Re: [Xen-devel] [PATCH RFC 0/8] enable swiotlb-xen on arm and arm64

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

Although the series should be enough to demonstrate the concept, it
contains a couple of errors. I'll send an update.

On Wed, 31 Jul 2013, Stefano Stabellini wrote:
> Hi all,
> this patch series enables xen-swiotlb on arm and arm64.
> 
> Considering that all guests, including dom0, run on xen on arm with
> second stage translation enabled, it follows that without an IOMMU no
> guests could actually drive the hardware.
> 
> The solution for platforms without an IOMMU is to use swiotlb-xen,
> adapted to autotranslate guests. swiotlb-xen provides a set of dma_ops
> that can be used by Linux to setup a contiguous buffer in stage-2
> addresses and use it for dma operations.
> Basically Linux asks Xen to make a buffer contiguous and gets the
> machine address for it. This buffer is going to be used by lib/swiotlb.c
> to allocate bounce buffers.
> 
> 
> The first 3 patches lay the groundwork on arm and arm64 to have
> alternative dma_ops and swiotlb.
> 
> The forth patch moves Xen initialization earlier so that we already know
> whether we are running on Xen at the time of initializing dma_ops on the
> platform.
> 
> The following patches adapt swiotlb-xen to autotranslate guests (guest
> with second stage translation in hardware) and provide an arm
> implementation of xen_create_contiguous_region.
> 
> 
> Feedback is very welcome.
> Cheers,
> 
> Stefano
> 
> 
> Stefano Stabellini (8):
>       arm: make SWIOTLB available
>       arm: introduce a global dma_ops pointer
>       arm64: do not initialize arm64_swiotlb if dma_ops is already set
>       xen/arm,arm64: move Xen initialization earlier
>       xen: introduce XENMEM_get_dma_buf and xen_put_dma_buf
>       xen: make xen_create_contiguous_region return the dma address
>       swiotlb-xen: support autotranslate guests
>       xen/arm,arm64: enable SWIOTLB_XEN
> 
>  arch/arm/Kconfig                      |    8 ++
>  arch/arm/common/dmabounce.c           |   10 +-
>  arch/arm/include/asm/dma-mapping.h    |   27 ++++++-
>  arch/arm/include/asm/xen/hypervisor.h |    6 ++
>  arch/arm/include/asm/xen/page.h       |    2 +
>  arch/arm/kernel/setup.c               |    2 +
>  arch/arm/mm/dma-mapping.c             |    3 +
>  arch/arm/xen/Makefile                 |    2 +-
>  arch/arm/xen/enlighten.c              |   24 ++++--
>  arch/arm/xen/mm.c                     |  118 ++++++++++++++++++++++++++
>  arch/arm64/Kconfig                    |    1 +
>  arch/arm64/kernel/setup.c             |    2 +
>  arch/arm64/mm/dma-mapping.c           |    2 +
>  arch/arm64/xen/Makefile               |    2 +-
>  arch/x86/xen/mmu.c                    |    4 +-
>  drivers/xen/Kconfig                   |    1 -
>  drivers/xen/swiotlb-xen.c             |  147 
> +++++++++++++++++++++++++++++----
>  include/xen/interface/memory.h        |   62 ++++++++++++++
>  include/xen/xen-ops.h                 |    3 +-
>  19 files changed, 391 insertions(+), 35 deletions(-)
>  create mode 100644 arch/arm/xen/mm.c
> 

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