1 files changed, 425 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/i915_vma_resource.c b/drivers/gpu/drm/i915/i915_vma_resource.c
new file mode 100644
index 000000000..6ba7a7fec
--- /dev/null
+++ b/drivers/gpu/drm/i915/i915_vma_resource.c
@@ -0,0 +1,425 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2021 Intel Corporation
+ */
+
+#include <linux/interval_tree_generic.h>
+#include <linux/sched/mm.h>
+
+#include "i915_sw_fence.h"
+#include "i915_vma_resource.h"
+#include "i915_drv.h"
+#include "intel_memory_region.h"
+
+#include "gt/intel_gtt.h"
+
+static struct kmem_cache *slab_vma_resources;
+
+/**
+ * DOC:
+ * We use a per-vm interval tree to keep track of vma_resources
+ * scheduled for unbind but not yet unbound. The tree is protected by
+ * the vm mutex, and nodes are removed just after the unbind fence signals.
+ * The removal takes the vm mutex from a kernel thread which we need to
+ * keep in mind so that we don't grab the mutex and try to wait for all
+ * pending unbinds to complete, because that will temporaryily block many
+ * of the workqueue threads, and people will get angry.
+ *
+ * We should consider using a single ordered fence per VM instead but that
+ * requires ordering the unbinds and might introduce unnecessary waiting
+ * for unrelated unbinds. Amount of code will probably be roughly the same
+ * due to the simplicity of using the interval tree interface.
+ *
+ * Another drawback of this interval tree is that the complexity of insertion
+ * and removal of fences increases as O(ln(pending_unbinds)) instead of
+ * O(1) for a single fence without interval tree.
+ */
+#define VMA_RES_START(_node) ((_node)->start - (_node)->guard)
+#define VMA_RES_LAST(_node) ((_node)->start + (_node)->node_size + (_node)->guard - 1)
+INTERVAL_TREE_DEFINE(struct i915_vma_resource, rb,
+		     u64, __subtree_last,
+		     VMA_RES_START, VMA_RES_LAST, static, vma_res_itree);
+
+/* Callbacks for the unbind dma-fence. */
+
+/**
+ * i915_vma_resource_alloc - Allocate a vma resource
+ *
+ * Return: A pointer to a cleared struct i915_vma_resource or
+ * a -ENOMEM error pointer if allocation fails.
+ */
+struct i915_vma_resource *i915_vma_resource_alloc(void)
+{
+	struct i915_vma_resource *vma_res =
+		kmem_cache_zalloc(slab_vma_resources, GFP_KERNEL);
+
+	return vma_res ? vma_res : ERR_PTR(-ENOMEM);
+}
+
+/**
+ * i915_vma_resource_free - Free a vma resource
+ * @vma_res: The vma resource to free.
+ */
+void i915_vma_resource_free(struct i915_vma_resource *vma_res)
+{
+	if (vma_res)
+		kmem_cache_free(slab_vma_resources, vma_res);
+}
+
+static const char *get_driver_name(struct dma_fence *fence)
+{
+	return "vma unbind fence";
+}
+
+static const char *get_timeline_name(struct dma_fence *fence)
+{
+	return "unbound";
+}
+
+static void unbind_fence_free_rcu(struct rcu_head *head)
+{
+	struct i915_vma_resource *vma_res =
+		container_of(head, typeof(*vma_res), unbind_fence.rcu);
+
+	i915_vma_resource_free(vma_res);
+}
+
+static void unbind_fence_release(struct dma_fence *fence)
+{
+	struct i915_vma_resource *vma_res =
+		container_of(fence, typeof(*vma_res), unbind_fence);
+
+	i915_sw_fence_fini(&vma_res->chain);
+
+	call_rcu(&fence->rcu, unbind_fence_free_rcu);
+}
+
+static struct dma_fence_ops unbind_fence_ops = {
+	.get_driver_name = get_driver_name,
+	.get_timeline_name = get_timeline_name,
+	.release = unbind_fence_release,
+};
+
+static void __i915_vma_resource_unhold(struct i915_vma_resource *vma_res)
+{
+	struct i915_address_space *vm;
+
+	if (!refcount_dec_and_test(&vma_res->hold_count))
+		return;
+
+	dma_fence_signal(&vma_res->unbind_fence);
+
+	vm = vma_res->vm;
+	if (vma_res->wakeref)
+		intel_runtime_pm_put(&vm->i915->runtime_pm, vma_res->wakeref);
+
+	vma_res->vm = NULL;
+	if (!RB_EMPTY_NODE(&vma_res->rb)) {
+		mutex_lock(&vm->mutex);
+		vma_res_itree_remove(vma_res, &vm->pending_unbind);
+		mutex_unlock(&vm->mutex);
+	}
+
+	if (vma_res->bi.pages_rsgt)
+		i915_refct_sgt_put(vma_res->bi.pages_rsgt);
+}
+
+/**
+ * i915_vma_resource_unhold - Unhold the signaling of the vma resource unbind
+ * fence.
