[PATCH 5.12 495/677] iommu/vt-d: Remove WO permissions on second-level paging entries

[Greg Kroah-Hartman]

From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>

[ Upstream commit eea53c5816889ee8b64544fa2e9311a81184ff9c ]

When the first level page table is used for IOVA translation, it only
supports Read-Only and Read-Write permissions. The Write-Only permission
is not supported as the PRESENT bit (implying Read permission) should
always set. When using second level, we still give separate permissions
that allows WriteOnly which seems inconsistent and awkward. We want to
have consistent behavior. After moving to 1st level, we don't want things
to work sometimes, and break if we use 2nd level for the same mappings.
Hence remove this configuration.

Suggested-by: Ashok Raj <ashok.raj@xxxxxxxxx>
Fixes: b802d070a52a1 ("iommu/vt-d: Use iova over first level")
Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210320025415.641201-3-baolu.lu@xxxxxxxxxxxxxxx
Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/iommu/intel/iommu.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index b5d3301b2700..36d60536ae8d 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -2346,8 +2346,9 @@ __domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
 		return -EINVAL;
 
 	attr = prot & (DMA_PTE_READ | DMA_PTE_WRITE | DMA_PTE_SNP);
+	attr |= DMA_FL_PTE_PRESENT;
 	if (domain_use_first_level(domain)) {
-		attr |= DMA_FL_PTE_PRESENT | DMA_FL_PTE_XD | DMA_FL_PTE_US;
+		attr |= DMA_FL_PTE_XD | DMA_FL_PTE_US;
 
 		if (domain->domain.type == IOMMU_DOMAIN_DMA) {
 			attr |= DMA_FL_PTE_ACCESS;
-- 
2.30.2