s390/AP: support new dynamic AP bus size limit

This patch provides support for new dynamic AP bus message limit
with the existing zcrypt device driver and AP bus core code.

There is support for a new field 'ml' from TAPQ query. The field
gives if != 0 the AP bus limit for this card in 4k chunk units.
The actual message size limit per card is shown as a new read-only
sysfs attribute. The sysfs attribute

  /sys/devices/ap/cardxx/max_msg_size

shows the upper limit in bytes used by the AP bus and zcrypt device
driver for requests and replies send to and received from this card.
Currently up to CEX7 support only max 12kB msg size and thus the field
shows 12288 meaning the upper limit of a valid msg for this card is
12kB. Please note that the usable payload is somewhat lower and
depends on the msg type and thus the header struct which is to be
prepended by the zcrypt dd.

The dispatcher responsible for choosing the right card and queue is
aware of the individual card AP bus message limit. So a request is
only assigned to a queue of a card which is able to handle the size of
the request (e.g. a 14kB request will never go to a max 12kB card).
If no such card is found the ioctl will fail with ENODEV.

The reply buffer held by the device driver is determined by the ml
field of the TAPQ for this card. If a response from the card exceeds
this limit however, the response is not truncated but the ioctl for
this request will fail with errno EMSGSIZE to indicate that the device
driver has dropped the response because it would overflow the buffer
limit.

If the request size does not indicate to the dispatcher that an
adapter with extended limit is to be used, a random card will be
chosen when no specific card is addressed (ANY addressing). This may
result in an ioctl failure when the reply size needs an adapter with
extended limit but the randomly chosen one is not capable of handling
the broader reply size. The user space application needs to use
dedicated addressing to forward such a request only to suitable cards
to get requests like this processed properly.

Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Ingo Tuchscherer <ingo.tuchscherer@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

drivers/s390/crypto/ap_bus.c

@@ -61,6 +61,9 @@ static char *aqm_str;
 module_param_named(aqmask, aqm_str, charp, 0440);
 MODULE_PARM_DESC(aqmask, "AP bus domain mask.");
 
+atomic_t ap_max_msg_size = ATOMIC_INIT(AP_DEFAULT_MAX_MSG_SIZE);
+EXPORT_SYMBOL(ap_max_msg_size);
+
 static struct device *ap_root_device;
 
 /* Hashtable of all queue devices on the AP bus */
@@ -316,19 +319,32 @@ EXPORT_SYMBOL(ap_test_config_ctrl_domain);
  * Returns true if TAPQ succeeded and the info is filled or
  * false otherwise.
  */
-static bool ap_queue_info(ap_qid_t qid, int *q_type,
-			  unsigned int *q_fac, int *q_depth, bool *q_decfg)
+static bool ap_queue_info(ap_qid_t qid, int *q_type, unsigned int *q_fac,
+			  int *q_depth, int *q_ml, bool *q_decfg)
 {
 	struct ap_queue_status status;
-	unsigned long info = 0;
+	union {
+		unsigned long value;
+		struct {
+			unsigned int fac   : 32; /* facility bits */
+			unsigned int at	   :  8; /* ap type */
+			unsigned int _res1 :  8;
+			unsigned int _res2 :  4;
+			unsigned int ml	   :  4; /* apxl ml */
+			unsigned int _res3 :  4;
+			unsigned int qd	   :  4; /* queue depth */
+		} tapq_gr2;
+	} tapq_info;
+
+	tapq_info.value = 0;
 
 	/* make sure we don't run into a specifiation exception */
 	if (AP_QID_CARD(qid) > ap_max_adapter_id ||
 	    AP_QID_QUEUE(qid) > ap_max_domain_id)
 		return false;
 
 	/* call TAPQ on this APQN */
-	status = ap_test_queue(qid, ap_apft_available(), &info);
+	status = ap_test_queue(qid, ap_apft_available(), &tapq_info.value);
 	switch (status.response_code) {
 	case AP_RESPONSE_NORMAL:
 	case AP_RESPONSE_RESET_IN_PROGRESS:
@@ -340,11 +356,12 @@ static bool ap_queue_info(ap_qid_t qid, int *q_type,
 		 * info should be filled. All bits 0 is not possible as
 		 * there is at least one of the mode bits set.
 		 */
-		if (WARN_ON_ONCE(!info))
+		if (WARN_ON_ONCE(!tapq_info.value))
 			return false;
-		*q_type = (int)((info >> 24) & 0xff);
-		*q_fac = (unsigned int)(info >> 32);
-		*q_depth = (int)(info & 0xff);
+		*q_type = tapq_info.tapq_gr2.at;
+		*q_fac = tapq_info.tapq_gr2.fac;
+		*q_depth = tapq_info.tapq_gr2.qd;
+		*q_ml = tapq_info.tapq_gr2.ml;
 		*q_decfg = status.response_code == AP_RESPONSE_DECONFIGURED;
 		switch (*q_type) {
 			/* For CEX2 and CEX3 the available functions
@@ -1516,7 +1533,7 @@ static inline void ap_scan_domains(struct ap_card *ac)
 	unsigned int func;
 	struct device *dev;
 	struct ap_queue *aq;
-	int rc, dom, depth, type;
+	int rc, dom, depth, type, ml;
 