+ * @vma_res: The vma resource.
+ * @lockdep_cookie: The lockdep cookie returned from i915_vma_resource_hold.
+ *
+ * The function may leave a dma_fence critical section.
+ */
+void i915_vma_resource_unhold(struct i915_vma_resource *vma_res,
+			      bool lockdep_cookie)
+{
+	dma_fence_end_signalling(lockdep_cookie);
+
+	if (IS_ENABLED(CONFIG_PROVE_LOCKING)) {
+		unsigned long irq_flags;
+
+		/* Inefficient open-coded might_lock_irqsave() */
+		spin_lock_irqsave(&vma_res->lock, irq_flags);
+		spin_unlock_irqrestore(&vma_res->lock, irq_flags);
+	}
+
+	__i915_vma_resource_unhold(vma_res);
+}
+
+/**
+ * i915_vma_resource_hold - Hold the signaling of the vma resource unbind fence.
+ * @vma_res: The vma resource.
+ * @lockdep_cookie: Pointer to a bool serving as a lockdep cooke that should
+ * be given as an argument to the pairing i915_vma_resource_unhold.
+ *
+ * If returning true, the function enters a dma_fence signalling critical
+ * section if not in one already.
+ *
+ * Return: true if holding successful, false if not.
+ */
+bool i915_vma_resource_hold(struct i915_vma_resource *vma_res,
+			    bool *lockdep_cookie)
+{
+	bool held = refcount_inc_not_zero(&vma_res->hold_count);
+
+	if (held)
+		*lockdep_cookie = dma_fence_begin_signalling();
+
+	return held;
+}
+
+static void i915_vma_resource_unbind_work(struct work_struct *work)
+{
+	struct i915_vma_resource *vma_res =
+		container_of(work, typeof(*vma_res), work);
+	struct i915_address_space *vm = vma_res->vm;
+	bool lockdep_cookie;
+
+	lockdep_cookie = dma_fence_begin_signalling();
+	if (likely(!vma_res->skip_pte_rewrite))
+		vma_res->ops->unbind_vma(vm, vma_res);
+
+	dma_fence_end_signalling(lockdep_cookie);
+	__i915_vma_resource_unhold(vma_res);
+	i915_vma_resource_put(vma_res);
+}
+
+static int
+i915_vma_resource_fence_notify(struct i915_sw_fence *fence,
+			       enum i915_sw_fence_notify state)
+{
+	struct i915_vma_resource *vma_res =
+		container_of(fence, typeof(*vma_res), chain);
+	struct dma_fence *unbind_fence =
+		&vma_res->unbind_fence;
+
+	switch (state) {
+	case FENCE_COMPLETE:
+		dma_fence_get(unbind_fence);
+		if (vma_res->immediate_unbind) {
+			i915_vma_resource_unbind_work(&vma_res->work);
+		} else {
+			INIT_WORK(&vma_res->work, i915_vma_resource_unbind_work);
+			queue_work(system_unbound_wq, &vma_res->work);
+		}
+		break;
+	case FENCE_FREE:
+		i915_vma_resource_put(vma_res);
+		break;
+	}
+
+	return NOTIFY_DONE;
+}
+
+/**
+ * i915_vma_resource_unbind - Unbind a vma resource
+ * @vma_res: The vma resource to unbind.
