linux-kernel - Re: [PATCH v4 06/21] KVM: arm64: Support SDEI_EVENT

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Date:   Thu, 13 Jan 2022 15:13:30 +0800
From:   Gavin Shan <gshan@...hat.com>
To:     Shannon Zhao <shannon.zhaosl@...il.com>,
        kvmarm@...ts.cs.columbia.edu
Cc:     maz@...nel.org, linux-kernel@...r.kernel.org,
        Jonathan.Cameron@...wei.com, pbonzini@...hat.com, will@...nel.org
Subject: Re: [PATCH v4 06/21] KVM: arm64: Support SDEI_EVENT_CONTEXT hypercall

Hi Shannon,

On 1/13/22 3:02 PM, Gavin Shan wrote:
> 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.
> 

oops... sorry. Please ignore my previous reply. I thought you talk about
the check on the SDEI event number wrongly. Yes, you're correct that the
check should be moved to kvm_sdei_hypercall().

Thanks,
Gavin