Re: [PATCH v4 09/21] KVM: arm64: Support SDEI_EVENT_GET_INFO hypercall

[Gavin Shan]

Hi Eric,

On 11/10/21 1:19 AM, Eric Auger wrote:
> On 8/15/21 2:13 AM, Gavin Shan wrote:
> > This supports SDEI_EVENT_GET_INFO hypercall. It's used by the guest
> > to retrieve various information about the supported (exported) events,
> > including type, signaled, route mode and affinity for the shared
> > events.
> >
> > Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
> > ---
> >   arch/arm64/kvm/sdei.c | 76 +++++++++++++++++++++++++++++++++++++++++++
> >   1 file changed, 76 insertions(+)
> >
> > diff --git a/arch/arm64/kvm/sdei.c b/arch/arm64/kvm/sdei.c
> > index b95b8c4455e1..5dfa74b093f1 100644
> > --- a/arch/arm64/kvm/sdei.c
> > +++ b/arch/arm64/kvm/sdei.c
> > @@ -415,6 +415,80 @@ static unsigned long kvm_sdei_hypercall_status(struct kvm_vcpu *vcpu)
> >   	return ret;
> >   }
> >   
> > +static unsigned long kvm_sdei_hypercall_info(struct kvm_vcpu *vcpu)
> > +{
> > +	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);
> > +	unsigned long event_info = smccc_get_arg2(vcpu);
> > +	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)) {
> > +		ret = SDEI_INVALID_PARAMETERS;
> > +		goto out;
> > +	}
> > +
> > +	/*
> > +	 * Check if the KVM event exists. The event might have been
> > +	 * registered, we need fetch the information from the registered
> s/fetch/to fetch

Ack.

> > +	 * event in that case.
> > +	 */
> > +	spin_lock(&ksdei->lock);
> > +	kske = kvm_sdei_find_kvm_event(kvm, event_num);
> > +	kse = kske ? kske->kse : NULL;
> > +	if (!kse) {
> > +		kse = kvm_sdei_find_event(kvm, event_num);
> > +		if (!kse) {
> > +			ret = SDEI_INVALID_PARAMETERS;
> this should have already be covered by !kvm_sdei_is_valid_event_num I
> think (although this latter only checks the since static event num with
> KVM owner mask)

Nope. Strictly speaking, kvm_sdei_find_event() covers the check carried
by !kvm_sdei_is_valid_event_num(). All the defined (exposed) events should
have virtual event number :)

> > +			goto unlock;
> > +		}
> > +	}
> > +
> > +	/* Retrieve the requested information */
> > +	switch (event_info) {
> > +	case SDEI_EVENT_INFO_EV_TYPE:
> > +		ret = kse->state.type;
> > +		break;
> > +	case SDEI_EVENT_INFO_EV_SIGNALED:
> > +		ret = kse->state.signaled;
> > +		break;
> > +	case SDEI_EVENT_INFO_EV_PRIORITY:
> > +		ret = kse->state.priority;
> > +		break;
> > +	case SDEI_EVENT_INFO_EV_ROUTING_MODE:
> > +	case SDEI_EVENT_INFO_EV_ROUTING_AFF:
> > +		if (kse->state.type != SDEI_EVENT_TYPE_SHARED) {
> > +			ret = SDEI_INVALID_PARAMETERS;
> > +			break;
> > +		}
> > +
> > +		if (event_info == SDEI_EVENT_INFO_EV_ROUTING_MODE) {
> > +			ret = kske ? kske->state.route_mode :
> > +				     SDEI_EVENT_REGISTER_RM_ANY;
> no, if event is not registered (!kske) DENIED should be returned

I don't think so. According to the specification, there is no DENIED
return value for STATUS hypercall. Either INVALID_PARAMETERS or NOT_SUPPORTED
should be returned from this hypercall :)

> > +		} else {
> same here
> > +			ret = kske ? kske->state.route_affinity : 0;
> > +		}
> > +
> > +		break;
> > +	default:
> > +		ret = SDEI_INVALID_PARAMETERS;
> > +	}
> > +
> > +unlock:
> > +	spin_unlock(&ksdei->lock);
> > +out:
> > +	return ret;
> > +}
> > +
> >   int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
> >   {
> >   	u32 func = smccc_get_function(vcpu);
> > @@ -446,6 +520,8 @@ int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
> >   		ret = kvm_sdei_hypercall_status(vcpu);
> >   		break;
> >   	case SDEI_1_0_FN_SDEI_EVENT_GET_INFO:
> > +		ret = kvm_sdei_hypercall_info(vcpu);
> > +		break;
> >   	case SDEI_1_0_FN_SDEI_EVENT_ROUTING_SET:
> >   	case SDEI_1_0_FN_SDEI_PE_MASK:
> >   	case SDEI_1_0_FN_SDEI_PE_UNMASK:

Thanks,
Gavin