
Add handling of POST_MESSAGE hypercall. For that, add an interface to regsiter a handler for the messages arrived from the guest on a particular connection id (IOW set up a message connection in Hyper-V speak). Signed-off-by: Roman Kagan <rkagan@virtuozzo.com> Message-Id: <20180921082217.29481-10-rkagan@virtuozzo.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>