Restrict the protocol version(s) that will be negotiated with the host
to be 5.2 or greater if the guest is running isolated.  This reduces the
footprint of the code that will be exercised by Confidential VMs and
hence the exposure to bugs and vulnerabilities.
Signed-off-by: NAndrea Parri (Microsoft) <parri.andrea@gmail.com>
Reviewed-by: NMichael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20210201144814.2701-4-parri.andrea@gmail.comSigned-off-by: NWei Liu <wei.liu@kernel.org>