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From:   John Garry <john.garry@huawei.com>
To:     <robin.murphy@arm.com>, <joro@8bytes.org>, <will@kernel.org>
CC:     <iommu@lists.linux.dev>, <linux-kernel@vger.kernel.org>,
        John Garry <john.garry@huawei.com>
Subject: [PATCH v2] iova: Re-order code to remove forward declarations
Date:   Tue, 26 Jul 2022 23:26:25 +0800
Message-ID: <1658849185-158209-1-git-send-email-john.garry@huawei.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

Now that the FQ code has been moved to dma-iommu.c and also the rcache-
related structures have been brought into iova.c, let's re-order the code
to remove all the forward declarations.

The general order will be as follows:
- RB tree code
- iova management
- magazine helpers
- rcache code and "fast" APIs
- iova domain public APIs

Re-order prototypes in iova.h to follow the same general group ordering.

A couple of pre-existing checkpatch warnings are also remedied:

A suspect indentation is also corrected:
WARNING: suspect code indent for conditional statements (16, 32)
 #374: FILE: drivers/iommu/iova.c:194:
+               } else if (overlap)
+                               break;

WARNING: Block comments should align the * on each line
 #1038: FILE: drivers/iommu/iova.c:787:
+ * fails too and the flush_rcache flag is set then the rcache will be flushed.
+*/

No functional change intended.

Signed-off-by: John Garry <john.garry@huawei.com>
---
Differences to v1:
- tweak ordering a bit
- rebase

diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
index e44f565c5319..ddac9dcf97c6 100644
--- a/drivers/iommu/iova.c
+++ b/drivers/iommu/iova.c
@@ -17,75 +17,45 @@
 
 #define IOVA_RANGE_CACHE_MAX_SIZE 6	/* log of max cached IOVA range size (in pages) */
 
-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 free_cpu_cached_iovas(unsigned int cpu, struct iova_domain *iovad);
-static void free_iova_rcaches(struct iova_domain *iovad);
+/*
+ * 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.
+ */
 
-static int iova_cpuhp_dead(unsigned int cpu, struct hlist_node *node)
-{
-	struct iova_domain *iovad;
+/*
+ * As kmalloc's buffer size is fixed to power of 2, 127 is chosen to
+ * assure size of 'iova_magazine' to be 1024 bytes, so that no memory
+ * will be wasted.
+ */
+#define IOVA_MAG_SIZE 127
+#define MAX_GLOBAL_MAGS 32	/* magazines per bin */
 
-	iovad = hlist_entry_safe(node, struct iova_domain, cpuhp_dead);
+struct iova_magazine {
+	unsigned long size;
+	unsigned long pfns[IOVA_MAG_SIZE];
+};
 
-	free_cpu_cached_iovas(cpu, iovad);
-	return 0;
-}
+struct iova_cpu_rcache {
+	spinlock_t lock;
+	struct iova_magazine *loaded;
+	struct iova_magazine *prev;
+};
 
-static void free_global_cached_iovas(struct iova_domain *iovad);
+struct iova_rcache {
+	spinlock_t lock;
+	unsigned long depot_size;
+	struct iova_magazine *depot[MAX_GLOBAL_MAGS];
+	struct iova_cpu_rcache __percpu *cpu_rcaches;
+};
 
 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->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);
-}
-EXPORT_SYMBOL_GPL(init_iova_domain);
-
-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)
 {
@@ -105,43 +75,6 @@ __cached_rbnode_delete_update(struct iova_domain *iovad, struct iova *free)
 		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,
@@ -170,65 +103,15 @@ iova_insert_rbtree(struct rb_root *root, struct iova *iova,
 	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)
+static int
+__is_range_overlap(struct rb_node *node,
+	unsigned long pfn_lo, unsigned long pfn_hi)
 {
-	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);
+	struct iova *iova = to_iova(node);
 
-	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
+	if ((pfn_lo <= iova->pfn_hi) && (pfn_hi >= iova->pfn_lo))
+		return 1;
 	return 0;
-
-iova32_full:
-	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
-	return -ENOMEM;
 }
 
 static struct kmem_cache *iova_cache;
@@ -246,88 +129,87 @@ static void free_iova_mem(struct iova *iova)
 		kmem_cache_free(iova_cache, iova);
 }
 
-int iova_cache_get(void)
+static inline struct iova *
+alloc_and_init_iova(unsigned long pfn_lo, unsigned long pfn_hi)
 {
-	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;
-		}
+	struct iova *iova;
 
