }

                siblings[n] = intel_engine_lookup_user(set->ctx->i915,
                                                       ci.engine_class,
                                                       ci.engine_instance);
                if (!siblings[n]) {
                        DRM_DEBUG("Invalid sibling[%d]: { class:%d, inst:%d }\n",
                                  n, ci.engine_class, ci.engine_instance);
                        err = -EINVAL;
                        goto out_siblings;
                }
        }

        ce = intel_execlists_create_virtual(set->ctx, siblings, n);
        if (IS_ERR(ce)) {
                err = PTR_ERR(ce);
                goto out_siblings;
        }

        if (cmpxchg(&set->engines->engines[idx], NULL, ce)) {
                intel_context_put(ce);
                err = -EEXIST;
                goto out_siblings;
        }

out_siblings:
        if (siblings != stack)
                kfree(siblings);

        return err;
}

static int
set_engines__bond(struct i915_user_extension __user *base, void *data)
{
        struct i915_context_engines_bond __user *ext =
                container_of_user(base, typeof(*ext), base);
        const struct set_engines *set = data;
        struct i915_engine_class_instance ci;
        struct intel_engine_cs *virtual;
        struct intel_engine_cs *master;
        u16 idx, num_bonds;
        int err, n;

        if (get_user(idx, &ext->virtual_index))
                return -EFAULT;

        if (idx >= set->engines->num_engines) {
                DRM_DEBUG("Invalid index for virtual engine: %d >= %d\n",
                          idx, set->engines->num_engines);
                return -EINVAL;
        }

        idx = array_index_nospec(idx, set->engines->num_engines);
        if (!set->engines->engines[idx]) {
                DRM_DEBUG("Invalid engine at %d\n", idx);
                return -EINVAL;
        }
        virtual = set->engines->engines[idx]->engine;

        err = check_user_mbz(&ext->flags);
        if (err)
                return err;

        for (n = 0; n < ARRAY_SIZE(ext->mbz64); n++) {
                err = check_user_mbz(&ext->mbz64[n]);
                if (err)
                        return err;
        }

        if (copy_from_user(&ci, &ext->master, sizeof(ci)))
                return -EFAULT;

        master = intel_engine_lookup_user(set->ctx->i915,
                                          ci.engine_class, ci.engine_instance);
        if (!master) {
                DRM_DEBUG("Unrecognised master engine: { class:%u, instance:%u }\n",
                          ci.engine_class, ci.engine_instance);
                return -EINVAL;
        }

        if (get_user(num_bonds, &ext->num_bonds))
                return -EFAULT;

        for (n = 0; n < num_bonds; n++) {
                struct intel_engine_cs *bond;

                if (copy_from_user(&ci, &ext->engines[n], sizeof(ci)))
                        return -EFAULT;

                bond = intel_engine_lookup_user(set->ctx->i915,
                                                ci.engine_class,
                                                ci.engine_instance);
                if (!bond) {
                        DRM_DEBUG("Unrecognised engine[%d] for bonding: { class:%d, instance: %d }\n",
                                  n, ci.engine_class, ci.engine_instance);
                        return -EINVAL;
                }

                /*
                 * A non-virtual engine has no siblings to choose between; and
                 * a submit fence will always be directed to the one engine.
                 */
                if (intel_engine_is_virtual(virtual)) {
                        err = intel_virtual_engine_attach_bond(virtual,
                                                               master,
                                                               bond);
                        if (err)
                                return err;
                }
        }

        return 0;
}

static const i915_user_extension_fn set_engines__extensions[] = {
        [I915_CONTEXT_ENGINES_EXT_LOAD_BALANCE] = set_engines__load_balance,
        [I915_CONTEXT_ENGINES_EXT_BOND] = set_engines__bond,
};

static int
set_engines(struct i915_gem_context *ctx,
            const struct drm_i915_gem_context_param *args)
{
        struct i915_context_param_engines __user *user =
                u64_to_user_ptr(args->value);
        struct set_engines set = { .ctx = ctx };
        unsigned int num_engines, n;
        u64 extensions;
        int err;

        if (!args->size) { /* switch back to legacy user_ring_map */
                if (!i915_gem_context_user_engines(ctx))
                        return 0;

                set.engines = default_engines(ctx);
                if (IS_ERR(set.engines))
                        return PTR_ERR(set.engines);

                goto replace;
        }

        BUILD_BUG_ON(!IS_ALIGNED(sizeof(*user), sizeof(*user->engines)));
        if (args->size < sizeof(*user) ||
            !IS_ALIGNED(args->size, sizeof(*user->engines))) {
                DRM_DEBUG("Invalid size for engine array: %d\n",
                          args->size);
                return -EINVAL;
        }

