diff --git a/arch/s390/crypto/aes_s390.c b/arch/s390/crypto/aes_s390.c
index 7a1033d8e00fe202ed15245b610f1455baf53f61..c5ca2dc5d4281ee67d7d67be936dec4ec2214ff0 100644
--- a/arch/s390/crypto/aes_s390.c
+++ b/arch/s390/crypto/aes_s390.c
@@ -114,80 +114,108 @@ static unsigned int aes_encrypt_ecb(const struct cipher_desc *desc, u8 *out,
 				    const u8 *in, unsigned int nbytes)
 {
 	struct s390_aes_ctx *sctx = crypto_tfm_ctx(desc->tfm);
+	int ret;
+
+	/* only use complete blocks */
+	nbytes &= ~(AES_BLOCK_SIZE - 1);
 
 	switch (sctx->key_len) {
 	case 16:
-		crypt_s390_km(KM_AES_128_ENCRYPT, &sctx->key, out, in, nbytes);
+		ret = crypt_s390_km(KM_AES_128_ENCRYPT, &sctx->key, out, in, nbytes);
+		BUG_ON((ret < 0) || (ret != nbytes));
 		break;
 	case 24:
-		crypt_s390_km(KM_AES_192_ENCRYPT, &sctx->key, out, in, nbytes);
+		ret = crypt_s390_km(KM_AES_192_ENCRYPT, &sctx->key, out, in, nbytes);
+		BUG_ON((ret < 0) || (ret != nbytes));
 		break;
 	case 32:
-		crypt_s390_km(KM_AES_256_ENCRYPT, &sctx->key, out, in, nbytes);
+		ret = crypt_s390_km(KM_AES_256_ENCRYPT, &sctx->key, out, in, nbytes);
+		BUG_ON((ret < 0) || (ret != nbytes));
 		break;
 	}
-	return nbytes & ~(AES_BLOCK_SIZE - 1);
+	return nbytes;
 }
 
 static unsigned int aes_decrypt_ecb(const struct cipher_desc *desc, u8 *out,
 				    const u8 *in, unsigned int nbytes)
 {
 	struct s390_aes_ctx *sctx = crypto_tfm_ctx(desc->tfm);
+	int ret;
+
+	/* only use complete blocks */
+	nbytes &= ~(AES_BLOCK_SIZE - 1);
 
 	switch (sctx->key_len) {
 	case 16:
-		crypt_s390_km(KM_AES_128_DECRYPT, &sctx->key, out, in, nbytes);
+		ret = crypt_s390_km(KM_AES_128_DECRYPT, &sctx->key, out, in, nbytes);
+		BUG_ON((ret < 0) || (ret != nbytes));
 		break;
 	case 24:
-		crypt_s390_km(KM_AES_192_DECRYPT, &sctx->key, out, in, nbytes);
+		ret = crypt_s390_km(KM_AES_192_DECRYPT, &sctx->key, out, in, nbytes);
+		BUG_ON((ret < 0) || (ret != nbytes));
 		break;
 	case 32:
-		crypt_s390_km(KM_AES_256_DECRYPT, &sctx->key, out, in, nbytes);
+		ret = crypt_s390_km(KM_AES_256_DECRYPT, &sctx->key, out, in, nbytes);
+		BUG_ON((ret < 0) || (ret != nbytes));
 		break;
 	}
-	return nbytes & ~(AES_BLOCK_SIZE - 1);
+	return nbytes;
 }
 
 static unsigned int aes_encrypt_cbc(const struct cipher_desc *desc, u8 *out,
 				    const u8 *in, unsigned int nbytes)
 {
 	struct s390_aes_ctx *sctx = crypto_tfm_ctx(desc->tfm);
+	int ret;
+
+	/* only use complete blocks */
+	nbytes &= ~(AES_BLOCK_SIZE - 1);
 
 	memcpy(&sctx->iv, desc->info, AES_BLOCK_SIZE);
 	switch (sctx->key_len) {
 	case 16:
-		crypt_s390_kmc(KMC_AES_128_ENCRYPT, &sctx->iv, out, in, nbytes);
+		ret = crypt_s390_kmc(KMC_AES_128_ENCRYPT, &sctx->iv, out, in, nbytes);
+		BUG_ON((ret < 0) || (ret != nbytes));
 		break;
 	case 24:
-		crypt_s390_kmc(KMC_AES_192_ENCRYPT, &sctx->iv, out, in, nbytes);
+		ret = crypt_s390_kmc(KMC_AES_192_ENCRYPT, &sctx->iv, out, in, nbytes);
+		BUG_ON((ret < 0) || (ret != nbytes));
 		break;
 	case 32:
-		crypt_s390_kmc(KMC_AES_256_ENCRYPT, &sctx->iv, out, in, nbytes);
+		ret = crypt_s390_kmc(KMC_AES_256_ENCRYPT, &sctx->iv, out, in, nbytes);
+		BUG_ON((ret < 0) || (ret != nbytes));
 		break;
 	}
 	memcpy(desc->info, &sctx->iv, AES_BLOCK_SIZE);
 
-	return nbytes & ~(AES_BLOCK_SIZE - 1);
+	return nbytes;
 }
 
 static unsigned int aes_decrypt_cbc(const struct cipher_desc *desc, u8 *out,
 				    const u8 *in, unsigned int nbytes)
 {
 	struct s390_aes_ctx *sctx = crypto_tfm_ctx(desc->tfm);
+	int ret;
+
+	/* only use complete blocks */
+	nbytes &= ~(AES_BLOCK_SIZE - 1);
 
 	memcpy(&sctx->iv, desc->info, AES_BLOCK_SIZE);
 	switch (sctx->key_len) {
 	case 16:
-		crypt_s390_kmc(KMC_AES_128_DECRYPT, &sctx->iv, out, in, nbytes);
+		ret = crypt_s390_kmc(KMC_AES_128_DECRYPT, &sctx->iv, out, in, nbytes);
+		BUG_ON((ret < 0) || (ret != nbytes));
 		break;
 	case 24:
-		crypt_s390_kmc(KMC_AES_192_DECRYPT, &sctx->iv, out, in, nbytes);
+		ret = crypt_s390_kmc(KMC_AES_192_DECRYPT, &sctx->iv, out, in, nbytes);
+		BUG_ON((ret < 0) || (ret != nbytes));
 		break;
 	case 32:
-		crypt_s390_kmc(KMC_AES_256_DECRYPT, &sctx->iv, out, in, nbytes);
+		ret = crypt_s390_kmc(KMC_AES_256_DECRYPT, &sctx->iv, out, in, nbytes);
+		BUG_ON((ret < 0) || (ret != nbytes));
 		break;
 	}
-	return nbytes & ~(AES_BLOCK_SIZE - 1);
+	return nbytes;
 }