[PATCH 1/2] KVM: arm64: Report SMCCC_VERSION and SMCCC_ARCH_FEATURES as implemented

[Fuad Tabba <fuad.tabba@linux.dev>]

KVM reports SMCCC v1.1 to guests, which makes SMCCC_VERSION and
SMCCC_ARCH_FEATURES mandatory, and DEN0028H 7.3.6 requires
SMCCC_ARCH_FEATURES to return SUCCESS for both function ids: "This
function must return SUCCESS when arch_func_id is the SMCCC_VERSION or
SMCCC_ARCH_FEATURES function id." With arch_func_id set to either, KVM's
guest handler returns NOT_SUPPORTED. Return SUCCESS.

A Linux guest is unaffected: it discovers SMCCC_VERSION through
PSCI_FEATURES, and issues SMCCC_ARCH_FEATURES only with arch_func_id set
to ARCH_SOC_ID, the ARCH_WORKAROUND_* ids or HV_PV_TIME_FEATURES.

Signed-off-by: Fuad Tabba <fuad.tabba@linux.dev>
---
 arch/arm64/kvm/hypercalls.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
index b11b8821c9fbc..66f16bf9a8ea7 100644
--- a/arch/arm64/kvm/hypercalls.c
+++ b/arch/arm64/kvm/hypercalls.c
@@ -293,6 +293,10 @@ int kvm_smccc_call_handler(struct kvm_vcpu *vcpu)
 	case ARM_SMCCC_ARCH_FEATURES_FUNC_ID:
 		feature = smccc_get_arg1(vcpu);
 		switch (feature) {
+		case ARM_SMCCC_VERSION_FUNC_ID:
+		case ARM_SMCCC_ARCH_FEATURES_FUNC_ID:
+			val[0] = SMCCC_RET_SUCCESS;
+			break;
 		case ARM_SMCCC_ARCH_WORKAROUND_1:
 			switch (arm64_get_spectre_v2_state()) {
 			case SPECTRE_VULNERABLE:
-- 
2.39.5