On Tue, Apr 04, 2017 at 07:46:12PM +0200, Christoffer Dall wrote:
> On Fri, Mar 31, 2017 at 06:06:56PM +0200, Andrew Jones wrote:
> > Refactor PMU overflow handling in order to remove the request-less
> > vcpu kick. Now, since kvm_vgic_inject_irq() uses vcpu requests,
> > there should be no chance that a kick sent at just the wrong time
> > (between the VCPU's call to kvm_pmu_flush_hwstate() and before it
> > enters guest mode) results in a failure for the guest to see updated
> > GIC state until its next exit some time later for some other reason.
> >
> > Signed-off-by: Andrew Jones <drjones@xxxxxxxxxx>
> > ---
> > virt/kvm/arm/pmu.c | 29 +++++++++++++++--------------
> > 1 file changed, 15 insertions(+), 14 deletions(-)
> >
> > diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c
> > index 69ccce308458..9d725f3afb11 100644
> > --- a/virt/kvm/arm/pmu.c
> > +++ b/virt/kvm/arm/pmu.c
> > @@ -203,6 +203,19 @@ static u64 kvm_pmu_overflow_status(struct kvm_vcpu *vcpu)
> > return reg;
> > }
> >
> > +static void kvm_pmu_check_overflow(struct kvm_vcpu *vcpu)
> > +{
> > + struct kvm_pmu *pmu = &vcpu->arch.pmu;
> > + bool overflow;
> > +
> > + overflow = !!kvm_pmu_overflow_status(vcpu);
> > + if (pmu->irq_level != overflow) {
> > + pmu->irq_level = overflow;
> > + kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id,
> > + pmu->irq_num, overflow);
> > + }
> > +}
> > +
>
> If we are changing the way the PMU works to adjust the interrupt
> signaling whenever the PMU changes its internal state, do we still ahv
> to call kvm_pmu_update_state() from each flush/sync path now?
The thought crossed my mind to rework that completely, in order to remove
that flush/sync, but then went for the smaller patch for this series. I
can take a look at it though.
Thanks,
drew
>
> > /**
> > * kvm_pmu_overflow_set - set PMU overflow interrupt
> > * @vcpu: The vcpu pointer
> > @@ -210,31 +223,19 @@ static u64 kvm_pmu_overflow_status(struct kvm_vcpu *vcpu)
> > */
> > void kvm_pmu_overflow_set(struct kvm_vcpu *vcpu, u64 val)
> > {
> > - u64 reg;
> > -
> > if (val == 0)
> > return;
> >
> > vcpu_sys_reg(vcpu, PMOVSSET_EL0) |= val;
> > - reg = kvm_pmu_overflow_status(vcpu);
> > - if (reg != 0)
> > - kvm_vcpu_kick(vcpu);
> > + kvm_pmu_check_overflow(vcpu);
> > }
> >
> > static void kvm_pmu_update_state(struct kvm_vcpu *vcpu)
> > {
> > - struct kvm_pmu *pmu = &vcpu->arch.pmu;
> > - bool overflow;
> > -
> > if (!kvm_arm_pmu_v3_ready(vcpu))
> > return;
> >
> > - overflow = !!kvm_pmu_overflow_status(vcpu);
> > - if (pmu->irq_level != overflow) {
> > - pmu->irq_level = overflow;
> > - kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id,
> > - pmu->irq_num, overflow);
> > - }
> > + kvm_pmu_check_overflow(vcpu);
> > }
> >
> > /**
> > --
> > 2.9.3
> >
>
> Thanks,
> -Christoffer
