KVM: arm64: Expose PSCI SYSTEM_RESET2 call to the guest

PSCI v1.1 introduces the optional SYSTEM_RESET2 call, which allows the
caller to provide a vendor-specific "reset type" and "cookie" to request
a particular form of reset or shutdown.

Expose this call to the guest and handle it in the same way as PSCI
SYSTEM_RESET, along with some basic range checking on the type argument.

Cc: Marc Zyngier <maz@kernel.org>
Cc: James Morse <james.morse@arm.com>
Cc: Alexandru Elisei <alexandru.elisei@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220221153524.15397-3-will@kernel.org

arch/arm64/kvm/psci.c

@@ -308,7 +308,7 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
 static int kvm_psci_1_x_call(struct kvm_vcpu *vcpu, u32 minor)
 {
 	u32 psci_fn = smccc_get_function(vcpu);
-	u32 feature;
+	u32 arg;
 	unsigned long val;
 	int ret = 1;
 
@@ -320,12 +320,12 @@ static int kvm_psci_1_x_call(struct kvm_vcpu *vcpu, u32 minor)
 		val = minor == 0 ? KVM_ARM_PSCI_1_0 : KVM_ARM_PSCI_1_1;
 		break;
 	case PSCI_1_0_FN_PSCI_FEATURES:
-		feature = smccc_get_arg1(vcpu);
-		val = kvm_psci_check_allowed_function(vcpu, feature);
+		arg = smccc_get_arg1(vcpu);
+		val = kvm_psci_check_allowed_function(vcpu, arg);
 		if (val)
 			break;
 
-		switch(feature) {
+		switch(arg) {
 		case PSCI_0_2_FN_PSCI_VERSION:
 		case PSCI_0_2_FN_CPU_SUSPEND:
 		case PSCI_0_2_FN64_CPU_SUSPEND:
@@ -341,11 +341,36 @@ static int kvm_psci_1_x_call(struct kvm_vcpu *vcpu, u32 minor)
 		case ARM_SMCCC_VERSION_FUNC_ID:
 			val = 0;
 			break;
+		case PSCI_1_1_FN_SYSTEM_RESET2:
+		case PSCI_1_1_FN64_SYSTEM_RESET2:
+			if (minor >= 1) {
+				val = 0;
+				break;
+			}
+			fallthrough;
 		default:
 			val = PSCI_RET_NOT_SUPPORTED;
 			break;
 		}
 		break;
+	case PSCI_1_1_FN_SYSTEM_RESET2:
+		kvm_psci_narrow_to_32bit(vcpu);
+		fallthrough;
+	case PSCI_1_1_FN64_SYSTEM_RESET2:
+		if (minor >= 1) {
+			arg = smccc_get_arg1(vcpu);
+
+			if (arg > PSCI_1_1_RESET_TYPE_SYSTEM_WARM_RESET &&
+			    arg < PSCI_1_1_RESET_TYPE_VENDOR_START) {
+				val = PSCI_RET_INVALID_PARAMS;
+			} else {
+				kvm_psci_system_reset(vcpu);
+				val = PSCI_RET_INTERNAL_FAILURE;
+				ret = 0;
+			}
+			break;
+		};
+		fallthrough;
 	default:
 		return kvm_psci_0_2_call(vcpu);
 	}

include/uapi/linux/psci.h

@@ -82,6 +82,10 @@
 #define PSCI_0_2_TOS_UP_NO_MIGRATE		1
 #define PSCI_0_2_TOS_MP				2
 
+/* PSCI v1.1 reset type encoding for SYSTEM_RESET2 */
+#define PSCI_1_1_RESET_TYPE_SYSTEM_WARM_RESET	0
+#define PSCI_1_1_RESET_TYPE_VENDOR_START	0x80000000U
+
 /* PSCI version decoding (independent of PSCI version) */
 #define PSCI_VERSION_MAJOR_SHIFT		16
 #define PSCI_VERSION_MINOR_MASK			\