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

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Date:   Thu, 27 Jan 2022 15:19:34 +0100
From:   Eric Auger <eauger@...hat.com>
To:     Gavin Shan <gshan@...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 Gavin,

On 1/12/22 3:46 AM, Gavin Shan wrote:
> 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 :)
you're right
> 
>>> +            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 :)

Look at table 5.1.10.2 Parameter a,d Return Values. DENIED is returned
in some cases

Eric
> 
>>> +        } 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
>