Re: [PATCH] pc-bios: s390x: Only set lowcore iplb address on list-directed IPL

[Cornelia Huck <cohuck@redhat.com>]

On Mon, 17 Aug 2020 10:17:34 -0400
"Jason J. Herne" <jjherne@linux.ibm.com> wrote:

> The POP states that the IPLB location is only written to 0x14 for
> list-directed IPL. Some operating systems expect 0x14 to not change on
> boot and will fail IPL if it does change.
> 
> Fixes: 9bfc04f9ef6802fff0

Should be

Fixes: 9bfc04f9ef68 ("pc-bios: s390x: Save iplb location in lowcore")

> Signed-off-by: Jason J. Herne <jjherne@linux.ibm.com>
> Reviewed-by: Janosch Frank <frankja@de.ibm.com>
> ---
>  pc-bios/s390-ccw/jump2ipl.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/pc-bios/s390-ccw/jump2ipl.c b/pc-bios/s390-ccw/jump2ipl.c
> index 767012bf0c..5e3e13f4b0 100644
> --- a/pc-bios/s390-ccw/jump2ipl.c
> +++ b/pc-bios/s390-ccw/jump2ipl.c
> @@ -33,7 +33,10 @@ void jump_to_IPL_code(uint64_t address)
>  {
>      /* store the subsystem information _after_ the bootmap was loaded */
>      write_subsystem_identification();
> -    write_iplb_location();
> +
> +    if (iplb.pbt != S390_IPL_TYPE_CCW) {
> +            write_iplb_location();
> +    }

What happens for ipl types other than CCW and FCP? IOW, should that
rather be a positive check for S390_IPL_TYPE_FCP?

>  
>      /* prevent unknown IPL types in the guest */
>      if (iplb.pbt == S390_IPL_TYPE_QEMU_SCSI) {