Re: [kvm-unit-tests PATCH v2 5/9] arm: pmu: Basic event counter Tests

[Andrew Jones <drjones@redhat.com>]

On Thu, Jan 30, 2020 at 12:25:06PM +0100, Eric Auger wrote:
> Adds the following tests:
> - event-counter-config: test event counter configuration
> - basic-event-count:
>   - programs counters #0 and #1 to count 2 required events
>   (resp. CPU_CYCLES and INST_RETIRED). Counter #0 is preset
>   to a value close enough to the 32b
>   overflow limit so that we check the overflow bit is set
>   after the execution of the asm loop.
> - mem-access: counts MEM_ACCESS event on counters #0 and #1
>   with and without 32-bit overflow.
> 
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> 
> ---
> 
> v1 -> v2:
> - fix PMCNTENSET_EL0 and PMCNTENCLR_EL0 op0
> - print PMEVTYPER SH
> - properly clobber used regs and add "cc"
> - simplify mem_access_loop
> ---
>  arm/pmu.c         | 269 ++++++++++++++++++++++++++++++++++++++++++++++
>  arm/unittests.cfg |  18 ++++
>  2 files changed, 287 insertions(+)
> 
> diff --git a/arm/pmu.c b/arm/pmu.c
> index 4a26a76..1b0101f 100644
> --- a/arm/pmu.c
> +++ b/arm/pmu.c
> @@ -18,9 +18,15 @@
>  #include "asm/barrier.h"
>  #include "asm/sysreg.h"
>  #include "asm/processor.h"
> +#include <bitops.h>
> +#include <asm/gic.h>
>  
>  #define PMU_PMCR_E         (1 << 0)
> +#define PMU_PMCR_P         (1 << 1)
>  #define PMU_PMCR_C         (1 << 2)
> +#define PMU_PMCR_D         (1 << 3)
> +#define PMU_PMCR_X         (1 << 4)
> +#define PMU_PMCR_DP        (1 << 5)
>  #define PMU_PMCR_LC        (1 << 6)
>  #define PMU_PMCR_N_SHIFT   11
>  #define PMU_PMCR_N_MASK    0x1f
> @@ -104,6 +110,9 @@ static inline void precise_instrs_loop(int loop, uint32_t pmcr)
>  
>  /* event counter tests only implemented for aarch64 */
>  static void test_event_introspection(void) {}
> +static void test_event_counter_config(void) {}
> +static void test_basic_event_count(void) {}
> +static void test_mem_access(void) {}
>  
>  #elif defined(__aarch64__)
>  #define ID_AA64DFR0_PERFMON_SHIFT 8
> @@ -145,6 +154,33 @@ static inline void precise_instrs_loop(int loop, uint32_t pmcr)
>  }
>  
>  #define PMCEID1_EL0 sys_reg(3, 3, 9, 12, 7)
> +#define PMCNTENSET_EL0 sys_reg(3, 3, 9, 12, 1)
> +#define PMCNTENCLR_EL0 sys_reg(3, 3, 9, 12, 2)
> +
> +#define PMEVTYPER_EXCLUDE_EL1 (1 << 31)
> +#define PMEVTYPER_EXCLUDE_EL0 (1 << 30)
> +
> +#define regn_el0(__reg, __n) __reg ## __n  ## _el0
> +#define write_regn(__reg, __n, __val) \
> +	write_sysreg((__val), __reg ## __n ## _el0)
> +
> +#define read_regn(__reg, __n) \
> +	read_sysreg(__reg ## __n ## _el0)

You can delete regn_el0() since you don't use it anyway.

The el0 should probably be in the macro names,

write_regn_el0()
read_regn_el0()

