iommu: Introduce a callback to struct iommu_resv_region

A callback is introduced to struct iommu_resv_region to free memory
allocations associated with the reserved region. This will be useful
when we introduce support for IORT RMR based reserved regions.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Steven Price <steven.price@arm.com>
Tested-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
Tested-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/20220615101044.1972-2-shameerali.kolothum.thodi@huawei.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index cdc86c3..f46431a 100644 (file)
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2590,16 +2590,22 @@ void iommu_put_resv_regions(struct device *dev, struct list_head *list)
  * @list: reserved region list for device
  *
  * IOMMU drivers can use this to implement their .put_resv_regions() callback
- * for simple reservations. Memory allocated for each reserved region will be
- * freed. If an IOMMU driver allocates additional resources per region, it is
- * going to have to implement a custom callback.
+ * for simple reservations. If a per region callback is provided that will be
+ * used to free all memory allocations associated with the reserved region or
+ * else just free up the memory for the regions. If an IOMMU driver allocates
+ * additional resources per region, it is going to have to implement a custom
+ * callback.
  */
 void generic_iommu_put_resv_regions(struct device *dev, struct list_head *list)
 {
        struct iommu_resv_region *entry, *next;
 
-       list_for_each_entry_safe(entry, next, list, list)
-               kfree(entry);
+       list_for_each_entry_safe(entry, next, list, list) {
+               if (entry->free)
+                       entry->free(dev, entry);
+               else
+                       kfree(entry);
+       }
 }
 EXPORT_SYMBOL(generic_iommu_put_resv_regions);
 

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 5e1afe1..b22ffa6 100644 (file)
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -135,6 +135,7 @@ enum iommu_resv_type {
  * @length: Length of the region in bytes
  * @prot: IOMMU Protection flags (READ/WRITE/...)
  * @type: Type of the reserved region
+ * @free: Callback to free associated memory allocations
  */
 struct iommu_resv_region {
        struct list_head        list;
@@ -142,6 +143,7 @@ struct iommu_resv_region {
        size_t                  length;
        int                     prot;
        enum iommu_resv_type    type;
+       void (*free)(struct device *dev, struct iommu_resv_region *region);
 };
 
 /**