s390/zcrypt: fix specification exception on z196 during ap probe

hfreude · Martin Schwidefsky · commit 8f9aca0c4532 · 2019-01-28T15:43:17.000+01:00
The older machines don't have the QCI instruction available. With support for up to 256 crypto cards the probing of each card has been extended to check card ids from 0 up to 255. For machines with QCI support there is a filter limiting the range of probed cards. The older machines (z196 and older) don't have this filter and so since support for 256 cards is in the driver all cards are probed. However, these machines also require to have the card id fit into 6 bits. Exceeding this limit results in a specification exception which happens on every kernel startup even when there is no crypto configured and used at all. This fix limits the range of probed crypto cards to 64 if there is no QCI instruction available to obey to the older ap architecture and so fixes the specification exceptions on z196 machines. Cc: stable@vger.kernel.org # v4.17+ Fixes: af4a722 ("s390/zcrypt: Support up to 256 crypto adapters.") Signed-off-by: Harald Freudenberger <freude@linux.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/crypto/ap_bus.c b/drivers/s390/crypto/ap_bus.c
@@ -248,7 +248,8 @@ static inline int ap_test_config(unsigned int *field, unsigned int nr)
 static inline int ap_test_config_card_id(unsigned int id)
 {
 	if (!ap_configuration)	/* QCI not supported */
-		return 1;
+		/* only ids 0...3F may be probed */
+		return id < 0x40 ? 1 : 0;
 	return ap_test_config(ap_configuration->apm, id);
 }
 

Original file line number	Diff line number	Diff line change
`@@ -248,7 +248,8 @@ static inline int ap_test_config(unsigned int *field, unsigned int nr)`
`248`	`248`	`static inline int ap_test_config_card_id(unsigned int id)`
`249`	`249`	`{`
`250`	`250`	`if (!ap_configuration) /* QCI not supported */`
`251`		`- return 1;`
	`251`	`+ /* only ids 0...3F may be probed */`
	`252`	`+ return id < 0x40 ? 1 : 0;`
`252`	`253`	`return ap_test_config(ap_configuration->apm, id);`
`253`	`254`	`}`
`254`	`255`