Re: [kvm-unit-tests PATCH] arm: pmu: Actually use counter 0 in test_event_counter_config()

[Eric Auger <eric.auger@redhat.com>]

Hi Oliver,


On 2/3/25 7:10 PM, Oliver Upton wrote:
> test_event_counter_config() checks that there is at least one event
> counter but mistakenly uses counter 1 for part of the test.
>
> Most implementations have more than a single event counter which is
> probably why this went unnoticed. However, due to limitations of the
> underlying hardware, KVM's PMUv3 emulation on Apple silicon can only
> provide 1 event counter.
>
> Consistenly use counter 0 throughout the test, matching the precondition
> and allowing the test to pass on Apple parts.
>
> Cc: Eric Auger <eric.auger@redhat.com>
> Fixes: 4ce2a804 ("arm: pmu: Basic event counter Tests")
> Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
> ---
>  arm/pmu.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/arm/pmu.c b/arm/pmu.c
> index 9ff7a301..2dc0822b 100644
> --- a/arm/pmu.c
> +++ b/arm/pmu.c
> @@ -396,13 +396,13 @@ static void test_event_counter_config(void)
>  	 * Test setting through PMESELR/PMXEVTYPER and PMEVTYPERn read,
>  	 * select counter 0
>  	 */
> -	write_sysreg(1, PMSELR_EL0);
> +	write_sysreg(0, PMSELR_EL0);
>  	/* program this counter to count unsupported event */
>  	write_sysreg(0xEA, PMXEVTYPER_EL0);
>  	write_sysreg(0xdeadbeef, PMXEVCNTR_EL0);
> -	report((read_regn_el0(pmevtyper, 1) & 0xFFF) == 0xEA,
> +	report((read_regn_el0(pmevtyper, 0) & 0xFFF) == 0xEA,
>  		"PMESELR/PMXEVTYPER/PMEVTYPERn");
> -	report((read_regn_el0(pmevcntr, 1) == 0xdeadbeef),
> +	report((read_regn_el0(pmevcntr, 0) == 0xdeadbeef),
>  		"PMESELR/PMXEVCNTR/PMEVCNTRn");
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Thank you for noticing and fixing that

Eric
>  
>  	/* try to configure an unsupported event within the range [0x0, 0x3F] */
>
> base-commit: 1f08a91a41402b0e032ecce8ed1b5952cbfca0ea