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Subject: Re: [PATCH v4 08/21] KVM: arm64: Support SDEI_EVENT_STATUS 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>
 <20210815001352.81927-9-gshan@redhat.com>
From:   Eric Auger <eauger@redhat.com>
Message-ID: <36f2f2cf-3e6e-30ce-53d2-6c44be93272d@redhat.com>
Date:   Tue, 9 Nov 2021 18:12:42 +0100
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On 8/15/21 2:13 AM, Gavin Shan wrote:
> This supports SDEI_EVENT_STATUS hypercall. It's used by the guest
> to retrieve a bitmap to indicate the SDEI event states, including
> registration, enablement and delivery state.
> 
> Signed-off-by: Gavin Shan <gshan@redhat.com>
> ---
>  arch/arm64/kvm/sdei.c | 50 +++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 50 insertions(+)
> 
> diff --git a/arch/arm64/kvm/sdei.c b/arch/arm64/kvm/sdei.c
> index a3ba69dc91cb..b95b8c4455e1 100644
> --- a/arch/arm64/kvm/sdei.c
> +++ b/arch/arm64/kvm/sdei.c
> @@ -367,6 +367,54 @@ static unsigned long kvm_sdei_hypercall_unregister(struct kvm_vcpu *vcpu)
>  	return ret;
>  }
>  
> +static unsigned long kvm_sdei_hypercall_status(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_event *kse = NULL;
> +	struct kvm_sdei_kvm_event *kske = NULL;
> +	unsigned long event_num = smccc_get_arg1(vcpu);
> +	int index = 0;
> +	unsigned long ret = SDEI_SUCCESS;
> +
> +	/* Sanity check */
> +	if (!(ksdei && vsdei)) {
> +		ret = SDEI_NOT_SUPPORTED;
> +		goto out;
> +	}
> +
> +	if (!kvm_sdei_is_valid_event_num(event_num)) {
> +		ret = SDEI_INVALID_PARAMETERS;
> +		goto out;
> +	}
if we were to support bound events, I do not know if a given even num
can disapper inbetween that check and the rest of the code, in which
case a lock would be needed?
> +
> +	/*
> +	 * Check if the KVM event exists. None of the flags
> +	 * will be set if it doesn't exist.
> +	 */
> +	spin_lock(&ksdei->lock);
> +	kske = kvm_sdei_find_kvm_event(kvm, event_num);
> +	if (!kske) {
> +		ret = 0;
> +		goto unlock;
> +	}
> +
> +	index = (kse->state.type == SDEI_EVENT_TYPE_PRIVATE) ?
> +		vcpu->vcpu_idx : 0;
> +	if (kvm_sdei_is_registered(kske, index))
> +		ret |= (1UL << SDEI_EVENT_STATUS_REGISTERED);
> +	if (kvm_sdei_is_enabled(kske, index))
> +		ret |= (1UL << SDEI_EVENT_STATUS_ENABLED);
> +	if (kske->state.refcount)
> +		ret |= (1UL << SDEI_EVENT_STATUS_RUNNING);
> +
> +unlock:
> +	spin_unlock(&ksdei->lock);
> +out:
> +	return ret;
> +}
> +
>  int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
>  {
>  	u32 func = smccc_get_function(vcpu);
> @@ -395,6 +443,8 @@ int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
>  		ret = kvm_sdei_hypercall_unregister(vcpu);
>  		break;
>  	case SDEI_1_0_FN_SDEI_EVENT_STATUS:
> +		ret = kvm_sdei_hypercall_status(vcpu);
> +		break;
>  	case SDEI_1_0_FN_SDEI_EVENT_GET_INFO:
>  	case SDEI_1_0_FN_SDEI_EVENT_ROUTING_SET:
>  	case SDEI_1_0_FN_SDEI_PE_MASK:
> 
Thanks

Eric