Messages in this thread | | | From | "Tian, Kevin" <> | Subject | RE: [PATCH v2 12/12] iommu/vt-d: Retire struct intel_svm | Date | Thu, 11 Apr 2024 08:32:11 +0000 |
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> From: Baolu Lu <baolu.lu@linux.intel.com> > Sent: Thursday, April 11, 2024 3:56 PM > > On 2024/4/10 23:49, Jason Gunthorpe wrote: > > On Wed, Apr 10, 2024 at 10:08:44AM +0800, Lu Baolu wrote: > >> @@ -4388,14 +4386,8 @@ static void > intel_iommu_remove_dev_pasid(struct device *dev, ioasid_t pasid) > >> WARN_ON_ONCE(!dev_pasid); > >> spin_unlock_irqrestore(&dmar_domain->lock, flags); > >> > >> - /* > >> - * The SVA implementation needs to handle its own stuffs like the > mm > >> - * notification. Before consolidating that code into iommu core, let > >> - * the intel sva code handle it. > >> - */ > >> if (domain->type == IOMMU_DOMAIN_SVA) { > >> cache_tag_unassign_domain(dmar_domain, > FLPT_DEFAULT_DID, dev, pasid); > >> - intel_svm_remove_dev_pasid(domain); > >> } else { > >> did = domain_id_iommu(dmar_domain, iommu); > >> cache_tag_unassign_domain(dmar_domain, did, dev, pasid); > > > > It seems very strange that SVA has a different DID scheme, why is > > this? PASID and SVA should not be different at this layer. > > The VT-d spec recommends that all SVA domains share a single domain ID. > The PASID is unique to each SVA domain, hence the cache tags are unique. > Currently, the Intel IOMMU driver assigns different domain IDs for all > domains except the SVA type. > > Sharing a domain ID is not specific to SVA. In general, for devices > under a single IOMMU, domains with unique PASIDs can share the same > domain ID. > > In the long term (also on my task list), we will extend the cache tag > code to support sharing domain IDs and remove the domain type check from > the main code. This will also benefit the nesting case, where user > domains nested on the same parent could share a domain ID. >
at least above might be changed to a unified call with the helper accepting an iommu parameter and then finding proper did internally based on domain type, e.g.
cache_tag_unassign_domain(domain, iommu, dev, pasid) { if (domain->type == IOMMU_DOMAIN_SVA) did = FLPT_DEFAULT_DID; else did = domain_id_iommu(domain, iommu);
... }
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