Re: [PATCH v4 05/21] KVM: arm64: Support SDEI_EVENT_{ENABLE, DISABLE} hypercall

[Gavin Shan]

Hi Eric,

On 11/10/21 12:02 AM, Eric Auger wrote:
> On 8/15/21 2:13 AM, Gavin Shan wrote:
> > This supports SDEI_EVENT_{ENABLE, DISABLE} hypercall. After SDEI
> > event is registered by guest, it won't be delivered to the guest
> > until it's enabled. On the other hand, the SDEI event won't be
> > raised to the guest or specific vCPU if it's has been disabled
> > on the guest or specific vCPU.
> >
> > Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
> > ---
> >   arch/arm64/kvm/sdei.c | 68 +++++++++++++++++++++++++++++++++++++++++++
> >   1 file changed, 68 insertions(+)
> >
> > diff --git a/arch/arm64/kvm/sdei.c b/arch/arm64/kvm/sdei.c
> > index d3ea3eee154b..b022ce0a202b 100644
> > --- a/arch/arm64/kvm/sdei.c
> > +++ b/arch/arm64/kvm/sdei.c
> > @@ -206,6 +206,70 @@ static unsigned long kvm_sdei_hypercall_register(struct kvm_vcpu *vcpu)
> >   	return ret;
> >   }
> >   
> > +static unsigned long kvm_sdei_hypercall_enable(struct kvm_vcpu *vcpu,
> > +					       bool enable)
> > +{
> > +	struct kvm *kvm = vcpu->kvm;
> > +	struct kvm_sdei_kvm *ksdei = kvm->arch.sdei;
> > +	struct kvm_sdei_vcpu *vsdei = vcpu->arch.sdei;
> > +	struct kvm_sdei_event *kse = NULL;
> > +	struct kvm_sdei_kvm_event *kske = NULL;
> > +	unsigned long event_num = smccc_get_arg1(vcpu);
> > +	int index = 0;
> > +	unsigned long ret = SDEI_SUCCESS;
> > +
> > +	/* Sanity check */
> > +	if (!(ksdei && vsdei)) {
> > +		ret = SDEI_NOT_SUPPORTED;
> > +		goto out;
> > +	}
> > +
> > +	if (!kvm_sdei_is_valid_event_num(event_num)) {
> I would rename into is_exposed_event_num()

kvm_sdei_is_virtual() has been recommended by you when you reviewed the following
patch. I think kvm_sdei_is_virtual() is good enough :)

   [PATCH v4 02/21] KVM: arm64: Add SDEI virtualization infrastructure

> > +		ret = SDEI_INVALID_PARAMETERS;
> > +		goto out;
> > +	}
> > +
> > +	/* Check if the KVM event exists */
> > +	spin_lock(&ksdei->lock);
> > +	kske = kvm_sdei_find_kvm_event(kvm, event_num);
> > +	if (!kske) {
> > +		ret = SDEI_INVALID_PARAMETERS;
> should be DENIED according to the spec, ie. nobody registered that event?

Ok.

> > +		goto unlock;
> > +	}
> > +
> > +	/* Check if there is pending events */
> does that match the "handler-unregister-pending state" case mentionned
> in the spec?
> > +	if (kske->state.refcount) {
> > +		ret = SDEI_PENDING;
> ? not documented in my A spec? DENIED?

Yep, It should be DENIED.

> > +		goto unlock;
> > +	}
> > +
> > +	/* Check if it has been registered */
> isn't duplicate of /* Check if the KVM event exists */ ?

It's not duplicate check, but the comment here seems misleading. I will
correct this to:

	/* Check if it has been defined or exposed */

> > +	kse = kske->kse;
> > +	index = (kse->state.type == SDEI_EVENT_TYPE_PRIVATE) ?
> > +		vcpu->vcpu_idx : 0;
> > +	if (!kvm_sdei_is_registered(kske, index)) {
> > +		ret = SDEI_DENIED;
> > +		goto unlock;
> > +	}
> > +
> > +	/* Verify its enablement state */
> > +	if (enable == kvm_sdei_is_enabled(kske, index)) {
> spec says:
> Enabling/disabled an event, which is already enabled/disabled, is
> permitted and has no effect. I guess ret should be OK.

yep, it should be ok.

> > +		ret = SDEI_DENIED;
> > +		goto unlock;
> > +	}
> > +
> > +	/* Update enablement state */
> > +	if (enable)
> > +		kvm_sdei_set_enabled(kske, index);
> > +	else
> > +		kvm_sdei_clear_enabled(kske, index);
> > +
> > +unlock:
> > +	spin_unlock(&ksdei->lock);
> > +out:
> > +	return ret;
> > +}
> > +
> >   int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
> >   {
> >   	u32 func = smccc_get_function(vcpu);
> > @@ -220,7 +284,11 @@ int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
> >   		ret = kvm_sdei_hypercall_register(vcpu);
> >   		break;
> >   	case SDEI_1_0_FN_SDEI_EVENT_ENABLE:
> > +		ret = kvm_sdei_hypercall_enable(vcpu, true);
> > +		break;
> >   	case SDEI_1_0_FN_SDEI_EVENT_DISABLE:
> > +		ret = kvm_sdei_hypercall_enable(vcpu, false);
> > +		break;
> >   	case SDEI_1_0_FN_SDEI_EVENT_CONTEXT:
> >   	case SDEI_1_0_FN_SDEI_EVENT_COMPLETE:
> >   	case SDEI_1_0_FN_SDEI_EVENT_COMPLETE_AND_RESUME:

Thanks,
Gavin