Also they could go in lib/arm64/asm/sysreg.h

> +
> +#define print_pmevtyper(__s, __n) do { \
> +	uint32_t val; \
> +	val = read_regn(pmevtyper, __n);\
> +	report_info("%s pmevtyper%d=0x%x, eventcount=0x%x (p=%ld, u=%ld nsk=%ld, nsu=%ld, nsh=%ld m=%ld, mt=%ld, sh=%ld)", \
> +			(__s), (__n), val, val & 0xFFFF,	\
> +			(BIT_MASK(31) & val) >> 31,		\
> +			(BIT_MASK(30) & val) >> 30,		\
> +			(BIT_MASK(29) & val) >> 29,		\
> +			(BIT_MASK(28) & val) >> 28,		\
> +			(BIT_MASK(27) & val) >> 27,		\
> +			(BIT_MASK(26) & val) >> 26,		\
> +			(BIT_MASK(25) & val) >> 25);		\
> +			(BIT_MASK(24) & val) >> 24);		\
> +	} while (0)
>  
>  static bool is_event_supported(uint32_t n, bool warn)
>  {
> @@ -198,6 +234,230 @@ static void test_event_introspection(void)
>  	report(required_events, "Check required events are implemented");
>  }
>  
> +/*
> + * Extra instructions inserted by the compiler would be difficult to compensate
> + * for, so hand assemble everything between, and including, the PMCR accesses
> + * to start and stop counting. isb instructions are inserted to make sure
> + * pmccntr read after this function returns the exact instructions executed
> + * in the controlled block. Loads @loop times the data at @address into x9.
> + */
> +static void mem_access_loop(void *addr, int loop, uint32_t pmcr)
> +{
> +asm volatile(
> +	"       msr     pmcr_el0, %[pmcr]\n"
> +	"       isb\n"
> +	"       mov     x10, %[loop]\n"
> +	"1:     sub     x10, x10, #1\n"
> +	"       ldr x9, [%[addr]]\n"

indent is wrong for line above

> +	"       cmp     x10, #0x0\n"
> +	"       b.gt    1b\n"
> +	"       msr     pmcr_el0, xzr\n"
> +	"       isb\n"
> +	:
> +	: [addr] "r" (addr), [pmcr] "r" (pmcr), [loop] "r" (loop)
> +	: "x9", "x10", "cc");
> +}
> +
> +static void pmu_reset(void)
> +{
> +	/* reset all counters, counting disabled at PMCR level*/
> +	set_pmcr(pmu.pmcr_ro | PMU_PMCR_LC | PMU_PMCR_C | PMU_PMCR_P);
> +	/* Disable all counters */
> +	write_sysreg_s(0xFFFFFFFF, PMCNTENCLR_EL0);
> +	/* clear overflow reg */
> +	write_sysreg(0xFFFFFFFF, pmovsclr_el0);
> +	/* disable overflow interrupts on all counters */
> +	write_sysreg(0xFFFFFFFF, pmintenclr_el1);
> +	isb();
> +}
> +
> +static void test_event_counter_config(void)
> +{
> +	int i;
> +
> +	if (!pmu.nb_implemented_counters) {
> +		report_skip("No event counter, skip ...");
> +		return;
> +	}
> +
> +	pmu_reset();
> +
> +	/*
> +	 * Test setting through PMESELR/PMXEVTYPER and PMEVTYPERn read,
> +	 * select counter 0
> +	 */
> +	write_sysreg(1, PMSELR_EL0);
> +	/* program this counter to count unsupported event */
> +	write_sysreg(0xEA, PMXEVTYPER_EL0);
> +	write_sysreg(0xdeadbeef, PMXEVCNTR_EL0);
> +	report((read_regn(pmevtyper, 1) & 0xFFF) == 0xEA,
> +		"PMESELR/PMXEVTYPER/PMEVTYPERn");
> +	report((read_regn(pmevcntr, 1) == 0xdeadbeef),
> +		"PMESELR/PMXEVCNTR/PMEVCNTRn");
> +
> +	/* try to configure an unsupported event within the range [0x0, 0x3F] */
> +	for (i = 0; i <= 0x3F; i++) {
> +		if (!is_event_supported(i, false))
> +			break;
> +	}
> +	if (i > 0x3F) {
> +		report_skip("pmevtyper: all events within [0x0, 0x3F] are supported");
> +		return;
> +	}
> +
> +	/* select counter 0 */
> +	write_sysreg(0, PMSELR_EL0);
> +	/* program this counter to count unsupported event */
> +	write_sysreg(i, PMXEVCNTR_EL0);
> +	/* read the counter value */
> +	read_sysreg(PMXEVCNTR_EL0);
> +	report(read_sysreg(PMXEVCNTR_EL0) == i,
> +		"read of a counter programmed with unsupported event");
> +
> +}
> +
> +static bool satisfy_prerequisites(uint32_t *events, unsigned int nb_events)
> +{
> +	int i;
> +
> +	if (pmu.nb_implemented_counters < nb_events) {
> +		report_skip("Skip test as number of counters is too small (%d)",
> +			    pmu.nb_implemented_counters);
> +		return false;
> +	}
> +
> +	for (i = 0; i < nb_events; i++) {
> +		if (!is_event_supported(events[i], false)) {
> +			report_skip("Skip test as event %d is not supported",
> +				    events[i]);
> +			return false;
> +		}
> +	}
> +	return true;
> +}
> +
> +static void test_basic_event_count(void)
> +{
> +	uint32_t implemented_counter_mask, non_implemented_counter_mask;
> +	uint32_t counter_mask;
> +	uint32_t events[] = {
> +		0x11,	/* CPU_CYCLES */
> +		0x8,	/* INST_RETIRED */
> +	};

#define CPU_CYCLES 0x11
#define INST_RETIRED 0x8

then no need for the comments and ...

