Hi Gavin,
On 1/12/22 3:38 AM, Gavin Shan wrote:
> Hi Eric,
>
> On 11/10/21 1:05 AM, Eric Auger wrote:
>> On 8/15/21 2:13 AM, Gavin Shan wrote:
>>> This supports SDEI_EVENT_UNREGISTER hypercall. It's used by the
>>> guest to unregister SDEI event. The SDEI event won't be raised to
>>> the guest or specific vCPU after it's unregistered successfully.
>>> It's notable the SDEI event is disabled automatically on the guest
>>> or specific vCPU once it's unregistered successfully.
>>>
>>> Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
>>> ---
>>> arch/arm64/kvm/sdei.c | 61 +++++++++++++++++++++++++++++++++++++++++++
>>> 1 file changed, 61 insertions(+)
>>>
>>> diff --git a/arch/arm64/kvm/sdei.c b/arch/arm64/kvm/sdei.c
>>> index b4162efda470..a3ba69dc91cb 100644
>>> --- a/arch/arm64/kvm/sdei.c
>>> +++ b/arch/arm64/kvm/sdei.c
>>> @@ -308,6 +308,65 @@ static unsigned long
>>> kvm_sdei_hypercall_context(struct kvm_vcpu *vcpu)
>>> return ret;
>>> }
>>> +static unsigned long kvm_sdei_hypercall_unregister(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;
>>> + }
>>> +
>>> + /* Check if the KVM event exists */
>>> + spin_lock(&ksdei->lock);
>>> + kske = kvm_sdei_find_kvm_event(kvm, event_num);
>>> + if (!kske) {
>>> + ret = SDEI_INVALID_PARAMETERS;
>>> + goto unlock;
>>> + }
>>> +
>>> + /* Check if there is pending events */
>>> + if (kske->state.refcount) {
>>> + ret = SDEI_PENDING;
>> don't you want to record the fact the unregistration is outstanding to
>> perform subsequent actions? Otherwise nothing will hapen when the
>> current executing handlers complete?>
> It's not necessary. The guest should retry in this case.
I do not understand that from the spec:
6.7 Unregistering an event says
With the PENDING status, the unregister request will be queued until the
event is completed using SDEI_EVENT_COMPLETE .
Also there is state called "Handler-unregister-pending"
But well I would need to dig further into the spec again :)
>
>>> + goto unlock;
>>> + }
>>> +
>>> + /* Check if it has been registered */
>>> + kse = kske->kse;
>>> + index = (kse->state.type == SDEI_EVENT_TYPE_PRIVATE) ?
>>> + vcpu->vcpu_idx : 0;
>> you could have an inline for the above as this is executed in many
>> functions. even including the code below.
>
> Ok, it's a good idea.
>
>>> + if (!kvm_sdei_is_registered(kske, index)) {
>>> + ret = SDEI_DENIED;
>>> + goto unlock;
>>> + }
>>> +
>>> + /* The event is disabled when it's unregistered */
>>> + kvm_sdei_clear_enabled(kske, index);
>>> + kvm_sdei_clear_registered(kske, index);
>>> + if (kvm_sdei_empty_registered(kske)) {
>> a refcount mechanism would be cleaner I think.
>
> A refcount isn't working well. We need a mapping here because the private
> SDEI event can be enabled/registered on multiple vCPUs. We need to know
> the exact vCPUs where the private SDEI event is enabled/registered.
I don't get why you can't increment/decrement the ref count each time
the event is registered/unregistered by a given vcpu to manage its life
cycle? Does not mean you don't need the bitmap to know the actual mapping.
Thanks
Eric
>
>>> + list_del(&kske->link);
>>> + kfree(kske);
>>> + }
>>> +
>>> +unlock:
>>> + spin_unlock(&ksdei->lock);
>>> +out:
>>> + return ret;
>>> +}
>>> +
>>> int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
>>> {
>>> u32 func = smccc_get_function(vcpu);
>>> @@ -333,6 +392,8 @@ int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
>>> case SDEI_1_0_FN_SDEI_EVENT_COMPLETE:
>>> case SDEI_1_0_FN_SDEI_EVENT_COMPLETE_AND_RESUME:
>>> case SDEI_1_0_FN_SDEI_EVENT_UNREGISTER:
>>> + ret = kvm_sdei_hypercall_unregister(vcpu);
>>> + break;
>>> case SDEI_1_0_FN_SDEI_EVENT_STATUS:
>>> case SDEI_1_0_FN_SDEI_EVENT_GET_INFO:
>>> case SDEI_1_0_FN_SDEI_EVENT_ROUTING_SET:
>>>
>
> Thanks,
> Gavin
>
_______________________________________________
kvmarm mailing list
kvmarm@xxxxxxxxxxxxxxxxxxxxx
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
