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SubjectRe: [PATCH kernel v11 34/34] vfio: powerpc/spapr: Support Dynamic DMA windows
On Fri, May 29, 2015 at 06:44:58PM +1000, Alexey Kardashevskiy wrote:
> This adds create/remove window ioctls to create and remove DMA windows.
> sPAPR defines a Dynamic DMA windows capability which allows
> para-virtualized guests to create additional DMA windows on a PCI bus.
> The existing linux kernels use this new window to map the entire guest
> memory and switch to the direct DMA operations saving time on map/unmap
> requests which would normally happen in a big amounts.
> This adds 2 ioctl handlers - VFIO_IOMMU_SPAPR_TCE_CREATE and
> VFIO_IOMMU_SPAPR_TCE_REMOVE - to create and remove windows.
> Up to 2 windows are supported now by the hardware and by this driver.
> This changes VFIO_IOMMU_SPAPR_TCE_GET_INFO handler to return additional
> information such as a number of supported windows and maximum number
> levels of TCE tables.
> DDW is added as a capability, not as a SPAPR TCE IOMMU v2 unique feature
> as we still want to support v2 on platforms which cannot do DDW for
> the sake of TCE acceleration in KVM (coming soon).
> Signed-off-by: Alexey Kardashevskiy <>
> [aw: for the vfio related changes]
> Acked-by: Alex Williamson <>

Reviewed-by: David Gibson <>

David Gibson | I'll have my music baroque, and my code
david AT | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
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