diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 54d96e847f16..41ff22748276 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -757,6 +757,17 @@ static int dma_info_to_prot(enum dma_data_direction dir, bool coherent,
 	}
 }
 
+static unsigned long size_to_iova_len(struct iova_domain *iovad, size_t size)
+{
+	size_t guard_size = 0;
+
+	/* allocate optional guard pages after the requested mapping */
+	if (1)
+		guard_size = iova_align(iovad, 1024 << 10);
+
+	return (size + guard_size) >> iova_shift(iovad);
+}
+
 static dma_addr_t iommu_dma_alloc_iova(struct iommu_domain *domain,
 		size_t size, u64 dma_limit, struct device *dev)
 {
@@ -770,7 +781,7 @@ static dma_addr_t iommu_dma_alloc_iova(struct iommu_domain *domain,
 	}
 
 	shift = iova_shift(iovad);
-	iova_len = size >> shift;
+	iova_len = size_to_iova_len(iovad, size);
 
 	dma_limit = min_not_zero(dma_limit, dev->bus_dma_limit);
 
@@ -807,17 +818,21 @@ static void iommu_dma_free_iova(struct iommu_domain *domain, dma_addr_t iova,
 				size_t size, struct iommu_iotlb_gather *gather)
 {
 	struct iova_domain *iovad = &domain->iova_cookie->iovad;
+	unsigned long iova_len;
 
 	/* The MSI case is only ever cleaning up its most recent allocation */
-	if (domain->cookie_type == IOMMU_COOKIE_DMA_MSI)
+	if (domain->cookie_type == IOMMU_COOKIE_DMA_MSI) {
 		domain->msi_cookie->msi_iova -= size;
-	else if (gather && gather->queued)
+		return;
+	}
+
+	iova_len = size_to_iova_len(iovad, size);
+
+	if (gather && gather->queued)
 		queue_iova(domain->iova_cookie, iova_pfn(iovad, iova),
-				size >> iova_shift(iovad),
-				&gather->freelist);
+				iova_len, &gather->freelist);
 	else
-		free_iova_fast(iovad, iova_pfn(iovad, iova),
-				size >> iova_shift(iovad));
+		free_iova_fast(iovad, iova_pfn(iovad, iova), iova_len);
 }
 
 static void __iommu_dma_unmap(struct device *dev, dma_addr_t dma_addr,