Re: [PATCH v4 12/21] KVM: arm64: Support SDEI_{PRIVATE, SHARED}_RESET hypercall

[Gavin Shan]

Hi Eric,

On 11/10/21 4:37 AM, Eric Auger wrote:
> On 8/15/21 2:13 AM, Gavin Shan wrote:
> > This supports SDEI_{PRIVATE, SHARED}_RESET. They are used by the
> > guest to purge the private or shared SDEI events, which are registered
> to reset all private SDEI event registrations of the calling PE (resp.
> PRIVATE or SHARED)

Ok.

> > previously.
> >
> > Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
> > ---
> >   arch/arm64/kvm/sdei.c | 29 +++++++++++++++++++++++++++++
> >   1 file changed, 29 insertions(+)
> >
> > diff --git a/arch/arm64/kvm/sdei.c b/arch/arm64/kvm/sdei.c
> > index 3fb33258b494..62efee2b67b8 100644
> > --- a/arch/arm64/kvm/sdei.c
> > +++ b/arch/arm64/kvm/sdei.c
> > @@ -582,6 +582,29 @@ static unsigned long kvm_sdei_hypercall_mask(struct kvm_vcpu *vcpu,
> >   	return ret;
> >   }
> >   
> > +static unsigned long kvm_sdei_hypercall_reset(struct kvm_vcpu *vcpu,
> > +					      bool private)
> > +{
> > +	struct kvm *kvm = vcpu->kvm;
> > +	struct kvm_sdei_kvm *ksdei = kvm->arch.sdei;
> > +	struct kvm_sdei_vcpu *vsdei = vcpu->arch.sdei;
> > +	unsigned int mask = private ? (1 << SDEI_EVENT_TYPE_PRIVATE) :
> > +				      (1 << SDEI_EVENT_TYPE_SHARED);
> > +	unsigned long ret = SDEI_SUCCESS;
> > +
> > +	/* Sanity check */
> > +	if (!(ksdei && vsdei)) {
> > +		ret = SDEI_NOT_SUPPORTED;
> > +		goto out;
> > +	}
> > +
> > +	spin_lock(&ksdei->lock);
> > +	kvm_sdei_remove_kvm_events(kvm, mask, false);
> With kvm_sdei_remove_kvm_events() implementation, why do you make sure
> that events which have a running handler get unregistered once the
> handler completes? I just see the refcount check that prevents the "KVM
> event object" from being removed.

Good point. I think here we need enhancement to cancel the pending
events prior to destroying them. I will think about it :)

> > +	spin_unlock(&ksdei->lock);
> > +out:
> > +	return ret;
> > +}
> > +
> >   int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
> >   {
> >   	u32 func = smccc_get_function(vcpu);
> > @@ -626,8 +649,14 @@ int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
> >   		break;
> >   	case SDEI_1_0_FN_SDEI_INTERRUPT_BIND:
> >   	case SDEI_1_0_FN_SDEI_INTERRUPT_RELEASE:
> > +		ret = SDEI_NOT_SUPPORTED;
> > +		break;
> >   	case SDEI_1_0_FN_SDEI_PRIVATE_RESET:
> > +		ret = kvm_sdei_hypercall_reset(vcpu, true);
> > +		break;
> >   	case SDEI_1_0_FN_SDEI_SHARED_RESET:
> > +		ret = kvm_sdei_hypercall_reset(vcpu, false);
> > +		break;
> >   	default:
> >   		ret = SDEI_NOT_SUPPORTED;
> >   	}

Thanks,
Gavin