[RFC PATCH 4/6] iommu: Split 'addr_merge' argument to iommu_pgsize() into separate parts

[Will Deacon]

The 'addr_merge' parameter to iommu_pgsize() is a fabricated address
intended to describe the alignment requirements to consider when
choosing an appropriate page size. On the iommu_map() path, this address
is the logical OR of the virtual and physical addresses.

Subsequent improvements to iommu_pgsize() will need to check the
alignment of the virtual and physical components of 'addr_merge'
independently, so pass them in as separate parameters and reconstruct
'addr_merge' locally.

No functional change.

Signed-off-by: Will Deacon <will at kernel.org>
---
 drivers/iommu/iommu.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index bcd623862bf9..ab689611a03b 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2357,12 +2357,13 @@ phys_addr_t iommu_iova_to_phys(struct iommu_domain *domain, dma_addr_t iova)
 }
 EXPORT_SYMBOL_GPL(iommu_iova_to_phys);
 
-static size_t iommu_pgsize(struct iommu_domain *domain,
-			   unsigned long addr_merge, size_t size)
+static size_t iommu_pgsize(struct iommu_domain *domain, unsigned long iova,
+			   phys_addr_t paddr, size_t size)
 {
 	unsigned int pgsize_idx;
 	unsigned long pgsizes;
 	size_t pgsize;
+	phys_addr_t addr_merge = paddr | iova;
 
 	/* Page sizes supported by the hardware and small enough for @size */
 	pgsizes = domain->pgsize_bitmap & GENMASK(__fls(size), 0);
@@ -2415,7 +2416,7 @@ static int __iommu_map(struct iommu_domain *domain, unsigned long iova,
 	pr_debug("map: iova 0x%lx pa %pa size 0x%zx\n", iova, &paddr, size);
 
 	while (size) {
-		size_t pgsize = iommu_pgsize(domain, iova | paddr, size);
+		size_t pgsize = iommu_pgsize(domain, iova, paddr, size);
 
 		pr_debug("mapping: iova 0x%lx pa %pa pgsize 0x%zx\n",
 			 iova, &paddr, pgsize);
@@ -2503,8 +2504,9 @@ static size_t __iommu_unmap(struct iommu_domain *domain,
 	 * or we hit an area that isn't mapped.
 	 */
 	while (unmapped < size) {
-		size_t pgsize = iommu_pgsize(domain, iova, size - unmapped);
+		size_t pgsize;
 
+		pgsize = iommu_pgsize(domain, iova, iova, size - unmapped);
 		unmapped_page = ops->unmap(domain, iova, pgsize, iotlb_gather);
 		if (!unmapped_page)
 			break;
-- 
2.31.0.291.g576ba9dcdaf-goog