s390/zcrypt: Introduce Failure Injection feature

s390/zcrypt: Introduce Failure Injection feature

Introduce a way to specify additional debug flags with an crpyto
request to be able to trigger certain failures within the zcrypt
device drivers and/or ap core code.

This failure injection possibility is only enabled with a kernel debug
build CONFIG_ZCRYPT_DEBUG) and should never be available on a regular
kernel running in production environment.

Details:

* The ioctl(ICARSAMODEXPO) get's a struct ica_rsa_modexpo. If the
  leftmost bit of the 32 bit unsigned int inputdatalength field is
  set, the uppermost 16 bits are separated and used as debug flag
  value. The process is checked to have the CAP_SYS_ADMIN capability
  enabled or EPERM is returned.

* The ioctl(ICARSACRT) get's a struct ica_rsa_modexpo_crt. If the
  leftmost bit of the 32 bit unsigned int inputdatalength field is set,
  the uppermost 16 bits are separated and used als debug flag
  value. The process is checked to have the CAP_SYS_ADMIN capability
  enabled or EPERM is returned.

* The ioctl(ZSECSENDCPRB) used to send CCA CPRBs get's a struct
  ica_xcRB. If the leftmost bit of the 32 bit unsigned int status
  field is set, the uppermost 16 bits of this field are used as debug
  flag value. The process is checked to have the CAP_SYS_ADMIN
  capability enabled or EPERM is returned.

* The ioctl(ZSENDEP11CPRB) used to send EP11 CPRBs get's a struct
  ep11_urb. If the leftmost bit of the 64 bit unsigned int req_len
  field is set, the uppermost 16 bits of this field are used as debug
  flag value. The process is checked to have the CAP_SYS_ADMIN
  capability enabled or EPERM is returned.

So it is possible to send an additional 16 bit value to the zcrypt API
to be used to carry a failure injection command which may trigger
special behavior within the zcrypt API and layers below. This 16 bit
value is for the rest of the test referred as 'fi command' for Failure
Injection.

The lower 8 bits of the fi command construct a numerical argument in
the range of 1-255 and is the 'fi action' to be performed with the
request or the resulting reply:

* 0x00 (all requests): No failure injection action but flags may be
  provided which may affect the processing of the request or reply.
* 0x01 (only CCA CPRBs): The CPRB's agent_ID field is set to
  'FF'. This results in an reply code 0x90 (Transport-Protocol
  Failure).
* 0x02 (only CCA CPRBs): After the APQN to send to has been chosen,
  the domain field within the CPRB is overwritten with value 99 to
  enforce an reply with RY 0x8A.
* 0x03 (all requests): At NQAP invocation the invalid qid value 0xFF00
  is used causing an response code of 0x01 (AP queue not valid).

The upper 8 bits of the fi command may carry bit flags which may
influence the processing of an request or response:

* 0x01: No retry. If this bit is set, the usual loop in the zcrypt API
  which retries an CPRB up to 10 times when the lower layers return
  with EAGAIN is abandoned after the first attempt to send the CPRB.
* 0x02: Toggle special. Toggles the special bit on this request. This
  should result in an reply code RY~0x41 and result in an ioctl
  failure with errno EINVAL.

This failure injection possibilities may get some further extensions
in the future. As of now this is a starting point for Continuous Test
and Integration to trigger some failures and watch for the reaction of
the ap bus and zcrypt device driver code.

Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>