Merge tag 'for-linus-4.10-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

Pull xen fix from Juergen Gross:
 "A fix for Xen running in nested virtualization environment"

* tag 'for-linus-4.10-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  partially revert "xen: Remove event channel notification through Xen PCI platform device"