text: // SPDX-License-Identifier: GPL-2.0-only
  /*
   * Copyright © 2006-2009, Intel Corporation.
   *
   * Author: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
   */
  
  #include <linux/iova.h>
  #include <linux/module.h>
  #include <linux/slab.h>
  #include <linux/smp.h>
  #include <linux/bitops.h>
  #include <linux/cpu.h>
  
  /* The anchor node sits above the top of the usable address space */
  #define IOVA_ANCHOR	~0UL
  
  static bool iova_rcache_insert(struct iova_domain *iovad,
  			       unsigned long pfn,
  			       unsigned long size);
  static unsigned long iova_rcache_get(struct iova_domain *iovad,
  				     unsigned long size,
  				     unsigned long limit_pfn);
  static void init_iova_rcaches(struct iova_domain *iovad);
  static void free_cpu_cached_iovas(unsigned int cpu, struct iova_domain *iovad);
  static void free_iova_rcaches(struct iova_domain *iovad);
  static void fq_destroy_all_entries(struct iova_domain *iovad);
  static void fq_flush_timeout(struct timer_list *t);
  
  static int iova_cpuhp_dead(unsigned int cpu, struct hlist_node *node)
  {
  	struct iova_domain *iovad;
  
  	iovad = hlist_entry_safe(node, struct iova_domain, cpuhp_dead);
  
  	free_cpu_cached_iovas(cpu, iovad);
  	return 0;
  }
  
  static void free_global_cached_iovas(struct iova_domain *iovad);
  
  static struct iova *to_iova(struct rb_node *node)
  {
  	return rb_entry(node, struct iova, node);
  }
  
  void
  init_iova_domain(struct iova_domain *iovad, unsigned long granule,
  	unsigned long start_pfn)
  {
  	/*
  	 * IOVA granularity will normally be equal to the smallest
  	 * supported IOMMU page size; both *must* be capable of
  	 * representing individual CPU pages exactly.
  	 */
  	BUG_ON((granule > PAGE_SIZE) || !is_power_of_2(granule));
  
  	spin_lock_init(&iovad->iova_rbtree_lock);
  	iovad->rbroot = RB_ROOT;
  	iovad->cached_node = &iovad->anchor.node;
  	iovad->cached32_node = &iovad->anchor.node;
  	iovad->granule = granule;
  	iovad->start_pfn = start_pfn;
  	iovad->dma_32bit_pfn = 1UL << (32 - iova_shift(iovad));
  	iovad->max32_alloc_size = iovad->dma_32bit_pfn;
  	iovad->flush_cb = NULL;
  	iovad->fq = NULL;
  	iovad->anchor.pfn_lo = iovad->anchor.pfn_hi = IOVA_ANCHOR;
  	rb_link_node(&iovad->anchor.node, NULL, &iovad->rbroot.rb_node);
  	rb_insert_color(&iovad->anchor.node, &iovad->rbroot);
  	cpuhp_state_add_instance_nocalls(CPUHP_IOMMU_IOVA_DEAD, &iovad->cpuhp_dead);
  	init_iova_rcaches(iovad);
  }
  EXPORT_SYMBOL_GPL(init_iova_domain);
  
  static bool has_iova_flush_queue(struct iova_domain *iovad)
  {
  	return !!iovad->fq;
  }
  
  static void free_iova_flush_queue(struct iova_domain *iovad)
  {
  	if (!has_iova_flush_queue(iovad))
  		return;
  
  	if (timer_pending(&iovad->fq_timer))
  		del_timer(&iovad->fq_timer);
  
  	fq_destroy_all_entries(iovad);
  
  	free_percpu(iovad->fq);
  
  	iovad->fq         = NULL;
  	iovad->flush_cb   = NULL;
  	iovad->entry_dtor = NULL;
  }
  
  int init_iova_flush_queue(struct iova_domain *iovad,
  			  iova_flush_cb flush_cb, iova_entry_dtor entry_dtor)
  {
  	struct iova_fq __percpu *queue;
  	int cpu;
  
  	atomic64_set(&iovad->fq_flush_start_cnt,  0);
  	atomic64_set(&iovad->fq_flush_finish_cnt, 0);
  
  	queue = alloc_percpu(struct iova_fq);
  	if (!queue)
  		return -ENOMEM;
  
  	iovad->flush_cb   = flush_cb;
  	iovad->entry_dtor = entry_dtor;
  
  	for_each_possible_cpu(cpu) {
  		struct iova_fq *fq;
  
  		fq = per_cpu_ptr(queue, cpu);
  		fq->head = 0;
  		fq->tail = 0;
  
  		spin_lock_init(&fq->lock);
  	}
  
  	smp_wmb();
  
  	iovad->fq = queue;
  
