Re: [PATCH v2 1/1] s390/ap: Fix MAPML computation

[Heiko Carstens <hca@linux.ibm.com>]

On Wed, Aug 05, 2026 at 11:29:28AM +0200, Finn Callies wrote:
> When the TAPQ subfunction of PQAP returns a value between 0 and 3 in the
> ml field, the Principles of Operation states that the Maximum AP Message
> Length (MAPML) must be 12 KB.
> 
> The previous code incorrectly calculated smaller sizes for ml values 1-2:
> - ml=1: 4 KB instead of 12 KB
> - ml=2: 8 KB instead of 12 KB
> 
> While no current hardware reports ml=1 or ml=2, this fix ensures correct
> behavior for specification compliance and future-proofing.
> 
> The fix ensures all ml values 0-3 correctly use the 12 KB default, with
> only values 4+ using the formula ml * 4096.
> 
> Reviewed-by: Harald Freudenberger <freude@linux.ibm.com>
> Signed-off-by: Finn Callies <fcallies@linux.ibm.com>
> ---
>  drivers/s390/crypto/ap_card.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Acked-by: Heiko Carstens <hca@linux.ibm.com>