Re: [Qemu-devel] [kvm-unit-tests PATCH v11 1/3] arm: Add PMU test

[Wei Huang]

On 11/23/2016 07:16 AM, Andre Przywara wrote:
> Hi,
> 
> On 22/11/16 18:29, Wei Huang wrote:
>> From: Christopher Covington <address@hidden>
>>
>> Beginning with a simple sanity check of the control register, add
>> a unit test for the ARM Performance Monitors Unit (PMU).
> 
> Mmh, the output of this is a bit confusing. How about to join some
> information? I changed it to give me:
> INFO: pmu: PMU implementer/ID code:     "A"(0x41)/0x0
> INFO: pmu: Event counters:      0
> PASS: pmu: Control register
> 
> ... by using the newly introduced report_info() to make it look nicer.
> 
>>
>> Signed-off-by: Christopher Covington <address@hidden>
>> Signed-off-by: Wei Huang <address@hidden>
>> Reviewed-by: Andrew Jones <address@hidden>
>> ---
>>  arm/Makefile.common |  3 ++-
>>  arm/pmu.c           | 74 
>> +++++++++++++++++++++++++++++++++++++++++++++++++++++
>>  arm/unittests.cfg   |  5 ++++
>>  3 files changed, 81 insertions(+), 1 deletion(-)
>>  create mode 100644 arm/pmu.c
>>
>> diff --git a/arm/Makefile.common b/arm/Makefile.common
>> index f37b5c2..5da2fdd 100644
>> --- a/arm/Makefile.common
>> +++ b/arm/Makefile.common
>> @@ -12,7 +12,8 @@ endif
>>  tests-common = \
>>      $(TEST_DIR)/selftest.flat \
>>      $(TEST_DIR)/spinlock-test.flat \
>> -    $(TEST_DIR)/pci-test.flat
>> +    $(TEST_DIR)/pci-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..9d9c53b
>> --- /dev/null
>> +++ b/arm/pmu.c
>> @@ -0,0 +1,74 @@
>> +/*
>> + * Test the ARM Performance Monitors Unit (PMU).
>> + *
>> + * Copyright (c) 2015-2016, 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"
>> +#include "asm/barrier.h"
>> +
>> +#define PMU_PMCR_N_SHIFT   11
>> +#define PMU_PMCR_N_MASK    0x1f
>> +#define PMU_PMCR_ID_SHIFT  16
>> +#define PMU_PMCR_ID_MASK   0xff
>> +#define PMU_PMCR_IMP_SHIFT 24
>> +#define PMU_PMCR_IMP_MASK  0xff
>> +
>> +#if defined(__arm__)
> 
> I guess you should use the arch specific header files we have in place
> for that (lib/arm{.64}/asm/processor.h). Also there are sysreg read
> wrappers (at least for arm64) in there already, can't we base this
> function on them: DEFINE_GET_SYSREG32(pmcr, el0)?
> (Requires a small change to get rid of the forced "_el1" suffix)
> 
> We should wait for the GIC series to be merged, as this contains some
> changes in this area.

We planned to add it after this series is merged. However if GIC series
has a similar support, we can piggy-back on it.

> 
>> +static inline uint32_t pmcr_read(void)
>> +{
>> +    uint32_t ret;
>> +
>> +    asm volatile("mrc p15, 0, %0, c9, c12, 0" : "=r" (ret));
>> +    return ret;
>> +}
>> +#elif defined(__aarch64__)
>> +static inline uint32_t pmcr_read(void)
>> +{
>> +    uint32_t ret;
>> +
>> +    asm volatile("mrs %0, pmcr_el0" : "=r" (ret));
>> +    return ret;
>> +}
>> +#endif
>> +
>> +/*
>> + * 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 2016, 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)
>> +{
>> +    uint32_t pmcr;
>> +
>> +    pmcr = pmcr_read();
>> +
>> +    printf("PMU implementer:     %c\n",
>> +           (pmcr >> PMU_PMCR_IMP_SHIFT) & PMU_PMCR_IMP_MASK);
> 
> If this register reads as zero, the output is mangled (since it cuts off
> the string before the newline):
> =====
> PMU implementer:     Identification code: 0x0
> =====
> 
> I guess you need something like:
> (pmcr >> PMU_PMCR_IMP_SHIFT) & PMU_PMCR_IMP_MASK ?: ' '
> 
>> +    printf("Identification code: 0x%x\n",
>> +           (pmcr >> PMU_PMCR_ID_SHIFT) & PMU_PMCR_ID_MASK);
> 
> As mentioned above this should use report_info() now, also it would be
> nice to merge this with the message above into one line of output.

I will take them into consideration. Thanks.

> 
> Cheers,
> Andre
> 
>> +    printf("Event counters:      %d\n",
>> +           (pmcr >> PMU_PMCR_N_SHIFT) & PMU_PMCR_N_MASK);
>> +
>> +    return ((pmcr >> PMU_PMCR_IMP_SHIFT) & PMU_PMCR_IMP_MASK) != 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 ae32a42..816f494 100644
>> --- a/arm/unittests.cfg
>> +++ b/arm/unittests.cfg
>> @@ -58,3 +58,8 @@ groups = selftest
>>  [pci-test]
>>  file = pci-test.flat
>>  groups = pci
>> +
>> +# Test PMU support
>> +[pmu]
>> +file = pmu.flat
>> +groups = pmu
>>