[PATCH 2/4] iommu/vt-d: Enable write protect propagation from guest

[Jacob Pan]

Write protect bit, when set, inhibits supervisor writes to the read-only
pages. In guest supervisor shared virtual addressing (SVA), write-protect
should be honored upon guest bind supervisor PASID request.

This patch extends the VT-d portion of the IOMMU UAPI to include WP bit.
WPE bit of the  supervisor PASID entry will be set to match CPU CR0.WP bit.

Signed-off-by: Sanjay Kumar <sanjay.k.kumar@xxxxxxxxx>
Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
---
 drivers/iommu/intel/pasid.c | 5 +++++
 include/uapi/linux/iommu.h  | 3 ++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c
index 0b7e0e726ade..c7a2ec930af4 100644
--- a/drivers/iommu/intel/pasid.c
+++ b/drivers/iommu/intel/pasid.c
@@ -763,6 +763,11 @@ intel_pasid_setup_bind_data(struct intel_iommu *iommu, struct pasid_entry *pte,
 			return -EINVAL;
 		}
 		pasid_set_sre(pte);
+		/* Enable write protect WP if guest requested */
+		if (pasid_data->flags & IOMMU_SVA_VTD_GPASID_WPE) {
+			if (pasid_enable_wpe(pte))
+				return -EINVAL;
+		}
 	}
 
 	if (pasid_data->flags & IOMMU_SVA_VTD_GPASID_EAFE) {
diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h
index 68cb558fe8db..33f3dc7a91de 100644
--- a/include/uapi/linux/iommu.h
+++ b/include/uapi/linux/iommu.h
@@ -288,7 +288,8 @@ struct iommu_gpasid_bind_data_vtd {
 #define IOMMU_SVA_VTD_GPASID_PWT	(1 << 3) /* page-level write through */
 #define IOMMU_SVA_VTD_GPASID_EMTE	(1 << 4) /* extended mem type enable */
 #define IOMMU_SVA_VTD_GPASID_CD		(1 << 5) /* PASID-level cache disable */
-#define IOMMU_SVA_VTD_GPASID_LAST	(1 << 6)
+#define IOMMU_SVA_VTD_GPASID_WPE	(1 << 6) /* Write protect enable */
+#define IOMMU_SVA_VTD_GPASID_LAST	(1 << 7)
 	__u64 flags;
 	__u32 pat;
 	__u32 emt;
-- 
2.25.1