Re: [PATCH v3] xen/sched: validate RTDS putinfo period and budget

[Oleksii Moisieiev <oleksii_moisieiev@xxxxxxxx>]

Hi Juergen

On 27/03/2026 14:51, Juergen Gross wrote:
> On 27.03.26 12:31, Oleksii Moisieiev wrote:
> > The RTDS domain-wide XEN_DOMCTL_SCHEDOP_putinfo path only checks for
> > zero values before applying period and budget to all vCPUs in the
> > domain.
> >
> > This is weaker than the per-vCPU XEN_DOMCTL_SCHEDOP_putvcpuinfo path,
> > which already rejects values below the minimum, above the maximum, and
> > cases where budget exceeds period.
> >
> > Use the same validation rules for putinfo as for putvcpuinfo, so
> > invalid domain-wide updates are rejected with -EINVAL instead of being
> > applied inconsistently.
> >
> > Signed-off-by: Oleksii Moisieiev <oleksii_moisieiev@xxxxxxxx>
> > ---
> >
> > Changes in v3:
> > - changed rt_validate_params input to get struct instead of
> > period and budget
> > - improved code readability
> >
> > Changes in v2:
> > - introduce rt_validate_params helper function to check period and 
> > budget
> >   xen/common/sched/rt.c | 37 ++++++++++++++++++++++++-------------
> >   1 file changed, 24 insertions(+), 13 deletions(-)
> >
> > diff --git a/xen/common/sched/rt.c b/xen/common/sched/rt.c
> > index 7b1f64a779..c161bf7f78 100644
> > --- a/xen/common/sched/rt.c
> > +++ b/xen/common/sched/rt.c
> > @@ -1362,6 +1362,23 @@ out:
> >       unit_schedule_unlock_irq(lock, unit);
> >   }
> >   +static int
> > +rt_validate_params(struct xen_domctl_sched_rtds *rtds,
> > +                   s_time_t *period, s_time_t *budget)
> > +{
> > +    s_time_t p = MICROSECS(rtds->period);
> > +    s_time_t b = MICROSECS(rtds->budget);
> > +
> > +    if ( p > RTDS_MAX_PERIOD || b < RTDS_MIN_BUDGET ||
> > +         b > p || p < RTDS_MIN_PERIOD )
> This sequence of tests makes it harder to read than necessary.
>
> Could you please rearrange to:
>
> +    if ( p < RTDS_MIN_PERIOD || p > RTDS_MAX_PERIOD ||
> +         b < RTDS_MIN_BUDGET || b > p )
>
> This makes it rather obvious what the allowed ranges are.
Sure. Will fix and post v4.
> With this and the "const" added mentioned by Jan you can add my:
>
> Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
>
>
> Juergen