target/arm/tcg: enable PMU feature for Cortex-A8 and A9

According to the technical reference manual, the Cortex-A9
has a Perfomance Unit Monitor (PMU):
https://developer.arm.com/documentation/100511/0401/performance-monitoring-unit/about-the-performance-monitoring-unit


The Cortex-A8 does also.

We already already define the PMU registers when emulating the
Cortex-A8 and Cortex-A9, because we put them in v7_cp_reginfo[]
rather than guarding them behind ARM_FEATURE_PMU.  So the only thing
that setting the feature bit changes is that the registers actually
do something.

Enable ARM_FEATURE_PMU for Cortex-A8 and Cortex-A9, to avoid
this anomaly.

(The A8 and A9 PMU predates the standardisation of ID_DFR0.PerfMon,
so the field there is 0, but the PMU is still present.)

Signed-off-by: Nikita Ostrenkov <n.ostrenkov@gmail.com>
Message-id: 20231112165658.2335-1-n.ostrenkov@gmail.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
[PMM: tweaked commit message; also enable PMU for A8]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

target/arm/tcg/cpu32.c

@@ -351,6 +351,7 @@ static void cortex_a8_initfn(Object *obj)
     set_feature(&cpu->env, ARM_FEATURE_THUMB2EE);
     set_feature(&cpu->env, ARM_FEATURE_DUMMY_C15_REGS);
     set_feature(&cpu->env, ARM_FEATURE_EL3);
+    set_feature(&cpu->env, ARM_FEATURE_PMU);
     cpu->midr = 0x410fc080;
     cpu->reset_fpsid = 0x410330c0;
     cpu->isar.mvfr0 = 0x11110222;
@@ -418,6 +419,7 @@ static void cortex_a9_initfn(Object *obj)
     set_feature(&cpu->env, ARM_FEATURE_NEON);
     set_feature(&cpu->env, ARM_FEATURE_THUMB2EE);
     set_feature(&cpu->env, ARM_FEATURE_EL3);
+    set_feature(&cpu->env, ARM_FEATURE_PMU);
     /*
      * Note that A9 supports the MP extensions even for
      * A9UP and single-core A9MP (which are both different