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iommu/vt-d: Require DMA domain if hardware not support passthrough
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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
Signed-off-by: Joerg Roedel <jroedel@suse.de>
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Lu Baolu authored and Joerg Roedel committed Sep 2, 2024
1 parent 7c626ce commit 184bee3
Showing 1 changed file with 10 additions and 0 deletions.
10 changes: 10 additions & 0 deletions drivers/iommu/intel/iommu.c
Original file line number Diff line number Diff line change
Expand Up @@ -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);

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