[PATCH v6 15/18] KVM: arm64: Support SDEI_FEATURES hypercall

[Gavin Shan <gshan@redhat.com>]

This supports SDEI_FEATURES hypercall. It's used by guest to
retrieve the supported features, which are number of slots for
the interrupt binding events and relative mode for the event
handler. Currently, none of them is supported.

Signed-off-by: Gavin Shan <gshan@redhat.com>
---
 arch/arm64/kvm/sdei.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/arch/arm64/kvm/sdei.c b/arch/arm64/kvm/sdei.c
index e1f6ab9800ee..ab0b7b5e3191 100644
--- a/arch/arm64/kvm/sdei.c
+++ b/arch/arm64/kvm/sdei.c
@@ -527,6 +527,23 @@ static unsigned long hypercall_reset(struct kvm_vcpu *vcpu, bool private)
 	return ret;
 }
 
+static unsigned long hypercall_features(struct kvm_vcpu *vcpu)
+{
+	unsigned long feature = smccc_get_arg(vcpu, 1);
+	unsigned long ret;
+
+	switch (feature) {
+	case 0: /* BIND_SLOTS */
+	case 1: /* RELATIVE_MODE */
+		ret = 0;
+		break;
+	default:
+		ret = SDEI_INVALID_PARAMETERS;
+	}
+
+	return ret;
+}
+
 int kvm_sdei_call(struct kvm_vcpu *vcpu)
 {
 	struct kvm_sdei_vcpu *vsdei = vcpu->arch.sdei;
@@ -590,6 +607,9 @@ int kvm_sdei_call(struct kvm_vcpu *vcpu)
 	case SDEI_1_0_FN_SDEI_SHARED_RESET:
 		ret = hypercall_reset(vcpu, false);
 		break;
+	case SDEI_1_1_FN_SDEI_FEATURES:
+		ret = hypercall_features(vcpu);
+		break;
 	default:
 		ret = SDEI_NOT_SUPPORTED;
 	}
-- 
2.23.0