-		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 = alloc_iova_mem();
+	if (iova) {
+		iova->pfn_lo = pfn_lo;
+		iova->pfn_hi = pfn_hi;
 	}
 
-	iova_cache_users++;
-	mutex_unlock(&iova_cache_mutex);
+	return iova;
+}
 
-	return 0;
+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;
 }
-EXPORT_SYMBOL_GPL(iova_cache_get);
 
-void iova_cache_put(void)
+static void
+__adjust_overlap_range(struct iova *iova,
+	unsigned long *pfn_lo, unsigned long *pfn_hi)
 {
-	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);
+	if (*pfn_lo < iova->pfn_lo)
+		iova->pfn_lo = *pfn_lo;
+	if (*pfn_hi > iova->pfn_hi)
+		*pfn_lo = iova->pfn_hi + 1;
 }
-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)
+ * 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 iova *new_iova;
-	int ret;
+	struct rb_node *node;
+	unsigned long flags;
+	struct iova *iova;
+	unsigned int overlap = 0;
 
-	new_iova = alloc_iova_mem();
-	if (!new_iova)
+	/* Don't allow nonsensical pfns */
+	if (WARN_ON((pfn_hi | pfn_lo) > (ULLONG_MAX >> iova_shift(iovad))))
 		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;
+	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;
 	}
 
-	return new_iova;
+	/* 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(alloc_iova);
+EXPORT_SYMBOL_GPL(reserve_iova);
 
 static struct iova *
 private_find_iova(struct iova_domain *iovad, unsigned long pfn)
@@ -357,6 +239,122 @@ static void remove_iova(struct iova_domain *iovad, struct iova *iova)
 	rb_erase(&iova->node, &iovad->rbroot);
 }
 
+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 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;
+}
+
+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;
+}
+
 /**
  * find_iova - finds an iova for a given pfn
  * @iovad: - iova domain in question.
@@ -377,6 +375,41 @@ struct iova *find_iova(struct iova_domain *iovad, unsigned long pfn)
 }
 EXPORT_SYMBOL_GPL(find_iova);
 
+/**
+ * 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);
+
 /**
  * __free_iova - frees the given iova
  * @iovad: iova domain in question.
@@ -420,234 +453,51 @@ free_iova(struct iova_domain *iovad, unsigned long pfn)
 }
 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)
+static bool iova_magazine_full(struct iova_magazine *mag)
 {
-	unsigned long iova_pfn;
-	struct iova *new_iova;
-
-	/*
-	 * Freeing non-power-of-two-sized allocations back into the IOVA caches
-	 * will come back to bite us badly, so we have to waste a bit of space
-	 * rounding up anything cacheable to make sure that can't happen. The
-	 * order of the unadjusted size will still match upon freeing.
-	 */
-	if (size < (1 << (IOVA_RANGE_CACHE_MAX_SIZE - 1)))
-		size = roundup_pow_of_two(size);
-
-	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;
+	return (mag && mag->size == IOVA_MAG_SIZE);
+}
 
-		if (!flush_rcache)
-			return 0;
+static void iova_magazine_push(struct iova_magazine *mag, unsigned long pfn)
+{
+	BUG_ON(iova_magazine_full(mag));
 
-		/* 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;
-	}
+	mag->pfns[mag->size++] = pfn;
+}
 
-	return new_iova->pfn_lo;
+static struct iova_magazine *iova_magazine_alloc(gfp_t flags)
+{
+	return kzalloc(sizeof(struct iova_magazine), flags);
 }
-EXPORT_SYMBOL_GPL(alloc_iova_fast);
 
-/**
- * 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);
-}
-EXPORT_SYMBOL_GPL(free_iova_fast);
-
-static void iova_domain_free_rcaches(struct iova_domain *iovad)
-{
-	cpuhp_state_remove_instance_nocalls(CPUHP_IOMMU_IOVA_DEAD,
-					    &iovad->cpuhp_dead);
-	free_iova_rcaches(iovad);
-}
-
-/**
- * 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;
-
-	if (iovad->rcaches)
-		iova_domain_free_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)
+static void iova_magazine_free(struct iova_magazine *mag)
 {
-	struct iova *iova;
-
-	iova = alloc_and_init_iova(pfn_lo, pfn_hi);
-	if (iova)
-		iova_insert_rbtree(&iovad->rbroot, iova, NULL);
-
-	return iova;
+	kfree(mag);
 }
 
