[PATCH v4 3/5] iommu/uapi: Use named union for user data

[Jacob Pan]

IOMMU UAPI data size is filled by the user space which must be validated
by ther kernel. To ensure backward compatibility, user data can only be
extended by either re-purpose padding bytes or extend the variable sized
union at the end. No size change is allowed before the union. Therefore,
the minimum size is the offset of the union.

To use offsetof() on the union, we must make it named.

Link: https://lkml.org/lkml/2020/6/11/834
Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
---
 drivers/iommu/intel/iommu.c | 24 ++++++++++++------------
 drivers/iommu/intel/svm.c   |  2 +-
 include/uapi/linux/iommu.h  |  4 ++--
 3 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 50fc62413a35..abd70b618a3f 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -5409,8 +5409,8 @@ intel_iommu_sva_invalidate(struct iommu_domain *domain, struct device *dev,
 
 	/* Size is only valid in address selective invalidation */
 	if (inv_info->granularity == IOMMU_INV_GRANU_ADDR)
-		size = to_vtd_size(inv_info->addr_info.granule_size,
-				   inv_info->addr_info.nb_granules);
+		size = to_vtd_size(inv_info->granu.addr_info.granule_size,
+				   inv_info->granu.addr_info.nb_granules);
 
 	for_each_set_bit(cache_type,
 			 (unsigned long *)&inv_info->cache,
@@ -5431,20 +5431,20 @@ intel_iommu_sva_invalidate(struct iommu_domain *domain, struct device *dev,
 		 * granularity.
 		 */
 		if (inv_info->granularity == IOMMU_INV_GRANU_PASID &&
-		    (inv_info->pasid_info.flags & IOMMU_INV_PASID_FLAGS_PASID))
-			pasid = inv_info->pasid_info.pasid;
+		    (inv_info->granu.pasid_info.flags & IOMMU_INV_PASID_FLAGS_PASID))
+			pasid = inv_info->granu.pasid_info.pasid;
 		else if (inv_info->granularity == IOMMU_INV_GRANU_ADDR &&
-			 (inv_info->addr_info.flags & IOMMU_INV_ADDR_FLAGS_PASID))
-			pasid = inv_info->addr_info.pasid;
+			 (inv_info->granu.addr_info.flags & IOMMU_INV_ADDR_FLAGS_PASID))
+			pasid = inv_info->granu.addr_info.pasid;
 
 		switch (BIT(cache_type)) {
 		case IOMMU_CACHE_INV_TYPE_IOTLB:
 			/* HW will ignore LSB bits based on address mask */
 			if (inv_info->granularity == IOMMU_INV_GRANU_ADDR &&
 			    size &&
-			    (inv_info->addr_info.addr & ((BIT(VTD_PAGE_SHIFT + size)) - 1))) {
+			    (inv_info->granu.addr_info.addr & ((BIT(VTD_PAGE_SHIFT + size)) - 1))) {
 				WARN_ONCE(1, "Address out of range, 0x%llx, size order %llu\n",
-					  inv_info->addr_info.addr, size);
+					  inv_info->granu.addr_info.addr, size);
 			}
 
 			/*
@@ -5452,9 +5452,9 @@ intel_iommu_sva_invalidate(struct iommu_domain *domain, struct device *dev,
 			 * We use npages = -1 to indicate that.
 			 */
 			qi_flush_piotlb(iommu, did, pasid,
-					mm_to_dma_pfn(inv_info->addr_info.addr),
+					mm_to_dma_pfn(inv_info->granu.addr_info.addr),
 					(granu == QI_GRAN_NONG_PASID) ? -1 : 1 << size,
-					inv_info->addr_info.flags & IOMMU_INV_ADDR_FLAGS_LEAF);
+					inv_info->granu.addr_info.flags & IOMMU_INV_ADDR_FLAGS_LEAF);
 
 			if (!info->ats_enabled)
 				break;
@@ -5475,13 +5475,13 @@ intel_iommu_sva_invalidate(struct iommu_domain *domain, struct device *dev,
 				size = 64 - VTD_PAGE_SHIFT;
 				addr = 0;
 			} else if (inv_info->granularity == IOMMU_INV_GRANU_ADDR)
-				addr = inv_info->addr_info.addr;
+				addr = inv_info->granu.addr_info.addr;
 
 			if (info->ats_enabled)
 				qi_flush_dev_iotlb_pasid(iommu, sid,
 						info->pfsid, pasid,
 						info->ats_qdep,
-						inv_info->addr_info.addr,
+						inv_info->granu.addr_info.addr,
 						size);
 			else
 				pr_warn_ratelimited("Passdown device IOTLB flush w/o ATS!\n");
diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
index d386853121a2..713b3a218483 100644
--- a/drivers/iommu/intel/svm.c
+++ b/drivers/iommu/intel/svm.c
@@ -338,7 +338,7 @@ int intel_svm_bind_gpasid(struct iommu_domain *domain, struct device *dev,
 	spin_lock(&iommu->lock);
 	ret = intel_pasid_setup_nested(iommu, dev,
 				       (pgd_t *)(uintptr_t)data->gpgd,
-				       data->hpasid, &data->vtd, dmar_domain,
+				       data->hpasid, &data->vendor.vtd, dmar_domain,
 				       data->addr_width);
 	spin_unlock(&iommu->lock);
 	if (ret) {
diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h
index 303f148a5cd7..1afc6610b0ad 100644
--- a/include/uapi/linux/iommu.h
+++ b/include/uapi/linux/iommu.h
@@ -263,7 +263,7 @@ struct iommu_cache_invalidate_info {
 	union {
 		struct iommu_inv_pasid_info pasid_info;
 		struct iommu_inv_addr_info addr_info;
-	};
+	} granu;
 };
 
 /**
@@ -329,7 +329,7 @@ struct iommu_gpasid_bind_data {
 	/* Vendor specific data */
 	union {
 		struct iommu_gpasid_bind_data_vtd vtd;
-	};
+	} vendor;
 };
 
 #endif /* _UAPI_IOMMU_H */
-- 
2.7.4