Re: [PATCH v2 05/20] s390/zcrypt: Introduce cprb mempool for cca misc functions

Holger Dengler
2025-03-18T14:17:01Z

On 04/03/2025 18:21, Harald Freudenberger wrote:
> Introduce a cprb mempool for the zcrypt cca misc functions
> (zcrypt_ccamisc.*) do some preparation rework to support
> a do-not-allocate path through some zcrypt cca misc functions.
>
> The mempool is by default space for 4 cprbs with each 16KB.
> For CCA a CPRB needs to hold the request and the reply, so
> the pool items only support requests/replies with a limit of
> about 8KB. The minimal number of items in the mempool can get
> adjusted via module parameter zcrypt.cca_cprbpool_min_items
> on module load.
>
> This is only part of an rework to support a new xflag
> ZCRYPT_XFLAG_NOMEMALLOC but not yet complete.
>
> Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>

One minor comment below. Beside that
Reviewed-by: Holger Dengler <dengler@linux.ibm.com>

> ---
> drivers/s390/crypto/zcrypt_api.c | 13 ++-
> drivers/s390/crypto/zcrypt_api.h | 2 +
> drivers/s390/crypto/zcrypt_ccamisc.c | 116 ++++++++++++++++++++-------
> drivers/s390/crypto/zcrypt_ccamisc.h | 1 +
> 4 files changed, 101 insertions(+), 31 deletions(-)
>
[...]
> diff --git a/drivers/s390/crypto/zcrypt_ccamisc.c b/drivers/s390/crypto/zcrypt_ccamisc.c
> index 521baaea06ff..2c2ca2d67e2d 100644
> --- a/drivers/s390/crypto/zcrypt_ccamisc.c
> +++ b/drivers/s390/crypto/zcrypt_ccamisc.c
[...]
> @@ -229,7 +241,15 @@ static int alloc_and_prep_cprbmem(size_t paramblen,
> * allocate consecutive memory for request CPRB, request param
> * block, reply CPRB and reply param block
> */
> - cprbmem = kcalloc(2, cprbplusparamblen, GFP_KERNEL);
> + if (xflags & ZCRYPT_XFLAG_NOMEMALLOC) {
> + if (cprb_mempool &&
> + 2 * cprbplusparamblen <= CPRB_MEMPOOL_ITEM_SIZE) {
> + cprbmem = mempool_alloc_preallocated(cprb_mempool);
> + memset(cprbmem, 0, 2 * cprbplusparamblen);
> + }
> + } else {

Just a nit: let the compiler decide, if code should be duplicated or not.

if (xflags & ZCRYPT_XFLAG_NOMEMALLOC) {
size_t len = 2 * cprbplusparamblen;

if (cprb_mempool && len <= CPRB_MEMPOOL_ITEM_SIZE) {
cprbmem = mempool_alloc_preallocated(cprb_mempool);
memset(cprbmem, 0, len);
}
} else {

> + cprbmem = kcalloc(2, cprbplusparamblen, GFP_KERNEL);
> + }
> if (!cprbmem)
> return -ENOMEM;
>
[...]

--
Mit freundlichen Grüßen / Kind regards
Holger Dengler
--
IBM Systems, Linux on IBM Z Development
dengler@linux.ibm.com