Comment 7 for bug 1678676

Hi minoura - I was able to verify that your proposed fix does prevent the NULL pointer exception. I had a question about the fix as I'm not very familiar with the code in vmx.c. Should we also check if to_vmx(vcpu)->nested.current_vmcs12 is NULL and, if so, break? I'm not clear if current_vmptr and current_vmcs12 are always guaranteed to have corresponding values.