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    SubjectRe: [PATCH v4] iommu/iova: Optimise attempts to allocate iova from 32bit address range
    Hi Joerg,

    can you please pull this patch?

    On Wed, Sep 5, 2018 at 9:58 AM Ganapatrao Kulkarni
    <ganapatrao.kulkarni@cavium.com> wrote:
    >
    > As an optimisation for PCI devices, there is always first attempt
    > been made to allocate iova from SAC address range. This will lead
    > to unnecessary attempts, when there are no free ranges
    > available. Adding fix to track recently failed iova address size and
    > allow further attempts, only if requested size is lesser than a failed
    > size. The size is updated when any replenish happens.
    >
    > Reviewed-by: Robin Murphy <robin.murphy@arm.com>
    > Signed-off-by: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com>
    > ---
    > v4:
    > Rebsaed to 4.19-rc2
    > v3:
    > Update with comments [3] from Robin Murphy <robin.murphy@arm.com>
    >
    > [3] https://lkml.org/lkml/2018/8/13/116
    >
    > v2: update with comments [2] from Robin Murphy <robin.murphy@arm.com>
    >
    > [2] https://lkml.org/lkml/2018/8/7/166
    >
    > v1: Based on comments from Robin Murphy <robin.murphy@arm.com>
    > for patch [1]
    >
    > [1] https://lkml.org/lkml/2018/4/19/780
    >
    > drivers/iommu/iova.c | 22 +++++++++++++++-------
    > include/linux/iova.h | 1 +
    > 2 files changed, 16 insertions(+), 7 deletions(-)
    >
    > diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
    > index 83fe2621effe..f8d3ba247523 100644
    > --- a/drivers/iommu/iova.c
    > +++ b/drivers/iommu/iova.c
    > @@ -56,6 +56,7 @@ init_iova_domain(struct iova_domain *iovad, unsigned long granule,
    > 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;
    > @@ -139,8 +140,10 @@ __cached_rbnode_delete_update(struct iova_domain *iovad, struct iova *free)
    >
    > cached_iova = rb_entry(iovad->cached32_node, struct iova, node);
    > if (free->pfn_hi < iovad->dma_32bit_pfn &&
    > - free->pfn_lo >= cached_iova->pfn_lo)
    > + free->pfn_lo >= cached_iova->pfn_lo) {
    > iovad->cached32_node = rb_next(&free->node);
    > + iovad->max32_alloc_size = iovad->dma_32bit_pfn;
    > + }
    >
    > cached_iova = rb_entry(iovad->cached_node, struct iova, node);
    > if (free->pfn_lo >= cached_iova->pfn_lo)
    > @@ -190,6 +193,10 @@ static int __alloc_and_insert_iova_range(struct iova_domain *iovad,
    >
    > /* 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 = rb_entry(curr, struct iova, node);
    > do {
    > @@ -200,10 +207,8 @@ static int __alloc_and_insert_iova_range(struct iova_domain *iovad,
    > curr_iova = rb_entry(curr, struct iova, node);
    > } while (curr && new_pfn <= curr_iova->pfn_hi);
    >
    > - if (limit_pfn < size || new_pfn < iovad->start_pfn) {
    > - spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
    > - return -ENOMEM;
    > - }
    > + if (limit_pfn < size || new_pfn < iovad->start_pfn)
    > + goto iova32_full;
    >
    > /* pfn_lo will point to size aligned address if size_aligned is set */
    > new->pfn_lo = new_pfn;
    > @@ -214,9 +219,12 @@ static int __alloc_and_insert_iova_range(struct iova_domain *iovad,
    > __cached_rbnode_insert_update(iovad, new);
    >
    > spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
    > -
    > -
    > return 0;
    > +
    > +iova32_full:
    > + iovad->max32_alloc_size = size;
    > + spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
    > + return -ENOMEM;
    > }
    >
    > static struct kmem_cache *iova_cache;
    > diff --git a/include/linux/iova.h b/include/linux/iova.h
    > index 928442dda565..0b93bf96693e 100644
    > --- a/include/linux/iova.h
    > +++ b/include/linux/iova.h
    > @@ -75,6 +75,7 @@ struct iova_domain {
    > unsigned long granule; /* pfn granularity for this domain */
    > unsigned long start_pfn; /* Lower limit for this domain */
    > unsigned long dma_32bit_pfn;
    > + unsigned long max32_alloc_size; /* Size of last failed allocation */
    > struct iova anchor; /* rbtree lookup anchor */
    > struct iova_rcache rcaches[IOVA_RANGE_CACHE_MAX_SIZE]; /* IOVA range caches */
    >
    > --
    > 2.18.0
    >
    thanks,
    Ganapat

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