On Fri, 20 Dec 2019 14:30:22 +0000, Andrew Murray <andrew.murray@xxxxxxx> wrote: > > A side effect of supporting the SPE in guests is that we prevent the > host from collecting data whilst inside a guest thus creating a black-out > window. This occurs because instead of emulating the SPE, we share it > with our guests. > > Let's accurately describe our capabilities by using the perf exclude > flags to prevent !exclude_guest and exclude_host flags from being used. > > Signed-off-by: Andrew Murray <andrew.murray@xxxxxxx> > --- > drivers/perf/arm_spe_pmu.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/perf/arm_spe_pmu.c b/drivers/perf/arm_spe_pmu.c > index 2d24af4cfcab..3703dbf459de 100644 > --- a/drivers/perf/arm_spe_pmu.c > +++ b/drivers/perf/arm_spe_pmu.c > @@ -679,6 +679,9 @@ static int arm_spe_pmu_event_init(struct perf_event *event) > if (attr->exclude_idle) > return -EOPNOTSUPP; > > + if (!attr->exclude_guest || attr->exclude_host) > + return -EOPNOTSUPP; > + I have the opposite approach. If the host decides to profile the guest, why should that be denied? If there is a black hole, it should take place in the guest. Today, the host does expect this to work, and there is no way that we unconditionally allow it to regress. M. -- Jazz is not dead, it just smells funny.
