[v1] KVM: x86: AVIC and local APIC fixes+cleanups

[PATCH 11/19] KVM: SVM: Add helper to perform final AVIC "kick" of single vCPU

Posted by Sean Christopherson 3 years, 7 months ago

Add a helper to perform the final kick, two instances of the ICR decoding
is one too many.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/svm/avic.c | 25 +++++++++++++------------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index 3959d4766911..2095ece70712 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -329,6 +329,16 @@ void avic_ring_doorbell(struct kvm_vcpu *vcpu)
 	put_cpu();
 }
 
+
+static void avic_kick_vcpu(struct kvm_vcpu *vcpu, u32 icrl)
+{
+	vcpu->arch.apic->irr_pending = true;
+	svm_complete_interrupt_delivery(vcpu,
+					icrl & APIC_MODE_MASK,
+					icrl & APIC_INT_LEVELTRIG,
+					icrl & APIC_VECTOR_MASK);
+}
+
 /*
  * A fast-path version of avic_kick_target_vcpus(), which attempts to match
  * destination APIC ID to vCPU without looping through all vCPUs.
@@ -427,11 +437,7 @@ static int avic_kick_target_vcpus_fast(struct kvm *kvm, struct kvm_lapic *source
 	if (unlikely(!target_vcpu))
 		return 0;
 
-	target_vcpu->arch.apic->irr_pending = true;
-	svm_complete_interrupt_delivery(target_vcpu,
-					icrl & APIC_MODE_MASK,
-					icrl & APIC_INT_LEVELTRIG,
-					icrl & APIC_VECTOR_MASK);
+	avic_kick_vcpu(target_vcpu, icrl);
 	return 0;
 }
 
@@ -455,13 +461,8 @@ static void avic_kick_target_vcpus(struct kvm *kvm, struct kvm_lapic *source,
 	 */
 	kvm_for_each_vcpu(i, vcpu, kvm) {
 		if (kvm_apic_match_dest(vcpu, source, icrl & APIC_SHORT_MASK,
-					dest, icrl & APIC_DEST_MASK)) {
-			vcpu->arch.apic->irr_pending = true;
-			svm_complete_interrupt_delivery(vcpu,
-							icrl & APIC_MODE_MASK,
-							icrl & APIC_INT_LEVELTRIG,
-							icrl & APIC_VECTOR_MASK);
-		}
+					dest, icrl & APIC_DEST_MASK))
+			avic_kick_vcpu(vcpu, icrl);
 	}
 }
 
-- 
2.37.2.672.g94769d06f0-goog

Re: [PATCH 11/19] KVM: SVM: Add helper to perform final AVIC "kick" of single vCPU

Posted by Maxim Levitsky 3 years, 7 months ago

On Wed, 2022-08-31 at 00:34 +0000, Sean Christopherson wrote:
> Add a helper to perform the final kick, two instances of the ICR decoding
> is one too many.
> 
> No functional change intended.
> 
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
>  arch/x86/kvm/svm/avic.c | 25 +++++++++++++------------
>  1 file changed, 13 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
> index 3959d4766911..2095ece70712 100644
> --- a/arch/x86/kvm/svm/avic.c
> +++ b/arch/x86/kvm/svm/avic.c
> @@ -329,6 +329,16 @@ void avic_ring_doorbell(struct kvm_vcpu *vcpu)
>  	put_cpu();
>  }
>  
> +
> +static void avic_kick_vcpu(struct kvm_vcpu *vcpu, u32 icrl)
> +{
> +	vcpu->arch.apic->irr_pending = true;
> +	svm_complete_interrupt_delivery(vcpu,
> +					icrl & APIC_MODE_MASK,
> +					icrl & APIC_INT_LEVELTRIG,
> +					icrl & APIC_VECTOR_MASK);
> +}
> +
>  /*
>   * A fast-path version of avic_kick_target_vcpus(), which attempts to match
>   * destination APIC ID to vCPU without looping through all vCPUs.
> @@ -427,11 +437,7 @@ static int avic_kick_target_vcpus_fast(struct kvm *kvm, struct kvm_lapic *source
>  	if (unlikely(!target_vcpu))
>  		return 0;
>  
> -	target_vcpu->arch.apic->irr_pending = true;
> -	svm_complete_interrupt_delivery(target_vcpu,
> -					icrl & APIC_MODE_MASK,
> -					icrl & APIC_INT_LEVELTRIG,
> -					icrl & APIC_VECTOR_MASK);
> +	avic_kick_vcpu(target_vcpu, icrl);
>  	return 0;
>  }
>  
> @@ -455,13 +461,8 @@ static void avic_kick_target_vcpus(struct kvm *kvm, struct kvm_lapic *source,
>  	 */
>  	kvm_for_each_vcpu(i, vcpu, kvm) {
>  		if (kvm_apic_match_dest(vcpu, source, icrl & APIC_SHORT_MASK,
> -					dest, icrl & APIC_DEST_MASK)) {
> -			vcpu->arch.apic->irr_pending = true;
> -			svm_complete_interrupt_delivery(vcpu,
> -							icrl & APIC_MODE_MASK,
> -							icrl & APIC_INT_LEVELTRIG,
> -							icrl & APIC_VECTOR_MASK);
> -		}
> +					dest, icrl & APIC_DEST_MASK))
> +			avic_kick_vcpu(vcpu, icrl);
>  	}
>  }
>  

