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xen-devel
[Xen-devel] Re: [XEN-IOMMU] Proposal of DMA protection/isolation support
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To: |
Wei Wang2 <wei.wang2@xxxxxxx> |
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Subject: |
[Xen-devel] Re: [XEN-IOMMU] Proposal of DMA protection/isolation support |
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From: |
Keir Fraser <Keir.Fraser@xxxxxxxxxxxx> |
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Date: |
Wed, 16 Jan 2008 16:45:29 +0000 |
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Cc: |
muli@xxxxxxxxxx, "Dannowski, Uwe" <Uwe.Dannowski@xxxxxxx>, "Hohmuth, Michael" <Michael.Hohmuth@xxxxxxx>, "Woller, Thomas" <thomas.woller@xxxxxxx>, iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxx, elsie.wahlig@xxxxxxx, amit.shah@xxxxxxxxxxxx |
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Wed, 16 Jan 2008 08:45:55 -0800 |
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[XEN-IOMMU] Proposal of DMA protection/isolation support |
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On 16/1/08 16:34, "Wei Wang2" <wei.wang2@xxxxxxx> wrote:
> 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.
Local pages could always be mapped into the iommu, and only remote pages
would need to be temporarily mapped via the gnttab hooks.
> 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.
An extra hypercall here will likely hurt performance.
-- Keir
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