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    Subject[PATCH v3 2/6] iommu/iova: insert start_pfn boundary of dma32
    Date
    Reserve the first granule size memory(start at start_pfn) as boundary
    iova, to make sure that iovad->cached32_node can not be NULL in future.
    Meanwhile, changed the assignment of iovad->cached32_node from rb_next to
    rb_prev of &free->node in function __cached_rbnode_delete_update.

    Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
    ---
    drivers/iommu/iova.c | 63 ++++++++++++++++++++++++++++++----------------------
    1 file changed, 37 insertions(+), 26 deletions(-)

    diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
    index 333a9cc..d0c19ec 100644
    --- a/drivers/iommu/iova.c
    +++ b/drivers/iommu/iova.c
    @@ -32,6 +32,17 @@ static unsigned long iova_rcache_get(struct iova_domain *iovad,
    static void init_iova_rcaches(struct iova_domain *iovad);
    static void free_iova_rcaches(struct iova_domain *iovad);

    +static void
    +insert_iova_boundary(struct iova_domain *iovad)
    +{
    + struct iova *iova;
    + unsigned long start_pfn_32bit = iovad->start_pfn;
    +
    + iova = reserve_iova(iovad, start_pfn_32bit, start_pfn_32bit);
    + BUG_ON(!iova);
    + iovad->cached32_node = &iova->node;
    +}
    +
    void
    init_iova_domain(struct iova_domain *iovad, unsigned long granule,
    unsigned long start_pfn, unsigned long pfn_32bit)
    @@ -45,27 +56,38 @@ init_iova_domain(struct iova_domain *iovad, unsigned long granule,

    spin_lock_init(&iovad->iova_rbtree_lock);
    iovad->rbroot = RB_ROOT;
    - iovad->cached32_node = NULL;
    iovad->granule = granule;
    iovad->start_pfn = start_pfn;
    iovad->dma_32bit_pfn = pfn_32bit;
    init_iova_rcaches(iovad);
    +
    + /*
    + * Insert boundary nodes for dma32. So cached32_node can not be NULL in
    + * future.
    + */
    + insert_iova_boundary(iovad);
    }
    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) ||
    - (iovad->cached32_node == NULL))
    + struct rb_node *cached_node;
    + struct rb_node *next_node;
    +
    + if (*limit_pfn > iovad->dma_32bit_pfn)
    return rb_last(&iovad->rbroot);
    - else {
    - struct rb_node *prev_node = rb_prev(iovad->cached32_node);
    - struct iova *curr_iova =
    - rb_entry(iovad->cached32_node, struct iova, node);
    - *limit_pfn = curr_iova->pfn_lo - 1;
    - return prev_node;
    + else
    + cached_node = iovad->cached32_node;
    +
    + next_node = rb_next(cached_node);
    + if (next_node) {
    + struct iova *next_iova = rb_entry(next_node, struct iova, node);
    +
    + *limit_pfn = min(*limit_pfn, next_iova->pfn_lo - 1);
    }
    +
    + return cached_node;
    }

    static void
    @@ -83,20 +105,13 @@ __cached_rbnode_delete_update(struct iova_domain *iovad, struct iova *free)
    struct iova *cached_iova;
    struct rb_node *curr;

    - if (!iovad->cached32_node)
    - return;
    curr = iovad->cached32_node;
    cached_iova = rb_entry(curr, struct iova, node);

    if (free->pfn_lo >= cached_iova->pfn_lo) {
    - struct rb_node *node = rb_next(&free->node);
    - struct iova *iova = rb_entry(node, struct iova, node);
    -
    /* only cache if it's below 32bit pfn */
    - if (node && iova->pfn_lo < iovad->dma_32bit_pfn)
    - iovad->cached32_node = node;
    - else
    - iovad->cached32_node = NULL;
    + if (free->pfn_hi <= iovad->dma_32bit_pfn)
    + iovad->cached32_node = rb_prev(&free->node);
    }
    }

    @@ -142,7 +157,7 @@ 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 *prev, *curr = NULL;
    + struct rb_node *prev, *curr;
    unsigned long flags;
    unsigned long saved_pfn;
    unsigned int pad_size = 0;
    @@ -172,13 +187,9 @@ static int __alloc_and_insert_iova_range(struct iova_domain *iovad,
    curr = rb_prev(curr);
    }

    - if (!curr) {
    - if (size_aligned)
    - pad_size = iova_get_pad_size(size, limit_pfn);
    - if ((iovad->start_pfn + size + pad_size) > limit_pfn) {
    - spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
    - return -ENOMEM;
    - }
    + if (unlikely(!curr)) {
    + spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
    + return -ENOMEM;
    }

    /* pfn_lo will point to size aligned address if size_aligned is set */
    --
    2.5.0

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