Re: [kvm-unit-tests PATCH v3 2/3] arm: pmu: Reset the pmu registers before starting some tests

[Andrew Jones <andrew.jones@linux.dev>]

On Thu, Aug 04, 2022 at 05:41:38PM -0700, Ricardo Koller wrote:
> Some registers like the PMOVS reset to an architecturally UNKNOWN value.
> Most tests expect them to be reset (mostly zeroed) using pmu_reset().
> Add a pmu_reset() on all the tests that need one.
> 
> As a bonus, fix a couple of comments related to the register state
> before a sub-test.
> 
> Reviewed-by: Eric Auger <eric.auger@redhat.com>
> Signed-off-by: Ricardo Koller <ricarkol@google.com>
> ---
>  arm/pmu.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/arm/pmu.c b/arm/pmu.c
> index 4c601b05..12e7d84e 100644
> --- a/arm/pmu.c
> +++ b/arm/pmu.c
> @@ -826,7 +826,7 @@ static void test_overflow_interrupt(void)
>  	write_regn_el0(pmevcntr, 1, PRE_OVERFLOW);
>  	isb();
>  
> -	/* interrupts are disabled */
> +	/* interrupts are disabled (PMINTENSET_EL1 == 0) */
>  
>  	mem_access_loop(addr, 200, pmu.pmcr_ro | PMU_PMCR_E);
>  	report(expect_interrupts(0), "no overflow interrupt after preset");
> @@ -842,7 +842,7 @@ static void test_overflow_interrupt(void)
>  	isb();
>  	report(expect_interrupts(0), "no overflow interrupt after counting");
>  
> -	/* enable interrupts */
> +	/* enable interrupts (PMINTENSET_EL1 <= ALL_SET) */
>  
>  	pmu_reset_stats();
>  
> @@ -890,6 +890,7 @@ static bool check_cycles_increase(void)
>  	bool success = true;
>  
>  	/* init before event access, this test only cares about cycle count */
> +	pmu_reset();

This and the other pmu_reset() call below break compilation on 32-bit arm,
because there's no pmu_reset() defined for it. It'd probably be best if
we actually implemented some sort of reset for arm, considering it's being
called in common tests.

Thanks,
drew

>  	set_pmcntenset(1 << PMU_CYCLE_IDX);
>  	set_pmccfiltr(0); /* count cycles in EL0, EL1, but not EL2 */
>  
> @@ -944,6 +945,7 @@ static bool check_cpi(int cpi)
>  	uint32_t pmcr = get_pmcr() | PMU_PMCR_LC | PMU_PMCR_C | PMU_PMCR_E;
>  
>  	/* init before event access, this test only cares about cycle count */
> +	pmu_reset();
>  	set_pmcntenset(1 << PMU_CYCLE_IDX);
>  	set_pmccfiltr(0); /* count cycles in EL0, EL1, but not EL2 */
>  
> -- 
> 2.37.1.559.g78731f0fdb-goog
> 
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