Messages in this thread | | | Date | Tue, 30 Mar 2021 10:07:55 -0300 | From | Jason Gunthorpe <> | Subject | Re: [PATCH V4 05/18] iommu/ioasid: Redefine IOASID set and allocation APIs |
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On Fri, Mar 26, 2021 at 09:06:42AM +0100, Jean-Philippe Brucker wrote:
> It's not inconceivable to have a control queue doing DMA tagged with > PASID. The devices I know either use untagged DMA, or have a choice to use > a PASID.
I don't think we should encourage that. A PASID and all the related is so expensive compared to just doing normal untagged kernel DMA.
I assume HW has these features because virtualization use cases might use them, eg by using mdev to assign a command queue - then it would need be be contained by a PASID.
Jason
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