[PATCH v7 15/22] KVM: arm64: Support SDEI_FEATURES hypercall

[Gavin Shan <gshan@redhat.com>]

This supports SDEI_FEATURES hypercall. It's used to retrieve the
supported features, including number of slots for the interrupt
binding events and relative mode for event handler. Currently,
we simply return zero, meaning none of them is supported.

Signed-off-by: Gavin Shan <gshan@redhat.com>
---
 arch/arm64/kvm/sdei.c         | 16 ++++++++++++++++
 include/uapi/linux/arm_sdei.h |  5 +++++
 2 files changed, 21 insertions(+)

diff --git a/arch/arm64/kvm/sdei.c b/arch/arm64/kvm/sdei.c
index a55797fce06a..d295f84f6940 100644
--- a/arch/arm64/kvm/sdei.c
+++ b/arch/arm64/kvm/sdei.c
@@ -277,6 +277,19 @@ static unsigned long event_reset(struct kvm_vcpu *vcpu, bool private)
 	return SDEI_SUCCESS;
 }
 
+static unsigned long sdei_features(struct kvm_vcpu *vcpu)
+{
+	unsigned int feature = smccc_get_arg(vcpu, 1);
+
+	switch (feature) {
+	case SDEI_FEATURE_BIND_SLOTS:
+	case SDEI_FEATURE_RELATIVE_MODE:
+		return 0;
+	}
+
+	return SDEI_INVALID_PARAMETERS;
+}
+
 int kvm_sdei_call(struct kvm_vcpu *vcpu)
 {
 	struct kvm_sdei_vcpu *vsdei = vcpu->arch.sdei;
@@ -337,6 +350,9 @@ int kvm_sdei_call(struct kvm_vcpu *vcpu)
 	case SDEI_1_0_FN_SDEI_SHARED_RESET:
 		ret = event_reset(vcpu, false);
 		break;
+	case SDEI_1_1_FN_SDEI_FEATURES:
+		ret = sdei_features(vcpu);
+		break;
 	default:
 		ret = SDEI_NOT_SUPPORTED;
 	}
diff --git a/include/uapi/linux/arm_sdei.h b/include/uapi/linux/arm_sdei.h
index 72b07114bbfa..5b783cc64617 100644
--- a/include/uapi/linux/arm_sdei.h
+++ b/include/uapi/linux/arm_sdei.h
@@ -23,6 +23,7 @@
 #define SDEI_1_0_FN_SDEI_INTERRUPT_BIND			SDEI_1_0_FN(0x0D)
 #define SDEI_1_0_FN_SDEI_INTERRUPT_RELEASE		SDEI_1_0_FN(0x0E)
 #define SDEI_1_1_FN_SDEI_EVENT_SIGNAL			SDEI_1_0_FN(0x0F)
+#define SDEI_1_1_FN_SDEI_FEATURES			SDEI_1_0_FN(0x10)
 #define SDEI_1_0_FN_SDEI_PRIVATE_RESET			SDEI_1_0_FN(0x11)
 #define SDEI_1_0_FN_SDEI_SHARED_RESET			SDEI_1_0_FN(0x12)
 
@@ -73,4 +74,8 @@
 #define SDEI_EVENT_PRIORITY_NORMAL		0
 #define SDEI_EVENT_PRIORITY_CRITICAL		1
 
+/* SDEI_FEATURES */
+#define SDEI_FEATURE_BIND_SLOTS			0
+#define SDEI_FEATURE_RELATIVE_MODE		1
+
 #endif /* _UAPI_LINUX_ARM_SDEI_H */
-- 
2.23.0