+ * @tlb: pointer to vma->obj->mm.tlb associated with the resource
+ *	 to be stored at vma_res->tlb. When not-NULL, it will be used
+ *	 to do TLB cache invalidation before freeing a VMA resource.
+ *	 Used only for async unbind.
+ *
+ * At this point this function does little more than publish a fence that
+ * signals immediately unless signaling is held back.
+ *
+ * Return: A refcounted pointer to a dma-fence that signals when unbinding is
+ * complete.
+ */
+struct dma_fence *i915_vma_resource_unbind(struct i915_vma_resource *vma_res,
+					   u32 *tlb)
+{
+	struct i915_address_space *vm = vma_res->vm;
+
+	vma_res->tlb = tlb;
+
+	/* Reference for the sw fence */
+	i915_vma_resource_get(vma_res);
+
+	/* Caller must already have a wakeref in this case. */
+	if (vma_res->needs_wakeref)
+		vma_res->wakeref = intel_runtime_pm_get_if_in_use(&vm->i915->runtime_pm);
+
+	if (atomic_read(&vma_res->chain.pending) <= 1) {
+		RB_CLEAR_NODE(&vma_res->rb);
+		vma_res->immediate_unbind = 1;
+	} else {
+		vma_res_itree_insert(vma_res, &vma_res->vm->pending_unbind);
+	}
+
+	i915_sw_fence_commit(&vma_res->chain);
+
+	return &vma_res->unbind_fence;
+}
+
+/**
+ * __i915_vma_resource_init - Initialize a vma resource.
+ * @vma_res: The vma resource to initialize
+ *
+ * Initializes the private members of a vma resource.
+ */
+void __i915_vma_resource_init(struct i915_vma_resource *vma_res)
+{
+	spin_lock_init(&vma_res->lock);
+	dma_fence_init(&vma_res->unbind_fence, &unbind_fence_ops,
+		       &vma_res->lock, 0, 0);
+	refcount_set(&vma_res->hold_count, 1);
+	i915_sw_fence_init(&vma_res->chain, i915_vma_resource_fence_notify);
+}
+
+static void
+i915_vma_resource_color_adjust_range(struct i915_address_space *vm,
+				     u64 *start,
+				     u64 *end)
+{
+	if (i915_vm_has_cache_coloring(vm)) {
+		if (*start)
+			*start -= I915_GTT_PAGE_SIZE;
+		*end += I915_GTT_PAGE_SIZE;
+	}
+}
+
+/**
+ * i915_vma_resource_bind_dep_sync - Wait for / sync all unbinds touching a
+ * certain vm range.
+ * @vm: The vm to look at.
+ * @offset: The range start.
+ * @size: The range size.
+ * @intr: Whether to wait interrubtible.
+ *
+ * The function needs to be called with the vm lock held.
+ *
+ * Return: Zero on success, -ERESTARTSYS if interrupted and @intr==true
+ */
+int i915_vma_resource_bind_dep_sync(struct i915_address_space *vm,
+				    u64 offset,
+				    u64 size,
+				    bool intr)
+{
+	struct i915_vma_resource *node;
+	u64 last = offset + size - 1;
+
+	lockdep_assert_held(&vm->mutex);
+	might_sleep();
+
+	i915_vma_resource_color_adjust_range(vm, &offset, &last);
+	node = vma_res_itree_iter_first(&vm->pending_unbind, offset, last);
+	while (node) {
+		int ret = dma_fence_wait(&node->unbind_fence, intr);
+
+		if (ret)
+			return ret;
+
+		node = vma_res_itree_iter_next(node, offset, last);
+	}
+
+	return 0;
+}
+
+/**
+ * i915_vma_resource_bind_dep_sync_all - Wait for / sync all unbinds of a vm,
+ * releasing the vm lock while waiting.
