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Subject: Re: [PATCH v4 18/21] KVM: arm64: Support SDEI event injection
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>
 <20210815001352.81927-19-gshan@redhat.com>
From:   Eric Auger <eauger@redhat.com>
Message-ID: <6c11ed83-796e-765e-bb6a-116947d33eab@redhat.com>
Date:   Wed, 10 Nov 2021 15:05:34 +0100
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On 8/15/21 2:13 AM, Gavin Shan wrote:
> This supports SDEI event injection by implementing kvm_sdei_inject().
> It's called by kernel directly or VMM through ioctl command to inject
> SDEI event to the specific vCPU.
> 
> Signed-off-by: Gavin Shan <gshan@redhat.com>
> ---
>  arch/arm64/include/asm/kvm_sdei.h      |   2 +
>  arch/arm64/include/uapi/asm/kvm_sdei.h |   1 +
>  arch/arm64/kvm/sdei.c                  | 108 +++++++++++++++++++++++++
>  3 files changed, 111 insertions(+)
> 
> diff --git a/arch/arm64/include/asm/kvm_sdei.h b/arch/arm64/include/asm/kvm_sdei.h
> index a997989bab77..51087fe971ba 100644
> --- a/arch/arm64/include/asm/kvm_sdei.h
> +++ b/arch/arm64/include/asm/kvm_sdei.h
> @@ -124,6 +124,8 @@ void kvm_sdei_create_vcpu(struct kvm_vcpu *vcpu);
>  int kvm_sdei_hypercall(struct kvm_vcpu *vcpu);
>  int kvm_sdei_register_notifier(struct kvm *kvm, unsigned long num,
>  			       kvm_sdei_notifier notifier);
> +int kvm_sdei_inject(struct kvm_vcpu *vcpu,
> +		    unsigned long num, bool immediate);
>  void kvm_sdei_deliver(struct kvm_vcpu *vcpu);
>  long kvm_sdei_vm_ioctl(struct kvm *kvm, unsigned long arg);
>  long kvm_sdei_vcpu_ioctl(struct kvm_vcpu *vcpu, unsigned long arg);
> diff --git a/arch/arm64/include/uapi/asm/kvm_sdei.h b/arch/arm64/include/uapi/asm/kvm_sdei.h
> index b916c3435646..f7a6b2b22b50 100644
> --- a/arch/arm64/include/uapi/asm/kvm_sdei.h
> +++ b/arch/arm64/include/uapi/asm/kvm_sdei.h
> @@ -67,6 +67,7 @@ struct kvm_sdei_vcpu_state {
>  #define KVM_SDEI_CMD_SET_VEVENT			7
>  #define KVM_SDEI_CMD_GET_VCPU_STATE		8
>  #define KVM_SDEI_CMD_SET_VCPU_STATE		9
> +#define KVM_SDEI_CMD_INJECT_EVENT		10
>  
>  struct kvm_sdei_cmd {
>  	__u32						cmd;
> diff --git a/arch/arm64/kvm/sdei.c b/arch/arm64/kvm/sdei.c
> index 79315b77f24b..7c2789cd1421 100644
> --- a/arch/arm64/kvm/sdei.c
> +++ b/arch/arm64/kvm/sdei.c
> @@ -802,6 +802,111 @@ int kvm_sdei_register_notifier(struct kvm *kvm,
>  	return ret;
>  }
>  
> +int kvm_sdei_inject(struct kvm_vcpu *vcpu,
> +		    unsigned long num,
> +		    bool immediate)
don't get the immediate param.
> +{
> +	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;
> +	struct kvm_sdei_vcpu_event *ksve = NULL;
> +	int index, ret = 0;
> +
> +	/* Sanity check */
> +	if (!(ksdei && vsdei)) {
> +		ret = -EPERM;
> +		goto out;
> +	}
> +
> +	if (!kvm_sdei_is_valid_event_num(num)) {
> +		ret = -EINVAL;
> +		goto out;
> +	}
> +
> +	/* Check the kvm event */
> +	spin_lock(&ksdei->lock);
> +	kske = kvm_sdei_find_kvm_event(kvm, num);
> +	if (!kske) {
> +		ret = -ENOENT;
> +		goto unlock_kvm;
> +	}
> +
> +	kse = kske->kse;
> +	index = (kse->state.type == SDEI_EVENT_TYPE_PRIVATE) ?
