Re: [kvm-unit-tests PATCH v3 7/7] s390x: Add test for STFLE interpretive execution (format-0)

[Nina Schoetterl-Glausch <nsg@linux.ibm.com>]

On Thu, 2024-10-10 at 10:27 +0200, Nico Boehr wrote:
> Quoting Nina Schoetterl-Glausch (2024-09-02 16:24:53)
> > On Tue, 2024-08-27 at 16:08 +0200, Nico Boehr wrote:
> > > Quoting Nina Schoetterl-Glausch (2024-06-20 16:17:00)
> > > [...]
> > > > diff --git a/lib/s390x/asm/facility.h b/lib/s390x/asm/facility.h
> > > > index a66fe56a..2bad05c5 100644
> > > > --- a/lib/s390x/asm/facility.h
> > > > +++ b/lib/s390x/asm/facility.h
> > > > @@ -27,12 +27,20 @@ static inline void stfl(void)
> > > >         asm volatile("  stfl    0(0)\n" : : : "memory");
> > > >  }
> > > >  
> > > > -static inline void stfle(uint64_t *fac, unsigned int nb_doublewords)
> > > > +static inline unsigned int stfle(uint64_t *fac, unsigned int nb_doublewords)
> > > 
> > > Why unsigned int?
> > 
> > The return value is 1-256, the size of the type is a bit arbitrary I suppose.
> > 
> > > 
> > > [...]
> > > > diff --git a/s390x/snippets/c/stfle.c b/s390x/snippets/c/stfle.c
> > > > new file mode 100644
> > > > index 00000000..eb024a6a
> > > > --- /dev/null
> > > > +++ b/s390x/snippets/c/stfle.c
> > > [...]
> > > > +int main(void)
> > > > +{
> > > > +       const unsigned int max_fac_len = 8;
> > > > +       uint64_t res[max_fac_len + 1];
> > > > +
> > > > +       res[0] = max_fac_len - 1;
> > > > +       asm volatile ( "lg      0,%[len]\n"
> > > > +               "       stfle   %[fac]\n"
> > > > +               "       stg     0,%[len]\n"
> > > > +               : [fac] "=QS"(*(uint64_t(*)[max_fac_len])&res[1]),
> 
> Nina, do you mind sending a new version where we have the constraints
> simplified, e.g. with just a memory clobber?

Will do