[PATCH 1/4] iommu/vt-d: Implement set device pasid op for default domain

[Jacob Pan <jacob.jun.pan@linux.intel.com>]

On VT-d platforms, legacy DMA requests without PASID use device’s
default domain, where RID_PASID is always attached. Device drivers
can then use the DMA API for all in-kernel DMA on the RID.

Ideally, devices capable of using ENQCMDS can also transparently use the
default domain, consequently DMA API. However, VT-d architecture
dictates that the PASID used by ENQCMDS must be different from the
RID_PASID value.

To provide support for transparent use of DMA API with non-RID_PASID
value, this patch implements the set_dev_pasid() function for the
default domain. The idea is that device drivers wishing to use ENQCMDS
to submit work on buffers mapped by DMA API will call
iommu_attach_device_pasid() beforehand.

Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
---
 drivers/iommu/intel/iommu.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 10f657828d3a..a0cb3bc851ac 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -4665,6 +4665,10 @@ static void intel_iommu_remove_dev_pasid(struct device *dev, ioasid_t pasid)
 		case IOMMU_DOMAIN_SVA:
 			intel_svm_remove_dev_pasid(dev, pasid);
 			break;
+		case IOMMU_DOMAIN_DMA:
+		case IOMMU_DOMAIN_DMA_FQ:
+		case IOMMU_DOMAIN_IDENTITY:
+			break;
 		default:
 			/* should never reach here */
 			WARN_ON(1);
@@ -4675,6 +4679,33 @@ static void intel_iommu_remove_dev_pasid(struct device *dev, ioasid_t pasid)
 	intel_pasid_tear_down_entry(iommu, dev, pasid, false);
 }
 
+static int intel_iommu_set_dev_pasid(struct iommu_domain *domain,
+				   struct device *dev, ioasid_t pasid)
+{
+	struct device_domain_info *info = dev_iommu_priv_get(dev);
+	struct dmar_domain *dmar_domain = to_dmar_domain(domain);
+	struct intel_iommu *iommu = info->iommu;
+	int ret = 0;
+
+	if (!sm_supported(iommu) || !info)
+		return -ENODEV;
+
+	if (WARN_ON(pasid == PASID_RID2PASID))
+		return -EINVAL;
+
+	if (hw_pass_through && domain_type_is_si(dmar_domain))
+		ret = intel_pasid_setup_pass_through(iommu, dmar_domain,
+						     dev, pasid);
+	else if (dmar_domain->use_first_level)
+		ret = domain_setup_first_level(iommu, dmar_domain,
+					       dev, pasid);
+	else
+		ret = intel_pasid_setup_second_level(iommu, dmar_domain,
+						     dev, pasid);
+
+	return ret;
+}
+
 const struct iommu_ops intel_iommu_ops = {
 	.capable		= intel_iommu_capable,
 	.domain_alloc		= intel_iommu_domain_alloc,
@@ -4702,6 +4733,7 @@ const struct iommu_ops intel_iommu_ops = {
 		.iova_to_phys		= intel_iommu_iova_to_phys,
 		.free			= intel_iommu_domain_free,
 		.enforce_cache_coherency = intel_iommu_enforce_cache_coherency,
+		.set_dev_pasid		= intel_iommu_set_dev_pasid,
 	}
 };
 
-- 
2.25.1