> +		vcpu->vcpu_idx : 0;
> +	if (!(kvm_sdei_is_registered(kske, index) &&
> +	      kvm_sdei_is_enabled(kske, index))) {
> +		ret = -EPERM;
> +		goto unlock_kvm;
> +	}
> +
> +	/* Check the vcpu state */
> +	spin_lock(&vsdei->lock);
> +	if (vsdei->state.masked) {
> +		ret = -EPERM;
> +		goto unlock_vcpu;
> +	}
> +
> +	/* Check if the event can be delivered immediately */
> +	if (immediate) {
According to the dispatcher pseudo code this should be always checked?
> +		if (kse->state.priority == SDEI_EVENT_PRIORITY_CRITICAL &&
> +		    !list_empty(&vsdei->critical_events)) {
> +			ret = -ENOSPC;
> +			goto unlock_vcpu;
> +		}
> +
> +		if (kse->state.priority == SDEI_EVENT_PRIORITY_NORMAL &&
> +		    (!list_empty(&vsdei->critical_events) ||
> +		     !list_empty(&vsdei->normal_events))) {
> +			ret = -ENOSPC;
> +			goto unlock_vcpu;
> +		}
> +	}
What about shared event dispatching. I don't see the afficinity checked
anywhere?
> +
> +	/* Check if the vcpu event exists */
> +	ksve = kvm_sdei_find_vcpu_event(vcpu, num);
> +	if (ksve) {
> +		kske->state.refcount++;
> +		ksve->state.refcount++;
why this double refcount increment??
> +		kvm_make_request(KVM_REQ_SDEI, vcpu);
> +		goto unlock_vcpu;
> +	}
> +
> +	/* Allocate vcpu event */
> +	ksve = kzalloc(sizeof(*ksve), GFP_KERNEL);
> +	if (!ksve) {
> +		ret = -ENOMEM;
> +		goto unlock_vcpu;
> +	}
> +
> +	/*
> +	 * We should take lock to update KVM event state because its
> +	 * reference count might be zero. In that case, the KVM event
> +	 * could be destroyed.
> +	 */
> +	kske->state.refcount++;
> +	ksve->state.num      = num;
> +	ksve->state.refcount = 1;
> +	ksve->kske           = kske;
> +	ksve->vcpu           = vcpu;
> +
> +	if (kse->state.priority == SDEI_EVENT_PRIORITY_CRITICAL)
> +		list_add_tail(&ksve->link, &vsdei->critical_events);
> +	else
> +		list_add_tail(&ksve->link, &vsdei->normal_events);
> +
> +	kvm_make_request(KVM_REQ_SDEI, vcpu);
> +
> +unlock_vcpu:
> +	spin_unlock(&vsdei->lock);
> +unlock_kvm:
> +	spin_unlock(&ksdei->lock);
> +out:
> +	return ret;
> +}
> +
>  void kvm_sdei_deliver(struct kvm_vcpu *vcpu)
>  {
>  	struct kvm *kvm = vcpu->kvm;
> @@ -1317,6 +1422,9 @@ long kvm_sdei_vcpu_ioctl(struct kvm_vcpu *vcpu, unsigned long arg)
>  	case KVM_SDEI_CMD_SET_VCPU_STATE:
>  		ret = kvm_sdei_set_vcpu_state(vcpu, &cmd->ksv_state);
>  		break;
> +	case KVM_SDEI_CMD_INJECT_EVENT:
> +		ret = kvm_sdei_inject(vcpu, cmd->num, false);
> +		break;
>  	default:
>  		ret = -EINVAL;
>  	}
> 
Eric