Reply-To: Thinking about the vhost-user protocol, VHOST_SET_MEM_TABLE is used to update the memory mappings.
So shouldn't we want for response? Otherwise e.g. guest can start using the memory that vhost-user can't access. Similarly, with an IOMMU vhost-user might access memory it shouldn't. VHOST_SET_VRING_CALL is used for MSI-X masking. Again, after vector is masted by switching the call fd, backend shouldn't assert the old one. Thoughts?
