a saner API for allocating DMA addressable pages

From: Christoph Hellwig <hch@lst.de>
To: Mauro Carvalho Chehab <mchehab@kernel.org>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	"James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
	Joonyoung Shim <jy0922.shim@samsung.com>,
	Seung-Woo Kim <sw0312.kim@samsung.com>,
	Kyungmin Park <kyungmin.park@samsung.com>,
	Ben Skeggs <bskeggs@redhat.com>, Pawel Osciak <pawel@osciak.com>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Matt Porter <mporter@kernel.crashing.org>,
	iommu@lists.linux-foundation.org
Cc: Tom Lendacky <thomas.lendacky@amd.com>,
	alsa-devel@alsa-project.org, linux-samsung-soc@vger.kernel.org,
	linux-ia64@vger.kernel.org, linux-scsi@vger.kernel.org,
	linux-parisc@vger.kernel.org, linux-doc@vger.kernel.org,
	nouveau@lists.freedesktop.org, linux-kernel@vger.kernel.org,
	linux-nvme@lists.infradead.org, linux-mips@vger.kernel.org,
	linux-mm@kvack.org, netdev@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-media@vger.kernel.org
Subject: a saner API for allocating DMA addressable pages
Date: Wed, 19 Aug 2020 08:55:27 +0200	[thread overview]
Message-ID: <20200819065555.1802761-1-hch@lst.de> (raw)

Hi all,

this series replaced the DMA_ATTR_NON_CONSISTENT flag to dma_alloc_attrs
with a separate new dma_alloc_pages API, which is available on all
platforms.  In addition to cleaning up the convoluted code path, this
ensures that other drivers that have asked for better support for
non-coherent DMA to pages with incurring bounce buffering over can finally
be properly supported.

I'm still a little unsure about the API naming, as alloc_pages sort of
implies a struct page return value, but we return a kernel virtual
address.  The other alternative would be to name the API
dma_alloc_noncoherent, but the whole non-coherent naming seems to put
people off.  As a follow up I plan to move the implementation of the
DMA_ATTR_NO_KERNEL_MAPPING flag over to this framework as well, given
that is also is a fundamentally non coherent allocation.  The replacement
for that flag would then return a struct page, as it is allowed to
actually return pages without a kernel mapping as the name suggested
(although most of the time they will actually have a kernel mapping..)

In addition to the conversions of the existing non-coherent DMA users
the last three patches also convert the DMA coherent allocations in
the NVMe driver to use this new framework through a dmapool addition.
This was both to give me a good testing vehicle, but also because it
should speed up the NVMe driver on platforms with non-coherent DMA
nicely, without a downside on platforms with cache coherent DMA.

A git tree is available here:

    git://git.infradead.org/users/hch/misc.git dma_alloc_pages

Gitweb:

    http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/dma_alloc_pages

Diffstat:
 Documentation/core-api/dma-api.rst                       |   92 ++----
 Documentation/core-api/dma-attributes.rst                |    8 
 Documentation/userspace-api/media/v4l/buffer.rst         |   17 -
 Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst |    1 
 arch/alpha/kernel/pci_iommu.c                            |    2 
 arch/arm/include/asm/dma-direct.h                        |    4 
 arch/arm/mm/dma-mapping-nommu.c                          |    2 
 arch/arm/mm/dma-mapping.c                                |    4 
 arch/ia64/Kconfig                                        |    3 
 arch/ia64/hp/common/sba_iommu.c                          |    2 
 arch/ia64/kernel/dma-mapping.c                           |   14 
 arch/ia64/mm/init.c                                      |    3 
 arch/mips/Kconfig                                        |    1 
 arch/mips/bmips/dma.c                                    |    4 
 arch/mips/cavium-octeon/dma-octeon.c                     |    4 
 arch/mips/include/asm/dma-direct.h                       |    4 
 arch/mips/include/asm/jazzdma.h                          |    2 
 arch/mips/jazz/jazzdma.c                                 |  102 +------
 arch/mips/loongson2ef/fuloong-2e/dma.c                   |    4 
 arch/mips/loongson2ef/lemote-2f/dma.c                    |    4 
 arch/mips/loongson64/dma.c                               |    4 
 arch/mips/mm/dma-noncoherent.c                           |   48 +--
 arch/mips/pci/pci-ar2315.c                               |    4 
 arch/mips/pci/pci-xtalk-bridge.c                         |    4 
 arch/mips/sgi-ip32/ip32-dma.c                            |    4 
 arch/parisc/Kconfig                                      |    1 
 arch/parisc/kernel/pci-dma.c                             |    6 
 arch/powerpc/include/asm/dma-direct.h                    |    4 
 arch/powerpc/kernel/dma-iommu.c                          |    2 
 arch/powerpc/platforms/ps3/system-bus.c                  |    4 
 arch/powerpc/platforms/pseries/vio.c                     |    2 
 arch/s390/pci/pci_dma.c                                  |    2 
 arch/x86/kernel/amd_gart_64.c                            |    8 
 drivers/gpu/drm/exynos/exynos_drm_gem.c                  |    2 
 drivers/gpu/drm/nouveau/nvkm/subdev/instmem/gk20a.c      |    3 
 drivers/iommu/dma-iommu.c                                |    2 
 drivers/iommu/intel/iommu.c                              |    6 
 drivers/media/common/videobuf2/videobuf2-core.c          |   36 --
 drivers/media/common/videobuf2/videobuf2-dma-contig.c    |   19 -
 drivers/media/common/videobuf2/videobuf2-dma-sg.c        |    3 
 drivers/media/common/videobuf2/videobuf2-v4l2.c          |   12 
 drivers/net/ethernet/amd/au1000_eth.c                    |   15 -
 drivers/net/ethernet/i825xx/lasi_82596.c                 |   36 +-
 drivers/net/ethernet/i825xx/lib82596.c                   |  148 +++++-----
 drivers/net/ethernet/i825xx/sni_82596.c                  |   23 -
 drivers/net/ethernet/seeq/sgiseeq.c                      |   24 -
 drivers/nvme/host/pci.c                                  |   79 ++---
 drivers/parisc/ccio-dma.c                                |    2 
 drivers/parisc/sba_iommu.c                               |    2 
 drivers/scsi/53c700.c                                    |  120 ++++----
 drivers/scsi/53c700.h                                    |    9 
 drivers/scsi/sgiwd93.c                                   |   14 
 drivers/xen/swiotlb-xen.c                                |    2 
 include/linux/dma-direct.h                               |   55 ++-
 include/linux/dma-mapping.h                              |   32 +-
 include/linux/dma-noncoherent.h                          |   21 -
 include/linux/dmapool.h                                  |   23 +
 include/linux/gfp.h                                      |    6 
 include/media/videobuf2-core.h                           |    3 
 include/uapi/linux/videodev2.h                           |    2 
 kernel/dma/Kconfig                                       |    9 
 kernel/dma/Makefile                                      |    1 
 kernel/dma/coherent.c                                    |   17 +
 kernel/dma/direct.c                                      |  112 +++++--
 kernel/dma/mapping.c                                     |  104 ++-----
 kernel/dma/ops_helpers.c                                 |   86 ++++++
 kernel/dma/pool.c                                        |    2 
 kernel/dma/swiotlb.c                                     |    4 
 kernel/dma/virt.c                                        |    2 
 mm/dmapool.c                                             |  211 +++++++++------
 sound/mips/hal2.c                                        |   58 +---
 71 files changed, 872 insertions(+), 803 deletions(-)
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