[PATCH 2/6] KVM: PPC: Book3E: Refactor SPE/FP exit handling

[Caraman Mihai Claudiu-B02008]

> > -#ifdef CONFIG_SPE
> > 	case BOOKE_INTERRUPT_SPE_ALTIVEC_UNAVAIL: {
> > -		if (vcpu->arch.shared->msr & MSR_SPE)
> > -			kvmppc_vcpu_enable_spe(vcpu);
> > -		else
> > -			kvmppc_booke_queue_irqprio(vcpu,
> > -
> BOOKE_IRQPRIO_SPE_ALTIVEC_UNAVAIL);
> > +		if (kvmppc_supports_spe()) {
> > +			bool enabled = false;
> > +
> > +#ifndef CONFIG_KVM_BOOKE_HV
> > +			if (vcpu->arch.shared->msr & MSR_SPE) {
> > +				kvmppc_vcpu_enable_spe(vcpu);
> > +				enabled = true;
> > +			}
> > +#endif
> 
> Why the #ifdef? On HV capable systems kvmppc_supports_spe() will just
> always return false. 

AltiVec and SPE unavailable exceptions follows the same path. While 
kvmppc_supports_spe() will always return false kvmppc_supports_altivec()
may not.

> And I don't really understand why HV would be special in the first place
> here. Is it because we're accessing shared->msr?

You are right on HV case MSP[SPV] should be always zero when an unavailabe
exception take place. The distrinction was made because on non HV the guest
doesn't have direct access to MSR[SPE]. The name of the bit (not the position)
was changed on HV cores.

> 
> > +			if (!enabled)
> > +				kvmppc_booke_queue_irqprio(vcpu,
> > +					BOOKE_IRQPRIO_SPE_ALTIVEC_UNAVAIL);
> > +		} else {
> > +			/*
> > +			 * Guest wants SPE, but host kernel doesn't support it.
> 
> host kernel or hardware

Ok.

-Mike