Re: [Qemu-devel] [kvm-unit-tests PATCHv7 1/3] arm: Add PMU test

[Andrew Jones]

On Thu, Nov 03, 2016 at 08:29:57AM -0600, address@hidden wrote:
> On 2016-11-03 04:14, Andrew Jones wrote:
> > On Wed, Nov 02, 2016 at 05:22:15PM -0500, Wei Huang wrote:
> > 
> > Missing
> >  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).
> > > 
> > > Signed-off-by: Christopher Covington <address@hidden>
> > 
> > Missing
> >   Signed-off-by: Wei Huang <address@hidden>
> > 
> > > ---
> > >  arm/Makefile.common |  3 +-
> > >  arm/pmu.c           | 82
> > > +++++++++++++++++++++++++++++++++++++++++++++++++++++
> > >  arm/unittests.cfg   | 20 +++++++++++++
> > >  3 files changed, 104 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.
> > 
> > Is the Linux Foundation correct for codeaurora patches? Should bump
> > the year to 2016.
> > 
> > > + *
> > > + * 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;
> > > +         };
> > > + };
> > > +};
> > 
> > I know I already reviewed/agreed to this bitfield, but I'm having second
> > thoughts. I think I'd prefer a bunch of defined shifts like the kernel
> > uses.
> > 
> > > +
> > > +/*
> > > + * 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
> > 
> > s/2015/2016/   how time flies...
> > 
> > > + * 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 3f6fa45..b647b69 100644
> > > --- a/arm/unittests.cfg
> > > +++ b/arm/unittests.cfg
> > > @@ -54,3 +54,23 @@ file = selftest.flat
> > >  smp = $MAX_SMP
> > >  extra_params = -append 'smp'
> > >  groups = selftest
> > > +
> > > +# Test PMU support (KVM)
> > > +[pmu-kvm]
> > > +file = pmu.flat
> > > +groups = pmu
> > > +accel = kvm
> > 
> > No need to specify kvm when it works for both. Both is assumed.
> > tcg-only or kvm-only tests are exceptions requiring the 'accel'
> > parameter and a comment explaining why it doesn't work on the
> > other.
> > 
> > > +
> > > +# Test PMU support (TCG) with -icount IPC=1
> > > +[pmu-tcg-icount-1]
> > > +file = pmu.flat
> > > +extra_params = -icount 0 -append '1'
> > > +groups = pmu
> > > +accel = tcg
> > > +
> > > +# Test PMU support (TCG) with -icount IPC=256
> > > +[pmu-tcg-icount-256]
> > > +file = pmu.flat
> > > +extra_params = -icount 8 -append '256'
> > > +groups = pmu
> > > +accel = tcg
> > 
> > Why are these entries added now. These tests aren't yet implemented.
> 
> What makes you say they aren't implemented? They're running the
> same binary with a different command line arguments (that turns on
> stricter TCG-specific checking).

Not in this patch, they're not. 'int main(void)' <-- arguments are
ignored. Please only introduce unittests.cfg blocks with the patch
that implements them.

Thanks,
drew