[PATCH v2 06/17] KVM: arm64: Advertise KVM UID to guests via SMCCC

[Gavin Shan]

From: Will Deacon <w...@kernel.org>

We can advertise ourselves to guests as KVM and provide a basic features
bitmap for discoverability of future hypervisor services.

Signed-off-by: Will Deacon <w...@kernel.org>
Signed-off-by: Gavin Shan <gs...@redhat.com>
---
 arch/arm64/kvm/hypercalls.c | 27 ++++++++++++++++++---------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
index a54c4805f2a6..e02e29a12bbf 100644
--- a/arch/arm64/kvm/hypercalls.c
+++ b/arch/arm64/kvm/hypercalls.c
@@ -12,13 +12,13 @@
 int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
 {
        u32 func_id = smccc_get_function(vcpu);
-       long val = SMCCC_RET_NOT_SUPPORTED;
+       long val[4] = { SMCCC_RET_NOT_SUPPORTED };
        u32 feature;
        gpa_t gpa;
 
        switch (func_id) {
        case ARM_SMCCC_VERSION_FUNC_ID:
-               val = ARM_SMCCC_VERSION_1_1;
+               val[0] = ARM_SMCCC_VERSION_1_1;
                break;
        case ARM_SMCCC_ARCH_FEATURES_FUNC_ID:
                feature = smccc_get_arg1(vcpu);
@@ -28,10 +28,10 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
                        case SPECTRE_VULNERABLE:
                                break;
                        case SPECTRE_MITIGATED:
-                               val = SMCCC_RET_SUCCESS;
+                               val[0] = SMCCC_RET_SUCCESS;
                                break;
                        case SPECTRE_UNAFFECTED:
-                               val = SMCCC_ARCH_WORKAROUND_RET_UNAFFECTED;
+                               val[0] = SMCCC_ARCH_WORKAROUND_RET_UNAFFECTED;
                                break;
                        }
                        break;
@@ -54,22 +54,31 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
                                        break;
                                fallthrough;
                        case SPECTRE_UNAFFECTED:
-                               val = SMCCC_RET_NOT_REQUIRED;
+                               val[0] = SMCCC_RET_NOT_REQUIRED;
                                break;
                        }
                        break;
                case ARM_SMCCC_HV_PV_TIME_FEATURES:
-                       val = SMCCC_RET_SUCCESS;
+                       val[0] = SMCCC_RET_SUCCESS;
                        break;
                }
                break;
        case ARM_SMCCC_HV_PV_TIME_FEATURES:
-               val = kvm_hypercall_pv_features(vcpu);
+               val[0] = kvm_hypercall_pv_features(vcpu);
                break;
        case ARM_SMCCC_HV_PV_TIME_ST:
                gpa = kvm_init_stolen_time(vcpu);
                if (gpa != GPA_INVALID)
-                       val = gpa;
+                       val[0] = gpa;
+               break;
+       case ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID:
+               val[0] = ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_0;
+               val[1] = ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_1;
+               val[2] = ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_2;
+               val[3] = ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_3;
+               break;
+       case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID:
+               val[0] = BIT(ARM_SMCCC_KVM_FUNC_FEATURES);
                break;
        case SDEI_1_0_FN_SDEI_VERSION:
        case SDEI_1_0_FN_SDEI_EVENT_REGISTER:
@@ -93,6 +102,6 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
                return kvm_psci_call(vcpu);
        }
 
-       smccc_set_retval(vcpu, val, 0, 0, 0);
+       smccc_set_retval(vcpu, val[0], val[1], val[2], val[3]);
        return 1;
 }
-- 
2.23.0