iommu/dma: Respect IOMMU aperture when allocating

Where a device driver has set a 64-bit DMA mask to indicate the absence
of addressing limitations, we still need to ensure that we don't
allocate IOVAs beyond the actual input size of the IOMMU. The reported
aperture is the most reliable way we have of inferring that input
address size, so use that to enforce a hard upper limit where available.

Fixes: 0db2e5d18f76 ("iommu: Implement common IOMMU ops for DMA mapping")
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 7d991c8..00c8a08 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -152,12 +152,15 @@
 	}
 }
 
-static struct iova *__alloc_iova(struct iova_domain *iovad, size_t size,
+static struct iova *__alloc_iova(struct iommu_domain *domain, size_t size,
 		dma_addr_t dma_limit)
 {
+	struct iova_domain *iovad = domain->iova_cookie;
 	unsigned long shift = iova_shift(iovad);
 	unsigned long length = iova_align(iovad, size) >> shift;
 
+	if (domain->geometry.force_aperture)
+		dma_limit = min(dma_limit, domain->geometry.aperture_end);
 	/*
 	 * Enforce size-alignment to be safe - there could perhaps be an
 	 * attribute to control this per-device, or at least per-domain...
@@ -315,7 +318,7 @@
 	if (!pages)
 		return NULL;
 
-	iova = __alloc_iova(iovad, size, dev->coherent_dma_mask);
+	iova = __alloc_iova(domain, size, dev->coherent_dma_mask);
 	if (!iova)
 		goto out_free_pages;
 
@@ -387,7 +390,7 @@
 	phys_addr_t phys = page_to_phys(page) + offset;
 	size_t iova_off = iova_offset(iovad, phys);
 	size_t len = iova_align(iovad, size + iova_off);
-	struct iova *iova = __alloc_iova(iovad, len, dma_get_mask(dev));
+	struct iova *iova = __alloc_iova(domain, len, dma_get_mask(dev));
 
 	if (!iova)
 		return DMA_ERROR_CODE;
@@ -539,7 +542,7 @@
 		prev = s;
 	}
 
-	iova = __alloc_iova(iovad, iova_len, dma_get_mask(dev));
+	iova = __alloc_iova(domain, iova_len, dma_get_mask(dev));
 	if (!iova)
 		goto out_restore_sg;