-static void
-__adjust_overlap_range(struct iova *iova,
-	unsigned long *pfn_lo, unsigned long *pfn_hi)
+static bool iova_magazine_empty(struct iova_magazine *mag)
 {
-	if (*pfn_lo < iova->pfn_lo)
-		iova->pfn_lo = *pfn_lo;
-	if (*pfn_hi > iova->pfn_hi)
-		*pfn_lo = iova->pfn_hi + 1;
+	return (!mag || mag->size == 0);
 }
 
-/**
- * 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)
+static unsigned long iova_magazine_pop(struct iova_magazine *mag,
+				       unsigned long limit_pfn)
 {
-	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.
- */
-
-/*
- * As kmalloc's buffer size is fixed to power of 2, 127 is chosen to
- * assure size of 'iova_magazine' to be 1024 bytes, so that no memory
- * will be wasted.
- */
-#define IOVA_MAG_SIZE 127
-#define MAX_GLOBAL_MAGS 32	/* magazines per bin */
-
-struct iova_magazine {
-	unsigned long size;
-	unsigned long pfns[IOVA_MAG_SIZE];
-};
+	int i;
+	unsigned long pfn;
 
-struct iova_cpu_rcache {
-	spinlock_t lock;
-	struct iova_magazine *loaded;
-	struct iova_magazine *prev;
-};
+	BUG_ON(iova_magazine_empty(mag));
 
-struct iova_rcache {
-	spinlock_t lock;
-	unsigned long depot_size;
-	struct iova_magazine *depot[MAX_GLOBAL_MAGS];
-	struct iova_cpu_rcache __percpu *cpu_rcaches;
-};
+	/* 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;
 
-static struct iova_magazine *iova_magazine_alloc(gfp_t flags)
-{
-	return kzalloc(sizeof(struct iova_magazine), flags);
-}
+	/* Swap it to pop it */
+	pfn = mag->pfns[i];
+	mag->pfns[i] = mag->pfns[--mag->size];
 
-static void iova_magazine_free(struct iova_magazine *mag)
-{
-	kfree(mag);
+	return pfn;
 }
 
 static void
@@ -676,91 +526,91 @@ iova_magazine_free_pfns(struct iova_magazine *mag, struct iova_domain *iovad)
 	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)
+/*
+ * 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;
-	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;
+	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);
+	}
 }
 
-static void iova_magazine_push(struct iova_magazine *mag, unsigned long pfn)
+static int iova_cpuhp_dead(unsigned int cpu, struct hlist_node *node)
 {
-	BUG_ON(iova_magazine_full(mag));
+	struct iova_domain *iovad;
 
-	mag->pfns[mag->size++] = pfn;
+	iovad = hlist_entry_safe(node, struct iova_domain, cpuhp_dead);
+
+	free_cpu_cached_iovas(cpu, iovad);
+	return 0;
 }
 
-int iova_domain_init_rcaches(struct iova_domain *iovad)
+/*
+ * free all the IOVA ranges of global cache
+ */
+static void free_global_cached_iovas(struct iova_domain *iovad)
 {
-	unsigned int cpu;
-	int i, ret;
-
-	iovad->rcaches = kcalloc(IOVA_RANGE_CACHE_MAX_SIZE,
-				 sizeof(struct iova_rcache),
-				 GFP_KERNEL);
-	if (!iovad->rcaches)
-		return -ENOMEM;
+	struct iova_rcache *rcache;
+	unsigned long flags;
+	int i, j;
 
 	for (i = 0; i < IOVA_RANGE_CACHE_MAX_SIZE; ++i) {
-		struct iova_cpu_rcache *cpu_rcache;
-		struct iova_rcache *rcache;
-
 		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 (!rcache->cpu_rcaches) {
-			ret = -ENOMEM;
-			goto out_err;
+		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]);
 		}
-		for_each_possible_cpu(cpu) {
-			cpu_rcache = per_cpu_ptr(rcache->cpu_rcaches, cpu);
+		rcache->depot_size = 0;
+		spin_unlock_irqrestore(&rcache->lock, flags);
+	}
+}
 
-			spin_lock_init(&cpu_rcache->lock);
-			cpu_rcache->loaded = iova_magazine_alloc(GFP_KERNEL);
-			cpu_rcache->prev = iova_magazine_alloc(GFP_KERNEL);
-			if (!cpu_rcache->loaded || !cpu_rcache->prev) {
-				ret = -ENOMEM;
-				goto out_err;
-			}
+/*
+ * 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];
+		if (!rcache->cpu_rcaches)
+			break;
+		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]);
 	}
 
-	ret = cpuhp_state_add_instance_nocalls(CPUHP_IOMMU_IOVA_DEAD,
-					       &iovad->cpuhp_dead);
-	if (ret)
-		goto out_err;
-	return 0;
+	kfree(iovad->rcaches);
+	iovad->rcaches = NULL;
+}
 
