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

[Alexey Kardashevskiy]

Anyone? Is it totally useless or wrong approach? Thanks,


On 08/04/2020 19:43, Alexey Kardashevskiy wrote:
> 
> 
> 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/
>>
>> 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