        /*
         * Note that I915_EXEC_RING_MASK limits execbuf to only using the
         * first 64 engines defined here.
         */
        num_engines = (args->size - sizeof(*user)) / sizeof(*user->engines);

        set.engines = kmalloc(struct_size(set.engines, engines, num_engines),
                              GFP_KERNEL);
        if (!set.engines)
                return -ENOMEM;

        init_rcu_head(&set.engines->rcu);
        for (n = 0; n < num_engines; n++) {
                struct i915_engine_class_instance ci;
                struct intel_engine_cs *engine;

                if (copy_from_user(&ci, &user->engines[n], sizeof(ci))) {
                        __free_engines(set.engines, n);
                        return -EFAULT;
                }

                if (ci.engine_class == (u16)I915_ENGINE_CLASS_INVALID &&
                    ci.engine_instance == (u16)I915_ENGINE_CLASS_INVALID_NONE) {
                        set.engines->engines[n] = NULL;
                        continue;
                }

                engine = intel_engine_lookup_user(ctx->i915,
                                                  ci.engine_class,
                                                  ci.engine_instance);
                if (!engine) {
                        DRM_DEBUG("Invalid engine[%d]: { class:%d, instance:%d }\n",
                                  n, ci.engine_class, ci.engine_instance);
                        __free_engines(set.engines, n);
                        return -ENOENT;
                }

                set.engines->engines[n] = intel_context_create(ctx, engine);
                if (!set.engines->engines[n]) {
                        __free_engines(set.engines, n);
                        return -ENOMEM;
                }
        }
        set.engines->num_engines = num_engines;

        err = -EFAULT;
        if (!get_user(extensions, &user->extensions))
                err = i915_user_extensions(u64_to_user_ptr(extensions),
                                           set_engines__extensions,
                                           ARRAY_SIZE(set_engines__extensions),
                                           &set);
        if (err) {
                free_engines(set.engines);
                return err;
        }

replace:
        mutex_lock(&ctx->engines_mutex);
        if (args->size)
                i915_gem_context_set_user_engines(ctx);
        else
                i915_gem_context_clear_user_engines(ctx);
        rcu_swap_protected(ctx->engines, set.engines, 1);
        mutex_unlock(&ctx->engines_mutex);

        call_rcu(&set.engines->rcu, free_engines_rcu);

        return 0;
}

static struct i915_gem_engines *
__copy_engines(struct i915_gem_engines *e)
{
        struct i915_gem_engines *copy;
        unsigned int n;

        copy = kmalloc(struct_size(e, engines, e->num_engines), GFP_KERNEL);
        if (!copy)
                return ERR_PTR(-ENOMEM);

        init_rcu_head(&copy->rcu);
        for (n = 0; n < e->num_engines; n++) {
                if (e->engines[n])
                        copy->engines[n] = intel_context_get(e->engines[n]);
                else
                        copy->engines[n] = NULL;
        }
        copy->num_engines = n;

        return copy;
}

static int
get_engines(struct i915_gem_context *ctx,
            struct drm_i915_gem_context_param *args)
{
        struct i915_context_param_engines __user *user;
        struct i915_gem_engines *e;
        size_t n, count, size;
        int err = 0;

        err = mutex_lock_interruptible(&ctx->engines_mutex);
        if (err)
                return err;

        e = NULL;
        if (i915_gem_context_user_engines(ctx))
                e = __copy_engines(i915_gem_context_engines(ctx));
        mutex_unlock(&ctx->engines_mutex);
        if (IS_ERR_OR_NULL(e)) {
                args->size = 0;
                return PTR_ERR_OR_ZERO(e);
        }

        count = e->num_engines;