> +
> +	if (!satisfy_prerequisites(events, ARRAY_SIZE(events)))
> +		return;
> +
> +	implemented_counter_mask = BIT(pmu.nb_implemented_counters) - 1;
> +	non_implemented_counter_mask = ~(BIT(31) | implemented_counter_mask);
> +	counter_mask = implemented_counter_mask | non_implemented_counter_mask;
> +
> +	write_regn(pmevtyper, 0, events[0] | PMEVTYPER_EXCLUDE_EL0);
> +	write_regn(pmevtyper, 1, events[1] | PMEVTYPER_EXCLUDE_EL0);

... here we can see what we're doing more clearing using the defines
instead of array members.

> +
> +	/* disable all counters */
> +	write_sysreg_s(0xFFFFFFFF, PMCNTENCLR_EL0);
> +	report(!read_sysreg_s(PMCNTENCLR_EL0) && !read_sysreg_s(PMCNTENSET_EL0),
> +		"pmcntenclr: disable all counters");
> +
> +	/*
> +	 * clear cycle and all event counters and allow counter enablement
> +	 * through PMCNTENSET. LC is RES1.
> +	 */
> +	set_pmcr(pmu.pmcr_ro | PMU_PMCR_LC | PMU_PMCR_C | PMU_PMCR_P);
> +	isb();
> +	report(get_pmcr() == (pmu.pmcr_ro | PMU_PMCR_LC), "pmcr: reset counters");
> +
> +	/* Preset counter #0 to 0xFFFFFFF0 to trigger an overflow interrupt */
> +	write_regn(pmevcntr, 0, 0xFFFFFFF0);
> +	report(read_regn(pmevcntr, 0) == 0xFFFFFFF0,
> +		"counter #0 preset to 0xFFFFFFF0");
> +	report(!read_regn(pmevcntr, 1), "counter #1 is 0");
> +
> +	/*
> +	 * Enable all implemented counters and also attempt to enable
> +	 * not supported counters. Counting still is disabled by !PMCR.E
> +	 */
> +	write_sysreg_s(counter_mask, PMCNTENSET_EL0);
> +
> +	/* check only those implemented are enabled */
> +	report((read_sysreg_s(PMCNTENSET_EL0) == read_sysreg_s(PMCNTENCLR_EL0)) &&
> +		(read_sysreg_s(PMCNTENSET_EL0) == implemented_counter_mask),
> +		"pmcntenset: enabled implemented_counters");
> +
> +	/* Disable all counters but counters #0 and #1 */
> +	write_sysreg_s(~0x3, PMCNTENCLR_EL0);

First time you've used ~ to define a mask. I prefer this to all the
0xFFF..'s, but I prefer consistency and defines even more.

> +	report((read_sysreg_s(PMCNTENSET_EL0) == read_sysreg_s(PMCNTENCLR_EL0)) &&
> +		(read_sysreg_s(PMCNTENSET_EL0) == 0x3),
> +		"pmcntenset: just enabled #0 and #1");
> +
> +	/* clear overflow register */
> +	write_sysreg(0xFFFFFFFF, pmovsclr_el0);
> +	report(!read_sysreg(pmovsclr_el0), "check overflow reg is 0");
> +
> +	/* disable overflow interrupts on all counters*/
> +	write_sysreg(0xFFFFFFFF, pmintenclr_el1);
> +	report(!read_sysreg(pmintenclr_el1),
> +		"pmintenclr_el1=0, all interrupts disabled");
> +
> +	/* enable overflow interrupts on all event counters */
> +	write_sysreg(implemented_counter_mask | non_implemented_counter_mask,
> +		     pmintenset_el1);
> +	report(read_sysreg(pmintenset_el1) == implemented_counter_mask,
> +		"overflow interrupts enabled on all implemented counters");
> +
> +	/* Set PMCR.E, execute asm code and unset PMCR.E */
> +	precise_instrs_loop(20, pmu.pmcr_ro | PMU_PMCR_E);
> +
> +	report_info("counter #0 is 0x%lx (CPU_CYCLES)",
> +		    read_regn(pmevcntr, 0));
> +	report_info("counter #1 is 0x%lx (INST_RETIRED)",
> +		    read_regn(pmevcntr, 1));
> +
> +	report_info("overflow reg = 0x%lx", read_sysreg(pmovsclr_el0));
> +	report(read_sysreg(pmovsclr_el0) & 0x1,
> +		"check overflow happened on #0 only");
> +}
> +
> +static void test_mem_access(void)
> +{
> +	void *addr = malloc(PAGE_SIZE);
> +	uint32_t events[] = {
> +		0x13,   /* MEM_ACCESS */
> +		0x13,   /* MEM_ACCESS */
> +	};

