Re: [PATCH v4 11/21] KVM: arm64: Support SDEI_PE_{MASK, UNMASK} hypercall

[Gavin Shan]

Hi Eric,

On 11/10/21 4:31 AM, Eric Auger wrote:
> On 8/15/21 2:13 AM, Gavin Shan wrote:
> > This supports SDEI_PE_{MASK, UNMASK} hypercall. They are used by
> > the guest to stop the specific vCPU from receiving SDEI events.
> >
> > Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
> > ---
> >   arch/arm64/kvm/sdei.c | 35 +++++++++++++++++++++++++++++++++++
> >   1 file changed, 35 insertions(+)
> >
> > diff --git a/arch/arm64/kvm/sdei.c b/arch/arm64/kvm/sdei.c
> > index 458695c2394f..3fb33258b494 100644
> > --- a/arch/arm64/kvm/sdei.c
> > +++ b/arch/arm64/kvm/sdei.c
> > @@ -551,6 +551,37 @@ static unsigned long kvm_sdei_hypercall_route(struct kvm_vcpu *vcpu)
> >   	return ret;
> >   }
> >   
> > +static unsigned long kvm_sdei_hypercall_mask(struct kvm_vcpu *vcpu,
> > +					     bool mask)
> > +{
> > +	struct kvm *kvm = vcpu->kvm;
> > +	struct kvm_sdei_kvm *ksdei = kvm->arch.sdei;
> > +	struct kvm_sdei_vcpu *vsdei = vcpu->arch.sdei;
> > +	unsigned long ret = SDEI_SUCCESS;
> > +
> > +	/* Sanity check */
> > +	if (!(ksdei && vsdei)) {
> > +		ret = SDEI_NOT_SUPPORTED;
> > +		goto out;
> > +	}
> > +
> > +	spin_lock(&vsdei->lock);
> > +
> > +	/* Check the state */
> > +	if (mask == vsdei->state.masked) {
> > +		ret = SDEI_DENIED;
> are you sure? I don't this error documented in 5.1.12?
>
> Besides the spec says:
> "
> This call can be invoked by the client to mask the PE, whether or not
> the PE is already masked."

Yep, I think this check can safely dropped.

> > +		goto unlock;
> > +	}
> > +
> > +	/* Update the state */
> > +	vsdei->state.masked = mask ? 1 : 0;
> > +
> > +unlock:
> > +	spin_unlock(&vsdei->lock);
> > +out:
> > +	return ret;
> In case of success the returned value is SUCESS for UNMASK but not for
> MASK (see table in 5.1.12).
>
> By the way I have just noticed there is a more recent of the spec than
> the A:
>
> ARM_DEN0054C
>
> You should update the cover letter and [PATCH v4 02/21] KVM: arm64: Add
> SDEI virtualization infrastructure commit msg

Thanks, Eric. You've looked into newer version of spec. I will update
the code and link to the spec accordingly :)

> > +}
> > +
> >   int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
> >   {
> >   	u32 func = smccc_get_function(vcpu);
> > @@ -588,7 +619,11 @@ int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
> >   		ret = kvm_sdei_hypercall_route(vcpu);
> >   		break;
> >   	case SDEI_1_0_FN_SDEI_PE_MASK:
> > +		ret = kvm_sdei_hypercall_mask(vcpu, true);
> > +		break;
> >   	case SDEI_1_0_FN_SDEI_PE_UNMASK:
> > +		ret = kvm_sdei_hypercall_mask(vcpu, false);
> > +		break;
> >   	case SDEI_1_0_FN_SDEI_INTERRUPT_BIND:
> >   	case SDEI_1_0_FN_SDEI_INTERRUPT_RELEASE:
> >   	case SDEI_1_0_FN_SDEI_PRIVATE_RESET:

Thanks,
Gavin