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Re: [PATCH v3 0/6] Add support for privileged mappings

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On Tue, Jul 19, 2016 at 01:36:49PM -0700, Mitchel Humpherys wrote:
> The following patch to the ARM SMMU driver:
> 
>     commit d346180e70b91b3d5a1ae7e5603e65593d4622bc
>     Author: Robin Murphy <robin.murphy@arm.com>
>     Date:   Tue Jan 26 18:06:34 2016 +0000
>     
>         iommu/arm-smmu: Treat all device transactions as unprivileged
> 
> started forcing all SMMU transactions to come through as "unprivileged".
> The rationale given was that:
> 
>   (1) There is no way in the IOMMU API to even request privileged mappings.
> 
>   (2) It's difficult to implement a DMA mapper that correctly models the
>       ARM VMSAv8 behavior of unprivileged-writeable =>
>       privileged-execute-never.
> 
> This series rectifies (1) by introducing an IOMMU API for privileged
> mappings and implements it in io-pgtable-arm.
> 
> This series rectifies (2) by introducing a new dma attribute
> (DMA_ATTR_PRIVILEGED) for users of the DMA API that need privileged
> mappings which are inaccessible to lesser-privileged execution levels, and
> implements it in the arm64 IOMMU DMA mapper.  The one known user (pl330.c)
> is converted over to the new attribute.
> 
> Jordan and Jeremy can provide more info on the use case if needed, but the
> high level is that it's a security feature to prevent attacks such as [1].

This all looks good to me:

Acked-by: Will Deacon <will.deacon@arm.com>

It looks pretty fiddly to merge, however. How are you planning to get
this upstream?

Will

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[PATCH v3 0/6] Add support for privileged mappings Mitchel Humpherys <mitchelh@codeaurora.org> - 2016-07-19 22:40 +0200
  [PATCH v3 3/6] common: DMA-mapping: add DMA_ATTR_PRIVILEGED attribute Mitchel Humpherys <mitchelh@codeaurora.org> - 2016-07-19 22:40 +0200
  [PATCH v3 1/6] iommu: add IOMMU_PRIV attribute Mitchel Humpherys <mitchelh@codeaurora.org> - 2016-07-19 22:40 +0200
  [PATCH v3 2/6] iommu/io-pgtable-arm: add support for the IOMMU_PRIV flag Mitchel Humpherys <mitchelh@codeaurora.org> - 2016-07-19 22:40 +0200
  Re: [PATCH v3 0/6] Add support for privileged mappings Will Deacon <will.deacon@arm.com> - 2016-07-22 19:00 +0200
    Re: [PATCH v3 0/6] Add support for privileged mappings Mitchel Humpherys <mitchelh@codeaurora.org> - 2016-07-22 22:40 +0200
      Re: [PATCH v3 0/6] Add support for privileged mappings Will Deacon <will.deacon@arm.com> - 2016-07-25 12:00 +0200
        Re: [PATCH v3 0/6] Add support for privileged mappings Mitchel Humpherys <mitchelh@codeaurora.org> - 2016-07-25 21:10 +0200

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