[PATCH v3 1/7] iommu/vt-d: Require DMA domain if hardware not support passthrough

[Lu Baolu <baolu.lu@linux.intel.com>]

The iommu core defines the def_domain_type callback to query the iommu
driver about hardware capability and quirks. The iommu driver should
declare IOMMU_DOMAIN_DMA requirement for hardware lacking pass-through
capability.

Earlier VT-d hardware implementations did not support pass-through
translation mode. The iommu driver relied on a paging domain with all
physical system memory addresses identically mapped to the same IOVA
to simulate pass-through translation before the def_domain_type was
introduced and it has been kept until now. It's time to adjust it now
to make the Intel iommu driver follow the def_domain_type semantics.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/iommu/intel/iommu.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 9ff8b83c19a3..90ad794a1be7 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -2149,6 +2149,16 @@ static bool device_rmrr_is_relaxable(struct device *dev)
 
 static int device_def_domain_type(struct device *dev)
 {
+	struct device_domain_info *info = dev_iommu_priv_get(dev);
+	struct intel_iommu *iommu = info->iommu;
+
+	/*
+	 * Hardware does not support the passthrough translation mode.
+	 * Always use a dynamaic mapping domain.
+	 */
+	if (!ecap_pass_through(iommu->ecap))
+		return IOMMU_DOMAIN_DMA;
+
 	if (dev_is_pci(dev)) {
 		struct pci_dev *pdev = to_pci_dev(dev);
 
-- 
2.34.1