  	timer_setup(&iovad->fq_timer, fq_flush_timeout, 0);
  	atomic_set(&iovad->fq_timer_on, 0);
  
  	return 0;
  }
  
  static struct rb_node *
  __get_cached_rbnode(struct iova_domain *iovad, unsigned long limit_pfn)
  {
  	if (limit_pfn <= iovad->dma_32bit_pfn)
  		return iovad->cached32_node;
  
  	return iovad->cached_node;
  }
  
  static void
  __cached_rbnode_insert_update(struct iova_domain *iovad, struct iova *new)
  {
  	if (new->pfn_hi < iovad->dma_32bit_pfn)
  		iovad->cached32_node = &new->node;
  	else
  		iovad->cached_node = &new->node;
  }
  
  static void
  __cached_rbnode_delete_update(struct iova_domain *iovad, struct iova *free)
  {
  	struct iova *cached_iova;
  
  	cached_iova = to_iova(iovad->cached32_node);
  	if (free == cached_iova ||
  	    (free->pfn_hi < iovad->dma_32bit_pfn &&
  	     free->pfn_lo >= cached_iova->pfn_lo)) {
  		iovad->cached32_node = rb_next(&free->node);
  		iovad->max32_alloc_size = iovad->dma_32bit_pfn;
  	}
  
  	cached_iova = to_iova(iovad->cached_node);
  	if (free->pfn_lo >= cached_iova->pfn_lo)
  		iovad->cached_node = rb_next(&free->node);
  }
  
  static struct rb_node *iova_find_limit(struct iova_domain *iovad, unsigned long limit_pfn)
  {
  	struct rb_node *node, *next;
  	/*
  	 * Ideally what we'd like to judge here is whether limit_pfn is close
  	 * enough to the highest-allocated IOVA that starting the allocation
  	 * walk from the anchor node will be quicker than this initial work to
  	 * find an exact starting point (especially if that ends up being the
  	 * anchor node anyway). This is an incredibly crude approximation which
  	 * only really helps the most likely case, but is at least trivially easy.
  	 */
  	if (limit_pfn > iovad->dma_32bit_pfn)
  		return &iovad->anchor.node;
  
  	node = iovad->rbroot.rb_node;
  	while (to_iova(node)->pfn_hi < limit_pfn)
  		node = node->rb_right;
  
  search_left:
  	while (node->rb_left && to_iova(node->rb_left)->pfn_lo >= limit_pfn)
  		node = node->rb_left;
  
  	if (!node->rb_left)
  		return node;
  
  	next = node->rb_left;
  	while (next->rb_right) {
  		next = next->rb_right;
  		if (to_iova(next)->pfn_lo >= limit_pfn) {
  			node = next;
  			goto search_left;
  		}
  	}
  
  	return node;
  }
  
  /* Insert the iova into domain rbtree by holding writer lock */
  static void
  iova_insert_rbtree(struct rb_root *root, struct iova *iova,
  		   struct rb_node *start)
  {
  	struct rb_node **new, *parent = NULL;
  
  	new = (start) ? &start : &(root->rb_node);
  	/* Figure out where to put new node */
  	while (*new) {
  		struct iova *this = to_iova(*new);
  
  		parent = *new;
  
  		if (iova->pfn_lo < this->pfn_lo)
  			new = &((*new)->rb_left);
  		else if (iova->pfn_lo > this->pfn_lo)
  			new = &((*new)->rb_right);
  		else {
  			WARN_ON(1); /* this should not happen */
  			return;
  		}
  	}
  	/* Add new node and rebalance tree. */
  	rb_link_node(&iova->node, parent, new);
  	rb_insert_color(&iova->node, root);
  }
  
  static int __alloc_and_insert_iova_range(struct iova_domain *iovad,
  		unsigned long size, unsigned long limit_pfn,
  			struct iova *new, bool size_aligned)
  {
  	struct rb_node *curr, *prev;
  	struct iova *curr_iova;
  	unsigned long flags;
  	unsigned long new_pfn, retry_pfn;
  	unsigned long align_mask = ~0UL;
  	unsigned long high_pfn = limit_pfn, low_pfn = iovad->start_pfn;
  
  	if (size_aligned)
  		align_mask <<= fls_long(size - 1);
  
