From 5e25537af702fdc66c123f3d563b7352bbf10c83 Mon Sep 17 00:00:00 2001 From: Liam Mark Date: Wed, 26 Feb 2020 14:16:19 -0800 Subject: [PATCH] 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: Isaac J. Manjarres --- drivers/iommu/dma-iommu.c | 18 ++++++++++ drivers/iommu/iova.c | 74 +++++++++++++++++++++++++++++++++++++-- include/linux/dma-iommu.h | 7 ++++ include/linux/iova.h | 1 + 4 files changed, 98 insertions(+), 2 deletions(-) diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c index 8cdb2436f4d0..5227a45905d3 100644 --- a/drivers/iommu/dma-iommu.c +++ b/drivers/iommu/dma-iommu.c @@ -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. diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c index 0e6a9536eca6..9e95de2c9103 100644 --- a/drivers/iommu/iova.c +++ b/drivers/iommu/iova.c @@ -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 @@ iova32_full: 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; - ret = __alloc_and_insert_iova_range(iovad, size, limit_pfn + 1, - new_iova, size_aligned); + 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); diff --git a/include/linux/dma-iommu.h b/include/linux/dma-iommu.h index 79eef7cf9013..f51561eda33b 100644 --- a/include/linux/dma-iommu.h +++ b/include/linux/dma-iommu.h @@ -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 */ diff --git a/include/linux/iova.h b/include/linux/iova.h index a0637abffee8..58713bb72a48 100644 --- a/include/linux/iova.h +++ b/include/linux/iova.h @@ -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)