Messages in this thread | | | Date | Mon, 4 Apr 2022 14:24:03 -0300 | From | Jason Gunthorpe <> | Subject | Re: [PATCH RFC v2 02/11] iommu: Add iommu_group_singleton_lockdown() |
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On Mon, Apr 04, 2022 at 01:43:49PM +0800, Lu Baolu wrote: > On 2022/3/30 19:58, Jason Gunthorpe wrote: > > > > Testing the group size is inherently the wrong test to make. > > > What is your suggestion then? > > Add a flag to the group that positively indicates the group can never > > have more than one member, even after hot plug. eg because it is > > impossible due to ACS, or lack of bridges, and so on. > > The check method seems to be bus specific. For platform devices, perhaps > this kind of information should be retrieved from firmware interfaces > like APCI or DT. > > From this point of view, would it be simpler and more reasonable for the > device driver to do such check? After all, it is the device driver that > decides whether to provide SVA services to the application via uacce.
The check has to do with the interconnect, not the device - I don't see how a device driver would know any better.
Why do you bring up uacce? Nothing should need uacce to access SVA.
Jason
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