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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>
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@ -325,6 +325,8 @@ static inline struct ap_queue_status ap_nqap(ap_qid_t qid,
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* @psmid: Pointer to program supplied message identifier
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* @msg: The message text
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* @length: The message length
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* @reslength: Resitual length on return
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* @resgr0: input: gr0 value (only used if != 0), output: resitual gr0 content
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*
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* Returns AP queue status structure.
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* Condition code 1 on DQAP means the receive has taken place
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@ -336,12 +338,25 @@ static inline struct ap_queue_status ap_nqap(ap_qid_t qid,
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* Note that gpr2 is used by the DQAP instruction to keep track of
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* any 'residual' length, in case the instruction gets interrupted.
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* Hence it gets zeroed before the instruction.
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* If the message does not fit into the buffer, this function will
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* return with a truncated message and the reply in the firmware queue
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* is not removed. This is indicated to the caller with an
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* ap_queue_status response_code value of all bits on (0xFF) and (if
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* the reslength ptr is given) the remaining length is stored in
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* *reslength and (if the resgr0 ptr is given) the updated gr0 value
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* for further processing of this msg entry is stored in *resgr0. The
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* caller needs to detect this situation and should invoke ap_dqap
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* with a valid resgr0 ptr and a value in there != 0 to indicate that
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* *resgr0 is to be used instead of qid to further process this entry.
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*/
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static inline struct ap_queue_status ap_dqap(ap_qid_t qid,
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unsigned long long *psmid,
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void *msg, size_t length)
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void *msg, size_t length,
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size_t *reslength,
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unsigned long *resgr0)
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{
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register unsigned long reg0 asm("0") = qid | 0x80000000UL;
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register unsigned long reg0 asm("0") =
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resgr0 && *resgr0 ? *resgr0 : qid | 0x80000000UL;
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register struct ap_queue_status reg1 asm ("1");
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register unsigned long reg2 asm("2") = 0UL;
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register unsigned long reg4 asm("4") = (unsigned long) msg;
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@ -349,14 +364,33 @@ static inline struct ap_queue_status ap_dqap(ap_qid_t qid,
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register unsigned long reg6 asm("6") = 0UL;
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register unsigned long reg7 asm("7") = 0UL;
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asm volatile(
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"0: .long 0xb2ae0064\n" /* DQAP */
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" brc 6,0b\n"
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"0: ltgr %[bl],%[bl]\n" /* if avail. buf len is 0 then */
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" jz 2f\n" /* go out of this asm block */
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"1: .long 0xb2ae0064\n" /* DQAP */
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" brc 6,0b\n" /* if partially do again */
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"2:\n"
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: "+d" (reg0), "=d" (reg1), "+d" (reg2),
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"+d" (reg4), "+d" (reg5), "+d" (reg6), "+d" (reg7)
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"+d" (reg4), [bl] "+d" (reg5), "+d" (reg6), "+d" (reg7)
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: : "cc", "memory");
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*psmid = (((unsigned long long) reg6) << 32) + reg7;
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if (reslength)
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*reslength = reg2;
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if (reg2 != 0 && reg5 == 0) {
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/*
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* Partially complete, status in gr1 is not set.
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* Signal the caller that this dqap is only partially received
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* with a special status response code 0xFF and *resgr0 updated
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*/
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reg1.response_code = 0xFF;
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if (resgr0)
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*resgr0 = reg0;
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} else {
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*psmid = (((unsigned long long) reg6) << 32) + reg7;
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if (resgr0)
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*resgr0 = 0;
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}
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return reg1;
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}
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@ -101,7 +101,7 @@ int ap_recv(ap_qid_t qid, unsigned long long *psmid, void *msg, size_t length)
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if (msg == NULL)
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return -EINVAL;
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status = ap_dqap(qid, psmid, msg, length);
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status = ap_dqap(qid, psmid, msg, length, NULL, NULL);
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switch (status.response_code) {
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case AP_RESPONSE_NORMAL:
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return 0;
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@ -136,9 +136,24 @@ static struct ap_queue_status ap_sm_recv(struct ap_queue *aq)
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struct ap_queue_status status;
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struct ap_message *ap_msg;
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bool found = false;
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size_t reslen;
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unsigned long resgr0 = 0;
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int parts = 0;
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/*
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* DQAP loop until response code and resgr0 indicate that
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* the msg is totally received. As we use the very same buffer
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* the msg is overwritten with each invocation. That's intended
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* and the receiver of the msg is informed with a msg rc code
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* of EMSGSIZE in such a case.
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*/
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do {
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status = ap_dqap(aq->qid, &aq->reply->psmid,
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aq->reply->msg, aq->reply->bufsize,
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&reslen, &resgr0);
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parts++;
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} while (status.response_code == 0xFF && resgr0 != 0);
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status = ap_dqap(aq->qid, &aq->reply->psmid,
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aq->reply->msg, aq->reply->bufsize);
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switch (status.response_code) {
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case AP_RESPONSE_NORMAL:
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aq->queue_count = max_t(int, 0, aq->queue_count - 1);
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@ -150,7 +165,12 @@ static struct ap_queue_status ap_sm_recv(struct ap_queue *aq)
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continue;
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list_del_init(&ap_msg->list);
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aq->pendingq_count--;
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ap_msg->receive(aq, ap_msg, aq->reply);
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if (parts > 1) {
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ap_msg->rc = -EMSGSIZE;
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ap_msg->receive(aq, ap_msg, NULL);
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} else {
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ap_msg->receive(aq, ap_msg, aq->reply);
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}
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found = true;
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break;
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}
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