s390/ap: Rework ap_dqap to deal with messages greater than recv buffer

Rework of the ap_dqap() inline function with the dqap inline assembler
invocation and the caller code in ap_queue.c to be able to handle
replies which exceed the receive buffer size.

ap_dqap() now provides two additional parameters to handle together
with the caller the case where a reply in the firmware queue entry
exceeds the given message buffer size. It depends on the caller how to
exactly handle this. The behavior implemented now by ap_sm_recv() in
ap_queue.c is to simple purge this entry from the firmware queue and
let the caller 'receive' a -EMSGSIZE for the request without
delivering any reply data - not even a truncated reply message.

However, the reworked ap_dqap() could now get invoked in a way that
the message is received in multiple parts and the caller assembles the
parts into one reply message.

Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Suggested-by: Juergen Christ <jchrist@linux.ibm.com>
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

1 files changed, 24 insertions, 4 deletions

diff --git a/drivers/s390/crypto/ap_queue.c b/drivers/s390/crypto/ap_queue.c
index c5e0fe0286e5..669f96fddad6 100644
--- a/drivers/s390/crypto/ap_queue.c
+++ b/drivers/s390/crypto/ap_queue.c
@@ -101,7 +101,7 @@ int ap_recv(ap_qid_t qid, unsigned long long *psmid, void *msg, size_t length)
 
 	if (msg == NULL)
 		return -EINVAL;
-	status = ap_dqap(qid, psmid, msg, length);
+	status = ap_dqap(qid, psmid, msg, length, NULL, NULL);
 	switch (status.response_code) {
 	case AP_RESPONSE_NORMAL:
 		return 0;
@@ -136,9 +136,24 @@ static struct ap_queue_status ap_sm_recv(struct ap_queue *aq)
 	struct ap_queue_status status;
 	struct ap_message *ap_msg;
 	bool found = false;
+	size_t reslen;
+	unsigned long resgr0 = 0;
+	int parts = 0;
+
+	/*
+	 * DQAP loop until response code and resgr0 indicate that
+	 * the msg is totally received. As we use the very same buffer
+	 * the msg is overwritten with each invocation. That's intended
+	 * and the receiver of the msg is informed with a msg rc code
+	 * of EMSGSIZE in such a case.
+	 */
+	do {
+		status = ap_dqap(aq->qid, &aq->reply->psmid,
+				 aq->reply->msg, aq->reply->bufsize,
+				 &reslen, &resgr0);
+		parts++;
+	} while (status.response_code == 0xFF && resgr0 != 0);
 
-	status = ap_dqap(aq->qid, &aq->reply->psmid,
-			 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);
@@ -150,7 +165,12 @@ static struct ap_queue_status ap_sm_recv(struct ap_queue *aq)
 				continue;
 			list_del_init(&ap_msg->list);
 			aq->pendingq_count--;
-			ap_msg->receive(aq, ap_msg, aq->reply);
+			if (parts > 1) {
+				ap_msg->rc = -EMSGSIZE;
+				ap_msg->receive(aq, ap_msg, NULL);
+			} else {
+				ap_msg->receive(aq, ap_msg, aq->reply);
+			}
 			found = true;
 			break;
 		}