[S390] zcrypt: cope with cca restriction of cex3

The cca on the crypto adapter has a restriction in the size of the
exponent if a key with a modulus bigger than 2048 bit is used. Thus
in that case we have to avoid that the crypto device driver thinks
the adapter is defect and sets it offline. Therfore a new member for
the zcrypt_device struct called max_exp_bit_length is introduced. This
will be set the first time the cca returns the error code function
not implemented. If this is done with an adapter twice it will return
-EINVAL.

Signed-off-by: Felix Beck <felix.beck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/crypto/zcrypt_api.h

@@ -109,6 +109,7 @@ struct zcrypt_device {
 	int request_count;		/* # current requests. */
 
 	struct ap_message reply;	/* Per-device reply structure. */
+	int max_exp_bit_length;
 };
 
 struct zcrypt_device *zcrypt_device_alloc(size_t);

drivers/s390/crypto/zcrypt_cex2a.c

@@ -441,6 +441,7 @@ static int zcrypt_cex2a_probe(struct ap_device *ap_dev)
 		zdev->max_mod_size = CEX2A_MAX_MOD_SIZE;
 		zdev->short_crt = 1;
 		zdev->speed_rating = CEX2A_SPEED_RATING;
+		zdev->max_exp_bit_length = CEX2A_MAX_MOD_SIZE;
 		break;
 	case AP_DEVICE_TYPE_CEX3A:
 		zdev = zcrypt_device_alloc(CEX3A_MAX_RESPONSE_SIZE);
@@ -450,8 +451,11 @@ static int zcrypt_cex2a_probe(struct ap_device *ap_dev)
 		zdev->type_string = "CEX3A";
 		zdev->min_mod_size = CEX2A_MIN_MOD_SIZE;
 		zdev->max_mod_size = CEX2A_MAX_MOD_SIZE;
-		if (ap_4096_commands_available(ap_dev->qid))
+		zdev->max_exp_bit_length = CEX2A_MAX_MOD_SIZE;
+		if (ap_4096_commands_available(ap_dev->qid)) {
 			zdev->max_mod_size = CEX3A_MAX_MOD_SIZE;
+			zdev->max_exp_bit_length = CEX3A_MAX_MOD_SIZE;
+		}
 		zdev->short_crt = 1;
 		zdev->speed_rating = CEX3A_SPEED_RATING;
 		break;

drivers/s390/crypto/zcrypt_pcica.c

@@ -373,6 +373,7 @@ static int zcrypt_pcica_probe(struct ap_device *ap_dev)
 	zdev->min_mod_size = PCICA_MIN_MOD_SIZE;
 	zdev->max_mod_size = PCICA_MAX_MOD_SIZE;
 	zdev->speed_rating = PCICA_SPEED_RATING;
+	zdev->max_exp_bit_length = PCICA_MAX_MOD_SIZE;
 	ap_dev->reply = &zdev->reply;
 	ap_dev->private = zdev;
 	rc = zcrypt_device_register(zdev);

drivers/s390/crypto/zcrypt_pcicc.c

@@ -579,6 +579,7 @@ static int zcrypt_pcicc_probe(struct ap_device *ap_dev)
 	zdev->min_mod_size = PCICC_MIN_MOD_SIZE;
 	zdev->max_mod_size = PCICC_MAX_MOD_SIZE;
 	zdev->speed_rating = PCICC_SPEED_RATING;
+	zdev->max_exp_bit_length = PCICC_MAX_MOD_SIZE;
 	ap_dev->reply = &zdev->reply;
 	ap_dev->private = zdev;
 	rc = zcrypt_device_register(zdev);

drivers/s390/crypto/zcrypt_pcixcc.c

@@ -567,6 +567,15 @@ static int convert_response_ica(struct zcrypt_device *zdev,
 	case TYPE88_RSP_CODE:
 		return convert_error(zdev, reply);
 	case TYPE86_RSP_CODE:
+		if (msg->cprbx.ccp_rtcode &&
+		   (msg->cprbx.ccp_rscode == 0x14f) &&
+		   (outputdatalength > 256)) {
+			if (zdev->max_exp_bit_length <= 17) {
+				zdev->max_exp_bit_length = 17;
+				return -EAGAIN;
+			} else
+				return -EINVAL;
+		}
 		if (msg->hdr.reply_code)
 			return convert_error(zdev, reply);
 		if (msg->cprbx.cprb_ver_id == 0x02)
@@ -1052,11 +1061,13 @@ static int zcrypt_pcixcc_probe(struct ap_device *ap_dev)
 			zdev->speed_rating = PCIXCC_MCL2_SPEED_RATING;
 			zdev->min_mod_size = PCIXCC_MIN_MOD_SIZE_OLD;
 			zdev->max_mod_size = PCIXCC_MAX_MOD_SIZE;
+			zdev->max_exp_bit_length = PCIXCC_MAX_MOD_SIZE;
 		} else {
 			zdev->type_string = "PCIXCC_MCL3";
 			zdev->speed_rating = PCIXCC_MCL3_SPEED_RATING;
 			zdev->min_mod_size = PCIXCC_MIN_MOD_SIZE;
 			zdev->max_mod_size = PCIXCC_MAX_MOD_SIZE;
+			zdev->max_exp_bit_length = PCIXCC_MAX_MOD_SIZE;
 		}
 		break;
 	case AP_DEVICE_TYPE_CEX2C:
@@ -1065,6 +1076,7 @@ static int zcrypt_pcixcc_probe(struct ap_device *ap_dev)
 		zdev->speed_rating = CEX2C_SPEED_RATING;
 		zdev->min_mod_size = PCIXCC_MIN_MOD_SIZE;
 		zdev->max_mod_size = PCIXCC_MAX_MOD_SIZE;
+		zdev->max_exp_bit_length = PCIXCC_MAX_MOD_SIZE;
 		break;
 	case AP_DEVICE_TYPE_CEX3C:
 		zdev->user_space_type = ZCRYPT_CEX3C;
@@ -1072,6 +1084,7 @@ static int zcrypt_pcixcc_probe(struct ap_device *ap_dev)
 		zdev->speed_rating = CEX3C_SPEED_RATING;
 		zdev->min_mod_size = CEX3C_MIN_MOD_SIZE;
 		zdev->max_mod_size = CEX3C_MAX_MOD_SIZE;
+		zdev->max_exp_bit_length = CEX3C_MAX_MOD_SIZE;
 		break;
 	default:
 		goto out_free;