s390/zcrypt: rework length information for dqap

The inline ap_dqap function does not return the number of
bytes actually written into the message buffer. The calling
code inspects the AP message header to figure out what kind
of AP message has been received and pulls the length
information from this header. This processing may not work
correctly in cases where only a fragment of the reply is
received.

With this patch the ap_dqap inline function now returns
the number of actually written bytes in the *length parameter.
So the calling function has a chance to compare the number of
received bytes against what the AP message header length
field states. This is especially useful in cases where a
message could only get partially received.

The low level reply processing functions needed some rework
to be able to catch this new length information and compare
it the right way. The rework also deals with some situations
where until now the reply length was not correctly calculated
and/or set.

All this has been heavily tested as the modifications on
the reply length information may affect crypto load.

Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Holger Dengler <dengler@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

1 files changed, 12 insertions, 6 deletions

diff --git a/arch/s390/include/asm/ap.h b/arch/s390/include/asm/ap.h
index 0744a00f92a5..6bb536e87897 100644
--- a/arch/s390/include/asm/ap.h
+++ b/arch/s390/include/asm/ap.h
@@ -359,10 +359,11 @@ static inline struct ap_queue_status ap_nqap(ap_qid_t qid,
  * ap_dqap(): Receive message from adjunct processor queue.
  * @qid: The AP queue number
  * @psmid: Pointer to program supplied message identifier
- * @msg: The message text
- * @length: The message length
- * @reslength: Resitual length on return
- * @resgr0: input: gr0 value (only used if != 0), output: resitual gr0 content
+ * @msg: Pointer to message buffer
+ * @msglen: Message buffer size
+ * @length: Pointer to length of actually written bytes
+ * @reslength: Residual length on return
+ * @resgr0: input: gr0 value (only used if != 0), output: residual gr0 content
  *
  * Returns AP queue status structure.
  * Condition code 1 on DQAP means the receive has taken place
@@ -387,7 +388,8 @@ static inline struct ap_queue_status ap_nqap(ap_qid_t qid,
  */
 static inline struct ap_queue_status ap_dqap(ap_qid_t qid,
 					     unsigned long *psmid,
-					     void *msg, size_t length,
+					     void *msg, size_t msglen,
+					     size_t *length,
 					     size_t *reslength,
 					     unsigned long *resgr0)
 {
@@ -399,7 +401,7 @@ static inline struct ap_queue_status ap_dqap(ap_qid_t qid,
 	rp1.even = 0UL;
 	rp1.odd  = 0UL;
 	rp2.even = (unsigned long)msg;
-	rp2.odd  = (unsigned long)length;
+	rp2.odd  = (unsigned long)msglen;
 
 	asm volatile(
 		"	lgr	0,%[reg0]\n"   /* qid param into gr0 */
@@ -434,6 +436,10 @@ static inline struct ap_queue_status ap_dqap(ap_qid_t qid,
 			*resgr0 = 0;
 	}
 
+	/* update *length with the nr of bytes stored into the msg buffer */
+	if (length)
+		*length = msglen - rp2.odd;
+
 	return reg1.status;
 }