iommu: Streamline iommu_iova_to_phys()

If people are going to insist on calling iommu_iova_to_phys()
pointlessly and expecting it to work, we can at least do ourselves a
favour by handling those cases in the core code, rather than repeatedly
across an inconsistent handful of drivers.

Since all the existing drivers implement the internal callback, and any
future ones are likely to want to work with iommu-dma which relies on
iova_to_phys a fair bit, we may as well remove that currently-redundant
check as well and consider it mandatory.

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/f564f3f6ff731b898ff7a898919bf871c2c7745a.1626354264.git.robin.murphy@arm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/amd/io_pgtable.c

@@ -493,9 +493,6 @@ static phys_addr_t iommu_v1_iova_to_phys(struct io_pgtable_ops *ops, unsigned lo
 	unsigned long offset_mask, pte_pgsize;
 	u64 *pte, __pte;
 
-	if (pgtable->mode == PAGE_MODE_NONE)
-		return iova;
-
 	pte = fetch_pte(pgtable, iova, &pte_pgsize);
 
 	if (!pte || !IOMMU_PTE_PRESENT(*pte))

drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c

@@ -2488,9 +2488,6 @@ arm_smmu_iova_to_phys(struct iommu_domain *domain, dma_addr_t iova)
 {
 	struct io_pgtable_ops *ops = to_smmu_domain(domain)->pgtbl_ops;
 
-	if (domain->type == IOMMU_DOMAIN_IDENTITY)
-		return iova;
-
 	if (!ops)
 		return 0;
 

drivers/iommu/arm/arm-smmu/arm-smmu.c

@@ -1322,9 +1322,6 @@ static phys_addr_t arm_smmu_iova_to_phys(struct iommu_domain *domain,
 	struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
 	struct io_pgtable_ops *ops = smmu_domain->pgtbl_ops;
 
-	if (domain->type == IOMMU_DOMAIN_IDENTITY)
-		return iova;
-
 	if (!ops)
 		return 0;
 

drivers/iommu/iommu.c

@@ -2372,7 +2372,10 @@ EXPORT_SYMBOL_GPL(iommu_detach_group);
 
 phys_addr_t iommu_iova_to_phys(struct iommu_domain *domain, dma_addr_t iova)
 {
-	if (unlikely(domain->ops->iova_to_phys == NULL))
+	if (domain->type == IOMMU_DOMAIN_IDENTITY)
+		return iova;
+
+	if (domain->type == IOMMU_DOMAIN_BLOCKED)
 		return 0;
 
 	return domain->ops->iova_to_phys(domain, iova);