[PATCH v2 00/20] AP bus/zcrypt/pkey/paes no-mem-alloc patches

Harald Freudenberger
2025-03-04T17:21:24Z

This series of patches has the goal to open up a do-not-allocate
memory path from the callers of the pkey in-kernel api down to
the crypto cards and back.

The asynch in-kernel cipher implementations (and the s390 PAES
cipher implementations are one of them) may be called in a
context where memory allocations which trigger IO is not acceptable.

So this patch series reworks the AP bus code, the zcrypt layer,
the pkey layer and the pkey handlers to respect this situation
by processing a new parameter xflags (execution hints flags).
There is a flag PKEY_XFLAG_NOMEMALLOC which tells the code to
not allocate memory which may lead to IO operations.

To reach this goal, the actual code changes have been differed.
The zcrypt misc functions which need memory for cprb build
use a pre allocated memory pool for this purpose. The findcard()
functions have one temp memory area preallocated and protected
with a mutex. Some smaller data is not allocated any more but went
to the stack instead. The AP bus also uses a pre-allocated
memory pool for building AP message requests.

Note that the PAES implementation still needs to get reworked
to run the protected key derivation in a real asynchronous way.
However, this rework of AP bus, zcrypt and pkey is the base work
required before reconsidering the PAES implementation.

The patch series starts bottom (AP bus) and goes up the call
chain (PKEY). At any time in the patch stack it should compile.
For easier review I tried to have one logic code change by
each patch and thus keep the patches "small". For the upstream
version I intend to fold them together into only a few commits.

Changelog:
v1: initial version
v2: - Rework on patch 0001 and 0002 based on feedback from Holger.
Also there was one place in zcrypt_msgtype50.c where still
an ap msg buffer was alloacated.
- Rework on patch 0003 - fixed feedback from Holger. Also the
min poolitems is now a module parameter and defaults to 8.
- Rework on patch 0004 - as suggested by Holger the "userspace"
parameter is now included into the ap msg flags.
- Rework on patch 0005 - nr of cca cprbs in the mempool is now
a module parameter.
- Rework on patch 0006 - nr of ep11 cprbs in the mempool is now
a module parameter.
- Rework on patch 0007 - as suggested by Holger instead of
implementing a copy-and-pasted new function
zcrypt_device_status_mask_ext2() use and extend the existing
the existing function to avoid code duplication.
- The rest of the patch series needed adaptions but there is
no functional change compared to v1.

Harald Freudenberger (20):
s390/ap: Move response_type struct into ap_msg struct
s390/ap/zcrypt: Rework AP message buffer allocation
s390/ap: Introduce ap message buffer pool
s390/ap/zcrypt: New xflag parameter and extension of the ap msg flags
s390/zcrypt: Introduce cprb mempool for cca misc functions
s390/zcrypt: Introduce cprb mempool for ep11 misc functions
s390/zcrypt: Rework zcrypt function zcrypt_device_status_mask_ext
s390/zcrypt: Introduce pre-allocated device status array for cca misc
s390/zcrypt: Introduce pre-allocated device status array for ep11 misc
s390/zcrypt/pkey: Rework cca findcard() implementation and callers
s390/zcrypt/pkey: Rework ep11 findcard() implementation and callers
s390/zcrypt: Rework cca misc functions kmallocs to use the cprb
mempool
s390/zcrypt: Add small mempool for cca info list entries
s390/zcrypt: Locate ep11_domain_query_info onto the stack instead of
kmalloc
s390/zcrypt: Rework ep11 misc functions to use cprb mempool
s390/zcrypt: Add small mempool for ep11 card info list entries
s390/pkey: Rework CCA pkey handler to use stack for small memory
allocs
s390/pkey: Rework EP11 pkey handler to use stack for small memory
allocs
s390/zcrypt/pkey: Provide and pass xflags within pkey and zcrypt
layers
s390/pkey/crypto: Introduce xflags param for pkey in-kernel API

arch/s390/crypto/paes_s390.c | 2 +-
arch/s390/include/asm/pkey.h | 15 +-
drivers/s390/crypto/ap_bus.c | 73 +++++
drivers/s390/crypto/ap_bus.h | 37 +--
drivers/s390/crypto/pkey_api.c | 54 ++--
drivers/s390/crypto/pkey_base.c | 34 ++-
drivers/s390/crypto/pkey_base.h | 37 ++-
drivers/s390/crypto/pkey_cca.c | 121 ++++----
drivers/s390/crypto/pkey_ep11.c | 106 +++----
drivers/s390/crypto/pkey_pckmo.c | 9 +-
drivers/s390/crypto/pkey_sysfs.c | 4 +-
drivers/s390/crypto/pkey_uv.c | 16 +-
drivers/s390/crypto/zcrypt_api.c | 172 +++++++----
drivers/s390/crypto/zcrypt_api.h | 42 ++-
drivers/s390/crypto/zcrypt_ccamisc.c | 350 +++++++++++++++-------
drivers/s390/crypto/zcrypt_ccamisc.h | 41 +--
drivers/s390/crypto/zcrypt_cex4.c | 16 +-
drivers/s390/crypto/zcrypt_ep11misc.c | 387 ++++++++++++++++---------
drivers/s390/crypto/zcrypt_ep11misc.h | 28 +-
drivers/s390/crypto/zcrypt_msgtype50.c | 36 ++-
drivers/s390/crypto/zcrypt_msgtype6.c | 121 ++++----
drivers/s390/crypto/zcrypt_msgtype6.h | 4 +-
22 files changed, 1032 insertions(+), 673 deletions(-)

--
2.43.0