        /* Be paranoid in case we have an impedance mismatch */
        if (!check_struct_size(user, engines, count, &size)) {
                err = -EINVAL;
                goto err_free;
        }
        if (overflows_type(size, args->size)) {
                err = -EINVAL;
                goto err_free;
        }

        if (!args->size) {
                args->size = size;
                goto err_free;
        }

        if (args->size < size) {
                err = -EINVAL;
                goto err_free;
        }

        user = u64_to_user_ptr(args->value);
        if (!access_ok(user, size)) {
                err = -EFAULT;
                goto err_free;
        }

        if (put_user(0, &user->extensions)) {
                err = -EFAULT;
                goto err_free;
        }

        for (n = 0; n < count; n++) {
                struct i915_engine_class_instance ci = {
                        .engine_class = I915_ENGINE_CLASS_INVALID,
                        .engine_instance = I915_ENGINE_CLASS_INVALID_NONE,
                };

                if (e->engines[n]) {
                        ci.engine_class = e->engines[n]->engine->uabi_class;
                        ci.engine_instance = e->engines[n]->engine->instance;
                }

                if (copy_to_user(&user->engines[n], &ci, sizeof(ci))) {
                        err = -EFAULT;
                        goto err_free;
                }
        }

        args->size = size;

err_free:
        free_engines(e);
        return err;
}

static int ctx_setparam(struct drm_i915_file_private *fpriv,
                        struct i915_gem_context *ctx,
                        struct drm_i915_gem_context_param *args)
{
        int ret = 0;

        switch (args->param) {
        case I915_CONTEXT_PARAM_NO_ZEROMAP:
                if (args->size)
                        ret = -EINVAL;
                else if (args->value)
                        set_bit(UCONTEXT_NO_ZEROMAP, &ctx->user_flags);
                else
                        clear_bit(UCONTEXT_NO_ZEROMAP, &ctx->user_flags);
                break;

        case I915_CONTEXT_PARAM_NO_ERROR_CAPTURE:
                if (args->size)
                        ret = -EINVAL;
                else if (args->value)
                        i915_gem_context_set_no_error_capture(ctx);
                else
                        i915_gem_context_clear_no_error_capture(ctx);
                break;

        case I915_CONTEXT_PARAM_BANNABLE:
                if (args->size)
                        ret = -EINVAL;
                else if (!capable(CAP_SYS_ADMIN) && !args->value)
                        ret = -EPERM;
                else if (args->value)
                        i915_gem_context_set_bannable(ctx);
                else
                        i915_gem_context_clear_bannable(ctx);
                break;

        case I915_CONTEXT_PARAM_RECOVERABLE:
                if (args->size)
                        ret = -EINVAL;
                else if (args->value)
                        i915_gem_context_set_recoverable(ctx);
                else
                        i915_gem_context_clear_recoverable(ctx);
                break;

        case I915_CONTEXT_PARAM_PRIORITY:
                {
                        s64 priority = args->value;

                        if (args->size)
                                ret = -EINVAL;
                        else if (!(ctx->i915->caps.scheduler & I915_SCHEDULER_CAP_PRIORITY))
                                ret = -ENODEV;
                        else if (priority > I915_CONTEXT_MAX_USER_PRIORITY ||
                                 priority < I915_CONTEXT_MIN_USER_PRIORITY)
                                ret = -EINVAL;
                        else if (priority > I915_CONTEXT_DEFAULT_PRIORITY &&
                                 !capable(CAP_SYS_NICE))
                                ret = -EPERM;
                        else
                                ctx->sched.priority =
                                        I915_USER_PRIORITY(priority);
                }
                break;

        case I915_CONTEXT_PARAM_SSEU:
                ret = set_sseu(ctx, args);
                break;

        case I915_CONTEXT_PARAM_VM:
                ret = set_ppgtt(fpriv, ctx, args);
                break;

        case I915_CONTEXT_PARAM_ENGINES:
                ret = set_engines(ctx, args);
                break;

        case I915_CONTEXT_PARAM_BAN_PERIOD:
        default:
                ret = -EINVAL;
                break;
        }

        return ret;
}

struct create_ext {
        struct i915_gem_context *ctx;
        struct drm_i915_file_private *fpriv;
};

static int create_setparam(struct i915_user_extension __user *ext, void *data)
{
        struct drm_i915_gem_context_create_ext_setparam local;
        const struct create_ext *arg = data;

        if (copy_from_user(&local, ext, sizeof(local)))
                return -EFAULT;

        if (local.param.ctx_id)
                return -EINVAL;

