KVM: arm64: Advertise KVM UID to guests via SMCCC

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

Cc: Marc Zyngier <maz@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Jianyong Wu <jianyong.wu@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20201209060932.212364-3-jianyong.wu@arm.com

diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
index ead21b9..78d32c3 100644 (file)
--- 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;
+       u64 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 ARM_SMCCC_TRNG_VERSION:
        case ARM_SMCCC_TRNG_FEATURES:
@@ -81,6 +90,6 @@ 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;
 }