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Date:   Tue, 15 Mar 2022 11:56:40 -0300
From:   Jason Gunthorpe <jgg@nvidia.com>
To:     Matthew Rosato <mjrosato@linux.ibm.com>
Cc:     linux-s390@vger.kernel.org, alex.williamson@redhat.com,
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Subject: Re: [PATCH v4 29/32] vfio-pci/zdev: add DTSM to clp group capability
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References: <20220314194451.58266-1-mjrosato@linux.ibm.com>
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 <20220314214928.GK11336@nvidia.com>
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On Tue, Mar 15, 2022 at 10:39:18AM -0400, Matthew Rosato wrote:
> > That is something that should be modeled as a nested iommu domain.
> > 
> > Querying the formats and any control logic for this should be on the
> > iommu side not built into VFIO.
> 
> I agree that the DTSM is really controlled by what the IOMMU domain can
> support (e.g. what guest table formats it can actually operate on) and so
> the DTSM value should come from there vs out of KVM; but is there harm in
> including the query response data here along with the rest of the response
> information for 'query this zPCI group'?

'Harm'? No, but I think it is wrong encapsulation and layering.

Jason