Re: [kvm-unit-tests PATCH v2 4/9] arm: pmu: Check Required Event Support

[Peter Maydell]

On Thu, 30 Jan 2020 at 11:25, Eric Auger <address@hidden> 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>
>
> ---
>

> +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;
> +       uint64_t reg;
> +
> +       /*
> +        * The low 32-bits of PMCEID0/1 respectly describe

"respectively"

> +        * event support for events 0-31/32-63. Their High
> +        * 32-bits describe support for extended events
> +        * starting at 0x4000, using the same split.
> +        */
> +       if (n >= 0x0  && n <= 0x3F)
> +               reg = (pmceid0 & 0xFFFFFFFF) | ((pmceid1 & 0xFFFFFFFF) << 32);
> +       else if  (n >= 0x4000 && n <= 0x403F)
> +               reg = (pmceid0 >> 32) | ((pmceid1 >> 32) << 32);
> +       else
> +               abort();
> +
> +       supported =  reg & (1UL << (n & 0x3F));
> +
> +       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;
> +       }
> +
> +       /* 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 (pmu.version == 0x4) {

This condition will only test for v8.1-required events if the PMU
is exactly 8.1, so you lose coverage if the implementation happens
to support ARMv8.4-PMU. Hopefully you have already bailed out
for "ID_AA64DFR0_EL1.PMUVer == 0xf" which means "non-standard IMPDEF
PMU", in which case you can just check >= 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);
> +       }
> +
> +       report(required_events, "Check required events are implemented");
> +}
> +
>  #endif

thanks
-- PMM