Re: [Qemu-devel] [kvm-unit-tests PATCHv6 1/3] arm: Add PMU test

[Wei Huang]

On 10/11/2016 01:40 PM, Christopher Covington wrote:
> Beginning with a simple sanity check of the control register, add
> a unit test for the ARM Performance Monitors Unit (PMU). As of
> October 2016, whether KVM mode has a PMU at all is a tricky
> question of which QEMU / mach-virt version is used. So only enable
> the TCG mode tests for now.

Given that we have KVM-based vPMU enabled in QEMU, it is very desirable
for these unit testing cases to work on KVM. Right now both
check_cycles_increase() and check_cpi() fail under KVM. I will help
debug it.

> 
> Signed-off-by: Christopher Covington <address@hidden>
> Reviewed-by: Andrew Jones <address@hidden>
> ---
>  arm/Makefile.common |  3 +-
>  arm/pmu.c           | 82 
> +++++++++++++++++++++++++++++++++++++++++++++++++++++
>  arm/unittests.cfg   | 14 +++++++++
>  3 files changed, 98 insertions(+), 1 deletion(-)
>  create mode 100644 arm/pmu.c
> 
> diff --git a/arm/Makefile.common b/arm/Makefile.common
> index ccb554d..f98f422 100644
> --- a/arm/Makefile.common
> +++ b/arm/Makefile.common
> @@ -11,7 +11,8 @@ endif
>  
>  tests-common = \
>       $(TEST_DIR)/selftest.flat \
> -     $(TEST_DIR)/spinlock-test.flat
> +     $(TEST_DIR)/spinlock-test.flat \
> +     $(TEST_DIR)/pmu.flat
>  
>  all: test_cases
>  
> diff --git a/arm/pmu.c b/arm/pmu.c
> new file mode 100644
> index 0000000..42d0ee1
> --- /dev/null
> +++ b/arm/pmu.c
> @@ -0,0 +1,82 @@
> +/*
> + * Test the ARM Performance Monitors Unit (PMU).
> + *
> + * Copyright 2015 The Linux Foundation. All rights reserved.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU Lesser General Public License version 2.1 and
> + * only version 2.1 as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful, but 
> WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 
> License
> + * for more details.
> + */
> +#include "libcflat.h"
> +
> +#if defined(__arm__)
> +static inline uint32_t get_pmcr(void)
> +{
> +     uint32_t ret;
> +
> +     asm volatile("mrc p15, 0, %0, c9, c12, 0" : "=r" (ret));
> +     return ret;
> +}
> +#elif defined(__aarch64__)
> +static inline uint32_t get_pmcr(void)
> +{
> +     uint32_t ret;
> +
> +     asm volatile("mrs %0, pmcr_el0" : "=r" (ret));
> +     return ret;
> +}
> +#endif
> +
> +struct pmu_data {
> +     union {
> +             uint32_t pmcr_el0;
> +             struct {
> +                     uint32_t enable:1;
> +                     uint32_t event_counter_reset:1;
> +                     uint32_t cycle_counter_reset:1;
> +                     uint32_t cycle_counter_clock_divider:1;
> +                     uint32_t event_counter_export:1;
> +                     uint32_t cycle_counter_disable_when_prohibited:1;
> +                     uint32_t cycle_counter_long:1;
> +                     uint32_t reserved:4;
> +                     uint32_t counters:5;
> +                     uint32_t identification_code:8;
> +                     uint32_t implementer:8;
> +             };
> +     };
> +};
> +
> +/*
> + * As a simple sanity check on the PMCR_EL0, ensure the implementer field 
> isn't
> + * null. Also print out a couple other interesting fields for diagnostic
> + * purposes. For example, as of fall 2015, QEMU TCG mode doesn't implement
> + * event counters and therefore reports zero event counters, but hopefully
> + * support for at least the instructions event will be added in the future 
> and
> + * the reported number of event counters will become nonzero.
> + */
> +static bool check_pmcr(void)
> +{
> +     struct pmu_data pmu;
> +
> +     pmu.pmcr_el0 = get_pmcr();
> +
> +     printf("PMU implementer:     %c\n", pmu.implementer);
> +     printf("Identification code: 0x%x\n", pmu.identification_code);
> +     printf("Event counters:      %d\n", pmu.counters);
> +
> +     return pmu.implementer != 0;
> +}
> +
> +int main(void)
> +{
> +     report_prefix_push("pmu");
> +
> +     report("Control register", check_pmcr());
> +
> +     return report_summary();
> +}
> diff --git a/arm/unittests.cfg b/arm/unittests.cfg
> index ffd12e5..edaed4a 100644
> --- a/arm/unittests.cfg
> +++ b/arm/unittests.cfg
> @@ -51,3 +51,17 @@ file = selftest.flat
>  smp = $MAX_SMP
>  extra_params = -append 'smp'
>  groups = selftest
> +
> +# Test PMU support with -icount IPC=1
> +[pmu-icount-1]
> +file = pmu.flat
> +extra_params = -icount 0 -append '1'
> +groups = pmu
> +accel = tcg
> +
> +# Test PMU support with -icount IPC=256
> +[pmu-icount-256]
> +file = pmu.flat
> +extra_params = -icount 8 -append '256'
> +groups = pmu
> +accel = tcg
>