iommu/vt-d: Return ID associated with an auxiliary domain

This adds support to return the default pasid associated with
an auxiliary domain. The PCI device which is bound with this
domain should use this value as the pasid for all DMA requests
of the subset of device which is isolated and protected with
this domain.

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

@@ -5697,6 +5697,15 @@ intel_iommu_dev_feat_enabled(struct device *dev, enum iommu_dev_features feat)
 	return false;
 }
 
+static int
+intel_iommu_aux_get_pasid(struct iommu_domain *domain, struct device *dev)
+{
+	struct dmar_domain *dmar_domain = to_dmar_domain(domain);
+
+	return dmar_domain->default_pasid > 0 ?
+			dmar_domain->default_pasid : -EINVAL;
+}
+
 const struct iommu_ops intel_iommu_ops = {
 	.capable		= intel_iommu_capable,
 	.domain_alloc		= intel_iommu_domain_alloc,
@@ -5705,6 +5714,7 @@ const struct iommu_ops intel_iommu_ops = {
 	.detach_dev		= intel_iommu_detach_device,
 	.aux_attach_dev		= intel_iommu_aux_attach_device,
 	.aux_detach_dev		= intel_iommu_aux_detach_device,
+	.aux_get_pasid		= intel_iommu_aux_get_pasid,
 	.map			= intel_iommu_map,
 	.unmap			= intel_iommu_unmap,
 	.iova_to_phys		= intel_iommu_iova_to_phys,