Subject: Re: linux-next: manual merge of the kvm-arm tree with Linus' tree

From: Christoffer Dall <[email-masked]>
Date: Wed, 8 Apr 2015 12:57:55 +0200

On Wed, Apr 08, 2015 at 09:15:13AM +0100, Marc Zyngier wrote:
> On Tue, 7 Apr 2015 17:20:15 +0100
> Paolo Bonzini <[email-masked]> wrote:
> 
> Hi Paolo,
> 
> > On 18/03/2015 08:55, Christoffer Dall wrote:
> > > Hi Stephen,
> > > 
> > > On Wed, Mar 18, 2015 at 02:41:11PM +1100, Stephen Rothwell wrote:
> > >> Hi all,
> > >>
> > >> Today's linux-next merge of the kvm-arm tree got a conflict in
> > >> virt/kvm/arm/vgic.c between commit ae705930fca6 ("arm/arm64: KVM: Keep
> > >> elrsr/aisr in sync with software model") from Linus' tree and commit
> > >> 71760950bf3d ("arm/arm64: KVM: add a common vgic_queue_irq_to_lr fn")
> > >> from the kvm-arm tree.
> > >>
> > >> I fixed it up (I think - see below) and can carry the fix as necessary
> > >> (no action is required).
> > >>
> > >> -- 
> > >> Cheers,
> > >> Stephen Rothwell                    [email-masked]
> > >>
> > >> diff --cc virt/kvm/arm/vgic.c
> > >> index c9f60f524588,ffd937ca5141..000000000000
> > >> --- a/virt/kvm/arm/vgic.c
> > >> +++ b/virt/kvm/arm/vgic.c
> > >> @@@ -982,9 -1092,7 +1098,8 @@@ bool vgic_queue_irq(struct kvm_vcpu *vc
> > >>   		if (vlr.source == sgi_source_id) {
> > >>   			kvm_debug("LR%d piggyback for IRQ%d\n", lr, vlr.irq);
> > >>   			BUG_ON(!test_bit(lr, vgic_cpu->lr_used));
> > >> - 			vlr.state |= LR_STATE_PENDING;
> > >> - 			vgic_set_lr(vcpu, lr, vlr);
> > >> + 			vgic_queue_irq_to_lr(vcpu, irq, lr, vlr);
> > >>  +			vgic_sync_lr_elrsr(vcpu, lr, vlr);
> > >>   			return true;
> > >>   		}
> > >>   	}
> > >> @@@ -1001,12 -1109,8 +1116,9 @@@
> > >>   
> > >>   	vlr.irq = irq;
> > >>   	vlr.source = sgi_source_id;
> > >> - 	vlr.state = LR_STATE_PENDING;
> > >> - 	if (!vgic_irq_is_edge(vcpu, irq))
> > >> - 		vlr.state |= LR_EOI_INT;
> > >> - 
> > >> - 	vgic_set_lr(vcpu, lr, vlr);
> > >> + 	vlr.state = 0;
> > >> + 	vgic_queue_irq_to_lr(vcpu, irq, lr, vlr);
> > >>  +	vgic_sync_lr_elrsr(vcpu, lr, vlr);
> > >>   
> > >>   	return true;
> > >>   }
> > > 
> > > Looks great, thanks!
> > > -Christoffer
> > 
> > Got the same conflict when pulling from the kvm-arm tree, I used
> > a different resolution though:
> > 
> > diff --cc virt/kvm/arm/vgic.c
> > index c9f60f524588,b70174e74868..8d550ff14700
> > --- a/virt/kvm/arm/vgic.c
> > +++ b/virt/kvm/arm/vgic.c
> > @@@ -955,6 -1095,25 +1101,26 @@@ static void vgic_retire_disabled_irqs(s
> >   	}
> >   }
> >   
> > + static void vgic_queue_irq_to_lr(struct kvm_vcpu *vcpu, int irq,
> > + 				 int lr_nr, struct vgic_lr vlr)
> > + {
> > + 	if (vgic_irq_is_active(vcpu, irq)) {
> > + 		vlr.state |= LR_STATE_ACTIVE;
> > + 		kvm_debug("Set active, clear distributor: 0x%x\n", vlr.state);
> > + 		vgic_irq_clear_active(vcpu, irq);
> > + 		vgic_update_state(vcpu->kvm);
> > + 	} else if (vgic_dist_irq_is_pending(vcpu, irq)) {
> > + 		vlr.state |= LR_STATE_PENDING;
> > + 		kvm_debug("Set pending: 0x%x\n", vlr.state);
> > + 	}
> > + 
> > + 	if (!vgic_irq_is_edge(vcpu, irq))
> > + 		vlr.state |= LR_EOI_INT;
> > + 
> > + 	vgic_set_lr(vcpu, lr_nr, vlr);
> > ++	vgic_sync_lr_elrsr(vcpu, lr_nr, vlr);
> > + }
> > + 
> >   /*
> >    * Queue an interrupt to a CPU virtual interface. Return true on success,
> >    * or false if it wasn't possible to queue it.
> > @@@ -982,9 -1141,7 +1148,7 @@@ bool vgic_queue_irq(struct kvm_vcpu *vc
> >                 if (vlr.source == sgi_source_id) {
> >                         kvm_debug("LR%d piggyback for IRQ%d\n", lr, vlr.irq);
> >                         BUG_ON(!test_bit(lr, vgic_cpu->lr_used));
> > -                       vlr.state |= LR_STATE_PENDING;
> > -                       vgic_set_lr(vcpu, lr, vlr);
> > -                       vgic_sync_lr_elrsr(vcpu, lr, vlr);
> > +                       vgic_queue_irq_to_lr(vcpu, irq, lr, vlr);
> >                         return true;
> >                 }
> >         }
> > @@@ -1001,12 -1158,8 +1165,8 @@@
> >   
> >         vlr.irq = irq;
> >         vlr.source = sgi_source_id;
> > -       vlr.state = LR_STATE_PENDING;
> > -       if (!vgic_irq_is_edge(vcpu, irq))
> > -               vlr.state |= LR_EOI_INT;
> > - 
> > -       vgic_set_lr(vcpu, lr, vlr);
> > -       vgic_sync_lr_elrsr(vcpu, lr, vlr);
> > +       vlr.state = 0;
> > +       vgic_queue_irq_to_lr(vcpu, irq, lr, vlr);
> >   
> >         return true;
> >   }
> > 
> > 
> > Christoffer, this is the same logic as Stephen's resolution, but
> > can you confirm that it makes sense "semantically" as well?
> 
> This looks like a sensible resolution to me. I've given it a spin, and
> it seems to behave as expected.
> 
Yes, this is semantically slightly nicer in fact.

Thanks,
-Christoffer