1 files changed, 19 insertions, 0 deletions

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index a3b7072e86e2..341573821864 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -41,6 +41,24 @@
 
 #define LOOP_TIMEOUT    100000
 
+/*
+ * This bitmap is used to advertise the page sizes our hardware support
+ * to the IOMMU core, which will then use this information to split
+ * physically contiguous memory regions it is mapping into page sizes
+ * that we support.
+ *
+ * Traditionally the IOMMU core just handed us the mappings directly,
+ * after making sure the size is an order of a 4KiB page and that the
+ * mapping has natural alignment.
+ *
+ * To retain this behavior, we currently advertise that we support
+ * all page sizes that are an order of 4KiB.
+ *
+ * If at some point we'd like to utilize the IOMMU core's new behavior,
+ * we could change this to advertise the real page sizes we support.
+ */
+#define AMD_IOMMU_PGSIZES       (~0xFFFUL)
+
 static DEFINE_RWLOCK(amd_iommu_devtable_lock);
 
 /* A list of preallocated protection domains */
@@ -2779,6 +2797,7 @@ static struct iommu_ops amd_iommu_ops = {
         .unmap = amd_iommu_unmap,
         .iova_to_phys = amd_iommu_iova_to_phys,
         .domain_has_cap = amd_iommu_domain_has_cap,
+        .pgsize_bitmap  = AMD_IOMMU_PGSIZES,
 };
 
 /*****************************************************************************