  	/* Walk the tree backwards */
  	spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
  	if (limit_pfn <= iovad->dma_32bit_pfn &&
  			size >= iovad->max32_alloc_size)
  		goto iova32_full;
  
  	curr = __get_cached_rbnode(iovad, limit_pfn);
  	curr_iova = to_iova(curr);
  	retry_pfn = curr_iova->pfn_hi + 1;
  
  retry:
  	do {
  		high_pfn = min(high_pfn, curr_iova->pfn_lo);
  		new_pfn = (high_pfn - size) & align_mask;
  		prev = curr;
  		curr = rb_prev(curr);
  		curr_iova = to_iova(curr);
  	} while (curr && new_pfn <= curr_iova->pfn_hi && new_pfn >= low_pfn);
  
  	if (high_pfn < size || new_pfn < low_pfn) {
  		if (low_pfn == iovad->start_pfn && retry_pfn < limit_pfn) {
  			high_pfn = limit_pfn;
  			low_pfn = retry_pfn;
  			curr = iova_find_limit(iovad, limit_pfn);
  			curr_iova = to_iova(curr);
  			goto retry;
  		}
  		iovad->max32_alloc_size = size;
  		goto iova32_full;
  	}
  
  	/* pfn_lo will point to size aligned address if size_aligned is set */
  	new->pfn_lo = new_pfn;
  	new->pfn_hi = new->pfn_lo + size - 1;
  
  	/* If we have 'prev', it's a valid place to start the insertion. */
  	iova_insert_rbtree(&iovad->rbroot, new, prev);
  	__cached_rbnode_insert_update(iovad, new);
  
  	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
  	return 0;
  
  iova32_full:
  	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
  	return -ENOMEM;
  }
  
  static struct kmem_cache *iova_cache;
  static unsigned int iova_cache_users;
  static DEFINE_MUTEX(iova_cache_mutex);
  
  static struct iova *alloc_iova_mem(void)
  {
  	return kmem_cache_zalloc(iova_cache, GFP_ATOMIC | __GFP_NOWARN);
  }
  
  static void free_iova_mem(struct iova *iova)
  {
  	if (iova->pfn_lo != IOVA_ANCHOR)
  		kmem_cache_free(iova_cache, iova);
  }
  
  int iova_cache_get(void)
  {
  	mutex_lock(&iova_cache_mutex);
  	if (!iova_cache_users) {
  		int ret;
  
  		ret = cpuhp_setup_state_multi(CPUHP_IOMMU_IOVA_DEAD, "iommu/iova:dead", NULL,
  					iova_cpuhp_dead);
  		if (ret) {
  			mutex_unlock(&iova_cache_mutex);
  			pr_err("Couldn't register cpuhp handler\n");
  			return ret;
  		}
  
  		iova_cache = kmem_cache_create(
  			"iommu_iova", sizeof(struct iova), 0,
  			SLAB_HWCACHE_ALIGN, NULL);
  		if (!iova_cache) {
  			cpuhp_remove_multi_state(CPUHP_IOMMU_IOVA_DEAD);
  			mutex_unlock(&iova_cache_mutex);
  			pr_err("Couldn't create iova cache\n");
  			return -ENOMEM;
  		}
  	}
  
  	iova_cache_users++;
  	mutex_unlock(&iova_cache_mutex);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(iova_cache_get);
  
  void iova_cache_put(void)
  {
  	mutex_lock(&iova_cache_mutex);
  	if (WARN_ON(!iova_cache_users)) {
  		mutex_unlock(&iova_cache_mutex);
  		return;
  	}
  	iova_cache_users--;
  	if (!iova_cache_users) {
  		cpuhp_remove_multi_state(CPUHP_IOMMU_IOVA_DEAD);
  		kmem_cache_destroy(iova_cache);
  	}
  	mutex_unlock(&iova_cache_mutex);
  }
  EXPORT_SYMBOL_GPL(iova_cache_put);
  
  /**
   * alloc_iova - allocates an iova
   * @iovad: - iova domain in question
   * @size: - size of page frames to allocate
   * @limit_pfn: - max limit address
   * @size_aligned: - set if size_aligned address range is required
   * This function allocates an iova in the range iovad->start_pfn to limit_pfn,
   * searching top-down from limit_pfn to iovad->start_pfn. If the size_aligned
   * flag is set then the allocated address iova->pfn_lo will be naturally
   * aligned on roundup_power_of_two(size).
   */
  struct iova *
  alloc_iova(struct iova_domain *iovad, unsigned long size,
  	unsigned long limit_pfn,
  	bool size_aligned)
  {
  	struct iova *new_iova;
  	int ret;
  
  	new_iova = alloc_iova_mem();
  	if (!new_iova)
  		return NULL;
  
  	ret = __alloc_and_insert_iova_range(iovad, size, limit_pfn + 1,
  			new_iova, size_aligned);
  
  	if (ret) {
  		free_iova_mem(new_iova);
  		return NULL;
  	}
  
  	return new_iova;
  }
  EXPORT_SYMBOL_GPL(alloc_iova);
  
  static struct iova *
  private_find_iova(struct iova_domain *iovad, unsigned long pfn)
  {
  	struct rb_node *node = iovad->rbroot.rb_node;
  