 	/*
 	 * Go through the configuration for the domains and compare them
@@ -1540,7 +1557,7 @@ static inline void ap_scan_domains(struct ap_card *ac)
 			continue;
 		}
 		/* domain is valid, get info from this APQN */
-		if (!ap_queue_info(qid, &type, &func, &depth, &decfg)) {
+		if (!ap_queue_info(qid, &type, &func, &depth, &ml, &decfg)) {
 			if (aq) {
 				AP_DBF_INFO(
 					"%s(%d,%d) ap_queue_info() not successful, rm queue device\n",
@@ -1639,7 +1656,7 @@ static inline void ap_scan_adapter(int ap)
 	unsigned int func;
 	struct device *dev;
 	struct ap_card *ac;
-	int rc, dom, depth, type, comp_type;
+	int rc, dom, depth, type, comp_type, ml;
 
 	/* Is there currently a card device for this adapter ? */
 	dev = bus_find_device(&ap_bus_type, NULL,
@@ -1668,7 +1685,8 @@ static inline void ap_scan_adapter(int ap)
 	for (dom = 0; dom <= ap_max_domain_id; dom++)
 		if (ap_test_config_usage_domain(dom)) {
 			qid = AP_MKQID(ap, dom);
-			if (ap_queue_info(qid, &type, &func, &depth, &decfg))
+			if (ap_queue_info(qid, &type, &func,
+					  &depth, &ml, &decfg))
 				break;
 		}
 	if (dom > ap_max_domain_id) {
@@ -1737,7 +1755,7 @@ static inline void ap_scan_adapter(int ap)
 				    __func__, ap, type);
 			return;
 		}
-		ac = ap_card_create(ap, depth, type, comp_type, func);
+		ac = ap_card_create(ap, depth, type, comp_type, func, ml);
 		if (!ac) {
 			AP_DBF_WARN("%s(%d) ap_card_create() failed\n",
 				    __func__, ap);
@@ -1748,6 +1766,12 @@ static inline void ap_scan_adapter(int ap)
 		dev->bus = &ap_bus_type;
 		dev->parent = ap_root_device;
 		dev_set_name(dev, "card%02x", ap);
+		/* maybe enlarge ap_max_msg_size to support this card */
+		if (ac->maxmsgsize > atomic_read(&ap_max_msg_size)) {
+			atomic_set(&ap_max_msg_size, ac->maxmsgsize);
+			AP_DBF_INFO("%s(%d) ap_max_msg_size update to %d byte\n",
+				    __func__, ap, atomic_read(&ap_max_msg_size));
+		}
 		/* Register the new card device with AP bus */
 		rc = device_register(dev);
 		if (rc) {

drivers/s390/crypto/ap_bus.h

@@ -25,8 +25,11 @@
 #define AP_RESET_TIMEOUT (HZ*0.7)	/* Time in ticks for reset timeouts. */
 #define AP_CONFIG_TIME 30	/* Time in seconds between AP bus rescans. */
 #define AP_POLL_TIME 1		/* Time in ticks between receive polls. */
+#define AP_DEFAULT_MAX_MSG_SIZE (12 * 1024)
+#define AP_TAPQ_ML_FIELD_CHUNK_SIZE (4096)
 
 extern int ap_domain_index;
+extern atomic_t ap_max_msg_size;
 
 extern DECLARE_HASHTABLE(ap_queues, 8);
 extern spinlock_t ap_queues_lock;
@@ -167,6 +170,7 @@ struct ap_card {
 	unsigned int functions;		/* AP device function bitfield. */
 	int queue_depth;		/* AP queue depth.*/
 	int id;				/* AP card number. */
+	unsigned int maxmsgsize;	/* AP msg limit for this card */
 	bool config;			/* configured state */
 	atomic64_t total_request_count;	/* # requests ever for this AP device.*/
 };
@@ -228,7 +232,8 @@ struct ap_message {
 	struct list_head list;		/* Request queueing. */
 	unsigned long long psmid;	/* Message id. */
 	void *msg;			/* Pointer to message buffer. */
-	unsigned int len;		/* Message length. */
+	unsigned int len;		/* actual msg len in msg buffer */
+	unsigned int bufsize;		/* allocated msg buffer size */
 	u16 flags;			/* Flags, see AP_MSG_FLAG_xxx */
 	struct ap_fi fi;		/* Failure Injection cmd */
 	int rc;				/* Return code for this message */
@@ -290,8 +295,8 @@ void ap_queue_prepare_remove(struct ap_queue *aq);
 void ap_queue_remove(struct ap_queue *aq);
 void ap_queue_init_state(struct ap_queue *aq);
 