        return ctx_setparam(arg->fpriv, arg->ctx, &local.param);
}

static int clone_engines(struct i915_gem_context *dst,
                         struct i915_gem_context *src)
{
        struct i915_gem_engines *e = i915_gem_context_lock_engines(src);
        struct i915_gem_engines *clone;
        bool user_engines;
        unsigned long n;

        clone = kmalloc(struct_size(e, engines, e->num_engines), GFP_KERNEL);
        if (!clone)
                goto err_unlock;

        init_rcu_head(&clone->rcu);
        for (n = 0; n < e->num_engines; n++) {
                struct intel_engine_cs *engine;

                if (!e->engines[n]) {
                        clone->engines[n] = NULL;
                        continue;
                }
                engine = e->engines[n]->engine;

                /*
                 * Virtual engines are singletons; they can only exist
                 * inside a single context, because they embed their
                 * HW context... As each virtual context implies a single
                 * timeline (each engine can only dequeue a single request
                 * at any time), it would be surprising for two contexts
                 * to use the same engine. So let's create a copy of
                 * the virtual engine instead.
                 */
                if (intel_engine_is_virtual(engine))
                        clone->engines[n] =
                                intel_execlists_clone_virtual(dst, engine);
                else
                        clone->engines[n] = intel_context_create(dst, engine);
                if (IS_ERR_OR_NULL(clone->engines[n])) {
                        __free_engines(clone, n);
                        goto err_unlock;
                }
        }
        clone->num_engines = n;

        user_engines = i915_gem_context_user_engines(src);
        i915_gem_context_unlock_engines(src);

        free_engines(dst->engines);
        RCU_INIT_POINTER(dst->engines, clone);
        if (user_engines)
                i915_gem_context_set_user_engines(dst);
        else
                i915_gem_context_clear_user_engines(dst);
        return 0;

err_unlock:
        i915_gem_context_unlock_engines(src);
        return -ENOMEM;
}

static int clone_flags(struct i915_gem_context *dst,
                       struct i915_gem_context *src)
{
        dst->user_flags = src->user_flags;
        return 0;
}

static int clone_schedattr(struct i915_gem_context *dst,
                           struct i915_gem_context *src)
{
        dst->sched = src->sched;
        return 0;
}

static int clone_sseu(struct i915_gem_context *dst,
                      struct i915_gem_context *src)
{
        struct i915_gem_engines *e = i915_gem_context_lock_engines(src);
        struct i915_gem_engines *clone;
        unsigned long n;
        int err;

        clone = dst->engines; /* no locking required; sole access */
        if (e->num_engines != clone->num_engines) {
                err = -EINVAL;
                goto unlock;
        }

        for (n = 0; n < e->num_engines; n++) {
                struct intel_context *ce = e->engines[n];

                if (clone->engines[n]->engine->class != ce->engine->class) {
                        /* Must have compatible engine maps! */
                        err = -EINVAL;
                        goto unlock;
                }

                /* serialises with set_sseu */
                err = intel_context_lock_pinned(ce);
                if (err)
                        goto unlock;

                clone->engines[n]->sseu = ce->sseu;
                intel_context_unlock_pinned(ce);
        }

        err = 0;
unlock:
        i915_gem_context_unlock_engines(src);
        return err;
}

static int clone_timeline(struct i915_gem_context *dst,
                          struct i915_gem_context *src)
{
        if (src->timeline) {
                GEM_BUG_ON(src->timeline == dst->timeline);

                if (dst->timeline)
                        i915_timeline_put(dst->timeline);
                dst->timeline = i915_timeline_get(src->timeline);
        }

        return 0;
}

static int clone_vm(struct i915_gem_context *dst,
                    struct i915_gem_context *src)
{
        struct i915_address_space *vm;

        rcu_read_lock();
        do {
                vm = READ_ONCE(src->vm);
                if (!vm)
                        break;

                if (!kref_get_unless_zero(&vm->ref))
                        continue;

