Re: [PATCH 1/7] xen/events: reset affinity of 2-level event initially

[Jürgen Groß <jgross@xxxxxxxx>]

On 06.02.21 12:20, Julien Grall wrote:
> Hi Juergen,
>
> On 06/02/2021 10:49, Juergen Gross wrote:
> > When creating a new event channel with 2-level events the affinity
> > needs to be reset initially in order to avoid using an old affinity
> > from earlier usage of the event channel port.
> >
> > The same applies to the affinity when onlining a vcpu: all old
> > affinity settings for this vcpu must be reset. As percpu events get
> > initialized before the percpu event channel hook is called,
> > resetting of the affinities happens after offlining a vcpu (this is
> > working, as initial percpu memory is zeroed out).
> >
> > Cc: stable@xxxxxxxxxxxxxxx
> > Reported-by: Julien Grall <julien@xxxxxxx>
> > Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> > ---
> >   drivers/xen/events/events_2l.c | 20 ++++++++++++++++++++
> >   1 file changed, 20 insertions(+)
> >
> > diff --git a/drivers/xen/events/events_2l.c 
> > b/drivers/xen/events/events_2l.c
> > index da87f3a1e351..23217940144a 100644
> > --- a/drivers/xen/events/events_2l.c
> > +++ b/drivers/xen/events/events_2l.c
> > @@ -47,6 +47,16 @@ static unsigned evtchn_2l_max_channels(void)
> >       return EVTCHN_2L_NR_CHANNELS;
> >   }
> > +static int evtchn_2l_setup(evtchn_port_t evtchn)
> > +{
> > +    unsigned int cpu;
> > +
> > +    for_each_online_cpu(cpu)
> > +        clear_bit(evtchn, BM(per_cpu(cpu_evtchn_mask, cpu)));
> The bit corresponding to the event channel can only be set on a single 
> CPU. Could we avoid the loop and instead clear the bit while closing the 
> port?
This would need another callback.


Juergen

Attachment: OpenPGP_0xB0DE9DD628BF132F.asc
Description: application/pgp-keys

Attachment: OpenPGP_signature
Description: OpenPGP digital signature