Re: [Xen-devel] Re: [XEN-IOMMU] Proposal of DMA protection/isolationsupport

[tgh <wwwwww4187@xxxxxxxxxxx>]

hi
IOMMU, 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
>
>
>   

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel