Re: [Qemu-ppc] [PATCH qemu] RFC: spapr/iommu: Enable in-kernel TCE acceleration via VFIO KVM device

[Paolo Bonzini]

On 20/12/2017 02:47, Alexey Kardashevskiy wrote:
>> - if we foresee having more IOMMU devices in KVM, let's rename
>> KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE to KVM_DEV_VFIO_GROUP_ATTACH_IOMMU and
>> add a new function
>>
>>      int iommu_memory_region_get_kvm_fd(IOMMUMemoryRegion *iommu);
>>
>> that requires no object-type check in VFIO.
>
> This is how it started and the comment was that this KVM fd needs to have a
> well defined semantic which I struggle to provide.

I don't think the definition should be anything more than "it can be
passed to KVM_DEV_VFIO_GROUP_ATTACH_IOMMU".  I'll discuss it with Alex
later today.

Paolo