                /*
                 * This ppgtt may have be reallocated between
                 * the read and the kref, and reassigned to a third
                 * context. In order to avoid inadvertent sharing
                 * of this ppgtt with that third context (and not
                 * src), we have to confirm that we have the same
                 * ppgtt after passing through the strong memory
                 * barrier implied by a successful
                 * kref_get_unless_zero().
                 *
                 * Once we have acquired the current ppgtt of src,
                 * we no longer care if it is released from src, as
                 * it cannot be reallocated elsewhere.
                 */

                if (vm == READ_ONCE(src->vm))
                        break;

                i915_vm_put(vm);
        } while (1);
        rcu_read_unlock();

        if (vm) {
                __assign_ppgtt(dst, vm);
                i915_vm_put(vm);
        }

        return 0;
}

static int create_clone(struct i915_user_extension __user *ext, void *data)
{
        static int (* const fn[])(struct i915_gem_context *dst,
                                  struct i915_gem_context *src) = {
#define MAP(x, y) [ilog2(I915_CONTEXT_CLONE_##x)] = y
                MAP(ENGINES, clone_engines),
                MAP(FLAGS, clone_flags),
                MAP(SCHEDATTR, clone_schedattr),
                MAP(SSEU, clone_sseu),
                MAP(TIMELINE, clone_timeline),
                MAP(VM, clone_vm),
#undef MAP
        };
        struct drm_i915_gem_context_create_ext_clone local;
        const struct create_ext *arg = data;
        struct i915_gem_context *dst = arg->ctx;
        struct i915_gem_context *src;
        int err, bit;

        if (copy_from_user(&local, ext, sizeof(local)))
                return -EFAULT;

        BUILD_BUG_ON(GENMASK(BITS_PER_TYPE(local.flags) - 1, ARRAY_SIZE(fn)) !=
                     I915_CONTEXT_CLONE_UNKNOWN);

        if (local.flags & I915_CONTEXT_CLONE_UNKNOWN)
                return -EINVAL;

        if (local.rsvd)
                return -EINVAL;

        rcu_read_lock();
        src = __i915_gem_context_lookup_rcu(arg->fpriv, local.clone_id);
        rcu_read_unlock();
        if (!src)
                return -ENOENT;

        GEM_BUG_ON(src == dst);

        for (bit = 0; bit < ARRAY_SIZE(fn); bit++) {
                if (!(local.flags & BIT(bit)))
                        continue;

                err = fn[bit](dst, src);
                if (err)
                        return err;
        }

        return 0;
}

static const i915_user_extension_fn create_extensions[] = {
        [I915_CONTEXT_CREATE_EXT_SETPARAM] = create_setparam,
        [I915_CONTEXT_CREATE_EXT_CLONE] = create_clone,
};

static bool client_is_banned(struct drm_i915_file_private *file_priv)
{
        return atomic_read(&file_priv->ban_score) >= I915_CLIENT_SCORE_BANNED;
}

int i915_gem_context_create_ioctl(struct drm_device *dev, void *data,
                                  struct drm_file *file)
{
        struct drm_i915_private *i915 = to_i915(dev);
        struct drm_i915_gem_context_create_ext *args = data;
        struct create_ext ext_data;
        int ret;

        if (!DRIVER_CAPS(i915)->has_logical_contexts)
                return -ENODEV;

        if (args->flags & I915_CONTEXT_CREATE_FLAGS_UNKNOWN)
                return -EINVAL;

        ret = i915_terminally_wedged(i915);
        if (ret)
                return ret;

        ext_data.fpriv = file->driver_priv;
        if (client_is_banned(ext_data.fpriv)) {
                DRM_DEBUG("client %s[%d] banned from creating ctx\n",
                          current->comm,
                          pid_nr(get_task_pid(current, PIDTYPE_PID)));
                return -EIO;
        }

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        ext_data.ctx = i915_gem_create_context(i915, args->flags);
        mutex_unlock(&dev->struct_mutex);
        if (IS_ERR(ext_data.ctx))
                return PTR_ERR(ext_data.ctx);

        if (args->flags & I915_CONTEXT_CREATE_FLAGS_USE_EXTENSIONS) {
                ret = i915_user_extensions(u64_to_user_ptr(args->extensions),
                                           create_extensions,
                                           ARRAY_SIZE(create_extensions),
                                           &ext_data);
                if (ret)
                        goto err_ctx;
        }

        ret = gem_context_register(ext_data.ctx, ext_data.fpriv);
        if (ret < 0)
                goto err_ctx;

        args->ctx_id = ret;
        DRM_DEBUG("HW context %d created\n", args->ctx_id);

        return 0;

