> From: Jason Gunthorpe <jgg@xxxxxxxx> > Sent: Wednesday, August 2, 2023 10:16 PM > > On Tue, Aug 01, 2023 at 02:31:23PM +0800, Lu Baolu wrote: > > The PCI PASID enabling interface guarantees that the address space used > > by each PASID is unique. This is achieved by checking that the PCI ACS > > path is enabled for the device. If the path is not enabled, then the > > PASID feature cannot be used. > > > > if (!pci_acs_path_enabled(pdev, NULL, PCI_ACS_RR | PCI_ACS_UF)) > > return -EINVAL; > > > > The PASID array is not an attribute of the IOMMU group. It is more > > natural to store the PASID array in the per-device IOMMU data. This > > makes the code clearer and easier to understand. No functional changes > > are intended. > > Is there a reason to do this? > > *PCI* requires the ACS/etc because PCI kind of messed up how switches > handled PASID so PASID doesn't work otherwise. > > But there is nothing that says other bus type can't have working > (non-PCI) PASID and still have device isolation issues. > > So unless there is a really strong reason to do this we should keep > the PASID list in the group just like the domain. > this comes from the consensus in [1]. [1] https://lore.kernel.org/linux-iommu/ZAcyEzN4102gPsWC@xxxxxxxxxx/
