Re: [Xen-devel] [PATCH RFC V6 1/5] kvm hypervisor : Add a hypercall to KVM hypervisor to support pv-ticketlocks

[Avi Kivity <avi@xxxxxxxxxx>]

On 04/24/2012 12:59 PM, Gleb Natapov wrote:
> >  
> > +/*
> > + * kvm_pv_kick_cpu_op:  Kick a vcpu.
> > + *
> > + * @apicid - apicid of vcpu to be kicked.
> > + */
> > +static void kvm_pv_kick_cpu_op(struct kvm *kvm, int apicid)
> > +{
> > +   struct kvm_vcpu *vcpu = NULL;
> > +   int i;
> > +
> > +   kvm_for_each_vcpu(i, vcpu, kvm) {
> > +           if (!kvm_apic_present(vcpu))
> > +                   continue;
> > +
> > +           if (kvm_apic_match_dest(vcpu, 0, 0, apicid, 0))
> > +                   break;
> > +   }
> > +   if (vcpu) {
> > +           /*
> > +            * Setting unhalt flag here can result in spurious runnable
> > +            * state when unhalt reset does not happen in vcpu_block.
> > +            * But that is harmless since that should soon result in halt.
> > +            */
> > +           vcpu->arch.pv.pv_unhalted = 1;
> > +           /* We need everybody see unhalt before vcpu unblocks */
> > +           smp_mb();
> > +           kvm_vcpu_kick(vcpu);
> > +   }
> > +}
> This is too similar to kvm_irq_delivery_to_apic(). Why not reuse it. We
> can use one of reserved delivery modes as PV delivery mode. We will
> disallow guest to trigger it through apic interface, so this will not be
> part of ABI and can be changed at will.
>

I'm not thrilled about this.  Those delivery modes will eventually
become unreserved.  We can have a kvm_lookup_apic_id() that is shared
among implementations.

-- 
error compiling committee.c: too many arguments to function


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