1 files changed, 50 insertions, 13 deletions

diff --git a/drivers/pci/iova.c b/drivers/pci/iova.c
index 717fafaa7e02..a84571c29360 100644
--- a/drivers/pci/iova.c
+++ b/drivers/pci/iova.c
@@ -57,12 +57,28 @@ __cached_rbnode_delete_update(struct iova_domain *iovad, struct iova *free)
                 iovad->cached32_node = rb_next(&free->node);
 }
 
-static int __alloc_iova_range(struct iova_domain *iovad,
-        unsigned long size, unsigned long limit_pfn, struct iova *new)
+/* Computes the padding size required, to make the
+ * the start address naturally aligned on its size
+ */
+static int
+iova_get_pad_size(int size, unsigned int limit_pfn)
+{
+        unsigned int pad_size = 0;
+        unsigned int order = ilog2(size);
+
+        if (order)
+                pad_size = (limit_pfn + 1) % (1 << order);
+
+        return pad_size;
+}
+
+static int __alloc_iova_range(struct iova_domain *iovad, unsigned long size,
+                unsigned long limit_pfn, struct iova *new, bool size_aligned)
 {
         struct rb_node *curr = NULL;
         unsigned long flags;
         unsigned long saved_pfn;
+        unsigned int pad_size = 0;
 
         /* Walk the tree backwards */
         spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
@@ -72,22 +88,32 @@ static int __alloc_iova_range(struct iova_domain *iovad,
                 struct iova *curr_iova = container_of(curr, struct iova, node);
                 if (limit_pfn < curr_iova->pfn_lo)
                         goto move_left;
-                if (limit_pfn < curr_iova->pfn_hi)
+                else if (limit_pfn < curr_iova->pfn_hi)
                         goto adjust_limit_pfn;
-                if ((curr_iova->pfn_hi + size) <= limit_pfn)
-                        break;  /* found a free slot */
+                else {
+                        if (size_aligned)
+                                pad_size = iova_get_pad_size(size, limit_pfn);
+                        if ((curr_iova->pfn_hi + size + pad_size) <= limit_pfn)
+                                break;  /* found a free slot */
+                }
 adjust_limit_pfn:
                 limit_pfn = curr_iova->pfn_lo - 1;
 move_left:
                 curr = rb_prev(curr);
         }
 
-        if ((!curr) && !(IOVA_START_PFN + size <= limit_pfn)) {
-                spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
-                return -ENOMEM;
+        if (!curr) {
+                if (size_aligned)
+                        pad_size = iova_get_pad_size(size, limit_pfn);
+                if ((IOVA_START_PFN + size + pad_size) > limit_pfn) {
+                        spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
+                        return -ENOMEM;
+                }
         }
-        new->pfn_hi = limit_pfn;
-        new->pfn_lo = limit_pfn - size + 1;
+
+        /* pfn_lo will point to size aligned address if size_aligned is set */
+        new->pfn_lo = limit_pfn - (size + pad_size) + 1;
+        new->pfn_hi = new->pfn_lo + size - 1;
 
         spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
         return 0;
@@ -119,12 +145,16 @@ iova_insert_rbtree(struct rb_root *root, struct iova *iova)
  * @iovad - iova domain in question
  * @size - size of page frames to allocate
  * @limit_pfn - max limit address
+ * @size_aligned - set if size_aligned address range is required
  * This function allocates an iova in the range limit_pfn to IOVA_START_PFN
- * looking from limit_pfn instead from IOVA_START_PFN.
+ * looking from limit_pfn instead from IOVA_START_PFN. If the size_aligned
+ * flag is set then the allocated address iova->pfn_lo will be naturally
+ * aligned on roundup_power_of_two(size).
  */
 struct iova *
 alloc_iova(struct iova_domain *iovad, unsigned long size,
-        unsigned long limit_pfn)
+        unsigned long limit_pfn,
+        bool size_aligned)
 {
         unsigned long flags;
         struct iova *new_iova;
@@ -134,8 +164,15 @@ alloc_iova(struct iova_domain *iovad, unsigned long size,
         if (!new_iova)
                 return NULL;
 
+        /* If size aligned is set then round the size to
+         * to next power of two.
+         */
+        if (size_aligned)
+                size = __roundup_pow_of_two(size);
+
         spin_lock_irqsave(&iovad->iova_alloc_lock, flags);
-        ret = __alloc_iova_range(iovad, size, limit_pfn, new_iova);
+        ret = __alloc_iova_range(iovad, size, limit_pfn, new_iova,
+                        size_aligned);
 
         if (ret) {
                 spin_unlock_irqrestore(&iovad->iova_alloc_lock, flags);