-out_err:
+static void iova_domain_free_rcaches(struct iova_domain *iovad)
+{
+	cpuhp_state_remove_instance_nocalls(CPUHP_IOMMU_IOVA_DEAD,
+					    &iovad->cpuhp_dead);
 	free_iova_rcaches(iovad);
-	return ret;
 }
-EXPORT_SYMBOL_GPL(iova_domain_init_rcaches);
 
 /*
  * Try inserting IOVA range starting with 'iova_pfn' into 'rcache', and
@@ -883,73 +733,212 @@ static unsigned long iova_rcache_get(struct iova_domain *iovad,
 	return __iova_rcache_get(&iovad->rcaches[log_size], limit_pfn - size);
 }
 
-/*
- * free rcache data structures.
+/**
+ * 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.
  */
-static void free_iova_rcaches(struct iova_domain *iovad)
+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;
+
+	/*
+	 * Freeing non-power-of-two-sized allocations back into the IOVA caches
+	 * will come back to bite us badly, so we have to waste a bit of space
+	 * rounding up anything cacheable to make sure that can't happen. The
+	 * order of the unadjusted size will still match upon freeing.
+	 */
+	if (size < (1 << (IOVA_RANGE_CACHE_MAX_SIZE - 1)))
+		size = roundup_pow_of_two(size);
+
+	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;
+}
+EXPORT_SYMBOL_GPL(alloc_iova_fast);
+
+/**
+ * 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);
+}
+EXPORT_SYMBOL_GPL(free_iova_fast);
+
+int iova_domain_init_rcaches(struct iova_domain *iovad)
 {
-	struct iova_rcache *rcache;
-	struct iova_cpu_rcache *cpu_rcache;
 	unsigned int cpu;
-	int i, j;
+	int i, ret;
+
+	iovad->rcaches = kcalloc(IOVA_RANGE_CACHE_MAX_SIZE,
+				 sizeof(struct iova_rcache),
+				 GFP_KERNEL);
+	if (!iovad->rcaches)
+		return -ENOMEM;
 
 	for (i = 0; i < IOVA_RANGE_CACHE_MAX_SIZE; ++i) {
+		struct iova_cpu_rcache *cpu_rcache;
+		struct iova_rcache *rcache;
+
 		rcache = &iovad->rcaches[i];
-		if (!rcache->cpu_rcaches)
-			break;
+		spin_lock_init(&rcache->lock);
+		rcache->depot_size = 0;
+		rcache->cpu_rcaches = __alloc_percpu(sizeof(*cpu_rcache),
+						     cache_line_size());
+		if (!rcache->cpu_rcaches) {
+			ret = -ENOMEM;
+			goto out_err;
+		}
 		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);
+
+			spin_lock_init(&cpu_rcache->lock);
+			cpu_rcache->loaded = iova_magazine_alloc(GFP_KERNEL);
+			cpu_rcache->prev = iova_magazine_alloc(GFP_KERNEL);
+			if (!cpu_rcache->loaded || !cpu_rcache->prev) {
+				ret = -ENOMEM;
+				goto out_err;
+			}
 		}
-		free_percpu(rcache->cpu_rcaches);
-		for (j = 0; j < rcache->depot_size; ++j)
-			iova_magazine_free(rcache->depot[j]);
 	}
 
-	kfree(iovad->rcaches);
-	iovad->rcaches = NULL;
+	ret = cpuhp_state_add_instance_nocalls(CPUHP_IOMMU_IOVA_DEAD,
+					       &iovad->cpuhp_dead);
+	if (ret)
+		goto out_err;
+	return 0;
+
+out_err:
+	free_iova_rcaches(iovad);
+	return ret;
 }
+EXPORT_SYMBOL_GPL(iova_domain_init_rcaches);
 
-/*
- * 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)
+void
+init_iova_domain(struct iova_domain *iovad, unsigned long granule,
+	unsigned long start_pfn)
 {
-	struct iova_cpu_rcache *cpu_rcache;
-	struct iova_rcache *rcache;
-	unsigned long flags;
-	int i;
+	/*
+	 * 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));
 
-	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);
-	}
+	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->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);
 }
+EXPORT_SYMBOL_GPL(init_iova_domain);
 
