Subject: Re: [Qemu-ppc] [RFC PATCH 04/17] KVM: PPC64: booke: Add guest computation mode for irq delivery

From: Scott Wood <[email-masked]>
Date: Thu, 5 Jul 2012 18:51:45 -0500

On 07/04/2012 08:40 AM, Alexander Graf wrote:
> On 25.06.2012, at 14:26, Mihai Caraman wrote:
>> @@ -381,7 +386,8 @@ static int kvmppc_booke_irqprio_deliver(struct kvm_vcpu *vcpu,
>> 			set_guest_esr(vcpu, vcpu->arch.queued_esr);
>> 		if (update_dear == true)
>> 			set_guest_dear(vcpu, vcpu->arch.queued_dear);
>> -		kvmppc_set_msr(vcpu, vcpu->arch.shared->msr & msr_mask);
>> +		kvmppc_set_msr(vcpu, (vcpu->arch.shared->msr & msr_mask)
>> +				| msr_cm);
> 
> Please split this computation out into its own variable and apply the masking regardless. Something like
> 
> ulong new_msr = vcpu->arch.shared->msr;
> if (vcpu->arch.epcr & SPRN_EPCR_ICM)
>     new_msr |= MSR_CM;
> new_msr &= msr_mask;
> kvmppc_set_msr(vcpu, new_msr);

This will fail to clear MSR[CM] in the odd but legal situation where you
have MSR[CM] set but EPCR[ICM] unset.

-Scott