err_ctx:
        context_close(ext_data.ctx);
        return ret;
}

int i915_gem_context_destroy_ioctl(struct drm_device *dev, void *data,
                                   struct drm_file *file)
{
        struct drm_i915_gem_context_destroy *args = data;
        struct drm_i915_file_private *file_priv = file->driver_priv;
        struct i915_gem_context *ctx;

        if (args->pad != 0)
                return -EINVAL;

        if (!args->ctx_id)
                return -ENOENT;

        if (mutex_lock_interruptible(&file_priv->context_idr_lock))
                return -EINTR;

        ctx = idr_remove(&file_priv->context_idr, args->ctx_id);
        mutex_unlock(&file_priv->context_idr_lock);
        if (!ctx)
                return -ENOENT;

        context_close(ctx);
        return 0;
}

static int get_sseu(struct i915_gem_context *ctx,
                    struct drm_i915_gem_context_param *args)
{
        struct drm_i915_gem_context_param_sseu user_sseu;
        struct intel_context *ce;
        unsigned long lookup;
        int err;

        if (args->size == 0)
                goto out;
        else if (args->size < sizeof(user_sseu))
                return -EINVAL;

        if (copy_from_user(&user_sseu, u64_to_user_ptr(args->value),
                           sizeof(user_sseu)))
                return -EFAULT;

        if (user_sseu.rsvd)
                return -EINVAL;

        if (user_sseu.flags & ~(I915_CONTEXT_SSEU_FLAG_ENGINE_INDEX))
                return -EINVAL;

        lookup = 0;
        if (user_sseu.flags & I915_CONTEXT_SSEU_FLAG_ENGINE_INDEX)
                lookup |= LOOKUP_USER_INDEX;

        ce = lookup_user_engine(ctx, lookup, &user_sseu.engine);
        if (IS_ERR(ce))
                return PTR_ERR(ce);

        err = intel_context_lock_pinned(ce); /* serialises with set_sseu */
        if (err) {
                intel_context_put(ce);
                return err;
        }

        user_sseu.slice_mask = ce->sseu.slice_mask;
        user_sseu.subslice_mask = ce->sseu.subslice_mask;
        user_sseu.min_eus_per_subslice = ce->sseu.min_eus_per_subslice;
        user_sseu.max_eus_per_subslice = ce->sseu.max_eus_per_subslice;

        intel_context_unlock_pinned(ce);
        intel_context_put(ce);

        if (copy_to_user(u64_to_user_ptr(args->value), &user_sseu,
                         sizeof(user_sseu)))
                return -EFAULT;

out:
        args->size = sizeof(user_sseu);

        return 0;
}

int i915_gem_context_getparam_ioctl(struct drm_device *dev, void *data,
                                    struct drm_file *file)
{
        struct drm_i915_file_private *file_priv = file->driver_priv;
        struct drm_i915_gem_context_param *args = data;
        struct i915_gem_context *ctx;
        int ret = 0;

        ctx = i915_gem_context_lookup(file_priv, args->ctx_id);
        if (!ctx)
                return -ENOENT;

        switch (args->param) {
        case I915_CONTEXT_PARAM_NO_ZEROMAP:
                args->size = 0;
                args->value = test_bit(UCONTEXT_NO_ZEROMAP, &ctx->user_flags);
                break;

        case I915_CONTEXT_PARAM_GTT_SIZE:
                args->size = 0;
                if (ctx->vm)
                        args->value = ctx->vm->total;
                else if (to_i915(dev)->mm.aliasing_ppgtt)
                        args->value = to_i915(dev)->mm.aliasing_ppgtt->vm.total;
                else
                        args->value = to_i915(dev)->ggtt.vm.total;
                break;

        case I915_CONTEXT_PARAM_NO_ERROR_CAPTURE:
                args->size = 0;
                args->value = i915_gem_context_no_error_capture(ctx);
                break;

        case I915_CONTEXT_PARAM_BANNABLE:
                args->size = 0;
                args->value = i915_gem_context_is_bannable(ctx);
                break;

        case I915_CONTEXT_PARAM_RECOVERABLE:
                args->size = 0;
                args->value = i915_gem_context_is_recoverable(ctx);
                break;

        case I915_CONTEXT_PARAM_PRIORITY:
                args->size = 0;
                args->value = ctx->sched.priority >> I915_USER_PRIORITY_SHIFT;
                break;

