Merge remote-tracking branch 'remotes/sstabellini-http/tags/xen-20180522-tag' into staging

Xen 2018/05/22

# gpg: Signature made Tue 22 May 2018 19:44:06 BST
# gpg:                using RSA key 894F8F4870E1AE90
# gpg: Good signature from "Stefano Stabellini <stefano.stabellini@eu.citrix.com>"
# gpg:                 aka "Stefano Stabellini <sstabellini@kernel.org>"
# Primary key fingerprint: D04E 33AB A51F 67BA 07D3  0AEA 894F 8F48 70E1 AE90

* remotes/sstabellini-http/tags/xen-20180522-tag:
  xen_disk: be consistent with use of xendev and blkdev->xendev
  xen_disk: use a single entry iovec
  xen_backend: make the xen_feature_grant_copy flag private
  xen_disk: remove use of grant map/unmap
  xen_backend: add an emulation of grant copy
  xen: remove other open-coded use of libxengnttab
  xen_disk: remove open-coded use of libxengnttab
  xen_backend: add grant table helpers
  xen: add a meaningful declaration of grant_copy_segment into xen_common.h
  checkpatch: generalize xen handle matching in the list of types
  xen-hvm: create separate function for ioreq server initialization
  xen_pt: Present the size of 64 bit BARs correctly
  configure: Add explanation for --enable-xen-pci-passthrough
  xen/pt: use address_space_memory object for memory region hooks
  xen-pvdevice: Introduce a simplistic xen-pvdevice save state

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