Re: [PATCH v3 16/16] objtool: Validate kCFI calls

[Xin Li]

On 7/25/2025 12:56 PM, Sean Christopherson wrote:
> > BTW, there is a declaration for vmx_do_interrupt_irqoff() in
> > arch/x86/kvm/vmx/vmx.c, so we'd better also do:
> >
> > --- a/arch/x86/kvm/vmx/vmx.c
> > +++ b/arch/x86/kvm/vmx/vmx.c
> > @@ -6945,7 +6945,9 @@ void vmx_load_eoi_exitmap(struct kvm_vcpu *vcpu, u64
> > *eoi_exit_bitmap)
> >          vmcs_write64(EOI_EXIT_BITMAP3, eoi_exit_bitmap[3]);
> >   }
> >
> > +#ifndef CONFIG_X86_FRED
> >   void vmx_do_interrupt_irqoff(unsigned long entry);
> > +#endif
> No, we want to keep the declaration.  Unconditionally decaring the symbol allows
> KVM to use IS_ENABLED():
>
> 	if (IS_ENABLED(CONFIG_X86_FRED))
>   		fred_entry_from_kvm(EVENT_TYPE_EXTINT, vector);
>
> Hiding the declaration would require that to be a "proper" #ifdef, which would
> be a net negative for readability.  The extra declaration won't hurt anything for
> CONFIG_X86_FRED=n, as "bad" usage will still fail at link time.

I did hit a compilation error, so yes, we have to keep it.