virtio, pc: fixes, features

New virtio iommu.
Unrealize memory leaks.
In-band kick/call support.
Bugfixes, documentation all over the place.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

# gpg: Signature made Thu 27 Feb 2020 08:46:33 GMT
# gpg:                using RSA key 5D09FD0871C8F85B94CA8A0D281F0DB8D28D5469
# gpg:                issuer "mst@redhat.com"
# gpg: Good signature from "Michael S. Tsirkin <mst@kernel.org>" [full]
# gpg:                 aka "Michael S. Tsirkin <mst@redhat.com>" [full]
# Primary key fingerprint: 0270 606B 6F3C DF3D 0B17  0970 C350 3912 AFBE 8E67
#      Subkey fingerprint: 5D09 FD08 71C8 F85B 94CA  8A0D 281F 0DB8 D28D 5469

* remotes/mst/tags/for_upstream: (30 commits)
  Fixed assert in vhost_user_set_mem_table_postcopy
  vhost-user: only set slave channel for first vq
  acpi: cpuhp: document CPHP_GET_CPU_ID_CMD command
  libvhost-user: implement in-band notifications
  docs: vhost-user: add in-band kick/call messages
  libvhost-user: handle NOFD flag in call/kick/err better
  libvhost-user-glib: use g_main_context_get_thread_default()
  libvhost-user-glib: fix VugDev main fd cleanup
  libvhost-user: implement VHOST_USER_PROTOCOL_F_REPLY_ACK
  MAINTAINERS: add virtio-iommu related files
  hw/arm/virt: Add the virtio-iommu device tree mappings
  virtio-iommu-pci: Add virtio iommu pci support
  virtio-iommu: Support migration
  virtio-iommu: Implement fault reporting
  virtio-iommu: Implement translate
  virtio-iommu: Implement map/unmap
  virtio-iommu: Implement attach/detach command
  virtio-iommu: Decode the command payload
  virtio-iommu: Add skeleton
  virtio: gracefully handle invalid region caches
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>