I don't know what I think about this, sometimes *minor* code duplication might actually
be a good thing, as it is easier to read the code, but I don't have much against this
as well.

I am not sure if before or after this code is more readable.

But anyway,

Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>

Best regards,
	Maxim Levitsky

Re: [PATCH 11/19] KVM: SVM: Add helper to perform final AVIC "kick" of single vCPU

Posted by Sean Christopherson 3 years, 7 months ago

On Wed, Aug 31, 2022, Maxim Levitsky wrote:
> On Wed, 2022-08-31 at 00:34 +0000, Sean Christopherson wrote:
> > @@ -455,13 +461,8 @@ static void avic_kick_target_vcpus(struct kvm *kvm, struct kvm_lapic *source,
> >  	 */
> >  	kvm_for_each_vcpu(i, vcpu, kvm) {
> >  		if (kvm_apic_match_dest(vcpu, source, icrl & APIC_SHORT_MASK,
> > -					dest, icrl & APIC_DEST_MASK)) {
> > -			vcpu->arch.apic->irr_pending = true;
> > -			svm_complete_interrupt_delivery(vcpu,
> > -							icrl & APIC_MODE_MASK,
> > -							icrl & APIC_INT_LEVELTRIG,
> > -							icrl & APIC_VECTOR_MASK);
> > -		}
> > +					dest, icrl & APIC_DEST_MASK))
> > +			avic_kick_vcpu(vcpu, icrl);
> >  	}
> >  }
> >  
> 
> I don't know what I think about this, sometimes *minor* code duplication
> might actually be a good thing, as it is easier to read the code, but I don't
> have much against this as well.
> 
> I am not sure if before or after this code is more readable.

I don't have a strong opinion either.  I think I prefer having the helper, but
have no objection to leaving things as is.  Originally I was thinking there was
going to be a third call site, but that didn't happen.

Re: [PATCH 11/19] KVM: SVM: Add helper to perform final AVIC "kick" of single vCPU

Posted by Maxim Levitsky 3 years, 7 months ago

On Wed, 2022-08-31 at 15:08 +0000, Sean Christopherson wrote:
> On Wed, Aug 31, 2022, Maxim Levitsky wrote:
> > On Wed, 2022-08-31 at 00:34 +0000, Sean Christopherson wrote:
> > > @@ -455,13 +461,8 @@ static void avic_kick_target_vcpus(struct kvm *kvm, struct kvm_lapic *source,
> > >  	 */
> > >  	kvm_for_each_vcpu(i, vcpu, kvm) {
> > >  		if (kvm_apic_match_dest(vcpu, source, icrl & APIC_SHORT_MASK,
> > > -					dest, icrl & APIC_DEST_MASK)) {
> > > -			vcpu->arch.apic->irr_pending = true;
> > > -			svm_complete_interrupt_delivery(vcpu,
> > > -							icrl & APIC_MODE_MASK,
> > > -							icrl & APIC_INT_LEVELTRIG,
> > > -							icrl & APIC_VECTOR_MASK);
> > > -		}
> > > +					dest, icrl & APIC_DEST_MASK))
> > > +			avic_kick_vcpu(vcpu, icrl);
> > >  	}
> > >  }
> > >  
> > 
> > I don't know what I think about this, sometimes *minor* code duplication
> > might actually be a good thing, as it is easier to read the code, but I don't
> > have much against this as well.
> > 
> > I am not sure if before or after this code is more readable.
> 
> I don't have a strong opinion either.  I think I prefer having the helper, but
> have no objection to leaving things as is.  Originally I was thinking there was
> going to be a third call site, but that didn't happen.
> 

Yep - when something is duplicated 3 times, it is really rare to not want to have a helper,
Anyway I don't have a strong opinion about this either.

I mostly was unsure about the fact that helper receives icrl and not icrh, kind of wierd,
but anyway let it be.

Best regards,
	Maxim Levitsky