Re: [PATCH v13 11/18] target/s390x: Base support for cpacf protected keys and pckmo

[Harald Freudenberger <freude@linux.ibm.com>]

On 2026-08-05 00:00, Ilya Leoshkevich wrote:
> On 8/3/26 18:12, Harald Freudenberger wrote:
>> Add base support for cpacf protected key handling.
>> Add support for the pckmo subfunctions PCKMO-Encrypt-AES-128-Key,
>> PCKMO-Encrypt-AES-192-Key and PCKMO-Encrypt-AES-256-Key which deal
>> with protected keys. These pckmo subfunctions derive a protected key
>> from an AES clear key by encrypting it with an internal AES wrapping
>> key. More details about protected keys can be found in the
>> "z/Architecture Prinziples of Operation" document.
>> 
>> The qemu version provided here is only a fake intended to make
>> protected key available for developing and testing purpose:
>> * The protected key is 'derived' from the clear key by xoring
>>    the fixed pattern 0xAAAA... onto the key value.
>> * The AES Wrapping Key Verification Pattern is a fixed
>>    value of 32 bytes 0xFACEFACE...
>> 
>> Add preprocessor defines for the xor pattern and wkvp used to
>> construct ('encrypt') a protected key from a clear key value with
>> this implementation. Also add some static functions to 'encrypt'
>> from clear key to protected key and 'decrypt' back to cpacf_aes.c.
>> 
>> The preprocessor defines shall be used later in testcases to
>> construct and decode protected keys.
>> 
>> Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
>> Tested-by: Holger Dengler <dengler@linux.ibm.com>
>> ---
>>   target/s390x/gen-features.c      |  3 ++
>>   target/s390x/tcg/cpacf.h         | 29 +++++++++++++++
>>   target/s390x/tcg/cpacf_aes.c     | 64 
>> ++++++++++++++++++++++++++++++++
>>   target/s390x/tcg/crypto_helper.c | 21 +++++++++++
>>   target/s390x/tcg/translate.c     |  9 ++++-
>>   5 files changed, 124 insertions(+), 2 deletions(-)
> 
> Should we add IF_PRIV to insn-data.h.inc? POp says PCKMO is privileged,
> but currently it seems to be defined as reachable from userspace:
> 
>     D(0xb928, PCKMO,   RRE,   MSA3, 0, 0, 0, 0, msa, 0, 
> S390_FEAT_TYPE_PCKMO)
> 
> This may mess up the test, but it should be convertible to a system
> test, which can be written in C, see tests/tcg/s390x/mvc-smc.c.
> 
> [...]

I have no experience in this. It is a privileged instruction and thus
should not be reachable from userspace. So yes, it should have the 
IF_PRIV
flag. For the tests: I explicit skipped the pckmo test because of this.
And the other protected key tests run fine as they all "derive" the 
protected
key from the clear key according to how this fake implementation works. 
So
the protected key tests I added should run fine (as long as you don't 
run
these tests on real hardware).