Re: [PATCH v3 0/5] Clean up VMD DMA Map Ops

[Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>]

On Fri, Jan 10, 2020 at 10:21:08AM -0700, Jon Derrick wrote:
> v2 Set: https://lore.kernel.org/linux-iommu/1578580256-3483-1-git-send-email-jonathan.derrick@intel.com/T/#t
> v1 Set: https://lore.kernel.org/linux-iommu/20200107134125.GD30750@8bytes.org/T/#t
> 
> VMD currently works with VT-d enabled by pointing DMA and IOMMU actions at the
> VMD endpoint. The problem with this approach is that the VMD endpoint's
> device-specific attributes, such as the DMA Mask Bits, are used instead.
> 
> This set cleans up VMD by removing the override that redirects DMA map
> operations to the VMD endpoint. Instead it introduces a new DMA alias mechanism
> into the existing DMA alias infrastructure.
> 
> v1 added a pointer in struct pci_dev that pointed to the DMA alias' struct
> pci_dev and did the necessary DMA alias and IOMMU modifications.
> 
> v2 introduced a new weak function to reference the 'Direct DMA Alias', and
> removed the need to add a pointer in struct device or pci_dev. Weak functions
> are generally frowned upon when it's a single architecture implementation, so I
> am open to alternatives.
> 
> v3 references the pci_dev rather than the struct device for the PCI
> 'Direct DMA Alias' (pci_direct_dma_alias()). This revision also allows
> pci_for_each_dma_alias() to call any DMA aliases for the Direct DMA alias
> device, though I don't expect the VMD endpoint to need intra-bus DMA aliases.
> 
> Changes from v2:
> Uses struct pci_dev for PCI Device 'Direct DMA aliasing' (pci_direct_dma_alias)
> Allows pci_for_each_dma_alias to iterate over the alias mask of the 'Direct DMA alias'
> 
> Changes from v1:
> Removed 1/5 & 2/5 misc fix patches that were merged
> Uses Christoph's staging/cleanup patches
> Introduce weak function rather than including pointer in struct device or pci_dev.
> 
> Based on Joerg's next:
> https://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu.git/
> 
> Jon Derrick (5):
>   x86/pci: Add a to_pci_sysdata helper
>   x86/PCI: Expose VMD's PCI Device in pci_sysdata
>   PCI: Introduce pci_direct_dma_alias()
>   PCI: vmd: Stop overriding dma_map_ops
>   x86/pci: Remove X86_DEV_DMA_OPS
> 
>  arch/x86/Kconfig               |   3 -
>  arch/x86/include/asm/device.h  |  10 ---
>  arch/x86/include/asm/pci.h     |  31 ++++-----
>  arch/x86/pci/common.c          |  45 ++----------
>  drivers/iommu/intel-iommu.c    |  18 +++--
>  drivers/pci/controller/Kconfig |   1 -
>  drivers/pci/controller/vmd.c   | 152 +----------------------------------------
>  drivers/pci/pci.c              |  19 +++++-
>  drivers/pci/search.c           |   7 ++
>  include/linux/pci.h            |   1 +
>  10 files changed, 61 insertions(+), 226 deletions(-)

Jon, Christoph,

AFAICS this series supersedes/overrides:

https://patchwork.kernel.org/patch/11114831/

Please let me know if that's correct, actually I was waiting to
see consensus on the patch above but if this series supersedes
it I would drop it from the PCI review queue.

Thanks,
Lorenzo