vfio: Do not register any IOMMU_NOTIFIER_DEVIOTLB_UNMAP notifier

In an attempt to fix smmu/virtio-iommu - vhost regression, commit
958ec33 ("vhost: Unbreak SMMU and virtio-iommu on dev-iotlb support")
broke virtio-iommu integration. This is due to the fact VFIO registers
IOMMU_NOTIFIER_ALL notifiers, which includes IOMMU_NOTIFIER_DEVIOTLB_UNMAP
and this latter now is rejected by the virtio-iommu. As a consequence,
the registration fails. VHOST behaves like a device with an ATC cache. The
VFIO device does not support this scheme yet.

Let's register only legacy MAP and UNMAP notifiers.

Fixes: 958ec33 ("vhost: Unbreak SMMU and virtio-iommu on dev-iotlb support")
Signed-off-by: Eric Auger <eric.auger@redhat.com>
Message-Id: <20210209213233.40985-2-eric.auger@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

hw/vfio/common.c

@@ -787,7 +787,7 @@ static void vfio_listener_region_add(MemoryListener *listener,
         iommu_idx = memory_region_iommu_attrs_to_index(iommu_mr,
                                                        MEMTXATTRS_UNSPECIFIED);
         iommu_notifier_init(&giommu->n, vfio_iommu_map_notify,
-                            IOMMU_NOTIFIER_ALL,
+                            IOMMU_NOTIFIER_IOTLB_EVENTS,
                             section->offset_within_region,
                             int128_get64(llend),
                             iommu_idx);