Merge remote-tracking branch 'remotes/mst/tags/for_upstream' into staging

pc, pci, virtio, vhost: fixes, features

Beginning of merging vDPA, new PCI ID, a new virtio balloon stat, intel
iommu rework fixing a couple of security problems (no CVEs yet), fixes
all over the place.

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

# gpg: Signature made Wed 23 May 2018 15:41:32 BST
# gpg:                using RSA key 281F0DB8D28D5469
# gpg: Good signature from "Michael S. Tsirkin <mst@kernel.org>"
# gpg:                 aka "Michael S. Tsirkin <mst@redhat.com>"
# 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: (28 commits)
  intel-iommu: rework the page walk logic
  util: implement simple iova tree
  intel-iommu: trace domain id during page walk
  intel-iommu: pass in address space when page walk
  intel-iommu: introduce vtd_page_walk_info
  intel-iommu: only do page walk for MAP notifiers
  intel-iommu: add iommu lock
  intel-iommu: remove IntelIOMMUNotifierNode
  intel-iommu: send PSI always even if across PDEs
  nvdimm: fix typo in label-size definition
  contrib/vhost-user-blk: enable protocol feature for vhost-user-blk
  hw/virtio: Fix brace Werror with clang 6.0.0
  libvhost-user: Send messages with no data
  vhost-user+postcopy: Use qemu_set_nonblock
  virtio: support setting memory region based host notifier
  vhost-user: support receiving file descriptors in slave_read
  vhost-user: add Net prefix to internal state structure
  linux-headers: add kvm header for mips
  linux-headers: add unistd.h on all arches
  update-linux-headers.sh: unistd.h, kvm consistency
  ...

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