  	assert_spin_locked(&iovad->iova_rbtree_lock);
  
  	while (node) {
  		struct iova *iova = to_iova(node);
  
  		if (pfn < iova->pfn_lo)
  			node = node->rb_left;
  		else if (pfn > iova->pfn_hi)
  			node = node->rb_right;
  		else
  			return iova;	/* pfn falls within iova's range */
  	}
  
  	return NULL;
  }
  
  static void private_free_iova(struct iova_domain *iovad, struct iova *iova)
  {
  	assert_spin_locked(&iovad->iova_rbtree_lock);
  	__cached_rbnode_delete_update(iovad, iova);
  	rb_erase(&iova->node, &iovad->rbroot);
  	free_iova_mem(iova);
  }
  
  /**
   * find_iova - finds an iova for a given pfn
   * @iovad: - iova domain in question.
   * @pfn: - page frame number
   * This function finds and returns an iova belonging to the
   * given domain which matches the given pfn.
   */
  struct iova *find_iova(struct iova_domain *iovad, unsigned long pfn)
  {
  	unsigned long flags;
  	struct iova *iova;
  
  	/* Take the lock so that no other thread is manipulating the rbtree */
  	spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
  	iova = private_find_iova(iovad, pfn);
  	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
  	return iova;
  }
  EXPORT_SYMBOL_GPL(find_iova);
  
  /**
   * __free_iova - frees the given iova
   * @iovad: iova domain in question.
   * @iova: iova in question.
   * Frees the given iova belonging to the giving domain
   */
  void
  __free_iova(struct iova_domain *iovad, struct iova *iova)
  {
  	unsigned long flags;
  
  	spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
  	private_free_iova(iovad, iova);
  	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
  }
  EXPORT_SYMBOL_GPL(__free_iova);
  
  /**
   * free_iova - finds and frees the iova for a given pfn
   * @iovad: - iova domain in question.
   * @pfn: - pfn that is allocated previously
   * This functions finds an iova for a given pfn and then
   * frees the iova from that domain.
   */
  void
  free_iova(struct iova_domain *iovad, unsigned long pfn)
  {
  	unsigned long flags;
  	struct iova *iova;
  
  	spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
  	iova = private_find_iova(iovad, pfn);
  	if (iova)
  		private_free_iova(iovad, iova);
  	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
  
  }
  EXPORT_SYMBOL_GPL(free_iova);
  
  /**
   * alloc_iova_fast - allocates an iova from rcache
   * @iovad: - iova domain in question
   * @size: - size of page frames to allocate
   * @limit_pfn: - max limit address
   * @flush_rcache: - set to flush rcache on regular allocation failure
   * This function tries to satisfy an iova allocation from the rcache,
   * and falls back to regular allocation on failure. If regular allocation
   * fails too and the flush_rcache flag is set then the rcache will be flushed.
  */
  unsigned long
  alloc_iova_fast(struct iova_domain *iovad, unsigned long size,
  		unsigned long limit_pfn, bool flush_rcache)
  {
  	unsigned long iova_pfn;
  	struct iova *new_iova;
  
  	iova_pfn = iova_rcache_get(iovad, size, limit_pfn + 1);
  	if (iova_pfn)
  		return iova_pfn;
  
  retry:
  	new_iova = alloc_iova(iovad, size, limit_pfn, true);
  	if (!new_iova) {
  		unsigned int cpu;
  
  		if (!flush_rcache)
  			return 0;
  
  		/* Try replenishing IOVAs by flushing rcache. */
  		flush_rcache = false;
  		for_each_online_cpu(cpu)
  			free_cpu_cached_iovas(cpu, iovad);
  		free_global_cached_iovas(iovad);
  		goto retry;
  	}
  
  	return new_iova->pfn_lo;
  }
  
  /**
   * free_iova_fast - free iova pfn range into rcache
   * @iovad: - iova domain in question.
   * @pfn: - pfn that is allocated previously
   * @size: - # of pages in range
   * This functions frees an iova range by trying to put it into the rcache,
   * falling back to regular iova deallocation via free_iova() if this fails.
   */
  void
  free_iova_fast(struct iova_domain *iovad, unsigned long pfn, unsigned long size)
  {
  	if (iova_rcache_insert(iovad, pfn, size))
  		return;
  
  	free_iova(iovad, pfn);
  }
  
  #define fq_ring_for_each(i, fq) \
  	for ((i) = (fq)->head; (i) != (fq)->tail; (i) = ((i) + 1) % IOVA_FQ_SIZE)
  
  static inline bool fq_full(struct iova_fq *fq)
  {
  	assert_spin_locked(&fq->lock);
  	return (((fq->tail + 1) % IOVA_FQ_SIZE) == fq->head);
  }
  
