[PATCH 01/14] iommu/vt-d: Require DMA domain if hardware not support passthrough

Lu Baolu
2024-09-02T02:31:21Z

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>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Link: https://lore.kernel.org/r/20240809055431.36513-2-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 4aa070cf56e7..5193986e420b 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -2151,6 +2151,16 @@ 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