There are almost no hypercalls which are valid from CPL > 0, and definitely
none which are handled by the kernel.

Fixes: 2fd6df2f ("KVM: x86/xen: intercept EVTCHNOP_send from guests")
Reported-by: NMichal Luczaj <mhal@rbox.co>
Signed-off-by: NDavid Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: NSean Christopherson <seanjc@google.com>
Cc: stable@kernel.org
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>