Re: [kvm-unit-tests RFC 04/10] pmu: Check Required Event Support

[Andrew Jones]

On Fri, Dec 06, 2019 at 06:27:18PM +0100, Eric Auger wrote:
> If event counters are implemented check the common events
> required by the PMUv3 are implemented.
> 
> Some are unconditionally required (SW_INCR, CPU_CYCLES,
> either INST_RETIRED or INST_SPEC). Some others only are
> required if the implementation implements some other features.
> 
> Check those wich are unconditionally required.
> 
> This test currently fails on TCG as neither INST_RETIRED
> or INST_SPEC are supported.
> 
> Signed-off-by: Eric Auger <address@hidden>
> ---
>  arm/pmu.c         | 70 +++++++++++++++++++++++++++++++++++++++++++++++
>  arm/unittests.cfg |  6 ++++
>  2 files changed, 76 insertions(+)
> 
> diff --git a/arm/pmu.c b/arm/pmu.c
> index 8e95251..f78c43f 100644
> --- a/arm/pmu.c
> +++ b/arm/pmu.c
> @@ -102,6 +102,10 @@ static inline void precise_instrs_loop(int loop, 
> uint32_t pmcr)
>       : [pmcr] "r" (pmcr), [z] "r" (0)
>       : "cc");
>  }
> +
> +/* event counter tests only implemented for aarch64 */
> +static void test_event_introspection(void) {}
> +
>  #elif defined(__aarch64__)
>  #define ID_AA64DFR0_PERFMON_SHIFT 8
>  #define ID_AA64DFR0_PERFMON_MASK  0xf
> @@ -140,6 +144,69 @@ static inline void precise_instrs_loop(int loop, 
> uint32_t pmcr)
>       : [pmcr] "r" (pmcr)
>       : "cc");
>  }
> +
> +#define PMCEID1_EL0 sys_reg(11, 3, 9, 12, 7)
> +
> +static bool is_event_supported(uint32_t n, bool warn)
> +{
> +     uint64_t pmceid0 = read_sysreg(pmceid0_el0);
> +     uint64_t pmceid1 = read_sysreg_s(PMCEID1_EL0);
> +     bool supported;
> +     uint32_t reg;
> +
> +     if (n >= 0x0  && n <= 0x1F) {
> +             reg = pmceid0 & 0xFFFFFFFF;
> +     } else if  (n >= 0x4000 && n <= 0x401F) {
> +             reg = pmceid0 >> 32;
> +     } else if (n >= 0x20  && n <= 0x3F) {
> +             reg = pmceid1 & 0xFFFFFFFF;
> +     } else if (n >= 0x4020 && n <= 0x403F) {
> +             reg = pmceid1 >> 32;


Lot's of stray spaces in there. Also the 0x4000 should probably get a
define, and maybe another for the size 0x20.

> +     } else {
> +             abort();
> +     }
> +     supported =  reg & (1 << n);
> +     if (!supported && warn)
> +             report_info("event %d is not supported", n);
> +     return supported;
> +}
> +
> +static void test_event_introspection(void)
> +{
> +     bool required_events;
> +
> +     if (!pmu.nb_implemented_counters) {
> +             report_skip("No event counter, skip ...");
> +             return;
> +     }
> +     if (pmu.nb_implemented_counters < 2)
> +             report_info("%d event counters are implemented. "
> +                            "ARM recommends to implement at least 2",
> +                            pmu.nb_implemented_counters);

nit: I'd use {} on these multi-line if's (even if they're just one line)

> +
> +     /* PMUv3 requires an implementation includes some common events */
> +     required_events = is_event_supported(0x0, true) /* SW_INCR */ &&
> +                       is_event_supported(0x11, true) /* CPU_CYCLES */ &&
> +                       (is_event_supported(0x8, true) /* INST_RETIRED */ ||
> +                        is_event_supported(0x1B, true) /* INST_PREC */);
> +     if (!is_event_supported(0x8, false))
> +             report_info("ARM strongly recomments INST_RETIRED (0x8) event "
                                          ^ recommends
> +                         "to be implemented");

Do we need to report Arm's recommendation?

> +
> +     if (pmu.version == 0x4) {
> +             /* ARMv8.1 PMU: STALL_FRONTEND and STALL_BACKEND are required */
> +             required_events = required_events ||
> +                               is_event_supported(0x23, true) ||
> +                               is_event_supported(0x24, true);
> +     }
> +
> +     /* L1D_CACHE_REFILL(0x3) and L1D_CACHE(0x4) are only required if
> +        L1 data / unified cache. BR_MIS_PRED(0x10), BR_PRED(0x12) are only
> +        required if program-flow prediction is implemented. */
> +
> +     report("Check required events are implemented", required_events);
> +}
> +
>  #endif
>  
>  /*
> @@ -324,6 +391,9 @@ int main(int argc, char *argv[])
>               report("Monotonically increasing cycle count", 
> check_cycles_increase());
>               report("Cycle/instruction ratio", check_cpi(cpi));
>               pmccntr64_test();
> +     } else if (strcmp(argv[1], "event-introspection") == 0) {
> +             report_prefix_push(argv[1]);
> +             test_event_introspection();
>       } else {
>               report_abort("Unknown subtest '%s'", argv[1]);
>       }
> diff --git a/arm/unittests.cfg b/arm/unittests.cfg
> index 79f0d7a..4433ef3 100644
> --- a/arm/unittests.cfg
> +++ b/arm/unittests.cfg
> @@ -66,6 +66,12 @@ file = pmu.flat
>  groups = pmu
>  extra_params = -append 'cycle-counter 0'
>  
> +[pmu-event-introspection]
> +file = pmu.flat
> +groups = pmu
> +arch = arm64
> +extra_params = -append 'event-introspection'
> +
>  # Test PMU support (TCG) with -icount IPC=1
>  #[pmu-tcg-icount-1]
>  #file = pmu.flat
> -- 
> 2.20.1
>

Thanks,
drew