Re: [PATCH kernel v2 0/7] powerpc/powenv/ioda: Allow huge DMA window at 4GB

On 23/03/2020 18:53, Alexey Kardashevskiy wrote:

Here is an attempt to support bigger DMA space for devices
supporting DMA masks less than 59 bits (GPUs come into mind
first). POWER9 PHBs have an option to map 2 windows at 0
and select a windows based on DMA address being below or above
4GB.

This adds the "iommu=iommu_bypass" kernel parameter and
supports VFIO+pseries machine - current this requires telling
upstream+unmodified QEMU about this via
-global spapr-pci-host-bridge.dma64_win_addr=0x100000000
or per-phb property. 4/4 advertises the new option but
there is no automation around it in QEMU (should it be?).

For now it is either 1<<59 or 4GB mode; dynamic switching is
not supported (could be via sysfs).

This is a rebased version of
https://lore.kernel.org/kvm/20191202015953.127902-1-aik@ozlabs.ru/ (local)

The main change since v1 is that now it is 7 patches with
clearer separation of steps.


This is based on 6c90b86a745a "Merge tag 'mmc-v5.6-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc"

Please comment. Thanks.

Ping?

Alexey Kardashevskiy (7):
  powerpc/powernv/ioda: Move TCE bypass base to PE
  powerpc/powernv/ioda: Rework for huge DMA window at 4GB
  powerpc/powernv/ioda: Allow smaller TCE table levels
  powerpc/powernv/phb4: Use IOMMU instead of bypassing
  powerpc/iommu: Add a window number to
    iommu_table_group_ops::get_table_size
  powerpc/powernv/phb4: Add 4GB IOMMU bypass mode
  vfio/spapr_tce: Advertise and allow a huge DMA windows at 4GB

 arch/powerpc/include/asm/iommu.h              |   3 +
 arch/powerpc/include/asm/opal-api.h           |   9 +-
 arch/powerpc/include/asm/opal.h               |   2 +
 arch/powerpc/platforms/powernv/pci.h          |   4 +-
 include/uapi/linux/vfio.h                     |   2 +
 arch/powerpc/platforms/powernv/npu-dma.c      |   1 +
 arch/powerpc/platforms/powernv/opal-call.c    |   2 +
 arch/powerpc/platforms/powernv/pci-ioda-tce.c |   4 +-
 arch/powerpc/platforms/powernv/pci-ioda.c     | 234 ++++++++++++++----
 drivers/vfio/vfio_iommu_spapr_tce.c           |  17 +-
 10 files changed, 213 insertions(+), 65 deletions(-)

-- 
Alexey