Re: [PATCH v7 5/7] xen/cpupool: Don't allow removing cpu0 from cpupool0

[Juergen Gross <jgross@xxxxxxxx>]

On 20.04.22 16:57, Luca Fancellu wrote:
> > On 11 Apr 2022, at 16:20, Luca Fancellu <Luca.Fancellu@xxxxxxx> wrote:
> >
> > Cpu0 must remain in cpupool0, otherwise some operations like moving cpus
> > between cpupools, cpu hotplug, destroying cpupools, shutdown of the host,
> > might not work in a sane way.
> >
> > Signed-off-by: Luca Fancellu <luca.fancellu@xxxxxxx>
> > ---
> > Changes in v7:
> > - new patch
> > ---
> > xen/common/sched/cpupool.c | 8 +++++++-
> > 1 file changed, 7 insertions(+), 1 deletion(-)
> >
> > diff --git a/xen/common/sched/cpupool.c b/xen/common/sched/cpupool.c
> > index 86a175f99cd5..0a93bcc631bf 100644
> > --- a/xen/common/sched/cpupool.c
> > +++ b/xen/common/sched/cpupool.c
> > @@ -572,6 +572,7 @@ static long cf_check cpupool_unassign_cpu_helper(void *info)
> >   * possible failures:
> >   * - last cpu and still active domains in cpupool
> >   * - cpu just being unplugged
> > + * - Attempt to remove boot cpu from cpupool0
> >   */
> > static int cpupool_unassign_cpu(struct cpupool *c, unsigned int cpu)
> > {
> > @@ -582,7 +583,12 @@ static int cpupool_unassign_cpu(struct cpupool *c, 
> > unsigned int cpu)
> >      debugtrace_printk("cpupool_unassign_cpu(pool=%u,cpu=%d)\n",
> >                        c->cpupool_id, cpu);
> >
> > -    if ( !cpu_online(cpu) )
> > +    /*
> > +     * Cpu0 must remain in cpupool0, otherwise some operations like moving cpus
> > +     * between cpupools, cpu hotplug, destroying cpupools, shutdown of the 
> > host,
> > +     * might not work in a sane way.
> > +     */
> > +    if ( (!c->cpupool_id && !cpu) || !cpu_online(cpu) )
> >          return -EINVAL;
> >
> >      master_cpu = sched_get_resource_cpu(cpu);
> > --
> > 2.17.1
> Hi,
>
> I’m going to address the comment on this serie before re-pushing it, I see there
> are no comments on this patch, so I’m wondering, when you have time, if you
> can give me some feedback on this one.
Sorry, I seem to have missed this one.

Reviewed-by: Juergen Gross <jgross@xxxxxxxx>


Juergen

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