Messages in this thread | | | Date | Fri, 10 Mar 2023 12:03:20 -0400 | From | Jason Gunthorpe <> | Subject | Re: [PATCH v1 02/14] iommufd: Add nesting related data structures for ARM SMMUv3 |
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On Fri, Mar 10, 2023 at 03:57:27PM +0000, Robin Murphy wrote:
> about the nitty-gritty of all the IOMMU-specific moving parts around it. For > guests that want to get into more advanced stuff like managing their own > PASID tables, pushing them towards "native" nesting probably does make more > sense.
IMHO with the simplified virtio model I would say the guest should not have its own PASID table.
hyper trap to install a PASID and let the hypervisor driver handle this abstractly. If abstractly is the whole point and benifit then virtio should lean into that.
This also means virtio protocol doesn't do PASID invalidation. It invalidates an ASID and the hypervisor takes care of whatever it is connected to. Very simple and general for the VM.
Adding a S1 iommu_domain op for invalidate address range is perfectly fine and the virtio kernel hypervisor driver can call it generically.
The primary reason to have guest-owned PASID tables is CC stuff, which definitely won't be part of virtio-iommu.
Jason
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