On Mon, Feb 18, 2019 at 11:00:19PM +0100, Christoffer Dall wrote:
> On Mon, Jan 14, 2019 at 04:11:48PM +0000, Andrew Murray wrote:
> > Enable/disable event counters as appropriate when entering and exiting
> > the guest to enable support for guest or host only event counting.
> >
> > For both VHE and non-VHE we switch the counters between host/guest at
> > EL2. EL2 is filtered out by the PMU when we are using the :G modifier.
>
> I don't think the last part is strictly true as per the former patch on
> a non-vhe system if you have the :h modifier, so maybe just leave that
> out of the commit message.
OK I'll remove that.
>
> >
> > The PMU may be on when we change which counters are enabled however
> > we avoid adding an isb as we instead rely on existing context
> > synchronisation events: the isb in kvm_arm_vhe_guest_exit for VHE and
> > the eret from the hvc in kvm_call_hyp.
> >
> > Signed-off-by: Andrew Murray <andrew.murray@xxxxxxx>
> > Reviewed-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
> > ---
> > arch/arm64/kvm/hyp/switch.c | 60 +++++++++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 60 insertions(+)
> >
> > diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
> > index b0b1478..9018fb3 100644
> > --- a/arch/arm64/kvm/hyp/switch.c
> > +++ b/arch/arm64/kvm/hyp/switch.c
> > @@ -357,6 +357,54 @@ static bool __hyp_text __hyp_switch_fpsimd(struct kvm_vcpu *vcpu)
> > return true;
> > }
> >
> > +static bool __hyp_text __pmu_switch_to_guest(struct kvm_cpu_context *host_ctxt)
> > +{
> > + struct kvm_host_data *host;
> > + struct kvm_pmu_events *pmu;
> > + u32 clr, set;
> > +
> > + host = container_of(host_ctxt, struct kvm_host_data, host_ctxt);
> > + pmu = &host->pmu_events;
> > +
> > + /* We can potentially avoid a sysreg write by only changing bits that
> > + * differ between the guest/host. E.g. where events are enabled in
> > + * both guest and host
> > + */
>
> super nit: kernel coding style requires 'wings' on both side of a
> multi-line comment. Only if you respin anyhow.
Ah I didn't notice that, I'll fix this up.
Thanks for the review.
Andrew Murray
>
> > + clr = pmu->events_host & ~pmu->events_guest;
> > + set = pmu->events_guest & ~pmu->events_host;
> > +
> > + if (clr)
> > + write_sysreg(clr, pmcntenclr_el0);
> > +
> > + if (set)
> > + write_sysreg(set, pmcntenset_el0);
> > +
> > + return (clr || set);
> > +}
> > +
> > +static void __hyp_text __pmu_switch_to_host(struct kvm_cpu_context *host_ctxt)
> > +{
> > + struct kvm_host_data *host;
> > + struct kvm_pmu_events *pmu;
> > + u32 clr, set;
> > +
> > + host = container_of(host_ctxt, struct kvm_host_data, host_ctxt);
> > + pmu = &host->pmu_events;
> > +
> > + /* We can potentially avoid a sysreg write by only changing bits that
> > + * differ between the guest/host. E.g. where events are enabled in
> > + * both guest and host
> > + */
>
> ditto
>
> > + clr = pmu->events_guest & ~pmu->events_host;
> > + set = pmu->events_host & ~pmu->events_guest;
> > +
> > + if (clr)
> > + write_sysreg(clr, pmcntenclr_el0);
> > +
> > + if (set)
> > + write_sysreg(set, pmcntenset_el0);
> > +}
> > +
> > /*
> > * Return true when we were able to fixup the guest exit and should return to
> > * the guest, false when we should restore the host state and return to the
> > @@ -464,12 +512,15 @@ int kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu)
> > {
> > struct kvm_cpu_context *host_ctxt;
> > struct kvm_cpu_context *guest_ctxt;
> > + bool pmu_switch_needed;
> > u64 exit_code;
> >
> > host_ctxt = vcpu->arch.host_cpu_context;
> > host_ctxt->__hyp_running_vcpu = vcpu;
> > guest_ctxt = &vcpu->arch.ctxt;
> >
> > + pmu_switch_needed = __pmu_switch_to_guest(host_ctxt);
> > +
> > sysreg_save_host_state_vhe(host_ctxt);
> >
> > /*
> > @@ -511,6 +562,9 @@ int kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu)
> >
> > __debug_switch_to_host(vcpu);
> >
> > + if (pmu_switch_needed)
> > + __pmu_switch_to_host(host_ctxt);
> > +
> > return exit_code;
> > }
> >
> > @@ -519,6 +573,7 @@ int __hyp_text __kvm_vcpu_run_nvhe(struct kvm_vcpu *vcpu)
> > {
> > struct kvm_cpu_context *host_ctxt;
> > struct kvm_cpu_context *guest_ctxt;
> > + bool pmu_switch_needed;
> > u64 exit_code;
> >
> > vcpu = kern_hyp_va(vcpu);
> > @@ -527,6 +582,8 @@ int __hyp_text __kvm_vcpu_run_nvhe(struct kvm_vcpu *vcpu)
> > host_ctxt->__hyp_running_vcpu = vcpu;
> > guest_ctxt = &vcpu->arch.ctxt;
> >
> > + pmu_switch_needed = __pmu_switch_to_guest(host_ctxt);
> > +
> > __sysreg_save_state_nvhe(host_ctxt);
> >
> > __activate_vm(kern_hyp_va(vcpu->kvm));
> > @@ -573,6 +630,9 @@ int __hyp_text __kvm_vcpu_run_nvhe(struct kvm_vcpu *vcpu)
> > */
> > __debug_switch_to_host(vcpu);
> >
> > + if (pmu_switch_needed)
> > + __pmu_switch_to_host(host_ctxt);
> > +
> > return exit_code;
> > }
> >
> > --
> > 2.7.4
> >
>
> Thanks,
>
> Christoffer
_______________________________________________
kvmarm mailing list
kvmarm@xxxxxxxxxxxxxxxxxxxxx
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