-struct ap_card *ap_card_create(int id, int queue_depth, int raw_device_type,
-			       int comp_device_type, unsigned int functions);
+struct ap_card *ap_card_create(int id, int queue_depth, int raw_type,
+			       int comp_type, unsigned int functions, int ml);
 
 struct ap_perms {
 	unsigned long ioctlm[BITS_TO_LONGS(AP_IOCTLS)];

drivers/s390/crypto/ap_card.c

@@ -174,6 +174,16 @@ static ssize_t config_store(struct device *dev,
 
 static DEVICE_ATTR_RW(config);
 
+static ssize_t max_msg_size_show(struct device *dev,
+				 struct device_attribute *attr, char *buf)
+{
+	struct ap_card *ac = to_ap_card(dev);
+
+	return scnprintf(buf, PAGE_SIZE, "%u\n", ac->maxmsgsize);
+}
+
+static DEVICE_ATTR_RO(max_msg_size);
+
 static struct attribute *ap_card_dev_attrs[] = {
 	&dev_attr_hwtype.attr,
 	&dev_attr_raw_hwtype.attr,
@@ -184,6 +194,7 @@ static struct attribute *ap_card_dev_attrs[] = {
 	&dev_attr_pendingq_count.attr,
 	&dev_attr_modalias.attr,
 	&dev_attr_config.attr,
+	&dev_attr_max_msg_size.attr,
 	NULL
 };
 
@@ -209,7 +220,7 @@ static void ap_card_device_release(struct device *dev)
 }
 
 struct ap_card *ap_card_create(int id, int queue_depth, int raw_type,
-			       int comp_type, unsigned int functions)
+			       int comp_type, unsigned int functions, int ml)
 {
 	struct ap_card *ac;
 
@@ -223,5 +234,8 @@ struct ap_card *ap_card_create(int id, int queue_depth, int raw_type,
 	ac->queue_depth = queue_depth;
 	ac->functions = functions;
 	ac->id = id;
+	ac->maxmsgsize = ml > 0 ?
+		ml * AP_TAPQ_ML_FIELD_CHUNK_SIZE : AP_DEFAULT_MAX_MSG_SIZE;
+
 	return ac;
 }

drivers/s390/crypto/ap_queue.c

@@ -138,7 +138,7 @@ static struct ap_queue_status ap_sm_recv(struct ap_queue *aq)
 	bool found = false;
 
 	status = ap_dqap(aq->qid, &aq->reply->psmid,
-			 aq->reply->msg, aq->reply->len);
+			 aq->reply->msg, aq->reply->bufsize);
 	switch (status.response_code) {
 	case AP_RESPONSE_NORMAL:
 		aq->queue_count = max_t(int, 0, aq->queue_count - 1);

drivers/s390/crypto/zcrypt_api.c

@@ -900,6 +900,9 @@ static long _zcrypt_send_cprb(bool userspace, struct ap_perms *perms,
 		if (xcRB->user_defined != AUTOSELECT &&
 		    xcRB->user_defined != zc->card->id)
 			continue;
+		/* check if request size exceeds card max msg size */
+		if (ap_msg.len > zc->card->maxmsgsize)
+			continue;
 		/* check if device node has admission for this card */
 		if (!zcrypt_check_card(perms, zc->card->id))
 			continue;
@@ -1068,6 +1071,9 @@ static long _zcrypt_send_ep11_cprb(bool userspace, struct ap_perms *perms,
 		if (targets &&
 		    !is_desired_ep11_card(zc->card->id, target_num, targets))
 			continue;
+		/* check if request size exceeds card max msg size */
+		if (ap_msg.len > zc->card->maxmsgsize)
+			continue;
 		/* check if device node has admission for this card */
 		if (!zcrypt_check_card(perms, zc->card->id))
 			continue;

drivers/s390/crypto/zcrypt_cex4.c

@@ -28,9 +28,6 @@
 #define CEX4C_MIN_MOD_SIZE	 16	/*  256 bits	*/
 #define CEX4C_MAX_MOD_SIZE	512	/* 4096 bits	*/
 
