RE: [PATCH v1 05/23] KVM: VMX: Initialize FRED VM entry/exit controls in vmcs_config

[Li, Xin3]

> > -	if (_vmexit_control & VM_EXIT_ACTIVATE_SECONDARY_CONTROLS)
> > +	if (_vmexit_control & VM_EXIT_ACTIVATE_SECONDARY_CONTROLS) {
> >   		_secondary_vmexit_control =
> >
> 	adjust_vmx_controls64(KVM_OPTIONAL_VMX_SECONDARY_VM_EXIT_CO
> NTROLS,
> >   					      MSR_IA32_VMX_EXIT_CTLS2);
> > +		if (cpu_feature_enabled(X86_FEATURE_FRED) &&
> > +		    !(_secondary_vmexit_control &
> SECONDARY_VM_EXIT_SAVE_IA32_FRED &&
> > +		      _secondary_vmexit_control &
> SECONDARY_VM_EXIT_LOAD_IA32_FRED)) {
> 
> Can those checks actually trigger? I.e if FEATURE_FRED is set it means
> the CPU implements the FRED spec. According to the spec it's guaranteed
> that VMX_EXIT_CTLS2 will contain those bits set to 1. So aren't those
> checks superfluous?

Such checks are for nVMX FRED.

> > +	if (cpu_feature_enabled(X86_FEATURE_FRED) &&
> > +	    !(_vmentry_control & VM_ENTRY_LOAD_IA32_FRED)) {
> DITTO
> 
> <snip>