RE: [PATCH v4 06/12] iommu/vt-d: Set the nested domain to a device

From: Liu, Yi L yi.l.liu@intel.com Sent: Monday, July 24, 2023 7:13 PM

+static int intel_nested_attach_dev(struct iommu_domain *domain,

• 		   struct device *dev)
  

+{

• 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;
• unsigned long flags;
• int ret = 0;
• if (info->domain)

• device_block_translation(dev);
  

• if (iommu->agaw < dmar_domain->s2_domain->agaw) {

• dev_err_ratelimited(dev, "Adjusted guest address width not
  

compatible\n");

• return -ENODEV;
  

• }

this is the check duplicated with patch04.

• ret = domain_attach_iommu(dmar_domain, iommu);
• if (ret) {

• dev_err_ratelimited(dev, "Failed to attach domain to
  

iommu\n");

• return ret;
  

• }

[...]

• domain_update_iommu_cap(dmar_domain);

iommu_cap is already updated in domain_attach_iommu().

static const struct iommu_domain_ops intel_nested_domain_ops = {

• .attach_dev = intel_nested_attach_dev, .free = intel_nested_domain_free,
• .enforce_cache_coherency = intel_iommu_enforce_cache_coherency,

this is not required. enforce_cache_coherency() will be called on parent hwpt when it's being created. patch04 should check parent's force_snooping to set pgsnp in the pasid entry.

As Jason explained it should be done only for kernel owned page table.