Re: [RESEND PATCH V7 2/2] drivers/perf: hisi: add driver for HNS3 PMU

[huangguangbin (A)]

On 2022/6/27 18:52, Will Deacon wrote:
> On Wed, May 25, 2022 at 08:52:11AM +0800, Guangbin Huang wrote:
> > HNS3(HiSilicon Network System 3) PMU is RCiEP device in HiSilicon SoC NIC,
> > supports collection of performance statistics such as bandwidth, latency,
> > packet rate and interrupt rate.
> >
> > NIC of each SICL has one PMU device for it. Driver registers each PMU
> > device to perf, and exports information of supported events, filter mode of
> > each event, bdf range, hardware clock frequency, identifier and so on via
> > sysfs.
> >
> > Each PMU device has its own registers of control, counters and interrupt,
> > and it supports 8 hardware events, each hardward event has its own
> > registers for configuration, counters and interrupt.
> >
> > Filter options contains:
> > event        - select event
> > port         - select physical port of nic
> > tc           - select tc(must be used with port)
> > func         - select PF/VF
> > queue        - select queue of PF/VF(must be used with func)
> > intr         - select interrupt number(must be used with func)
> > global       - select all functions of IO DIE
> >
> > Signed-off-by: Guangbin Huang <huangguangbin2@xxxxxxxxxx>
> > Reviewed-by: John Garry <john.garry@xxxxxxxxxx>
> > Reviewed-by: Shaokun Zhang <zhangshaokun@xxxxxxxxxxxxx>
> > ---
> >   MAINTAINERS                       |    6 +
> >   drivers/perf/hisilicon/Kconfig    |   10 +
> >   drivers/perf/hisilicon/Makefile   |    1 +
> >   drivers/perf/hisilicon/hns3_pmu.c | 1662 +++++++++++++++++++++++++++++
> >   include/linux/cpuhotplug.h        |    1 +
> >   5 files changed, 1680 insertions(+)
> >   create mode 100644 drivers/perf/hisilicon/hns3_pmu.c
>
> This mostly looks good to me, but I have one niggling concern with the ABI:
>
> > +#define HNS3_PMU_FILTER_ATTR(_name, _config, _start, _end)               \
> > +	static inline u64 hns3_pmu_get_##_name(struct perf_event *event) \
> > +	{                                                                \
> > +		return FIELD_GET(GENMASK_ULL(_end, _start),              \
> > +				 event->attr._config);                   \
> > +	}
> > +
> > +HNS3_PMU_FILTER_ATTR(event, config, 0, 16);
> > +HNS3_PMU_FILTER_ATTR(subevent, config, 0, 7);
> > +HNS3_PMU_FILTER_ATTR(event_type, config, 8, 15);
> > +HNS3_PMU_FILTER_ATTR(ext_counter_used, config, 16, 16);
> > +HNS3_PMU_FILTER_ATTR(real_event, config, 0, 15);
>
> How does perf tool deal with overlapping fields like this? It seems like
> quite a bad idea to allow things like "event=0xffff,subevent=0" when they
> are no longer distinct and I don't _think_ any other drivers do this.
>
> Can you remove 'event' and 'real_event' for now, or are they needed?
>
> Will
> .
Ok, I will modify this part.