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

[Marc Zyngier]

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...