Re: [PATCH RFC v1 02/15] iommu: Add a simple PASID table library
flat view
From: Jean-Philippe Brucker <hidden>
Date: 2021-03-29 16:27:11
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linux-arm-kernel, linux-iommu, lkml
On Fri, Mar 12, 2021 at 06:17:55PM +0530, Vivek Kumar Gautam wrote:
quoted
Regarding the overall design, I was initially assigning page directories instead of whole PASID tables, which would simplify the driver and host implementation. A major complication, however, is SMMUv3 accesses PASID tables using a guest-physical address, so there is a messy negotiation needed between host and guest when the host needs to allocate PASID tables. Plus vSMMU needs PASID table assignment, so that's what the host driver will implement.By assigning the page directories, you mean setting up just the stage-1 page table ops, and passing that information to the host using ATTACH_TABLE?
Yes. And we can support nested translation with SMMUv2 that way. But with SMMUv3 the guest has to manage the whole PASID table.
Right now when using kvmtool, the struct iommu_pasid_table_config is populated with the correct information, and this whole memory is mapped between host and guest by creating a mem bank using kvm__for_each_mem_bank(). Did I get you or did I fail terribly in understanding the point you are making here?
Makes sense Thanks, Jean _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization