Re: [PATCH v8 33/33] KVM: x86/vmx: refactor VMX_DO_EVENT_IRQOFF to generate FRED stack frames

[Sean Christopherson]

On Tue, Apr 11, 2023, Xin3 Li wrote:
> > 
> >  	kvm_before_interrupt(vcpu, KVM_HANDLING_IRQ);
> > -	vmx_do_interrupt_irqoff(gate_offset(desc));
> > +	if (cpu_feature_enabled(X86_FEATURE_FRED))
> > +		vmx_do_fred_interrupt_irqoff(vector);
> > +	else
> > +		vmx_do_interrupt_irqoff(gate_offset((gate_desc *)host_idt_base
> 
> 
> external_interrupt() is always available on x86_64, even when CONFIG_X86_FRED
> is not defined. I prefer to always call external_interrupt() on x86_64 for IRQ
> handling, which avoids re-entering noinstr code. how do you think? Too
> aggressive?

I think it's completely orthogonal to FRED enabling.  If you or anyone else wants
to convert the non-FRED handling to external_interrupt(), then do so after FRED
lands, or at the very least in a separate patch after enabling FRED in KVM.