[PATCH v4 0/10] enable swiotlb-xen on arm and arm64

[Stefano Stabellini <stefano.stabellini@eu.citrix.com>]

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 5 patches lay the groundwork on arm and arm64 to have
alternative dma_ops and swiotlb.

The sixth 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


Changes in v4:
- rename XENMEM_get_dma_buf to XENMEM_exchange_and_pin;
- rename XENMEM_put_dma_buf to XENMEM_unpin;
- improve the documentation of the new hypercalls;
- add a note about out.address_bits for XENMEM_exchange;
- code style fixes;
- add err_out label in xen_dma_add_entry;
- remove INVALID_ADDRESS, use DMA_ERROR_CODE instead;
- add in-code comments regarding the usage of xen_dma_seg[0].dma_addr.

Changes in v3:
- add a patch to compile SWIOTLB without CONFIG_NEED_SG_DMA_LENGTH;
- add a patch to compile SWIOTLB_XEN without CONFIG_NEED_SG_DMA_LENGTH;
- arm/dma_capable: do not treat dma_mask as a limit;
- arm/dmabounce: keep using arm_dma_ops;
- add missing __init in xen_early_init declaration;
- many code style and name changes in swiotlb-xen.c;
- improve error checks in xen_dma_add_entry;
- warn on XENMEM_put_dma_buf failures.

Changes in v2:
- fixed a couple of errors in xen_bus_to_phys, xen_phys_to_bus and
xen_swiotlb_fixup.



EUNBONG SONG (1):
      swiotlb: replace dma_length with sg_dma_len() macro

Stefano Stabellini (9):
      swiotlb-xen: replace dma_length with sg_dma_len() macro
      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_exchange_and_pin and XENMEM_unpin
      xen: make xen_create_contiguous_region return the dma address
      swiotlb-xen: support autotranslate guests
      xen/arm,arm64: enable SWIOTLB_XEN

 arch/arm/Kconfig                      |    7 +
 arch/arm/include/asm/dma-mapping.h    |   33 ++++++-
 arch/arm/include/asm/xen/hypervisor.h |    8 ++
 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                     |  117 +++++++++++++++++++
 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             |  198 +++++++++++++++++++++++++++++----
 include/xen/interface/memory.h        |   37 ++++++
 include/xen/xen-ops.h                 |    3 +-
 lib/swiotlb.c                         |    8 +-
 19 files changed, 418 insertions(+), 38 deletions(-)
 create mode 100644 arch/arm/xen/mm.c

git://git.kernel.org/pub/scm/linux/kernel/git/sstabellini/xen.git swiotlb-xen-4