Messages in this thread | | | Date | Mon, 21 Nov 2011 15:35:05 -0800 | From | Chris Wright <> | Subject | Re: [PATCH] iommu: Include MSI susceptibility to DMA in creating iommu groups |
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* Joerg Roedel (joro@8bytes.org) wrote: > >From device standpoint a MSI transaction is always a DMA memory write > to a given address range. The IOMMU-API should export a feature flag > whether it supports filtering on those transaction or not. We have that > today with the IOMMU_CAP_INTR_REMAP. I agree that the interface to get > this information is ugly because a domain is needed. But the interface > can be fixed. While doing this I suggest to rename that feature > IOMMU_CAP_INTR_ISOLATION or something like that. > VFIO can then check for this flag on module-load and refuse to load if > it is not available.
I can see that the native grouping (the typical pci bridge type) is really more a property of the topology.
The isolation properties of a group (arguably the whole point of the group) is subtly different.
Leaves the questions:
What is the value of a group w/out complete isolation? Is there a practical problem w/ conflating the subtleties above?
thanks, -chris
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