KVM: Fix iommu map/unmap to handle memory slot moves

commit e40f193f5bb022e927a57a4f5d5194e4f12ddb74 upstream.

The iommu integration into memory slots expects memory slots to be
added or removed and doesn't handle the move case.  We can unmap
slots from the iommu after we mark them invalid and map them before
installing the final memslot array.  Also re-order the kmemdup vs
map so we don't leave iommu mappings if we get ENOMEM.

Reviewed-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Luis Henriques <luis.henriques@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>