Messages in this thread | | | Date | Sat, 11 Mar 2023 09:18:30 -0800 | Subject | Re: [PATCH v4 3/6] iommu/sva: Stop using ioasid_set for SVA | From | Fenghua Yu <> |
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Hi, Jason and Jacob,
On 3/8/23 10:23, Jason Gunthorpe wrote: > On Tue, Mar 07, 2023 at 02:32:09PM -0800, Jacob Pan wrote: >> Hi Jason, >> >> On Fri, 3 Mar 2023 09:15:45 -0400, Jason Gunthorpe <jgg@nvidia.com> wrote: >> >>> On Fri, Mar 03, 2023 at 05:57:41PM +0800, Baolu Lu wrote: >>>> On 2023/3/3 17:32, Jean-Philippe Brucker wrote: >>>>>> I suppose the common thing is reserving some kind of special >>>>>> PASIDs. >>>>> Are you planning to use RID_PASID != 0 in VT-d? Otherwise we could >>>>> just communicate min_pasid from the IOMMU driver the same way we do >>>>> max_pasid. >>>>> >>>>> Otherwise I guess re-introduce a lighter ioasid_alloc() that the IOMMU >>>>> driver calls to reserve PASID0/RID_PASID. >>>> >>>> Yes. We probably will use a non-zero RID_PASID in the future. An >>>> interface to reserve (or allocate) a PASID from iommu_global_pasid_ida >>>> should work then. >>> >>> Just allowing the driver to store XA_ZERO_ENTRY would be fine >>> >> It looks like there are incoming users of iommu_sva_find() >> https://lore.kernel.org/lkml/20230306163138.587484-1-fenghua.yu@intel.com/T/#m1fc97725a0e56ea269c8bdabacee447070d51846 >> Should we keep the xa here instead of the global ida? > > I'm not sure this should be in the iommu core, it is really gross. > > I would expect IDXD to keep track of the PASID's and mms it is using > and do this kind of stuff itself. > > And why is this using access_remote_vm anyhow? If you know you are in > a kthread then kthread_use_mm() is probably better anyhow. > > In any event we don't need a iommu_sva_find() function to wrapper > xa_load for another function inside the same .c file.
Ok. I will maintain mm and find mm from PASID inside IDXD driver. And will implement accessing the remote mm inside IDXD driver although the implementation will have duplicate code as access_remote_vm().
Thanks.
-Fenghua
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