crypto: s390 - Respect STFL bit

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: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

arch/s390/crypto/crypt_s390.h

@@ -296,6 +296,10 @@ static inline int crypt_s390_func_available(int func)
 	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);