  static inline unsigned fq_ring_add(struct iova_fq *fq)
  {
  	unsigned idx = fq->tail;
  
  	assert_spin_locked(&fq->lock);
  
  	fq->tail = (idx + 1) % IOVA_FQ_SIZE;
  
  	return idx;
  }
  
  static void fq_ring_free(struct iova_domain *iovad, struct iova_fq *fq)
  {
  	u64 counter = atomic64_read(&iovad->fq_flush_finish_cnt);
  	unsigned idx;
  
  	assert_spin_locked(&fq->lock);
  
  	fq_ring_for_each(idx, fq) {
  
  		if (fq->entries[idx].counter >= counter)
  			break;
  
  		if (iovad->entry_dtor)
  			iovad->entry_dtor(fq->entries[idx].data);
  
  		free_iova_fast(iovad,
  			       fq->entries[idx].iova_pfn,
  			       fq->entries[idx].pages);
  
  		fq->head = (fq->head + 1) % IOVA_FQ_SIZE;
  	}
  }
  
  static void iova_domain_flush(struct iova_domain *iovad)
  {
  	atomic64_inc(&iovad->fq_flush_start_cnt);
  	iovad->flush_cb(iovad);
  	atomic64_inc(&iovad->fq_flush_finish_cnt);
  }
  
  static void fq_destroy_all_entries(struct iova_domain *iovad)
  {
  	int cpu;
  
  	/*
  	 * This code runs when the iova_domain is being detroyed, so don't
  	 * bother to free iovas, just call the entry_dtor on all remaining
  	 * entries.
  	 */
  	if (!iovad->entry_dtor)
  		return;
  
  	for_each_possible_cpu(cpu) {
  		struct iova_fq *fq = per_cpu_ptr(iovad->fq, cpu);
  		int idx;
  
  		fq_ring_for_each(idx, fq)
  			iovad->entry_dtor(fq->entries[idx].data);
  	}
  }
  
  static void fq_flush_timeout(struct timer_list *t)
  {
  	struct iova_domain *iovad = from_timer(iovad, t, fq_timer);
  	int cpu;
  
  	atomic_set(&iovad->fq_timer_on, 0);
  	iova_domain_flush(iovad);
  
  	for_each_possible_cpu(cpu) {
  		unsigned long flags;
  		struct iova_fq *fq;
  
  		fq = per_cpu_ptr(iovad->fq, cpu);
  		spin_lock_irqsave(&fq->lock, flags);
  		fq_ring_free(iovad, fq);
  		spin_unlock_irqrestore(&fq->lock, flags);
  	}
  }
  
  void queue_iova(struct iova_domain *iovad,
  		unsigned long pfn, unsigned long pages,
  		unsigned long data)
  {
  	struct iova_fq *fq = raw_cpu_ptr(iovad->fq);
  	unsigned long flags;
  	unsigned idx;
  
  	spin_lock_irqsave(&fq->lock, flags);
  
  	/*
  	 * First remove all entries from the flush queue that have already been
  	 * flushed out on another CPU. This makes the fq_full() check below less
  	 * likely to be true.
  	 */
  	fq_ring_free(iovad, fq);
  
  	if (fq_full(fq)) {
  		iova_domain_flush(iovad);
  		fq_ring_free(iovad, fq);
  	}
  
  	idx = fq_ring_add(fq);
  
  	fq->entries[idx].iova_pfn = pfn;
  	fq->entries[idx].pages    = pages;
  	fq->entries[idx].data     = data;
  	fq->entries[idx].counter  = atomic64_read(&iovad->fq_flush_start_cnt);
  
  	spin_unlock_irqrestore(&fq->lock, flags);
  
  	/* Avoid false sharing as much as possible. */
  	if (!atomic_read(&iovad->fq_timer_on) &&
  	    !atomic_xchg(&iovad->fq_timer_on, 1))
  		mod_timer(&iovad->fq_timer,
  			  jiffies + msecs_to_jiffies(IOVA_FQ_TIMEOUT));
  }
  
