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