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

[Gavin Shan <gshan@redhat.com>]

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;
+		goto unlock;
+	}
+
+	/* Check if it has been registered */
+	kse = kske->kse;
+	index = (kse->state.type == SDEI_EVENT_TYPE_PRIVATE) ?
+		vcpu->vcpu_idx : 0;
+	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)) {
+		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:
-- 
2.23.0