Re: [PATCH v4 07/21] KVM: arm64: Support SDEI_EVENT_UNREGISTER hypercall

Eric Auger
2021-11-09T17:05:10Z

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@redhat.com>
> ---
> 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?
> + 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.
> + 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.
> + 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:
>