+ * @vm: The vm to look at.
+ *
+ * The function may not be called with the vm lock held.
+ * Typically this is called at vm destruction to finish any pending
+ * unbind operations. The vm mutex is released while waiting to avoid
+ * stalling kernel workqueues trying to grab the mutex.
+ */
+void i915_vma_resource_bind_dep_sync_all(struct i915_address_space *vm)
+{
+	struct i915_vma_resource *node;
+	struct dma_fence *fence;
+
+	do {
+		fence = NULL;
+		mutex_lock(&vm->mutex);
+		node = vma_res_itree_iter_first(&vm->pending_unbind, 0,
+						U64_MAX);
+		if (node)
+			fence = dma_fence_get_rcu(&node->unbind_fence);
+		mutex_unlock(&vm->mutex);
+
+		if (fence) {
+			/*
+			 * The wait makes sure the node eventually removes
+			 * itself from the tree.
+			 */
+			dma_fence_wait(fence, false);
+			dma_fence_put(fence);
+		}
+	} while (node);
+}
+
+/**
+ * i915_vma_resource_bind_dep_await - Have a struct i915_sw_fence await all
+ * pending unbinds in a certain range of a vm.
+ * @vm: The vm to look at.
+ * @sw_fence: The struct i915_sw_fence that will be awaiting the unbinds.
+ * @offset: The range start.
+ * @size: The range size.
+ * @intr: Whether to wait interrubtible.
+ * @gfp: Allocation mode for memory allocations.
+ *
+ * The function makes @sw_fence await all pending unbinds in a certain
+ * vm range before calling the complete notifier. To be able to await
+ * each individual unbind, the function needs to allocate memory using
+ * the @gpf allocation mode. If that fails, the function will instead
+ * wait for the unbind fence to signal, using @intr to judge whether to
+ * wait interruptible or not. Note that @gfp should ideally be selected so
+ * as to avoid any expensive memory allocation stalls and rather fail and
+ * synchronize itself. For now the vm mutex is required when calling this
+ * function with means that @gfp can't call into direct reclaim. In reality
+ * this means that during heavy memory pressure, we will sync in this
+ * function.
+ *
+ * Return: Zero on success, -ERESTARTSYS if interrupted and @intr==true
+ */
+int i915_vma_resource_bind_dep_await(struct i915_address_space *vm,
+				     struct i915_sw_fence *sw_fence,
+				     u64 offset,
+				     u64 size,
+				     bool intr,
+				     gfp_t gfp)
+{
+	struct i915_vma_resource *node;
+	u64 last = offset + size - 1;
+
+	lockdep_assert_held(&vm->mutex);
+	might_alloc(gfp);
+	might_sleep();
+
+	i915_vma_resource_color_adjust_range(vm, &offset, &last);
+	node = vma_res_itree_iter_first(&vm->pending_unbind, offset, last);
+	while (node) {
+		int ret;
+
+		ret = i915_sw_fence_await_dma_fence(sw_fence,
+						    &node->unbind_fence,
+						    0, gfp);
+		if (ret < 0) {
+			ret = dma_fence_wait(&node->unbind_fence, intr);
+			if (ret)
+				return ret;
+		}
+
+		node = vma_res_itree_iter_next(node, offset, last);
+	}
+
+	return 0;
+}
+
+void i915_vma_resource_module_exit(void)
+{
+	kmem_cache_destroy(slab_vma_resources);
+}
+
+int __init i915_vma_resource_module_init(void)
+{
+	slab_vma_resources = KMEM_CACHE(i915_vma_resource, SLAB_HWCACHE_ALIGN);
+	if (!slab_vma_resources)
+		return -ENOMEM;
+
+	return 0;
+}