        case I915_CONTEXT_PARAM_SSEU:
                ret = get_sseu(ctx, args);
                break;

        case I915_CONTEXT_PARAM_VM:
                ret = get_ppgtt(file_priv, ctx, args);
                break;

        case I915_CONTEXT_PARAM_ENGINES:
                ret = get_engines(ctx, args);
                break;

        case I915_CONTEXT_PARAM_BAN_PERIOD:
        default:
                ret = -EINVAL;
                break;
        }

        i915_gem_context_put(ctx);
        return ret;
}

int i915_gem_context_setparam_ioctl(struct drm_device *dev, void *data,
                                    struct drm_file *file)
{
        struct drm_i915_file_private *file_priv = file->driver_priv;
        struct drm_i915_gem_context_param *args = data;
        struct i915_gem_context *ctx;
        int ret;

        ctx = i915_gem_context_lookup(file_priv, args->ctx_id);
        if (!ctx)
                return -ENOENT;

        ret = ctx_setparam(file_priv, ctx, args);

        i915_gem_context_put(ctx);
        return ret;
}

int i915_gem_context_reset_stats_ioctl(struct drm_device *dev,
                                       void *data, struct drm_file *file)
{
        struct drm_i915_private *dev_priv = to_i915(dev);
        struct drm_i915_reset_stats *args = data;
        struct i915_gem_context *ctx;
        int ret;

        if (args->flags || args->pad)
                return -EINVAL;

        ret = -ENOENT;
        rcu_read_lock();
        ctx = __i915_gem_context_lookup_rcu(file->driver_priv, args->ctx_id);
        if (!ctx)
                goto out;

        /*
         * We opt for unserialised reads here. This may result in tearing
         * in the extremely unlikely event of a GPU hang on this context
         * as we are querying them. If we need that extra layer of protection,
         * we should wrap the hangstats with a seqlock.
         */

        if (capable(CAP_SYS_ADMIN))
                args->reset_count = i915_reset_count(&dev_priv->gpu_error);
        else
                args->reset_count = 0;

        args->batch_active = atomic_read(&ctx->guilty_count);
        args->batch_pending = atomic_read(&ctx->active_count);

        ret = 0;
out:
        rcu_read_unlock();
        return ret;
}

int __i915_gem_context_pin_hw_id(struct i915_gem_context *ctx)
{
        struct drm_i915_private *i915 = ctx->i915;
        int err = 0;

        mutex_lock(&i915->contexts.mutex);

        GEM_BUG_ON(i915_gem_context_is_closed(ctx));

        if (list_empty(&ctx->hw_id_link)) {
                GEM_BUG_ON(atomic_read(&ctx->hw_id_pin_count));

                err = assign_hw_id(i915, &ctx->hw_id);
                if (err)
                        goto out_unlock;

                list_add_tail(&ctx->hw_id_link, &i915->contexts.hw_id_list);
        }

        GEM_BUG_ON(atomic_read(&ctx->hw_id_pin_count) == ~0u);
        atomic_inc(&ctx->hw_id_pin_count);

out_unlock:
        mutex_unlock(&i915->contexts.mutex);
        return err;
}

/* GEM context-engines iterator: for_each_gem_engine() */
struct intel_context *
i915_gem_engines_iter_next(struct i915_gem_engines_iter *it)
{
        const struct i915_gem_engines *e = it->engines;
        struct intel_context *ctx;

        do {
                if (it->idx >= e->num_engines)
                        return NULL;

                ctx = e->engines[it->idx++];
        } while (!ctx);

        return ctx;
}

#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
#include "selftests/mock_context.c"
#include "selftests/i915_gem_context.c"
#endif

static void i915_global_gem_context_shrink(void)
{
        kmem_cache_shrink(global.slab_luts);
}

static void i915_global_gem_context_exit(void)
{
        kmem_cache_destroy(global.slab_luts);
}

static struct i915_global_gem_context global = { {
        .shrink = i915_global_gem_context_shrink,
        .exit = i915_global_gem_context_exit,
} };

int __init i915_global_gem_context_init(void)
{
        global.slab_luts = KMEM_CACHE(i915_lut_handle, 0);
        if (!global.slab_luts)
                return -ENOMEM;

        i915_global_register(&global.base);
        return 0;
}