Re: [PATCH v1 05/20] s390/zcrypt: Introduce cprb mempool for cca misc functions

[Holger Dengler <dengler@linux.ibm.com>]

On 23/02/2025 10:54, Harald Freudenberger wrote:
> Intruduce a cprb mempool for the zcrypt cca misc functions

typo: Introduce 

> (zcrypt_ccamisc.*) do some preparation rework to support
> a do-not-allocate path through some zcrypt cca misc functions.
> 
> This is only part of an rework to support a new xflag
> ZCRYPT_XFLAG_NOMEMALLOC but not jet complete.

typo: yet

See my comment below. Beside that and the typos, looks good to me.
Reviewed-by: Holger Dengler <dengler@linux.ibm.com>

> 
> Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
> ---
>  drivers/s390/crypto/zcrypt_api.c     |   9 ++-
>  drivers/s390/crypto/zcrypt_ccamisc.c | 115 ++++++++++++++++++++-------
>  drivers/s390/crypto/zcrypt_ccamisc.h |   1 +
>  3 files changed, 94 insertions(+), 31 deletions(-)
> 
[...]
> diff --git a/drivers/s390/crypto/zcrypt_ccamisc.c b/drivers/s390/crypto/zcrypt_ccamisc.c
> index 521baaea06ff..e604a69e40fc 100644
> --- a/drivers/s390/crypto/zcrypt_ccamisc.c
> +++ b/drivers/s390/crypto/zcrypt_ccamisc.c
[...]
> @@ -40,6 +41,17 @@ struct cca_info_list_entry {
>  static LIST_HEAD(cca_info_list);
>  static DEFINE_SPINLOCK(cca_info_list_lock);
>  
> +/*
> + * Cprb memory pool held for urgend cases where no memory

typo: urgent

> + * can be allocated via kmalloc. This pool is only used
> + * when alloc_and_prep_cprbmem() is called with the xflag
> + * ZCRYPT_XFLAG_NOMEMALLOC. The cprb memory needs to hold
> + * space for request AND reply!
> + */
> +#define CPRB_MEMPOOL_MIN_ITEMS 4

4 slots might not be sufficient in setups with a large number of encrypted filesystems. In my opinion, this should be a module parameter (with default 4).

> +#define CPRB_MEMPOOL_ITEM_SIZE (16 * 1024)
> +static mempool_t *cprb_mempool;
> +
>  /*
>   * Simple check if the token is a valid CCA secure AES data key
>   * token. If keybitsize is given, the bitsize of the key is
[...]

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