diff --git a/drivers/s390/crypto/ap_bus.h b/drivers/s390/crypto/ap_bus.h
index a35362241805..fcf2497556dd 100644
--- a/drivers/s390/crypto/ap_bus.h
+++ b/drivers/s390/crypto/ap_bus.h
@@ -167,6 +167,17 @@ struct ap_message {
 	.dev_type=(dt),					\
 	.match_flags=AP_DEVICE_ID_MATCH_DEVICE_TYPE,
 
+/**
+ * ap_init_message() - Initialize ap_message.
+ * Initialize a message before using. Otherwise this might result in
+ * unexpected behaviour.
+ */
+static inline void ap_init_message(struct ap_message *ap_msg)
+{
+	ap_msg->psmid = 0;
+	ap_msg->length = 0;
+}
+
 /*
  * Note: don't use ap_send/ap_recv after using ap_queue_message
  * for the first time. Otherwise the ap message queue will get
diff --git a/drivers/s390/crypto/zcrypt_cex2a.c b/drivers/s390/crypto/zcrypt_cex2a.c
index 326ea08f67c9..ad61a6a59374 100644
--- a/drivers/s390/crypto/zcrypt_cex2a.c
+++ b/drivers/s390/crypto/zcrypt_cex2a.c
@@ -298,6 +298,7 @@ static long zcrypt_cex2a_modexpo(struct zcrypt_device *zdev,
 	struct completion work;
 	int rc;
 
+	ap_init_message(&ap_msg);
 	ap_msg.message = kmalloc(CEX2A_MAX_MESSAGE_SIZE, GFP_KERNEL);
 	if (!ap_msg.message)
 		return -ENOMEM;
@@ -335,6 +336,7 @@ static long zcrypt_cex2a_modexpo_crt(struct zcrypt_device *zdev,
 	struct completion work;
 	int rc;
 
+	ap_init_message(&ap_msg);
 	ap_msg.message = kmalloc(CEX2A_MAX_MESSAGE_SIZE, GFP_KERNEL);
 	if (!ap_msg.message)
 		return -ENOMEM;
diff --git a/drivers/s390/crypto/zcrypt_pcica.c b/drivers/s390/crypto/zcrypt_pcica.c
index 17ba81b58c78..e78df3671caf 100644
--- a/drivers/s390/crypto/zcrypt_pcica.c
+++ b/drivers/s390/crypto/zcrypt_pcica.c
@@ -281,6 +281,7 @@ static long zcrypt_pcica_modexpo(struct zcrypt_device *zdev,
 	struct completion work;
 	int rc;
 
+	ap_init_message(&ap_msg);
 	ap_msg.message = kmalloc(PCICA_MAX_MESSAGE_SIZE, GFP_KERNEL);
 	if (!ap_msg.message)
 		return -ENOMEM;
@@ -318,6 +319,7 @@ static long zcrypt_pcica_modexpo_crt(struct zcrypt_device *zdev,
 	struct completion work;
 	int rc;
 
+	ap_init_message(&ap_msg);
 	ap_msg.message = kmalloc(PCICA_MAX_MESSAGE_SIZE, GFP_KERNEL);
 	if (!ap_msg.message)
 		return -ENOMEM;
diff --git a/drivers/s390/crypto/zcrypt_pcicc.c b/drivers/s390/crypto/zcrypt_pcicc.c
index f4b0c4795434..a23726a0735c 100644
--- a/drivers/s390/crypto/zcrypt_pcicc.c
+++ b/drivers/s390/crypto/zcrypt_pcicc.c
@@ -483,6 +483,7 @@ static long zcrypt_pcicc_modexpo(struct zcrypt_device *zdev,
 	struct completion work;
 	int rc;
 
+	ap_init_message(&ap_msg);
 	ap_msg.message = (void *) get_zeroed_page(GFP_KERNEL);
 	if (!ap_msg.message)
 		return -ENOMEM;
@@ -521,6 +522,7 @@ static long zcrypt_pcicc_modexpo_crt(struct zcrypt_device *zdev,
 	struct completion work;
 	int rc;
 
+	ap_init_message(&ap_msg);
 	ap_msg.message = (void *) get_zeroed_page(GFP_KERNEL);
 	if (!ap_msg.message)
 		return -ENOMEM;
diff --git a/drivers/s390/crypto/zcrypt_pcixcc.c b/drivers/s390/crypto/zcrypt_pcixcc.c
index 5677b40e4ac0..11ca6dc99b23 100644
--- a/drivers/s390/crypto/zcrypt_pcixcc.c
+++ b/drivers/s390/crypto/zcrypt_pcixcc.c
@@ -688,6 +688,7 @@ static long zcrypt_pcixcc_modexpo(struct zcrypt_device *zdev,
 	};
 	int rc;
 
+	ap_init_message(&ap_msg);
 	ap_msg.message = (void *) get_zeroed_page(GFP_KERNEL);
 	if (!ap_msg.message)
 		return -ENOMEM;
@@ -727,6 +728,7 @@ static long zcrypt_pcixcc_modexpo_crt(struct zcrypt_device *zdev,
 	};
 	int rc;
 
+	ap_init_message(&ap_msg);
 	ap_msg.message = (void *) get_zeroed_page(GFP_KERNEL);
 	if (!ap_msg.message)
 		return -ENOMEM;
@@ -766,6 +768,7 @@ static long zcrypt_pcixcc_send_cprb(struct zcrypt_device *zdev,
 	};
 	int rc;
 
+	ap_init_message(&ap_msg);
 	ap_msg.message = kmalloc(PCIXCC_MAX_XCRB_MESSAGE_SIZE, GFP_KERNEL);
 	if (!ap_msg.message)
 		return -ENOMEM;
@@ -805,6 +808,7 @@ static long zcrypt_pcixcc_rng(struct zcrypt_device *zdev,
 	};
 	int rc;
 
+	ap_init_message(&ap_msg);
 	ap_msg.message = kmalloc(PCIXCC_MAX_XCRB_MESSAGE_SIZE, GFP_KERNEL);
 	if (!ap_msg.message)
 		return -ENOMEM;
@@ -972,6 +976,7 @@ static int zcrypt_pcixcc_rng_supported(struct ap_device *ap_dev)
 	} __attribute__((packed)) *reply;
 	int rc, i;
 
+	ap_init_message(&ap_msg);
 	ap_msg.message = (void *) get_zeroed_page(GFP_KERNEL);
 	if (!ap_msg.message)
 		return -ENOMEM;