Re: [PATCH v5 0/4] iommu/s390: add support for IOMMU passthrough

[Joerg Roedel <joro@8bytes.org>]

On Wed, Feb 12, 2025 at 04:34:14PM -0500, Matthew Rosato wrote:
> This series introduces the ability for certain devices on s390 to bypass
> a layer of IOMMU via the iommu.passthrough=1 option.  In order to enable
> this, the concept of an identity domain is added to s390-iommu.  On s390,
> IOMMU passthrough is only allowed if indicated via a special bit in s390
> CLP data for the associated device group, otherwise we must fall back to
> dma-iommu.
> 
> Changes for v5:
> - Fixup error checking for bus_dma_region size
> - Add review/test tags
> 
> Changes for v4:
> - Additional patch to handle IOAT registration within s390-iommu.  This
>   fixes an issue with re-registration of identity domain during events
>   like zpci_hot_reset_device
> - Fixup page alignment for bus_dma_region setup
> - Dropped a few review/test tags due to above changes
> 
> Changes for v3:
> - Rebase onto 6.13
> - fixed bus_dma_region size (Niklas) 
> 
> Changes for v2:
> - Remove ARCH_HAS_PHYS_TO_DMA, use bus_dma_region
> - Remove use of def_domain_type, use 1 of 2 ops chosen at init
> 
> Matthew Rosato (4):
>   s390/pci: check for relaxed translation capability
>   s390/pci: store DMA offset in bus_dma_region
>   iommu/s390: handle IOAT registration based on domain
>   iommu/s390: implement iommu passthrough via identity domain
> 
>  arch/s390/include/asm/pci.h     |   4 +-
>  arch/s390/include/asm/pci_clp.h |   4 +-
>  arch/s390/kvm/pci.c             |  17 +---
>  arch/s390/pci/pci.c             |  35 ++++----
>  arch/s390/pci/pci_bus.c         |  25 ++++++
>  arch/s390/pci/pci_clp.c         |   1 +
>  arch/s390/pci/pci_sysfs.c       |  11 +--
>  drivers/iommu/s390-iommu.c      | 138 ++++++++++++++++++++++++++------
>  8 files changed, 168 insertions(+), 67 deletions(-)

Applied, thanks.