[PATCH v9 0/7] iommu: enhance IOMMU default DMA mode build options

[Zhen Lei]

v8--> v9
1. Fix some text editing errors

v7--> v8
1. Split into multiple small patches base on ARCHs or IOMMU drivers.
2. Hide the unsupported build options on the related ARCH or IOMMU.

v6 --> v7:
1. Fix some text editing errors

v5 --> v6:
1. give up adding boot option iommu.dma_mode

v4 --> v5:
As Hanjun and Thomas Gleixner's suggestion:
1. Keep the old ARCH specific boot options no change.
2. Keep build option CONFIG_IOMMU_DEFAULT_PASSTHROUGH no change.

v4:
As Robin Murphy's suggestion:
"It's also not necessarily obvious to the user how this interacts with
IOMMU_DEFAULT_PASSTHROUGH, so if we really do go down this route, maybe it
would be better to refactor the whole lot into a single selection of something
like IOMMU_DEFAULT_MODE anyway."

In this version, I tried to normalize the IOMMU dma mode boot options for all
ARCHs. When IOMMU is enabled, there are 3 dma modes: paasthrough(bypass),
lazy(mapping but defer the IOTLB invalidation), strict. But currently each
ARCHs defined their private boot options, different with each other. For
example, to enable/disable "passthrough", ARM64 use iommu.passthrough=1/0,
X86 use iommu=pt/nopt, PPC/POWERNV use iommu=nobypass.

Zhen Lei (7):
  iommu: enhance IOMMU default DMA mode build options
  x86/dma: use IS_ENABLED() to simplify the code
  s390/pci: add support for IOMMU default DMA mode build options
  powernv/iommu: add support for IOMMU default DMA mode build options
  iommu/vt-d: add support for IOMMU default DMA mode build options
  iommu/amd: add support for IOMMU default DMA mode build options
  ia64: hide build option IOMMU_DEFAULT_PASSTHROUGH

 arch/powerpc/platforms/powernv/pci-ioda.c |  3 +-
 arch/s390/pci/pci_dma.c                   |  2 +-
 arch/x86/kernel/pci-dma.c                 |  6 +---
 drivers/iommu/Kconfig                     | 48 +++++++++++++++++++++++++------
 drivers/iommu/amd_iommu_init.c            |  2 +-
 drivers/iommu/intel-iommu.c               |  2 +-
 drivers/iommu/iommu.c                     |  3 +-
 7 files changed, 48 insertions(+), 18 deletions(-)

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1.8.3