Re: [PATCH 0/8] Initial support for SMMUv3 nested translation

[Mostafa Saleh <smostafa@google.com>]

Hi Jason,

On Tue, Aug 06, 2024 at 08:41:13PM -0300, Jason Gunthorpe wrote:
> This brings support for the IOMMFD ioctls:
> 
>  - IOMMU_GET_HW_INFO
>  - IOMMU_HWPT_ALLOC_NEST_PARENT
>  - IOMMU_DOMAIN_NESTED
>  - ops->enforce_cache_coherency()
> 
> This is quite straightforward as the nested STE can just be built in the
> special NESTED domain op and fed through the generic update machinery.
> 
> The design allows the user provided STE fragment to control several
> aspects of the translation, including putting the STE into a "virtual
> bypass" or a aborting state. This duplicates functionality available by
> other means, but it allows trivially preserving the VMID in the STE as we
> eventually move towards the VIOMMU owning the VMID.
> 
> Nesting support requires the system to either support S2FWB or the
> stronger CANWBS ACPI flag. This is to ensure the VM cannot bypass the
> cache and view incoherent data, currently VFIO lacks any cache flushing
> that would make this safe.
> 
> Yan has a series to add some of the needed infrastructure for VFIO cache
> flushing here:
> 
>  https://lore.kernel.org/linux-iommu/20240507061802.20184-1-yan.y.zhao@intel.com/
> 
> Which may someday allow relaxing this further.
> 
> Remove VFIO_TYPE1_NESTING_IOMMU since it was never used and superseded by
> this.
> 
> This is the first series in what will be several to complete nesting
> support. At least:
>  - IOMMU_RESV_SW_MSI related fixups
>  - VIOMMU object support to allow ATS invalidations
>  - vCMDQ hypervisor support for direct invalidation queue assignment
>  - KVM pinned VMID using VIOMMU for vBTM
>  - Cross instance S2 sharing
>  - Virtual Machine Structure using VIOMMU (for vMPAM?)
>  - Fault forwarding support through IOMMUFD's fault fd for vSVA
> 
> It is enough to allow significant amounts of qemu work to progress.
> 
Are there any qemu patches to tests this?
As I am confused with some of the user space bits and that would help.

Thanks,
Mostafa

> This is on github: https://github.com/jgunthorpe/linux/commits/smmuv3_nesting
> 
> Jason Gunthorpe (5):
>   vfio: Remove VFIO_TYPE1_NESTING_IOMMU
>   iommu/arm-smmu-v3: Use S2FWB when available
>   iommu/arm-smmu-v3: Report IOMMU_CAP_ENFORCE_CACHE_COHERENCY for CANWBS
>   iommu/arm-smmu-v3: Implement IOMMU_HWPT_ALLOC_NEST_PARENT
>   iommu/arm-smmu-v3: Support IOMMU_DOMAIN_NESTED
> 
> Nicolin Chen (3):
>   ACPI/IORT: Support CANWBS memory access flag
>   iommu/arm-smmu-v3: Support IOMMU_GET_HW_INFO via struct
>     arm_smmu_hw_info
>   iommu/arm-smmu-v3: Add arm_smmu_cache_invalidate_user
> 
>  drivers/acpi/arm64/iort.c                   |  13 +
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 398 ++++++++++++++++++--
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h |  27 ++
>  drivers/iommu/arm/arm-smmu/arm-smmu.c       |  16 -
>  drivers/iommu/io-pgtable-arm.c              |  24 +-
>  drivers/iommu/iommu.c                       |  10 -
>  drivers/iommu/iommufd/vfio_compat.c         |   7 +-
>  drivers/vfio/vfio_iommu_type1.c             |  12 +-
>  include/acpi/actbl2.h                       |   1 +
>  include/linux/io-pgtable.h                  |   2 +
>  include/linux/iommu.h                       |  54 ++-
>  include/uapi/linux/iommufd.h                |  79 ++++
>  include/uapi/linux/vfio.h                   |   2 +-
>  13 files changed, 572 insertions(+), 73 deletions(-)
> 
> 
> base-commit: e5e288d94186b266b062b3e44c82c285dfe68712
> -- 
> 2.46.0
>