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Subject: Re: [PATCH v4 03/21] KVM: arm64: Support SDEI_VERSION hypercall
To:     Gavin Shan <gshan@redhat.com>, kvmarm@lists.cs.columbia.edu
Cc:     maz@kernel.org, linux-kernel@vger.kernel.org,
        Jonathan.Cameron@huawei.com, pbonzini@redhat.com, will@kernel.org
References: <20210815001352.81927-1-gshan@redhat.com>
 <20210815001352.81927-4-gshan@redhat.com>
From:   Eric Auger <eauger@redhat.com>
Message-ID: <3160dd62-1d96-7dcb-e99a-7ac923abc2c7@redhat.com>
Date:   Tue, 9 Nov 2021 16:26:05 +0100
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Hi Gavin

On 8/15/21 2:13 AM, Gavin Shan wrote:
> This supports SDEI_VERSION hypercall by returning v1.0.0 simply
s/This supports/Add Support. I think this is the prefered way to start
the commit msg. Here and elsewhere.
> when the functionality is supported on the VM and vCPU.
Can you explain when the functionality isn't supported on either. From
the infra patch I have the impression that an allocation failure is the
sole cause of lack of support?
> 
> Signed-off-by: Gavin Shan <gshan@redhat.com>
> ---
>  arch/arm64/kvm/sdei.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/arch/arm64/kvm/sdei.c b/arch/arm64/kvm/sdei.c
> index ab330b74a965..aa9485f076a9 100644
> --- a/arch/arm64/kvm/sdei.c
> +++ b/arch/arm64/kvm/sdei.c
> @@ -70,6 +70,22 @@ static void kvm_sdei_remove_vcpu_events(struct kvm_vcpu *vcpu)
>  	}
>  }
>  
> +static unsigned long kvm_sdei_hypercall_version(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;
> +	unsigned long ret = SDEI_NOT_SUPPORTED;
nit: I would remove ret local variable
> +
> +	if (!(ksdei && vsdei))
> +		return ret;
> +
> +	/* v1.0.0 */
> +	ret = (1UL << SDEI_VERSION_MAJOR_SHIFT);
> +
> +	return ret;
> +}
> +
>  int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
>  {
>  	u32 func = smccc_get_function(vcpu);
> @@ -78,6 +94,8 @@ int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
>  
>  	switch (func) {
>  	case SDEI_1_0_FN_SDEI_VERSION:
> +		ret = kvm_sdei_hypercall_version(vcpu);
> +		break;
>  	case SDEI_1_0_FN_SDEI_EVENT_REGISTER:
>  	case SDEI_1_0_FN_SDEI_EVENT_ENABLE:
>  	case SDEI_1_0_FN_SDEI_EVENT_DISABLE:
> 

Eric