Re: [kvm-unit-tests PATCH v1 1/2] arm/pmu: skip the PMU introspection test if missing

[Marc Zyngier <maz@kernel.org>]

On 2024-07-03 08:09, Zenghui Yu wrote:
> On 2024/7/3 0:35, Alex Bennée wrote:
>> The test for number of events is not a substitute for properly
>> checking the feature register. Fix the define and skip if PMUv3 is not
>> available on the system. This includes emulator such as QEMU which
>> don't implement PMU counters as a matter of policy.
>> 
>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
>> Cc: Anders Roxell <anders.roxell@linaro.org>
>> ---
>>  arm/pmu.c | 7 ++++++-
>>  1 file changed, 6 insertions(+), 1 deletion(-)
>> 
>> diff --git a/arm/pmu.c b/arm/pmu.c
>> index 9ff7a301..66163a40 100644
>> --- a/arm/pmu.c
>> +++ b/arm/pmu.c
>> @@ -200,7 +200,7 @@ static void test_overflow_interrupt(bool 
>> overflow_at_64bits) {}
>>  #define ID_AA64DFR0_PERFMON_MASK  0xf
>>   #define ID_DFR0_PMU_NOTIMPL	0b0000
>> -#define ID_DFR0_PMU_V3		0b0001
>> +#define ID_DFR0_PMU_V3		0b0011
> 
> Why? This is a macro used for AArch64 and DDI0487J.a (D19.2.59, the
> description of the PMUVer field) says that
> 
> "0b0001	Performance Monitors Extension, PMUv3 implemented."
> 
> while 0b0011 is a reserved value.

I think this is a mix of 32bit and 64bit views (ID_DFR0_EL1.PerfMon
instead of ID_AA64DFR0_EL1.PMUVer), and the whole thing is a mess
(ID_AA64DFR0_PERFMON_MASK is clearly confused...).

I haven't looked at how this patch fits in the rest of the code though.

         M.
-- 
Jazz is not dead. It just smells funny...