On Tue, Apr 04, 2017 at 08:29:18PM +0200, Andrew Jones wrote:
> 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.
>
Actually, now when I actually read what this code will be doing, the
extra thing in flush/sync won't do any work because it will find that
omu->irq_level == overflow, so never mind - we can improve that later as
an optimization patch.
Let's focus on getting it right.
Thanks,
-Christoffer
> >
> > > /**
> > > * 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
> > >