  /**
   * put_iova_domain - destroys the iova domain
   * @iovad: - iova domain in question.
   * All the iova's in that domain are destroyed.
   */
  void put_iova_domain(struct iova_domain *iovad)
  {
  	struct iova *iova, *tmp;
  
  	cpuhp_state_remove_instance_nocalls(CPUHP_IOMMU_IOVA_DEAD,
  					    &iovad->cpuhp_dead);
  
  	free_iova_flush_queue(iovad);
  	free_iova_rcaches(iovad);
  	rbtree_postorder_for_each_entry_safe(iova, tmp, &iovad->rbroot, node)
  		free_iova_mem(iova);
  }
  EXPORT_SYMBOL_GPL(put_iova_domain);
  
  static int
  __is_range_overlap(struct rb_node *node,
  	unsigned long pfn_lo, unsigned long pfn_hi)
  {
  	struct iova *iova = to_iova(node);
  
  	if ((pfn_lo <= iova->pfn_hi) && (pfn_hi >= iova->pfn_lo))
  		return 1;
  	return 0;
  }
  
  static inline struct iova *
  alloc_and_init_iova(unsigned long pfn_lo, unsigned long pfn_hi)
  {
  	struct iova *iova;
  
  	iova = alloc_iova_mem();
  	if (iova) {
  		iova->pfn_lo = pfn_lo;
  		iova->pfn_hi = pfn_hi;
  	}
  
  	return iova;
  }
  
  static struct iova *
  __insert_new_range(struct iova_domain *iovad,
  	unsigned long pfn_lo, unsigned long pfn_hi)
  {
  	struct iova *iova;
  
  	iova = alloc_and_init_iova(pfn_lo, pfn_hi);
  	if (iova)
  		iova_insert_rbtree(&iovad->rbroot, iova, NULL);
  
  	return iova;
  }
  
  static void
  __adjust_overlap_range(struct iova *iova,
  	unsigned long *pfn_lo, unsigned long *pfn_hi)
  {
  	if (*pfn_lo < iova->pfn_lo)
  		iova->pfn_lo = *pfn_lo;
  	if (*pfn_hi > iova->pfn_hi)
  		*pfn_lo = iova->pfn_hi + 1;
  }
  
  /**
   * reserve_iova - reserves an iova in the given range
   * @iovad: - iova domain pointer
   * @pfn_lo: - lower page frame address
   * @pfn_hi:- higher pfn adderss
   * This function allocates reserves the address range from pfn_lo to pfn_hi so
   * that this address is not dished out as part of alloc_iova.
   */
  struct iova *
  reserve_iova(struct iova_domain *iovad,
  	unsigned long pfn_lo, unsigned long pfn_hi)
  {
  	struct rb_node *node;
  	unsigned long flags;
  	struct iova *iova;
  	unsigned int overlap = 0;
  
  	/* Don't allow nonsensical pfns */
  	if (WARN_ON((pfn_hi | pfn_lo) > (ULLONG_MAX >> iova_shift(iovad))))
  		return NULL;
  
  	spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
  	for (node = rb_first(&iovad->rbroot); node; node = rb_next(node)) {
  		if (__is_range_overlap(node, pfn_lo, pfn_hi)) {
  			iova = to_iova(node);
  			__adjust_overlap_range(iova, &pfn_lo, &pfn_hi);
  			if ((pfn_lo >= iova->pfn_lo) &&
  				(pfn_hi <= iova->pfn_hi))
  				goto finish;
  			overlap = 1;
  
  		} else if (overlap)
  				break;
  	}
  
  	/* We are here either because this is the first reserver node
  	 * or need to insert remaining non overlap addr range
  	 */
  	iova = __insert_new_range(iovad, pfn_lo, pfn_hi);
  finish:
  
  	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
  	return iova;
  }
  EXPORT_SYMBOL_GPL(reserve_iova);
  
  /*
   * Magazine caches for IOVA ranges.  For an introduction to magazines,
   * see the USENIX 2001 paper "Magazines and Vmem: Extending the Slab
   * Allocator to Many CPUs and Arbitrary Resources" by Bonwick and Adams.
   * For simplicity, we use a static magazine size and don't implement the
   * dynamic size tuning described in the paper.
   */
  
  #define IOVA_MAG_SIZE 128
  
  struct iova_magazine {
  	unsigned long size;
  	unsigned long pfns[IOVA_MAG_SIZE];
  };
  
  struct iova_cpu_rcache {
  	spinlock_t lock;
  	struct iova_magazine *loaded;
  	struct iova_magazine *prev;
  };
  
  static struct iova_magazine *iova_magazine_alloc(gfp_t flags)
  {
  	return kzalloc(sizeof(struct iova_magazine), flags);
  }
  
  static void iova_magazine_free(struct iova_magazine *mag)
  {
  	kfree(mag);
  }
  
  static void
  iova_magazine_free_pfns(struct iova_magazine *mag, struct iova_domain *iovad)
  {
  	unsigned long flags;
  	int i;
  
  	if (!mag)
  		return;
  
  	spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
  
  	for (i = 0 ; i < mag->size; ++i) {
  		struct iova *iova = private_find_iova(iovad, mag->pfns[i]);
  
  		if (WARN_ON(!iova))
  			continue;
  
  		private_free_iova(iovad, iova);
  	}
  
  	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
  
  	mag->size = 0;
  }
  
  static bool iova_magazine_full(struct iova_magazine *mag)
  {
  	return (mag && mag->size == IOVA_MAG_SIZE);
  }
  
  static bool iova_magazine_empty(struct iova_magazine *mag)
  {
  	return (!mag || mag->size == 0);
  }
  
  static unsigned long iova_magazine_pop(struct iova_magazine *mag,
  				       unsigned long limit_pfn)
  {
  	int i;
  	unsigned long pfn;
  
