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Re: [Xen-devel] Re: [XEN-IOMMU] Proposal of DMA protection/isolationsupport
hiIOMMU, could it be used in KVM ,or not? if it could , what about the difference between the usage in xen and the usage in KVM?
Thanks Ian Pratt åé:
After looking into the grant mapping code (use block device as an example), I got some ideas to share with you and the list. Please correct me if I missed something. There might be 2 places to trigger iommu mapping: 1) Before submitting io request to generic block layer, block backend driver will invoke GNTTABOPs to map granted remote pages . However creating iommu mapping only in GNTTABOP not very enough because local pages will also be submitted to block layer and they should also be translated by iommu. 2) When dma layer is invoked to prepare a bus address for native block device driver. It would be better to have a "hypervisor-aware" dma layer which always maps virtual address to bus address via hypercall. __gnttab_dma_map_page() might be a good place to trigger this new hypercall. Both remote and local pages can be mapped by this way.It's much better to create most mappings in #1 when the operations are easily batchable into a single hypercall, and then fill in the missing mappings when required at #2. Since in many situations dom0 does very little IO for itself, this should be a significant win, especially for networking. Ian_______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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