-/*
- * free all the IOVA ranges of global cache
+/**
+ * put_iova_domain - destroys the iova domain
+ * @iovad: - iova domain in question.
+ * All the iova's in that domain are destroyed.
  */
-static void free_global_cached_iovas(struct iova_domain *iovad)
+void put_iova_domain(struct iova_domain *iovad)
 {
-	struct iova_rcache *rcache;
-	unsigned long flags;
-	int i, j;
+	struct iova *iova, *tmp;
 
-	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]);
+	if (iovad->rcaches)
+		iova_domain_free_rcaches(iovad);
+
+	rbtree_postorder_for_each_entry_safe(iova, tmp, &iovad->rbroot, node)
+		free_iova_mem(iova);
+}
+EXPORT_SYMBOL_GPL(put_iova_domain);
+
+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;
 		}
-		rcache->depot_size = 0;
-		spin_unlock_irqrestore(&rcache->lock, flags);
+
+		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);
+
 MODULE_AUTHOR("Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>");
 MODULE_LICENSE("GPL");
diff --git a/include/linux/iova.h b/include/linux/iova.h
index 320a70e40233..a167fb22c899 100644
--- a/include/linux/iova.h
+++ b/include/linux/iova.h
@@ -76,35 +76,26 @@ static inline unsigned long iova_pfn(struct iova_domain *iovad, dma_addr_t iova)
 }
 
 #if IS_ENABLED(CONFIG_IOMMU_IOVA)
-int iova_cache_get(void);
-void iova_cache_put(void);
-
 void free_iova(struct iova_domain *iovad, unsigned long pfn);
 void __free_iova(struct iova_domain *iovad, struct iova *iova);
 struct iova *alloc_iova(struct iova_domain *iovad, unsigned long size,
 	unsigned long limit_pfn,
 	bool size_aligned);
+struct iova *reserve_iova(struct iova_domain *iovad, unsigned long pfn_lo,
+	unsigned long pfn_hi);
+struct iova *find_iova(struct iova_domain *iovad, unsigned long pfn);
 void free_iova_fast(struct iova_domain *iovad, unsigned long pfn,
 		    unsigned long size);
 unsigned long alloc_iova_fast(struct iova_domain *iovad, unsigned long size,
 			      unsigned long limit_pfn, bool flush_rcache);
-struct iova *reserve_iova(struct iova_domain *iovad, unsigned long pfn_lo,
-	unsigned long pfn_hi);
+int iova_domain_init_rcaches(struct iova_domain *iovad);
 void init_iova_domain(struct iova_domain *iovad, unsigned long granule,
 	unsigned long start_pfn);
-int iova_domain_init_rcaches(struct iova_domain *iovad);
-struct iova *find_iova(struct iova_domain *iovad, unsigned long pfn);
 void put_iova_domain(struct iova_domain *iovad);
-#else
-static inline int iova_cache_get(void)
-{
-	return -ENOTSUPP;
-}
-
-static inline void iova_cache_put(void)
-{
-}
+int iova_cache_get(void);
+void iova_cache_put(void);
 
+#else
 static inline void free_iova(struct iova_domain *iovad, unsigned long pfn)
 {
 }
@@ -121,6 +112,19 @@ static inline struct iova *alloc_iova(struct iova_domain *iovad,
 	return NULL;
 }
 
+static inline struct iova *reserve_iova(struct iova_domain *iovad,
+					unsigned long pfn_lo,
+					unsigned long pfn_hi)
+{
+	return NULL;
+}
+
+static inline struct iova *find_iova(struct iova_domain *iovad,
+				     unsigned long pfn)
+{
+	return NULL;
+}
+
 static inline void free_iova_fast(struct iova_domain *iovad,
 				  unsigned long pfn,
 				  unsigned long size)
@@ -135,12 +139,6 @@ static inline unsigned long alloc_iova_fast(struct iova_domain *iovad,
 	return 0;
 }
 
-static inline struct iova *reserve_iova(struct iova_domain *iovad,
-					unsigned long pfn_lo,
-					unsigned long pfn_hi)
-{
-	return NULL;
-}
 
 static inline void init_iova_domain(struct iova_domain *iovad,
 				    unsigned long granule,
@@ -148,13 +146,17 @@ static inline void init_iova_domain(struct iova_domain *iovad,
 {
 }
 
-static inline struct iova *find_iova(struct iova_domain *iovad,
-				     unsigned long pfn)
+
+static inline void put_iova_domain(struct iova_domain *iovad)
 {
-	return NULL;
 }
 
-static inline void put_iova_domain(struct iova_domain *iovad)
+static inline int iova_cache_get(void)
+{
+	return -ENOTSUPP;
+}
+
+static inline void iova_cache_put(void)
 {
 }
 
-- 
2.35.3