iommu/vt-d: Use user privilege for RID2PASID translation

When first-level page tables are used for IOVA translation, we use user
privilege by setting U/S bit in the page table entry. This is to make it
consistent with the second level translation, where the U/S enforcement
is not available. Clear the SRE (Supervisor Request Enable) field in the
pasid table entry of RID2PASID so that requests requesting the supervisor
privilege are blocked and treated as DMA remapping faults.

Fixes: b802d070 ("iommu/vt-d: Use iova over first level")
Suggested-by: NJacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: NLu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210512064426.3440915-1-baolu.lu@linux.intel.com
Link: https://lore.kernel.org/r/20210519015027.108468-3-baolu.lu@linux.intel.comSigned-off-by: NJoerg Roedel <jroedel@suse.de>

drivers/iommu/intel/iommu.c

@@ -2525,9 +2525,9 @@ static int domain_setup_first_level(struct intel_iommu *iommu,
 				    struct device *dev,
 				    u32 pasid)
 {
-	int flags = PASID_FLAG_SUPERVISOR_MODE;
 	struct dma_pte *pgd = domain->pgd;
 	int agaw, level;
+	int flags = 0;
 
 	/*
 	 * Skip top levels of page tables for iommu which has
@@ -2543,7 +2543,10 @@ static int domain_setup_first_level(struct intel_iommu *iommu,
 	if (level != 4 && level != 5)
 		return -EINVAL;
 
-	flags |= (level == 5) ? PASID_FLAG_FL5LP : 0;
+	if (pasid != PASID_RID2PASID)
+		flags |= PASID_FLAG_SUPERVISOR_MODE;
+	if (level == 5)
+		flags |= PASID_FLAG_FL5LP;
 
 	if (domain->domain.type == IOMMU_DOMAIN_UNMANAGED)
 		flags |= PASID_FLAG_PAGE_SNOOP;

drivers/iommu/intel/pasid.c

@@ -699,7 +699,8 @@ int intel_pasid_setup_second_level(struct intel_iommu *iommu,
 	 * Since it is a second level only translation setup, we should
 	 * set SRE bit as well (addresses are expected to be GPAs).
 	 */
-	pasid_set_sre(pte);
+	if (pasid != PASID_RID2PASID)
+		pasid_set_sre(pte);
 	pasid_set_present(pte);
 	pasid_flush_caches(iommu, pte, pasid, did);