spapr_iommu: Realloc guest visible TCE table when starting/stopping listening

spapr_iommu: Realloc guest visible TCE table when starting/stopping listening

The sPAPR TCE tables manage 2 copies when VFIO is using an IOMMU -
a guest view of the table and a hardware TCE table. If there is no VFIO
presense in the address space, then just the guest view is used, if
this is the case, it is allocated in the KVM. However since there is no
support yet for VFIO in KVM TCE hypercalls, when we start using VFIO,
we need to move the guest view from KVM to the userspace; and we need
to do this for every IOMMU on a bus with VFIO devices.

This implements the callbacks for the sPAPR IOMMU - notify_started()
reallocated the guest view to the user space, notify_stopped() does
the opposite.

This removes explicit spapr_tce_set_need_vfio() call from PCI hotplug
path as the new callbacks do this better - they notify IOMMU at
the exact moment when the configuration is changed, and this also
includes the case of PCI hot unplug.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>