Re: [PATCH] check for s390 crypto facility availablility

[Jan Glauber <jang@linux.vnet.ibm.com>]

[PATCH] respect STFL bit for s390 crypto

From: <jang@linux.vnet.ibm.com>

Bevore issuing any s390 crypto operation check whether the
CPACF facility is enabled in the facility list. That way a
virtualization layer can prevent usage of the CPACF facility
regardless of the availability of the crypto instructions.

Signed-off-by: <jang@linux.vnet.ibm.com>

--- ./arch/s390/crypto/crypt_s390.h.stfle
+++ ./arch/s390/crypto/crypt_s390.h
@@ -294,6 +294,10 @@ static inline int crypt_s390_func_availa
 	unsigned char status[16];
 	int ret;
 
+	/* check if CPACF facility (bit 17) is available */
+	if (!(stfl() & 1ULL << (31 - 17)))
+		return 0;
+
 	switch (func & CRYPT_S390_OP_MASK) {
 	case CRYPT_S390_KM:
 		ret = crypt_s390_km(KM_QUERY, &status, NULL, NULL, 0);