iommu/vt-d: Enable write protect propagation from guest

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: NSanjay Kumar <sanjay.k.kumar@intel.com>
Signed-off-by: NJacob Pan <jacob.jun.pan@linux.intel.com>
Acked-by: NLu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/1614680040-1989-3-git-send-email-jacob.jun.pan@linux.intel.comSigned-off-by: NJoerg Roedel <jroedel@suse.de>

drivers/iommu/intel/pasid.c

@@ -732,6 +732,9 @@ 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)
+			pasid_set_wpe(pte);
 	}
 
 	if (pasid_data->flags & IOMMU_SVA_VTD_GPASID_EAFE) {

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;