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

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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>
This commit is contained in:
Harald Freudenberger 2021-06-30 16:10:56 +02:00 committed by Vasily Gorbik
parent bd39654a22
commit 1f0d22defd
2 changed files with 65 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

46
arch/s390/include/asm/ap.h
View File

@ -325,6 +325,8 @@ static inline struct ap_queue_status ap_nqap(ap_qid_t qid,
* @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
*
* Returns AP queue status structure.
* Condition code 1 on DQAP means the receive has taken place
@ -336,12 +338,25 @@ static inline struct ap_queue_status ap_nqap(ap_qid_t qid,
* Note that gpr2 is used by the DQAP instruction to keep track of
* any 'residual' length, in case the instruction gets interrupted.
* Hence it gets zeroed before the instruction.
* If the message does not fit into the buffer, this function will
* return with a truncated message and the reply in the firmware queue
* is not removed. This is indicated to the caller with an
* ap_queue_status response_code value of all bits on (0xFF) and (if
* the reslength ptr is given) the remaining length is stored in
* *reslength and (if the resgr0 ptr is given) the updated gr0 value
* for further processing of this msg entry is stored in *resgr0. The
* caller needs to detect this situation and should invoke ap_dqap
* with a valid resgr0 ptr and a value in there != 0 to indicate that
* *resgr0 is to be used instead of qid to further process this entry.
*/
static inline struct ap_queue_status ap_dqap(ap_qid_t qid,
unsigned long long *psmid,
void *msg, size_t length)
void *msg, size_t length,
size_t *reslength,
unsigned long *resgr0)
{
register unsigned long reg0 asm("0") = qid | 0x80000000UL;
register unsigned long reg0 asm("0") =
resgr0 && *resgr0 ? *resgr0 : qid | 0x80000000UL;
register struct ap_queue_status reg1 asm ("1");
register unsigned long reg2 asm("2") = 0UL;
register unsigned long reg4 asm("4") = (unsigned long) msg;
@ -349,14 +364,33 @@ static inline struct ap_queue_status ap_dqap(ap_qid_t qid,
register unsigned long reg6 asm("6") = 0UL;
register unsigned long reg7 asm("7") = 0UL;
asm volatile(
"0: .long 0xb2ae0064\n" /* DQAP */
" brc 6,0b\n"
"0: ltgr %[bl],%[bl]\n" /* if avail. buf len is 0 then */
" jz 2f\n" /* go out of this asm block */
"1: .long 0xb2ae0064\n" /* DQAP */
" brc 6,0b\n" /* if partially do again */
"2:\n"
: "+d" (reg0), "=d" (reg1), "+d" (reg2),
"+d" (reg4), "+d" (reg5), "+d" (reg6), "+d" (reg7)
"+d" (reg4), [bl] "+d" (reg5), "+d" (reg6), "+d" (reg7)
: : "cc", "memory");
if (reslength)
*reslength = reg2;
if (reg2 != 0 && reg5 == 0) {
/*
* Partially complete, status in gr1 is not set.
* Signal the caller that this dqap is only partially received
* with a special status response code 0xFF and *resgr0 updated
*/
reg1.response_code = 0xFF;
if (resgr0)
*resgr0 = reg0;
} else {
*psmid = (((unsigned long long) reg6) << 32) + reg7;
if (resgr0)
*resgr0 = 0;
}
return reg1;
}

24
drivers/s390/crypto/ap_queue.c
View File

@ -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);
aq->reply->msg, aq->reply->bufsize,
&reslen, &resgr0);
parts++;
} while (status.response_code == 0xFF && resgr0 != 0);
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--;
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;
}