RE: [PATCH v1 11/23] KVM: x86: Add kvm_is_fred_enabled()

...

• return cpu_feature_enabled(X86_FEATURE_FRED) &&

•       kvm_is_cr4_bit_set(vcpu, X86_CR4_FRED);
  

FRED is enabled when CR4.FRED = IA32_EFER.LMA = 1. Any reason to omit the check about long mode?

It won' t allow CR4.FRED to be set if not in long mode, I don't expect it at runtime. Or you have one?

If you are talking about save/restore a corrupted vCPU state, a following VM entry should fail anyway.