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

[Auger Eric <eric.auger@redhat.com>]

Hi Peter,

On 2/11/20 4:33 PM, Peter Maydell wrote:
> On Thu, 30 Jan 2020 at 11:25, Eric Auger <eric.auger@redhat.com> 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 <eric.auger@redhat.com>
>>
>> ---
>>
> 
>> +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.
OK thanks

Eric
> 
>> +               /* 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
> 

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