Currently, the identity domain attachment follows the same path as the paging domain attachment and is subject to the same compatibility checks as a normal paging domain. However, this level of check is unnecessary for the identity domain since it only requires the hardware to support passthrough mode, which is a given for modern hardware. On the early VT-d platforms, where hardware passthrough mode is not yet supported, the identity domain is supported by a makeshift paging domain with the entire system memory 1:1 mapped. For such early hardware, the appropriate domain type should be returned in device_def_domain_type(), and the identity domain should be simplified in compatibility checks. The identity domain workaround in prepare_domain_attach_device() is just temporary and should be removed once the identity domain is converted to have its own dedicated attachment path. Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx> --- drivers/iommu/intel/iommu.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index eb8e08699b80..693a6d7c79ed 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -2190,6 +2190,16 @@ 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); @@ -3802,6 +3812,14 @@ int prepare_domain_attach_device(struct iommu_domain *domain, struct intel_iommu *iommu = info->iommu; int addr_width; + /* + * This is a temporary solution as the identity domain attachment + * goes through this path as well. It should be removed once the + * identity domain has its own attach path. + */ + if (domain->type == IOMMU_DOMAIN_IDENTITY) + return ecap_pass_through(iommu->ecap) ? 0 : -EOPNOTSUPP; + if (dmar_domain->force_snooping && !ecap_sc_support(iommu->ecap)) return -EINVAL; -- 2.34.1