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

[Claudio Imbrenda <imbrenda@linux.ibm.com>]

On Thu, 3 Feb 2022 09:45:56 +0100
Janosch Frank <frankja@linux.ibm.com> wrote:

> 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.

yes, in fact this is something I was already planning to do :)

for sigp, we can either convert, or add a wrapper with idx.

> 
> > 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(-)
> >   
>