> >+/* > >+ * It's enough to check just CR4.FRED (X86_CR4_FRED) to tell if > >+ * a vCPU is running with FRED enabled, because: > >+ * 1) CR4.FRED can be set to 1 only _after_ IA32_EFER.LMA = 1. > >+ * 2) To leave IA-32e mode, CR4.FRED must be cleared first. > >+ * > >+ * More details at FRED Spec 6.0 Section 4.2 Enabling in CR4. > >+ */ > > I think we can give more context here, e.g., > > Although FRED architecture applies to 64-bit mode only, there is no need to check if > the CPU is in 64-bit mode (i.e., IA32_EFER.LMA and CS.L) to tell if FRED is enabled > because CR4.FRED=1 implies the CPU is in 64-bit mode. What is "more context" here? > Specifically,
