diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 14c2ef8b3aec2..563a9f31b83d3 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -57,9 +57,8 @@ static u64 core_reg_offset_from_id(u64 id)
 	return id & ~(KVM_REG_ARCH_MASK | KVM_REG_SIZE_MASK | KVM_REG_ARM_CORE);
 }
 
-static int validate_core_offset(const struct kvm_one_reg *reg)
+static int core_reg_size_from_offset(u64 off)
 {
-	u64 off = core_reg_offset_from_id(reg->id);
 	int size;
 
 	switch (off) {
@@ -89,11 +88,24 @@ static int validate_core_offset(const struct kvm_one_reg *reg)
 		return -EINVAL;
 	}
 
-	if (KVM_REG_SIZE(reg->id) == size &&
-	    IS_ALIGNED(off, size / sizeof(__u32)))
-		return 0;
+	if (!IS_ALIGNED(off, size / sizeof(__u32)))
+		return -EINVAL;
 
-	return -EINVAL;
+	return size;
+}
+
+static int validate_core_offset(const struct kvm_one_reg *reg)
+{
+	u64 off = core_reg_offset_from_id(reg->id);
+	int size = core_reg_size_from_offset(off);
+
+	if (size < 0)
+		return -EINVAL;
+
+	if (KVM_REG_SIZE(reg->id) != size)
+		return -EINVAL;
+
+	return 0;
 }
 
 static int get_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
@@ -204,11 +216,34 @@ static int kvm_arm_copy_core_reg_indices(u64 __user *uindices)
 {
 	unsigned int i;
 	int n = 0;
-	const u64 core_reg = KVM_REG_ARM64 | KVM_REG_SIZE_U64 | KVM_REG_ARM_CORE;
 
 	for (i = 0; i < sizeof(struct kvm_regs) / sizeof(__u32); i++) {
+		u64 reg = KVM_REG_ARM64 | KVM_REG_ARM_CORE | i;
+		int size = core_reg_size_from_offset(i);
+
+		if (size < 0)
+			continue;
+
+		switch (size) {
+		case sizeof(__u32):
+			reg |= KVM_REG_SIZE_U32;
+			break;
+
+		case sizeof(__u64):
+			reg |= KVM_REG_SIZE_U64;
+			break;
+
+		case sizeof(__uint128_t):
+			reg |= KVM_REG_SIZE_U128;
+			break;
+
+		default:
+			WARN_ON(1);
+			continue;
+		}
+
 		if (uindices) {
-			if (put_user(core_reg | i, uindices))
+			if (put_user(reg, uindices))
 				return -EFAULT;
 			uindices++;
 		}