[Xen-devel] [PATCH v7 0/17] enable swiotlb-xen on arm and arm64

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

Hi all,
this patch series enables xen-swiotlb on arm and arm64.

It has been heavily reworked compared to the previous versions in order
to achieve better performances and to address review comments.

We are not using dma_mark_clean to ensure coherency anymore. We call the
platform implementation of map_page and unmap_page.

We assume that dom0 has been mapped 1:1 (physical address ==
machine address), that is what Xen on ARM currently does.
As a consequence we only use the swiotlb to handle dma
requests involving pages corresponding to grant refs. Obviously these
pages cannot be part of the 1:1 because they belong to another domain.

To improve code readability this version of the series introduces a
"p2m" for arm and arm64, implemented using two red-black trees.  The p2m
tracks physical to machine and machine to physical mappings. Given that
we assume a 1:1 mapping in dom0, the only entries in both trees are
grant refs that have been mapped in dom0.

Another consequence of the new approach is that the hypercalls we were
previously introducing (XENMEM_exchange_and_pin, XENMEM_pin,
XENMEM_unpin) are not needed anymore. The patch series still needs a
small change to the hypervisor: XENMEM_exchanged doesn't currently
return the mfn of the exchanged pages for autotranslate guests. This
work needs Xen to return the mfns as it would normally do with
non-autotranslate guests. This change to the hypervisor is not upstream
yet.

Cheers,

Stefano


Changes in v7:
- dma_mark_clean: switch to an empty implementation (we are going to use
  the platform map_page and unmap_page to ensure coherency);
- dma_capable: use coherent_dma_mask if dma_mask hasn't been
  allocated;
- introduce a p2m for xen on arm and arm64;
- call __set_phys_to_machine_multi from xen_create_contiguous_region to
  update the p2m;
- remove XENMEM_unpin and XENMEM_exchange_and_pin;
- set nr_exchanged to 0 before calling the hypercall;
- return xen_dma_ops only if we are the initial domain;
- rename __get_dma_ops to __generic_dma_ops;
- call __generic_dma_ops(hwdev)->alloc/free on arm64 too;
- introduce xen_dma_map/unmap_page and xen_dma_sync_single_for_cpu/device;
- use xen_dma_map/unmap_page, xen_dma_sync_single_for_cpu/device in
  swiotlb-xen;
- use dev_warn instead of pr_warn;
- remove the extra autotranslate check in biomerge.c;
- call set_phys_to_machine after mapping grant refs in gnttab_map_refs;
- call set_phys_to_machine after unmapping grant refs in gnttab_unmap_refs;
- allow __set_phys_to_machine to be called for autotranslate guests on
  x86.

Changes in v6:
- check for dev->dma_mask being NULL in dma_capable;
- update the comments and the hypercalls structures;
- add a xen_dma_info entry to the rbtree in xen_swiotlb_alloc_coherent
to keep track of the new mapping. Free the entry in xen_swiotlb_free_coherent;
- rename xen_dma_seg to dma_info in xen_swiotlb_alloc/free_coherent to
avoid confusions;
- introduce and export xen_dma_ops;
- call xen_mm_init from as arch_initcall;
- call __get_dma_ops to get the native dma_ops pointer on arm;
- do not merge biovecs;
- add single page optimization: pin the page rather than bouncing.

Changes in v5:
- dropped the first two patches, already in the Xen tree;
- implement dma_mark_clean using dmac_flush_range on arm;
- add "arm64: define DMA_ERROR_CODE"
- better comment for XENMEM_exchange_and_pin return codes;
- fix xen_dma_add_entry error path;
- remove the spin_lock: the red-black tree is not modified at run time;
- add "swiotlb-xen: introduce xen_swiotlb_set_dma_mask";
- add "xen: introduce xen_alloc/free_coherent_pages";
- add "swiotlb-xen: use xen_alloc/free_coherent_pages";
- add "swiotlb: don't assume that io_tlb_start-io_tlb_end is coherent".

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.





Julien Grall (1):
      ASoC: Samsung: Rename dma_ops by samsung_dma_ops


Julien Grall (1):
      ASoC: Samsung: Rename dma_ops by samsung_dma_ops

Stefano Stabellini (16):
      arm: make SWIOTLB available
      arm64: define DMA_ERROR_CODE
      arm/xen,arm64/xen: introduce p2m
      xen/x86: allow __set_phys_to_machine for autotranslate guests
      xen: make xen_create_contiguous_region return the dma address
      xen/arm,arm64: enable SWIOTLB_XEN
      swiotlb-xen: introduce xen_swiotlb_set_dma_mask
      arm/xen: get_dma_ops: return xen_dma_ops if we are running as 
xen_initial_domain
      arm64/xen: get_dma_ops: return xen_dma_ops if we are running as 
xen_initial_domain
      xen: introduce xen_alloc/free_coherent_pages
      swiotlb-xen: use xen_alloc/free_coherent_pages
      xen: introduce xen_dma_map/unmap_page and 
xen_dma_sync_single_for_cpu/device
      swiotlb-xen: use xen_dma_map/unmap_page, 
xen_dma_sync_single_for_cpu/device
      swiotlb: print a warning when the swiotlb is full
      arm,arm64: do not always merge biovec if we are running on Xen
      grant-table: call set_phys_to_machine after mapping grant refs

 arch/arm/Kconfig                           |    7 +
 arch/arm/include/asm/dma-mapping.h         |   50 ++++++-
 arch/arm/include/asm/io.h                  |    8 +
 arch/arm/include/asm/xen/hypervisor.h      |    2 +
 arch/arm/include/asm/xen/page-coherent.h   |   50 ++++++
 arch/arm/include/asm/xen/page.h            |   15 +-
 arch/arm/xen/Makefile                      |    2 +-
 arch/arm/xen/mm.c                          |  116 ++++++++++++++
 arch/arm/xen/p2m.c                         |  237 ++++++++++++++++++++++++++++
 arch/arm64/Kconfig                         |    1 +
 arch/arm64/include/asm/dma-mapping.h       |   14 ++-
 arch/arm64/include/asm/io.h                |    9 +
 arch/arm64/include/asm/xen/page-coherent.h |   47 ++++++
 arch/arm64/xen/Makefile                    |    2 +-
 arch/ia64/include/asm/xen/page-coherent.h  |   38 +++++
 arch/x86/include/asm/xen/page-coherent.h   |   38 +++++
 arch/x86/xen/mmu.c                         |   11 +-
 arch/x86/xen/p2m.c                         |    6 +-
 drivers/xen/Kconfig                        |    1 -
 drivers/xen/grant-table.c                  |   17 ++-
 drivers/xen/swiotlb-xen.c                  |  104 ++++++++++---
 include/xen/swiotlb-xen.h                  |    2 +
 include/xen/xen-ops.h                      |    7 +-
 lib/swiotlb.c                              |    1 +
 sound/soc/samsung/dma.c                    |    4 +-
 25 files changed, 743 insertions(+), 46 deletions(-)

git://git.kernel.org/pub/scm/linux/kernel/git/sstabellini/xen.git swiotlb-xen-7

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