On Tue, Aug 14, 2012 at 07:10:43PM -0500, Scott Wood wrote:
> On 08/14/2012 06:04 PM, Alexander Graf wrote:
> > We need a central place to check for pending requests in. Add one that
> > only does the timer check we already do in a different place.
> >
> > Later, this central function can be extended by more checks.
> >
> > Signed-off-by: Alexander Graf <agraf@xxxxxxx>
> > ---
> > arch/powerpc/kvm/booke.c | 24 +++++++++++++++++-------
> > 1 files changed, 17 insertions(+), 7 deletions(-)
> >
> > diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
> > index 1d4ce9a..bcf87fe 100644
> > --- a/arch/powerpc/kvm/booke.c
> > +++ b/arch/powerpc/kvm/booke.c
> > @@ -419,13 +419,6 @@ static void kvmppc_core_check_exceptions(struct kvm_vcpu *vcpu)
> > unsigned long *pending = &vcpu->arch.pending_exceptions;
> > unsigned int priority;
> >
> > - if (vcpu->requests) {
> > - if (kvm_check_request(KVM_REQ_PENDING_TIMER, vcpu)) {
> > - smp_mb();
> > - update_timer_ints(vcpu);
> > - }
> > - }
> > -
> > priority = __ffs(*pending);
> > while (priority < BOOKE_IRQPRIO_MAX) {
> > if (kvmppc_booke_irqprio_deliver(vcpu, priority))
> > @@ -461,6 +454,14 @@ int kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
> > return r;
> > }
> >
> > +static void kvmppc_check_requests(struct kvm_vcpu *vcpu)
> > +{
> > + if (vcpu->requests) {
> > + if (kvm_check_request(KVM_REQ_PENDING_TIMER, vcpu))
> > + update_timer_ints(vcpu);
> > + }
> > +}
> > +
> > /*
> > * Common checks before entering the guest world. Call with interrupts
> > * disabled.
> > @@ -485,6 +486,15 @@ static int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu)
> > break;
> > }
> >
> > + smp_mb();
> > + if (vcpu->requests) {
> > + /* Make sure we process requests preemptable */
> > + local_irq_enable();
> > + kvmppc_check_requests(vcpu);
> > + local_irq_disable();
> > + continue;
> > + }
>
> What previous memory access is the smp_mb() ordering against?
>
> -Scott
It is good practice to document each memory barrier.
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