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Commit 5e25537a authored by Liam Mark's avatar Liam Mark Committed by Todd Kjos
Browse files

FROMLIST: iommu/iova: Add a best-fit algorithm 

Using the best-fit algorithm, instead of the first-fit
algorithm, may reduce fragmentation when allocating
IOVAs.

Bug: 149544392
Link: https://lore.kernel.org/lkml/7239ddd532e94a4371289f3be23c66a3@codeaurora.org/


Change-Id: Icfbac0cc7be972a092915335508cbc73c47471cf
Signed-off-by: default avatarIsaac J. Manjarres <isaacm@codeaurora.org>
parent 741f92f5

drivers/iommu/dma-iommu.c

+18 −0
Original line number Diff line number Diff line
@@ -380,6 +380,24 @@ int iommu_dma_reserve_iova(struct device *dev, dma_addr_t base, 
}

EXPORT_SYMBOL(iommu_dma_reserve_iova);



/*

 * Should be called prior to using dma-apis.

 */

int iommu_dma_enable_best_fit_algo(struct device *dev)

{

	struct iommu_domain *domain;

	struct iova_domain *iovad;



	domain = iommu_get_domain_for_dev(dev);

	if (!domain || !domain->iova_cookie)

		return -EINVAL;



	iovad = &((struct iommu_dma_cookie *)domain->iova_cookie)->iovad;

	iovad->best_fit = true;

	return 0;

}

EXPORT_SYMBOL(iommu_dma_enable_best_fit_algo);



/**

 * dma_info_to_prot - Translate DMA API directions and attributes to IOMMU API

 *                    page flags.

drivers/iommu/iova.c

+72 −2
Original line number Diff line number Diff line
@@ -50,6 +50,7 @@ init_iova_domain(struct iova_domain *iovad, unsigned long granule, 
	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);

	iovad->best_fit = false;

	init_iova_rcaches(iovad);

}

EXPORT_SYMBOL_GPL(init_iova_domain);
@@ -227,6 +228,70 @@ static int __alloc_and_insert_iova_range(struct iova_domain *iovad, 
	return -ENOMEM;

}



static int __alloc_and_insert_iova_best_fit(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, *prev_iova;

	unsigned long flags;

	unsigned long align_mask = ~0UL;

	struct rb_node *candidate_rb_parent;

	unsigned long new_pfn, candidate_pfn = ~0UL;

	unsigned long gap, candidate_gap = ~0UL;



	if (size_aligned)

		align_mask <<= limit_align(iovad, fls_long(size - 1));



	/* Walk the tree backwards */

	spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);

	curr = &iovad->anchor.node;

	prev = rb_prev(curr);

	for (; prev; curr = prev, prev = rb_prev(curr)) {

		curr_iova = rb_entry(curr, struct iova, node);

		prev_iova = rb_entry(prev, struct iova, node);



		limit_pfn = min(limit_pfn, curr_iova->pfn_lo);

		new_pfn = (limit_pfn - size) & align_mask;

		gap = curr_iova->pfn_lo - prev_iova->pfn_hi - 1;

		if ((limit_pfn >= size) && (new_pfn > prev_iova->pfn_hi)

				&& (gap < candidate_gap)) {

			candidate_gap = gap;

			candidate_pfn = new_pfn;

			candidate_rb_parent = curr;

			if (gap == size)

				goto insert;

		}

	}



	curr_iova = rb_entry(curr, struct iova, node);

	limit_pfn = min(limit_pfn, curr_iova->pfn_lo);

	new_pfn = (limit_pfn - size) & align_mask;

	gap = curr_iova->pfn_lo - iovad->start_pfn;

	if (limit_pfn >= size && new_pfn >= iovad->start_pfn &&

			gap < candidate_gap) {

		candidate_gap = gap;

		candidate_pfn = new_pfn;

		candidate_rb_parent = curr;

	}



insert:

	if (candidate_pfn == ~0UL) {

		spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);

		return -ENOMEM;

	}



	/* pfn_lo will point to size aligned address if size_aligned is set */

	new->pfn_lo = candidate_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, candidate_rb_parent);

	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);

	return 0;

}



static struct kmem_cache *iova_cache;

static unsigned int iova_cache_users;

static DEFINE_MUTEX(iova_cache_mutex);
@@ -302,8 +367,13 @@ alloc_iova(struct iova_domain *iovad, unsigned long size, 
	if (!new_iova)

		return NULL;



	if (iovad->best_fit) {

		ret = __alloc_and_insert_iova_range(iovad, size,

				limit_pfn + 1, new_iova, size_aligned);

	} else {

		ret = __alloc_and_insert_iova_range(iovad, size, limit_pfn + 1,

				new_iova, size_aligned);

	}



	if (ret) {

		free_iova_mem(new_iova);

include/linux/dma-iommu.h

+7 −0
Original line number Diff line number Diff line
@@ -40,6 +40,8 @@ void iommu_dma_get_resv_regions(struct device *dev, struct list_head *list); 
int iommu_dma_reserve_iova(struct device *dev, dma_addr_t base,

			   u64 size);



int iommu_dma_enable_best_fit_algo(struct device *dev);



#else /* CONFIG_IOMMU_DMA */



struct iommu_domain;
@@ -87,5 +89,10 @@ static inline int iommu_dma_reserve_iova(struct device *dev, dma_addr_t base, 
	return -ENODEV;

}



static inline int iommu_dma_enable_best_fit_algo(struct device *dev)

{

	return -ENODEV;

}



#endif	/* CONFIG_IOMMU_DMA */

#endif	/* __DMA_IOMMU_H */

include/linux/iova.h

+1 −0
Original line number Diff line number Diff line
@@ -95,6 +95,7 @@ struct iova_domain { 
						   flush-queues */

	atomic_t fq_timer_on;			/* 1 when timer is active, 0

						   when not */

	bool best_fit;

};



static inline unsigned long iova_size(struct iova *iova)