-#define CEX4A_MAX_MESSAGE_SIZE	MSGTYPE50_CRB3_MAX_MSG_SIZE
-#define CEX4C_MAX_MESSAGE_SIZE	MSGTYPE06_MAX_MSG_SIZE
-
 /* Waiting time for requests to be processed.
  * Currently there are some types of request which are not deterministic.
  * But the maximum time limit managed by the stomper code is set to 60sec.
@@ -605,19 +602,19 @@ static int zcrypt_cex4_queue_probe(struct ap_device *ap_dev)
 	int rc;
 
 	if (ap_test_bit(&aq->card->functions, AP_FUNC_ACCEL)) {
-		zq = zcrypt_queue_alloc(CEX4A_MAX_MESSAGE_SIZE);
+		zq = zcrypt_queue_alloc(aq->card->maxmsgsize);
 		if (!zq)
 			return -ENOMEM;
 		zq->ops = zcrypt_msgtype(MSGTYPE50_NAME,
 					 MSGTYPE50_VARIANT_DEFAULT);
 	} else if (ap_test_bit(&aq->card->functions, AP_FUNC_COPRO)) {
-		zq = zcrypt_queue_alloc(CEX4C_MAX_MESSAGE_SIZE);
+		zq = zcrypt_queue_alloc(aq->card->maxmsgsize);
 		if (!zq)
 			return -ENOMEM;
 		zq->ops = zcrypt_msgtype(MSGTYPE06_NAME,
 					 MSGTYPE06_VARIANT_DEFAULT);
 	} else if (ap_test_bit(&aq->card->functions, AP_FUNC_EP11)) {
-		zq = zcrypt_queue_alloc(CEX4C_MAX_MESSAGE_SIZE);
+		zq = zcrypt_queue_alloc(aq->card->maxmsgsize);
 		if (!zq)
 			return -ENOMEM;
 		zq->ops = zcrypt_msgtype(MSGTYPE06_NAME,

drivers/s390/crypto/zcrypt_msgtype50.c

@@ -442,11 +442,13 @@ static void zcrypt_cex2a_receive(struct ap_queue *aq,
 		goto out;	/* ap_msg->rc indicates the error */
 	t80h = reply->msg;
 	if (t80h->type == TYPE80_RSP_CODE) {
-		if (aq->ap_dev.device_type == AP_DEVICE_TYPE_CEX2A)
-			len = min_t(int, CEX2A_MAX_RESPONSE_SIZE, t80h->len);
-		else
-			len = min_t(int, CEX3A_MAX_RESPONSE_SIZE, t80h->len);
-		memcpy(msg->msg, reply->msg, len);
+		len = t80h->len;
+		if (len > reply->bufsize || len > msg->bufsize) {
+			msg->rc = -EMSGSIZE;
+		} else {
+			memcpy(msg->msg, reply->msg, len);
+			msg->len = len;
+		}
 	} else
 		memcpy(msg->msg, reply->msg, sizeof(error_reply));
 out:
@@ -469,10 +471,9 @@ static long zcrypt_cex2a_modexpo(struct zcrypt_queue *zq,
 	struct completion work;
 	int rc;
 
-	if (zq->zcard->user_space_type == ZCRYPT_CEX2A)
-		ap_msg->msg = kmalloc(MSGTYPE50_CRB2_MAX_MSG_SIZE, GFP_KERNEL);
-	else
-		ap_msg->msg = kmalloc(MSGTYPE50_CRB3_MAX_MSG_SIZE, GFP_KERNEL);
+	ap_msg->bufsize = (zq->zcard->user_space_type == ZCRYPT_CEX2A) ?
+		MSGTYPE50_CRB2_MAX_MSG_SIZE : MSGTYPE50_CRB3_MAX_MSG_SIZE;
+	ap_msg->msg = kmalloc(ap_msg->bufsize, GFP_KERNEL);
 	if (!ap_msg->msg)
 		return -ENOMEM;
 	ap_msg->receive = zcrypt_cex2a_receive;
@@ -515,10 +516,9 @@ static long zcrypt_cex2a_modexpo_crt(struct zcrypt_queue *zq,
 	struct completion work;
 	int rc;
 
-	if (zq->zcard->user_space_type == ZCRYPT_CEX2A)
-		ap_msg->msg = kmalloc(MSGTYPE50_CRB2_MAX_MSG_SIZE, GFP_KERNEL);
-	else
-		ap_msg->msg = kmalloc(MSGTYPE50_CRB3_MAX_MSG_SIZE, GFP_KERNEL);
+	ap_msg->bufsize = (zq->zcard->user_space_type == ZCRYPT_CEX2A) ?
+		MSGTYPE50_CRB2_MAX_MSG_SIZE : MSGTYPE50_CRB3_MAX_MSG_SIZE;
+	ap_msg->msg = kmalloc(ap_msg->bufsize, GFP_KERNEL);
 	if (!ap_msg->msg)
 		return -ENOMEM;
 	ap_msg->receive = zcrypt_cex2a_receive;