  	BUG_ON(iova_magazine_empty(mag));
  
  	/* Only fall back to the rbtree if we have no suitable pfns at all */
  	for (i = mag->size - 1; mag->pfns[i] > limit_pfn; i--)
  		if (i == 0)
  			return 0;
  
  	/* Swap it to pop it */
  	pfn = mag->pfns[i];
  	mag->pfns[i] = mag->pfns[--mag->size];
  
  	return pfn;
  }
  
  static void iova_magazine_push(struct iova_magazine *mag, unsigned long pfn)
  {
  	BUG_ON(iova_magazine_full(mag));
  
  	mag->pfns[mag->size++] = pfn;
  }
  
  static void init_iova_rcaches(struct iova_domain *iovad)
  {
  	struct iova_cpu_rcache *cpu_rcache;
  	struct iova_rcache *rcache;
  	unsigned int cpu;
  	int i;
  
  	for (i = 0; i < IOVA_RANGE_CACHE_MAX_SIZE; ++i) {
  		rcache = &iovad->rcaches[i];
  		spin_lock_init(&rcache->lock);
  		rcache->depot_size = 0;
  		rcache->cpu_rcaches = __alloc_percpu(sizeof(*cpu_rcache), cache_line_size());
  		if (WARN_ON(!rcache->cpu_rcaches))
  			continue;
  		for_each_possible_cpu(cpu) {
  			cpu_rcache = per_cpu_ptr(rcache->cpu_rcaches, cpu);
  			spin_lock_init(&cpu_rcache->lock);
  			cpu_rcache->loaded = iova_magazine_alloc(GFP_KERNEL);
  			cpu_rcache->prev = iova_magazine_alloc(GFP_KERNEL);
  		}
  	}
  }
  
  /*
   * Try inserting IOVA range starting with 'iova_pfn' into 'rcache', and
   * return true on success.  Can fail if rcache is full and we can't free
   * space, and free_iova() (our only caller) will then return the IOVA
   * range to the rbtree instead.
   */
  static bool __iova_rcache_insert(struct iova_domain *iovad,
  				 struct iova_rcache *rcache,
  				 unsigned long iova_pfn)
  {
  	struct iova_magazine *mag_to_free = NULL;
  	struct iova_cpu_rcache *cpu_rcache;
  	bool can_insert = false;
  	unsigned long flags;
  
  	cpu_rcache = raw_cpu_ptr(rcache->cpu_rcaches);
  	spin_lock_irqsave(&cpu_rcache->lock, flags);
  
  	if (!iova_magazine_full(cpu_rcache->loaded)) {
  		can_insert = true;
  	} else if (!iova_magazine_full(cpu_rcache->prev)) {
  		swap(cpu_rcache->prev, cpu_rcache->loaded);
  		can_insert = true;
  	} else {
  		struct iova_magazine *new_mag = iova_magazine_alloc(GFP_ATOMIC);
  
  		if (new_mag) {
  			spin_lock(&rcache->lock);
  			if (rcache->depot_size < MAX_GLOBAL_MAGS) {
  				rcache->depot[rcache->depot_size++] =
  						cpu_rcache->loaded;
  			} else {
  				mag_to_free = cpu_rcache->loaded;
  			}
  			spin_unlock(&rcache->lock);
  
  			cpu_rcache->loaded = new_mag;
  			can_insert = true;
  		}
  	}
  
  	if (can_insert)
  		iova_magazine_push(cpu_rcache->loaded, iova_pfn);
  
  	spin_unlock_irqrestore(&cpu_rcache->lock, flags);
  
  	if (mag_to_free) {
  		iova_magazine_free_pfns(mag_to_free, iovad);
  		iova_magazine_free(mag_to_free);
  	}
  
  	return can_insert;
  }
  
  static bool iova_rcache_insert(struct iova_domain *iovad, unsigned long pfn,
  			       unsigned long size)
  {
  	unsigned int log_size = order_base_2(size);
  
  	if (log_size >= IOVA_RANGE_CACHE_MAX_SIZE)
  		return false;
  
