Re: [PATCH v4 10/21] KVM: arm64: Support SDEI_EVENT_ROUTING_SET hypercall

[Gavin Shan]

Hi Eric,

On 11/10/21 2:47 AM, Eric Auger wrote:
> On 8/15/21 2:13 AM, Gavin Shan wrote:
> > This supports SDEI_EVENT_ROUTING_SET hypercall. It's used by the
> > guest to set route mode and affinity for the registered KVM event.
> > It's only valid for the shared events. It's not allowed to do so
> > when the corresponding event has been raised to the guest.
> >
> > Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
> > ---
> >   arch/arm64/kvm/sdei.c | 64 +++++++++++++++++++++++++++++++++++++++++++
> >   1 file changed, 64 insertions(+)
> >
> > diff --git a/arch/arm64/kvm/sdei.c b/arch/arm64/kvm/sdei.c
> > index 5dfa74b093f1..458695c2394f 100644
> > --- a/arch/arm64/kvm/sdei.c
> > +++ b/arch/arm64/kvm/sdei.c
> > @@ -489,6 +489,68 @@ static unsigned long kvm_sdei_hypercall_info(struct kvm_vcpu *vcpu)
> >   	return ret;
> >   }
> >   
> > +static unsigned long kvm_sdei_hypercall_route(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 route_mode = smccc_get_arg2(vcpu);
> > +	unsigned long route_affinity = smccc_get_arg3(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 (!(route_mode == SDEI_EVENT_REGISTER_RM_ANY ||
> > +	      route_mode == SDEI_EVENT_REGISTER_RM_PE)) {
> > +		ret = SDEI_INVALID_PARAMETERS;
> > +		goto out;
> > +	}
> Some sanity checking on the affinity arg could be made as well according
> to 5.1.2  affinity desc. The fn shall return INVALID_PARAMETER in case
> of invalid affinity.

Yep, you're right. I didn't figure out it. I may put a comment here.
For now, the SDEI client driver in the guest kernel doesn't attempt
to change the routing mode.

	/* FIXME: The affinity should be verified */

> > +
> > +	/* Check if the KVM event has been registered */
> > +	spin_lock(&ksdei->lock);
> > +	kske = kvm_sdei_find_kvm_event(kvm, event_num);
> > +	if (!kske) {
> > +		ret = SDEI_INVALID_PARAMETERS;
> > +		goto unlock;
> > +	}
> > +
> > +	/* Validate KVM event state */
> > +	kse = kske->kse;
> > +	if (kse->state.type != SDEI_EVENT_TYPE_SHARED) {
> > +		ret = SDEI_INVALID_PARAMETERS;
> > +		goto unlock;
> > +	}
> > +
> Event handler is in a state other than: handler-registered.

They're equivalent as the handler is provided as a parameter when
the event is registered.

> > +	if (!kvm_sdei_is_registered(kske, index) ||
> > +	    kvm_sdei_is_enabled(kske, index)     ||
> > +	    kske->state.refcount) {
> I am not sure about the refcount role here. Does it make sure the state
> is != handler-enabled and running or handler-unregister-pending?
>
> I think we would gain in readibility if we had a helper to check whether
> we are in those states?

@refcount here indicates pending SDEI event for delivery. In this case,
chaning its routing mode is disallowed.

> > +		ret = SDEI_DENIED;
> > +		goto unlock;
> > +	}
> > +
> > +	/* Update state */
> > +	kske->state.route_mode     = route_mode;
> > +	kske->state.route_affinity = route_affinity;
> > +
> > +unlock:
> > +	spin_unlock(&ksdei->lock);
> > +out:
> > +	return ret;
> > +}
> > +
> >   int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
> >   {
> >   	u32 func = smccc_get_function(vcpu);
> > @@ -523,6 +585,8 @@ int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
> >   		ret = kvm_sdei_hypercall_info(vcpu);
> >   		break;
> >   	case SDEI_1_0_FN_SDEI_EVENT_ROUTING_SET:
> > +		ret = kvm_sdei_hypercall_route(vcpu);
> > +		break;
> >   	case SDEI_1_0_FN_SDEI_PE_MASK:
> >   	case SDEI_1_0_FN_SDEI_PE_UNMASK:
> >   	case SDEI_1_0_FN_SDEI_INTERRUPT_BIND:

Thanks,
Gavin