#define MEM_ACCESS 0x13

> +
> +	if (!satisfy_prerequisites(events, ARRAY_SIZE(events)))

No need to check the same event twice. Just call satisfy_prerequisites
with ((uint32_t []){ MEM_ACCESS }, 1)

> +		return;
> +
> +	pmu_reset();
> +
> +	write_regn(pmevtyper, 0, events[0] | PMEVTYPER_EXCLUDE_EL0);
> +	write_regn(pmevtyper, 1, events[1] | PMEVTYPER_EXCLUDE_EL0);

Same comment on using defines rather than array members.

> +	write_sysreg_s(0x3, PMCNTENSET_EL0);
> +	isb();
> +	mem_access_loop(addr, 20, pmu.pmcr_ro | PMU_PMCR_E);
> +	report_info("counter #0 is %ld (MEM_ACCESS)", read_regn(pmevcntr, 0));
> +	report_info("counter #1 is %ld (MEM_ACCESS)", read_regn(pmevcntr, 1));
> +	/* We may measure more than 20 mem access depending on the core */
> +	report((read_regn(pmevcntr, 0) == read_regn(pmevcntr, 1)) &&
> +	       (read_regn(pmevcntr, 0) >= 20) && !read_sysreg(pmovsclr_el0),
> +	       "Ran 20 mem accesses");
> +
> +	pmu_reset();
> +
> +	write_regn(pmevcntr, 0, 0xFFFFFFFA);
> +	write_regn(pmevcntr, 1, 0xFFFFFFF0);
> +	write_sysreg_s(0x3, PMCNTENSET_EL0);
> +	isb();
> +	mem_access_loop(addr, 20, pmu.pmcr_ro | PMU_PMCR_E);
> +	report(read_sysreg(pmovsclr_el0) == 0x3,
> +	       "Ran 20 mem accesses with expected overflows on both counters");
> +	report_info("cnt#0 = %ld cnt#1=%ld overflow=0x%lx",
> +			read_regn(pmevcntr, 0), read_regn(pmevcntr, 1),
> +			read_sysreg(pmovsclr_el0));
> +}
> +
>  #endif
>  
>  /*
> @@ -388,6 +648,15 @@ int main(int argc, char *argv[])
>  	} else if (strcmp(argv[1], "event-introspection") == 0) {
>  		report_prefix_push(argv[1]);
>  		test_event_introspection();
> +	} else if (strcmp(argv[1], "event-counter-config") == 0) {
> +		report_prefix_push(argv[1]);
> +		test_event_counter_config();
> +	} else if (strcmp(argv[1], "basic-event-count") == 0) {
> +		report_prefix_push(argv[1]);
> +		test_basic_event_count();
> +	} else if (strcmp(argv[1], "mem-access") == 0) {
> +		report_prefix_push(argv[1]);
> +		test_mem_access();

missing the pops. I know they're not necessary since we finish the tests
afterwards, but the universe must stay balanced. Where there's a yin, we
should put a yang.

>  	} else {
>  		report_abort("Unknown sub-test '%s'", argv[1]);
>  	}
> diff --git a/arm/unittests.cfg b/arm/unittests.cfg
> index 4433ef3..7a59403 100644
> --- a/arm/unittests.cfg
> +++ b/arm/unittests.cfg
> @@ -72,6 +72,24 @@ groups = pmu
>  arch = arm64
>  extra_params = -append 'event-introspection'
>  
> +[pmu-event-counter-config]
> +file = pmu.flat
> +groups = pmu
> +arch = arm64
> +extra_params = -append 'event-counter-config'
> +
> +[pmu-basic-event-count]
> +file = pmu.flat
> +groups = pmu
> +arch = arm64
> +extra_params = -append 'basic-event-count'
> +
> +[pmu-mem-access]
> +file = pmu.flat
> +groups = pmu
> +arch = arm64
> +extra_params = -append 'mem-access'
> +
>  # Test PMU support (TCG) with -icount IPC=1
>  #[pmu-tcg-icount-1]
>  #file = pmu.flat
> -- 
> 2.20.1
> 
>

I only skimmed this looking for style/framework issues. I'd prefer more
defines in general to all the hex, but I won't insist on that.

Thanks,
drew

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