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

Joerg Roedel
2025-02-21T11:02:40Z

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.