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Subject: Re: [PATCH v4 06/21] KVM: arm64: Support SDEI_EVENT_CONTEXT hypercall
To:     Gavin Shan <gshan@redhat.com>,
        Shannon Zhao <shannon.zhaosl@gmail.com>,
        kvmarm@lists.cs.columbia.edu
Cc:     maz@kernel.org, pbonzini@redhat.com, will@kernel.org,
        linux-kernel@vger.kernel.org, Jonathan.Cameron@huawei.com
References: <20210815001352.81927-1-gshan@redhat.com>
 <20210815001352.81927-7-gshan@redhat.com>
 <40d818a2-0c91-e06e-6ce8-ac8123b8d1d4@gmail.com>
 <798ecbb0-f369-f3e7-ad50-78acfd902d1d@redhat.com>
From:   Eric Auger <eauger@redhat.com>
Message-ID: <3d791443-d3d3-29fb-98a4-bebadb84597e@redhat.com>
Date:   Tue, 25 Jan 2022 19:31:39 +0100
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Hi Gavin,

On 1/13/22 8:02 AM, Gavin Shan wrote:
> 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;
>            }
at least you can use an inline function taking the vcpu as param?

Thanks

Eric
> 
>            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
> 
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