Re: [kvm-unit-tests Patch v3 03/11] x86: pmu: Add asserts to warn inconsistent fixed events and counters

[Mi, Dapeng]

On 3/27/2024 1:30 PM, Mingwei Zhang wrote:
> On Wed, Jan 03, 2024, Dapeng Mi wrote:
> > Current PMU code deosn't check whether PMU fixed counter number is
> > larger than pre-defined fixed events. If so, it would cause memory
> > access out of range.
> >
> > So add assert to warn this invalid case.
> >
> > Signed-off-by: Dapeng Mi <dapeng1.mi@xxxxxxxxxxxxxxx>
> Reviewed-by: Mingwei Zhang <mizhang@xxxxxxxxxx>
> > ---
> >   x86/pmu.c | 10 ++++++++--
> >   1 file changed, 8 insertions(+), 2 deletions(-)
> >
> > diff --git a/x86/pmu.c b/x86/pmu.c
> > index a13b8a8398c6..a42fff8d8b36 100644
> > --- a/x86/pmu.c
> > +++ b/x86/pmu.c
> > @@ -111,8 +111,12 @@ static struct pmu_event* get_counter_event(pmu_counter_t *cnt)
> >   		for (i = 0; i < gp_events_size; i++)
> >   			if (gp_events[i].unit_sel == (cnt->config & 0xffff))
> >   				return &gp_events[i];
> > -	} else
> > -		return &fixed_events[cnt->ctr - MSR_CORE_PERF_FIXED_CTR0];
> > +	} else {
> > +		int idx = cnt->ctr - MSR_CORE_PERF_FIXED_CTR0;
> maybe unsigned int is better?

Make sense. Thanks for review.

> > +
> > +		assert(idx < ARRAY_SIZE(fixed_events));
> > +		return &fixed_events[idx];
> > +	}
> >   
> >   	return (void*)0;
> >   }
> > @@ -245,6 +249,7 @@ static void check_fixed_counters(void)
> >   	};
> >   	int i;
> >   
> > +	assert(pmu.nr_fixed_counters <= ARRAY_SIZE(fixed_events));
> >   	for (i = 0; i < pmu.nr_fixed_counters; i++) {
> >   		cnt.ctr = fixed_events[i].unit_sel;
> >   		measure_one(&cnt);
> > @@ -266,6 +271,7 @@ static void check_counters_many(void)
> >   			gp_events[i % gp_events_size].unit_sel;
> >   		n++;
> >   	}
> > +	assert(pmu.nr_fixed_counters <= ARRAY_SIZE(fixed_events));
> >   	for (i = 0; i < pmu.nr_fixed_counters; i++) {
> >   		cnt[n].ctr = fixed_events[i].unit_sel;
> >   		cnt[n].config = EVNTSEL_OS | EVNTSEL_USR;
> > --
> > 2.34.1