Messages in this thread | | | From | "Tian, Kevin" <> | Subject | RE: [PATCH v2 3/8] iommu/vt-d: Implement device_pasid domain attach ops | Date | Fri, 18 Mar 2022 05:33:38 +0000 |
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> From: Jacob Pan > Sent: Thursday, March 17, 2022 5:02 AM > > Hi Kevin, > > On Wed, 16 Mar 2022 07:41:34 +0000, "Tian, Kevin" <kevin.tian@intel.com> > wrote: > > > > From: Jason Gunthorpe <jgg@nvidia.com> > > > Sent: Tuesday, March 15, 2022 10:33 PM > > > > > > On Mon, Mar 14, 2022 at 10:07:07PM -0700, Jacob Pan wrote: > > > > + /* > > > > + * Each domain could have multiple devices attached with > > > > shared or > > > per > > > > + * device PASIDs. At the domain level, we keep track of > > > > unique PASIDs > > > and > > > > + * device user count. > > > > + * E.g. If a domain has two devices attached, device A has > > > > PASID 0, 1; > > > > + * device B has PASID 0, 2. Then the domain would have PASID > > > > 0, 1, 2. > > > > + */ > > > > > > A 2d array of xarray's seems like a poor data structure for this task. > > > Perhaps i mis-presented here, I am not using 2D array. It is an 1D xarray > for domain PASIDs only. Then I use the existing device list in each domain, > adding another xa to track per-device-domain PASIDs. > > besides that it also doesn't work when we support per-device PASID > > allocation in the future. In that case merging device PASIDs together is > > conceptually wrong. > > > Sorry, could you elaborate? If we do per-dev PASID allocation, we could use > the ioasid_set for each pdev, right?
My point is simply about the comment above which says the domain will have PASID 0, 1, 2 when there is [devA, PASID0] and [devB, PASID0]. You can maintain a single PASID list only when it's globally allocated cross devices. otherwise this has to be a tuple including device and PASID.
Thanks Kevin
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