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SubjectRe: [RESEND PATCH V6 0/6] Add support for privileged mappings
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Hi Sricharan,

On 02/12/16 14:55, Sricharan R wrote:
> This series is a resend of the V5 that Mitch sent sometime back [2]
> All the patches are the same and i have just rebased. Not sure why this
> finally did not make it last time. The last patch in the previous
> series does not apply now [3], so just redid that. Also Copied the tags
> that he had from last time as well.

Heh, I was assuming this would be down to me to pick up. Vinod did have
some complaints last time about the commit message on the PL330 patch -
I did get as far as rewriting that and reworking onto my SMMU
changes[1], I just hadn't got round to sending it, so it fell onto the
"after the next merge window" pile.

I'd give some review comments, but they'd essentially be a diff against
that branch :)

Robin.

[1]:http://www.linux-arm.org/git?p=linux-rm.git;a=shortlog;h=refs/heads/mh/dma-priv

> 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].
>
> [1] https://github.com/robclark/kilroy
> [2] https://lkml.org/lkml/2016/7/27/590
> [3] https://patchwork.kernel.org/patch/9250493/
>
> Changelog:
>
> v5..v6
> - Rebased all the patches and redid 6/6 as it does not apply in
> this code base.
>
> v4..v5
>
> - Simplified patch 4/6 (suggested by Robin Murphy).
>
> v3..v4
>
> - Rebased and reworked on linux next due to the dma attrs rework going
> on over there. Patches changed: 3/6, 4/6, and 5/6.
>
> v2..v3
>
> - Incorporated feedback from Robin:
> * Various comments and re-wordings.
> * Use existing bit definitions for IOMMU_PRIV implementation
> in io-pgtable-arm.
> * Renamed and redocumented dma_direction_to_prot.
> * Don't worry about executability in new DMA attr.
>
> v1..v2
>
> - Added a new DMA attribute to make executable privileged mappings
> work, and use that in the pl330 driver (suggested by Will).
>
> Jeremy Gebben (1):
> iommu/io-pgtable-arm: add support for the IOMMU_PRIV flag
>
> Mitchel Humpherys (4):
> iommu: add IOMMU_PRIV attribute
> common: DMA-mapping: add DMA_ATTR_PRIVILEGED attribute
> arm64/dma-mapping: Implement DMA_ATTR_PRIVILEGED
> dmaengine: pl330: Make sure microcode is privileged
>
> Sricharan R (1):
> iommu/arm-smmu: Set privileged attribute to 'default' instead of
> 'unprivileged'
>
> Documentation/DMA-attributes.txt | 10 ++++++++++
> arch/arm64/mm/dma-mapping.c | 6 +++---
> drivers/dma/pl330.c | 6 ++++--
> drivers/iommu/arm-smmu.c | 2 +-
> drivers/iommu/dma-iommu.c | 10 ++++++++--
> drivers/iommu/io-pgtable-arm.c | 5 ++++-
> include/linux/dma-iommu.h | 3 ++-
> include/linux/dma-mapping.h | 7 +++++++
> include/linux/iommu.h | 1 +
> 9 files changed, 40 insertions(+), 10 deletions(-)
>

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