iommu/vt-d: Reserve a domain id for FL and PT modes

Vt-d spec rev3.0 (section 6.2.3.1) requires that each pasid
entry for first-level or pass-through translation should be
programmed with a domain id different from those used for
second-level or nested translation. It is recommended that
software could use a same domain id for all first-only and
pass-through translations.

This reserves a domain id for first-level and pass-through
translations.

Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: Kevin Tian <kevin.tian@intel.com>
Cc: Liu Yi L <yi.l.liu@intel.com>
Cc: Sanjay Kumar <sanjay.k.kumar@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/intel-iommu.c

@@ -1621,6 +1621,16 @@ static int iommu_init_domains(struct intel_iommu *iommu)
 	 */
 	set_bit(0, iommu->domain_ids);
 
+	/*
+	 * Vt-d spec rev3.0 (section 6.2.3.1) requires that each pasid
+	 * entry for first-level or pass-through translation modes should
+	 * be programmed with a domain id different from those used for
+	 * second-level or nested translation. We reserve a domain id for
+	 * this purpose.
+	 */
+	if (sm_supported(iommu))
+		set_bit(FLPT_DEFAULT_DID, iommu->domain_ids);
+
 	return 0;
 }
 

drivers/iommu/intel-pasid.h

@@ -17,6 +17,12 @@
 #define PDE_PFN_MASK			PAGE_MASK
 #define PASID_PDE_SHIFT			6
 
+/*
+ * Domain ID reserved for pasid entries programmed for first-level
+ * only and pass-through transfer modes.
+ */
+#define FLPT_DEFAULT_DID		1
+
 struct pasid_dir_entry {
 	u64 val;
 };