Re: [kvm-unit-tests PATCH v1 0/5] s390x: smp: avoid hardcoded CPU addresses

[Janosch Frank <frankja@linux.ibm.com>]

On 1/28/22 19:54, Claudio Imbrenda wrote:
> On s390x there are no guarantees about the CPU addresses, except that
> they shall be unique. This means that in some environments, it's
> possible that there is no match between the CPU address and its
> position (index) in the list of available CPUs returned by the system.

While I support this patch set I've yet to find an environment where 
this gave me headaches.

> 
> This series fixes a small bug in the SMP initialization code, adds a
> guarantee that the boot CPU will always have index 0, and introduces
> some functions to allow tests to use CPU indexes instead of using
> hardcoded CPU addresses. This will allow the tests to run successfully
> in more environments (e.g. z/VM, LPAR).

I'm wondering if we should do it the other way round and make the smp_* 
functions take a idx instead of a cpu addr. The only instance where this 
gets a bit ugly is the sigp calls which we would also need to convert.

> Some existing tests are adapted to take advantage of the new
> functionalities.
> 
> Claudio Imbrenda (5):
>    lib: s390x: smp: add functions to work with CPU indexes
>    lib: s390x: smp: guarantee that boot CPU has index 0
>    s390x: smp: avoid hardcoded CPU addresses
>    s390x: firq: avoid hardcoded CPU addresses
>    s390x: skrf: avoid hardcoded CPU addresses
> 
>   lib/s390x/smp.h |  2 ++
>   lib/s390x/smp.c | 28 ++++++++++++-----
>   s390x/firq.c    | 17 +++++-----
>   s390x/skrf.c    |  8 +++--
>   s390x/smp.c     | 83 ++++++++++++++++++++++++++-----------------------
>   5 files changed, 79 insertions(+), 59 deletions(-)
>