Messages in this thread | | | From | "Tian, Kevin" <> | Subject | RE: [PATCH v7 03/10] iommu/sva: Add iommu_sva_domain support | Date | Tue, 24 May 2022 09:39:52 +0000 |
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> From: Lu Baolu <baolu.lu@linux.intel.com> > Sent: Thursday, May 19, 2022 3:21 PM > > The iommu_sva_domain represents a hardware pagetable that the IOMMU > hardware could use for SVA translation. This adds some infrastructure > to support SVA domain in the iommu common layer. It includes: > > - Add a new struct iommu_sva_domain and new IOMMU_DOMAIN_SVA > domain > type. > - Add a new domain ops pointer in iommu_ops. The IOMMU drivers that > support SVA should provide the callbacks. > - Add helpers to allocate and free an SVA domain. > - Add helpers to set an SVA domain to a device and the reverse > operation. > > Some buses, like PCI, route packets without considering the PASID value. > Thus a DMA target address with PASID might be treated as P2P if the > address falls into the MMIO BAR of other devices in the group. To make > things simple, the attach/detach interfaces only apply to devices > belonging to the singleton groups, and the singleton is immutable in > fabric i.e. not affected by hotplug. > > The iommu_set/block_device_pasid() can be used for other purposes, > such as kernel DMA with pasid, mediation device, etc. Hence, it is put > in the iommu.c.
usually we have 'set/clear' pair or 'allow/block'. Having 'set' paired with 'block' doesn't read very clearly.
> +static bool device_group_immutable_singleton(struct device *dev) > +{ > + struct iommu_group *group = iommu_group_get(dev);
what about passing group as the parameter since the caller will get the group again right after calling this function? In that case the function could be renamed as:
iommu_group_immutable_singleton()
or be shorter:
iommu_group_fixed_singleton()
> + int count; > + > + if (!group) > + return false; > + > + mutex_lock(&group->mutex); > + count = iommu_group_device_count(group); > + mutex_unlock(&group->mutex); > + iommu_group_put(group); > + > + if (count != 1) > + return false;
For non-pci devices above doesn't check anything against immutable. Please add some comment to explain why doing so is correct.
> + > + /* > + * The PCI device could be considered to be fully isolated if all > + * devices on the path from the device to the host-PCI bridge are > + * protected from peer-to-peer DMA by ACS. > + */ > + if (dev_is_pci(dev)) > + return pci_acs_path_enabled(to_pci_dev(dev), NULL, > + REQ_ACS_FLAGS); > + > + return true; > +} > +
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