  	return __iova_rcache_insert(iovad, &iovad->rcaches[log_size], pfn);
  }
  
  /*
   * Caller wants to allocate a new IOVA range from 'rcache'.  If we can
   * satisfy the request, return a matching non-NULL range and remove
   * it from the 'rcache'.
   */
  static unsigned long __iova_rcache_get(struct iova_rcache *rcache,
  				       unsigned long limit_pfn)
  {
  	struct iova_cpu_rcache *cpu_rcache;
  	unsigned long iova_pfn = 0;
  	bool has_pfn = false;
  	unsigned long flags;
  
  	cpu_rcache = raw_cpu_ptr(rcache->cpu_rcaches);
  	spin_lock_irqsave(&cpu_rcache->lock, flags);
  
  	if (!iova_magazine_empty(cpu_rcache->loaded)) {
  		has_pfn = true;
  	} else if (!iova_magazine_empty(cpu_rcache->prev)) {
  		swap(cpu_rcache->prev, cpu_rcache->loaded);
  		has_pfn = true;
  	} else {
  		spin_lock(&rcache->lock);
  		if (rcache->depot_size > 0) {
  			iova_magazine_free(cpu_rcache->loaded);
  			cpu_rcache->loaded = rcache->depot[--rcache->depot_size];
  			has_pfn = true;
  		}
  		spin_unlock(&rcache->lock);
  	}
  
  	if (has_pfn)
  		iova_pfn = iova_magazine_pop(cpu_rcache->loaded, limit_pfn);
  
  	spin_unlock_irqrestore(&cpu_rcache->lock, flags);
  
  	return iova_pfn;
  }
  
  /*
   * Try to satisfy IOVA allocation range from rcache.  Fail if requested
   * size is too big or the DMA limit we are given isn't satisfied by the
   * top element in the magazine.
   */
  static unsigned long iova_rcache_get(struct iova_domain *iovad,
  				     unsigned long size,
  				     unsigned long limit_pfn)
  {
  	unsigned int log_size = order_base_2(size);
  
  	if (log_size >= IOVA_RANGE_CACHE_MAX_SIZE)
  		return 0;
  
  	return __iova_rcache_get(&iovad->rcaches[log_size], limit_pfn - size);
  }
  
  /*
   * free rcache data structures.
   */
  static void free_iova_rcaches(struct iova_domain *iovad)
  {
  	struct iova_rcache *rcache;
  	struct iova_cpu_rcache *cpu_rcache;
  	unsigned int cpu;
  	int i, j;
  
  	for (i = 0; i < IOVA_RANGE_CACHE_MAX_SIZE; ++i) {
  		rcache = &iovad->rcaches[i];
  		for_each_possible_cpu(cpu) {
  			cpu_rcache = per_cpu_ptr(rcache->cpu_rcaches, cpu);
  			iova_magazine_free(cpu_rcache->loaded);
  			iova_magazine_free(cpu_rcache->prev);
  		}
  		free_percpu(rcache->cpu_rcaches);
  		for (j = 0; j < rcache->depot_size; ++j)
  			iova_magazine_free(rcache->depot[j]);
  	}
  }
  
  /*
   * free all the IOVA ranges cached by a cpu (used when cpu is unplugged)
   */
  static void free_cpu_cached_iovas(unsigned int cpu, struct iova_domain *iovad)
  {
  	struct iova_cpu_rcache *cpu_rcache;
  	struct iova_rcache *rcache;
  	unsigned long flags;
  	int i;
  
  	for (i = 0; i < IOVA_RANGE_CACHE_MAX_SIZE; ++i) {
  		rcache = &iovad->rcaches[i];
  		cpu_rcache = per_cpu_ptr(rcache->cpu_rcaches, cpu);
  		spin_lock_irqsave(&cpu_rcache->lock, flags);
  		iova_magazine_free_pfns(cpu_rcache->loaded, iovad);
  		iova_magazine_free_pfns(cpu_rcache->prev, iovad);
  		spin_unlock_irqrestore(&cpu_rcache->lock, flags);
  	}
  }
  
  /*
   * free all the IOVA ranges of global cache
   */
  static void free_global_cached_iovas(struct iova_domain *iovad)
  {
  	struct iova_rcache *rcache;
  	unsigned long flags;
  	int i, j;
  
  	for (i = 0; i < IOVA_RANGE_CACHE_MAX_SIZE; ++i) {
  		rcache = &iovad->rcaches[i];
  		spin_lock_irqsave(&rcache->lock, flags);
  		for (j = 0; j < rcache->depot_size; ++j) {
  			iova_magazine_free_pfns(rcache->depot[j], iovad);
  			iova_magazine_free(rcache->depot[j]);
  		}
  		rcache->depot_size = 0;
  		spin_unlock_irqrestore(&rcache->lock, flags);
  	}
  }
  MODULE_AUTHOR("Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>");
  MODULE_LICENSE("GPL");
  