Messages in this thread | | | From | "Tian, Kevin" <> | Subject | RE: [PATCH v7 03/10] iommu/sva: Add iommu_sva_domain support | Date | Wed, 25 May 2022 00:44:28 +0000 |
| |
> From: Jason Gunthorpe <jgg@nvidia.com> > Sent: Tuesday, May 24, 2022 9:39 PM > > On Tue, May 24, 2022 at 09:39:52AM +0000, Tian, Kevin wrote: > > > 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. > > I thought we agreed we'd use the blocking domain for this? Why did it > go back to an op? >
Probably it's based on following discussion:
https://lore.kernel.org/all/c8492b29-bc27-ae12-d5c4-9fbbc797e310@linux.intel.com/
-- > FWIW from my point of view I'm happy with having a .detach_dev_pasid op > meaning implicitly-blocked access for now.
If this is the path then lets not call it attach/detach please. 'set_dev_pasid' and 'set_dev_blocking_pasid' are clearer names. --
Looks Baolu chooses this path and plans to use the blocking domain later.
Thanks Kevin
| |