linux-kernel - Re: [PATCH v4 09/21] KVM: arm64: Support SDEI_EVENT_GET

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Date:   Wed, 12 Jan 2022 10:46:23 +0800
From:   Gavin Shan <gshan@...hat.com>
To:     Eric Auger <eauger@...hat.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 09/21] KVM: arm64: Support SDEI_EVENT_GET_INFO
 hypercall

Hi Eric,

On 11/10/21 1:19 AM, Eric Auger wrote:
> On 8/15/21 2:13 AM, Gavin Shan wrote:
>> This supports SDEI_EVENT_GET_INFO hypercall. It's used by the guest
>> to retrieve various information about the supported (exported) events,
>> including type, signaled, route mode and affinity for the shared
>> events.
>>
>> Signed-off-by: Gavin Shan <gshan@...hat.com>
>> ---
>>   arch/arm64/kvm/sdei.c | 76 +++++++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 76 insertions(+)
>>
>> diff --git a/arch/arm64/kvm/sdei.c b/arch/arm64/kvm/sdei.c
>> index b95b8c4455e1..5dfa74b093f1 100644
>> --- a/arch/arm64/kvm/sdei.c
>> +++ b/arch/arm64/kvm/sdei.c
>> @@ -415,6 +415,80 @@ static unsigned long kvm_sdei_hypercall_status(struct kvm_vcpu *vcpu)
>>   	return ret;
>>   }
>>   
>> +static unsigned long kvm_sdei_hypercall_info(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);
>> +	unsigned long event_info = smccc_get_arg2(vcpu);
>> +	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;
>> +	}
>> +
>> +	/*
>> +	 * Check if the KVM event exists. The event might have been
>> +	 * registered, we need fetch the information from the registered
> s/fetch/to fetch

Ack.

>> +	 * event in that case.
>> +	 */
>> +	spin_lock(&ksdei->lock);
>> +	kske = kvm_sdei_find_kvm_event(kvm, event_num);
>> +	kse = kske ? kske->kse : NULL;
>> +	if (!kse) {
>> +		kse = kvm_sdei_find_event(kvm, event_num);
>> +		if (!kse) {
>> +			ret = SDEI_INVALID_PARAMETERS;
> this should have already be covered by !kvm_sdei_is_valid_event_num I
> think (although this latter only checks the since static event num with
> KVM owner mask)

Nope. Strictly speaking, kvm_sdei_find_event() covers the check carried
by !kvm_sdei_is_valid_event_num(). All the defined (exposed) events should
have virtual event number :)

>> +			goto unlock;
>> +		}
>> +	}
>> +
>> +	/* Retrieve the requested information */
>> +	switch (event_info) {
>> +	case SDEI_EVENT_INFO_EV_TYPE:
>> +		ret = kse->state.type;
>> +		break;
>> +	case SDEI_EVENT_INFO_EV_SIGNALED:
>> +		ret = kse->state.signaled;
>> +		break;
>> +	case SDEI_EVENT_INFO_EV_PRIORITY:
>> +		ret = kse->state.priority;
>> +		break;
>> +	case SDEI_EVENT_INFO_EV_ROUTING_MODE:
>> +	case SDEI_EVENT_INFO_EV_ROUTING_AFF:
>> +		if (kse->state.type != SDEI_EVENT_TYPE_SHARED) {
>> +			ret = SDEI_INVALID_PARAMETERS;
>> +			break;
>> +		}
>> +
>> +		if (event_info == SDEI_EVENT_INFO_EV_ROUTING_MODE) {
>> +			ret = kske ? kske->state.route_mode :
>> +				     SDEI_EVENT_REGISTER_RM_ANY;
> no, if event is not registered (!kske) DENIED should be returned

I don't think so. According to the specification, there is no DENIED
return value for STATUS hypercall. Either INVALID_PARAMETERS or NOT_SUPPORTED
should be returned from this hypercall :)

>> +		} else {
> same here
>> +			ret = kske ? kske->state.route_affinity : 0;
>> +		}
>> +
>> +		break;
>> +	default:
>> +		ret = SDEI_INVALID_PARAMETERS;
>> +	}
>> +
>> +unlock:
>> +	spin_unlock(&ksdei->lock);
>> +out:
>> +	return ret;
>> +}
>> +
>>   int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
>>   {
>>   	u32 func = smccc_get_function(vcpu);
>> @@ -446,6 +520,8 @@ int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
>>   		ret = kvm_sdei_hypercall_status(vcpu);
>>   		break;
>>   	case SDEI_1_0_FN_SDEI_EVENT_GET_INFO:
>> +		ret = kvm_sdei_hypercall_info(vcpu);
>> +		break;
>>   	case SDEI_1_0_FN_SDEI_EVENT_ROUTING_SET:
>>   	case SDEI_1_0_FN_SDEI_PE_MASK:
>>   	case SDEI_1_0_FN_SDEI_PE_UNMASK:
>>

Thanks,
Gavin