linux-kernel - [RFC PATCH v12 02/11] arm/arm64: KVM: Advertise KVM UID to guests via SMCCC

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Message-Id: <20200522083724.38182-3-jianyong.wu@arm.com>
Date:   Fri, 22 May 2020 16:37:15 +0800
From:   Jianyong Wu <jianyong.wu@....com>
To:     netdev@...r.kernel.org, yangbo.lu@....com, john.stultz@...aro.org,
        tglx@...utronix.de, pbonzini@...hat.com,
        sean.j.christopherson@...el.com, maz@...nel.org,
        richardcochran@...il.com, Mark.Rutland@....com, will@...nel.org,
        suzuki.poulose@....com, steven.price@....com
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        kvmarm@...ts.cs.columbia.edu, kvm@...r.kernel.org,
        Steve.Capper@....com, Kaly.Xin@....com, justin.he@....com,
        Wei.Chen@....com, jianyong.wu@....com, nd@....com
Subject: [RFC PATCH v12 02/11] arm/arm64: KVM: Advertise KVM UID to guests via SMCCC

From: Will Deacon <will@...nel.org>

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

Cc: Marc Zyngier <maz@...nel.org>
Signed-off-by: Will Deacon <will@...nel.org>
Signed-off-by: Jianyong Wu <jianyong.wu@....com>
---
 virt/kvm/arm/hypercalls.c | 29 +++++++++++++++++++----------
 1 file changed, 19 insertions(+), 10 deletions(-)

diff --git a/virt/kvm/arm/hypercalls.c b/virt/kvm/arm/hypercalls.c
index 550dfa3e53cd..db6dce3d0e23 100644
--- a/virt/kvm/arm/hypercalls.c
+++ b/virt/kvm/arm/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;
+	u32 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 KVM_BP_HARDEN_UNKNOWN:
 				break;
 			case KVM_BP_HARDEN_WA_NEEDED:
-				val = SMCCC_RET_SUCCESS;
+				val[0] = SMCCC_RET_SUCCESS;
 				break;
 			case KVM_BP_HARDEN_NOT_REQUIRED:
-				val = SMCCC_RET_NOT_REQUIRED;
+				val[0] = SMCCC_RET_NOT_REQUIRED;
 				break;
 			}
 			break;
@@ -41,31 +41,40 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
 			case KVM_SSBD_UNKNOWN:
 				break;
 			case KVM_SSBD_KERNEL:
-				val = SMCCC_RET_SUCCESS;
+				val[0] = SMCCC_RET_SUCCESS;
 				break;
 			case KVM_SSBD_FORCE_ENABLE:
 			case KVM_SSBD_MITIGATED:
-				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;
 	default:
 		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;
 }
-- 
2.17.1