Re: [PATCH v4 06/21] KVM: arm64: Support SDEI_EVENT_CONTEXT hypercall

[Gavin Shan]

Hi Shannon,

On 1/11/22 5:43 PM, Shannon Zhao wrote:
> On 2021/8/15 8:13, Gavin Shan wrote:
> > +static unsigned long kvm_sdei_hypercall_context(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_vcpu_regs *regs;
> > +    unsigned long index = smccc_get_arg1(vcpu);
> > +    unsigned long ret = SDEI_SUCCESS;
> > +
> > +    /* Sanity check */
> > +    if (!(ksdei && vsdei)) {
> > +        ret = SDEI_NOT_SUPPORTED;
> > +        goto out;
> > +    }
> Maybe we could move these common sanity check codes to kvm_sdei_hypercall to save some lines.

Not all hypercalls need this check. For example, COMPLETE/COMPLETE_RESUME/CONTEXT don't
have SDEI event number as the argument. If we really want move this check into function
kvm_sdei_hypercall(), we would have code like below. Too much duplicated snippets will
be seen. I don't think it's better than what we have if I fully understand your comments.

      switch (...) {
      case REGISTER:
           if (!(ksdei && vsdei)) {
               ret = SDEI_NOT_SUPPORTED;
               break;
           }

           ret = kvm_sdei_hypercall_register(vcpu);
           break;
      case UNREGISTER:
           if (!(ksdei && vsdei)) {
               ret = SDEI_NOT_SUPPORTED;
               break;
           }

           ret = kvm_sdei_hypercall_unregister(vcpu);
           break;
     case CONTEXT:
           ret = kvm_sdei_hypercall_context(vcpu);
           break;
       :
    }

Thanks,
Gavin