Re: [PATCH v4 08/21] KVM: arm64: Support SDEI_EVENT_STATUS hypercall

[Gavin Shan]

Hi Eric,

On 11/10/21 1:12 AM, Eric Auger wrote:
> On 8/15/21 2:13 AM, Gavin Shan wrote:
> > This supports SDEI_EVENT_STATUS hypercall. It's used by the guest
> > to retrieve a bitmap to indicate the SDEI event states, including
> > registration, enablement and delivery state.
> >
> > Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
> > ---
> >   arch/arm64/kvm/sdei.c | 50 +++++++++++++++++++++++++++++++++++++++++++
> >   1 file changed, 50 insertions(+)
> >
> > diff --git a/arch/arm64/kvm/sdei.c b/arch/arm64/kvm/sdei.c
> > index a3ba69dc91cb..b95b8c4455e1 100644
> > --- a/arch/arm64/kvm/sdei.c
> > +++ b/arch/arm64/kvm/sdei.c
> > @@ -367,6 +367,54 @@ static unsigned long kvm_sdei_hypercall_unregister(struct kvm_vcpu *vcpu)
> >   	return ret;
> >   }
> >   
> > +static unsigned long kvm_sdei_hypercall_status(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);
> > +	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)) {
> > +		ret = SDEI_INVALID_PARAMETERS;
> > +		goto out;
> > +	}
> if we were to support bound events, I do not know if a given even num
> can disapper inbetween that check and the rest of the code, in which
> case a lock would be needed?

For the bound events, it's possbile. However, @ksdei->lock can be reused
in that cause. Anyway, it's something for future :)

> > +
> > +	/*
> > +	 * Check if the KVM event exists. None of the flags
> > +	 * will be set if it doesn't exist.
> > +	 */
> > +	spin_lock(&ksdei->lock);
> > +	kske = kvm_sdei_find_kvm_event(kvm, event_num);
> > +	if (!kske) {
> > +		ret = 0;
> > +		goto unlock;
> > +	}
> > +
> > +	index = (kse->state.type == SDEI_EVENT_TYPE_PRIVATE) ?
> > +		vcpu->vcpu_idx : 0;
> > +	if (kvm_sdei_is_registered(kske, index))
> > +		ret |= (1UL << SDEI_EVENT_STATUS_REGISTERED);
> > +	if (kvm_sdei_is_enabled(kske, index))
> > +		ret |= (1UL << SDEI_EVENT_STATUS_ENABLED);
> > +	if (kske->state.refcount)
> > +		ret |= (1UL << SDEI_EVENT_STATUS_RUNNING);
> > +
> > +unlock:
> > +	spin_unlock(&ksdei->lock);
> > +out:
> > +	return ret;
> > +}
> > +
> >   int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
> >   {
> >   	u32 func = smccc_get_function(vcpu);
> > @@ -395,6 +443,8 @@ int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
> >   		ret = kvm_sdei_hypercall_unregister(vcpu);
> >   		break;
> >   	case SDEI_1_0_FN_SDEI_EVENT_STATUS:
> > +		ret = kvm_sdei_hypercall_status(vcpu);
> > +		break;
> >   	case SDEI_1_0_FN_SDEI_EVENT_GET_INFO:
> >   	case SDEI_1_0_FN_SDEI_EVENT_ROUTING_SET:
> >   	case SDEI_1_0_FN_SDEI_PE_MASK:

Thanks,
Gavin