spapr/iommu: Enable in-kernel TCE acceleration via VFIO KVM device

spapr/iommu: Enable in-kernel TCE acceleration via VFIO KVM device

In order to enable TCE operations support in KVM, we have to inform
the KVM about VFIO groups being attached to specific LIOBNs;
the necessary bits are implemented already by IOMMU MR and VFIO.

This defines get_attr() for the SPAPR TCE IOMMU MR which makes VFIO
call the KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE ioctl and establish
LIOBN-to-IOMMU link.

This changes spapr_tce_set_need_vfio() to avoid TCE table reallocation
if the kernel supports the TCE acceleration.

Signed-off-by: Alexey Kardashevskiy <[email protected]>
Acked-by: Paolo Bonzini <[email protected]>
Acked-by: David Gibson <[email protected]>
[aw - remove unnecessary sys/ioctl.h include]
Signed-off-by: Alex Williamson <[email protected]>