Re: [PATCH v3 0/9] iommu/amd: Add Generic IO Page Table Framework Support for v2 Page Table

[Vasant Hegde <vasant.hegde@amd.com>]

Hi Joerg, Robin,

Ping. Did you get a chance to look into this series?

-Vasant

On 8/25/2022 12:09 PM, Vasant Hegde wrote:
> This series introduces a new usage model for the v2 page table, where it
> can be used to implement support for DMA-API by adopting the generic
> IO page table framework.
> 
> One of the target usecases is to support nested IO page tables
> where the guest uses the guest IO page table (v2) for translating
> GVA to GPA, and the hypervisor uses the host I/O page table (v1) for
> translating GPA to SPA. This is a pre-requisite for supporting the new
> HW-assisted vIOMMU presented at the KVM Forum 2020.
> 
>   https://static.sched.com/hosted_files/kvmforum2020/26/vIOMMU%20KVM%20Forum%202020.pdf
> 
> The following components are introduced in this series:
> 
> - Part 1 (patch 1-3)
>   Move AMD v1 page table to use [un]map_pages interfaces and minor fixes to unmap path.
> 
> - Part 1 (patch 4-5 and 8)
>   Refactor the current IOMMU page table code to adopt the generic IO page
>   table framework, and add AMD IOMMU Guest (v2) page table management code.
> 
> - Part 2 (patch 7)
>   Add support for the AMD IOMMU Guest IO Protection feature (GIOV)
>   where requests from the I/O device without a PASID are treated as
>   if they have PASID of 0.
> 
> - Part 3 (patch 9)
>   Introduce new "amd_iommu_pgtable" command-line to allow users
>   to select the mode of operation (v1 or v2).
> 
> See AMD I/O Virtualization Technology Specification for more detail.
> 
>   http://www.amd.com/system/files/TechDocs/48882_IOMMU_3.05_PUB.pdf
> 
> 
> Thanks,
> Vasant
> 
> Changes from v2 -> v3 :
>   - As Robin suggested added support to use [un]map_pages interface (Patch 1 - 3)
>   - Removed [un]map interface from AMD IOMMU driver
>   - Updated v2 page table to use [un]map_pages interface
> 
> V2 patchset: https://lore.kernel.org/linux-iommu/20220713053034.12061-1-vasant.hegde@amd.com/
> 
> Changes from v1 -> v2 :
>   - Allow v2 page table only when FEATURE_GT is enabled
>   - V2 page table doesn't support IOMMU passthrough mode. Hence added
>     check to fall back to v1 mode if system is booted with iommu=pt
>   - Overloaded amd_iommu command line option (removed amd_iommu_pgtable
>     option)
>   - Override supported page sizes dynamically instead of selecting at
>     boot time.
> 
> V1 patchset : https://lore.kernel.org/linux-iommu/20220603112107.8603-1-vasant.hegde@amd.com/T/#t
> 
> Changes from RFC -> v1:
>   - Addressed review comments from Joerg
>   - Reimplemented v2 page table
> 
> RFC patchset : https://lore.kernel.org/linux-iommu/20210312090411.6030-1-suravee.suthikulpanit@amd.com/T/#t
> 
> 
> Suravee Suthikulpanit (4):
>   iommu/amd: Refactor amd_iommu_domain_enable_v2 to remove locking
>   iommu/amd: Update sanity check when enable PRI/ATS for IOMMU v1 table
>   iommu/amd: Add support for Guest IO protection
>   iommu/amd: Add support for using AMD IOMMU v2 page table for DMA-API
> 
> Vasant Hegde (5):
>   iommu/amd/io-pgtable: Implement map_pages io_pgtable_ops callback
>   iommu/amd/io-pgtable: Implement unmap_pages io_pgtable_ops callback
>   iommu/amd: Add map/unmap_pages() iommu_domain_ops callback support
>   iommu/amd: Initial support for AMD IOMMU v2 page table
>   iommu/amd: Add command-line option to enable different page table
> 
>  .../admin-guide/kernel-parameters.txt         |   2 +
>  drivers/iommu/amd/Makefile                    |   2 +-
>  drivers/iommu/amd/amd_iommu_types.h           |   8 +-
>  drivers/iommu/amd/init.c                      |  36 +-
>  drivers/iommu/amd/io_pgtable.c                |  76 ++--
>  drivers/iommu/amd/io_pgtable_v2.c             | 415 ++++++++++++++++++
>  drivers/iommu/amd/iommu.c                     | 117 +++--
>  drivers/iommu/io-pgtable.c                    |   1 +
>  include/linux/io-pgtable.h                    |   2 +
>  9 files changed, 584 insertions(+), 75 deletions(-)
>  create mode 100644 drivers/iommu/amd/io_pgtable_v2.c
>