Function vmw_backdoor::probe_backdoor_privileged

pub fn probe_backdoor_privileged() -> Result<BackdoorGuard, VmwError>

Try to acquire access to the backdoor, and probe its presence.

On Linux, this tries to change I/O access level via iopl(). That requires running with CAP_SYS_RAWIO capability and it is not compatible with kernel_lockdown.