[PATCH v3 2/6] iommu/iova: insert start_pfn boundary of dma32

From: Zhen Lei
Date: Thu May 18 2017 - 04:04:10 EST


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@xxxxxxxxxx>
---
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