linux-kernel - Re: [PATCH 4/4] KVM: riscv: selftests: Allow number of interrupts to be configurable

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Message-ID: <20250227-f7b303813dab128b5060b0c3@orel>
Date: Thu, 27 Feb 2025 09:16:19 +0100
From: Andrew Jones <ajones@...tanamicro.com>
To: Atish Patra <atishp@...osinc.com>
Cc: Anup Patel <anup@...infault.org>, Atish Patra <atishp@...shpatra.org>, 
	Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>, 
	Paolo Bonzini <pbonzini@...hat.com>, Shuah Khan <shuah@...nel.org>, kvm@...r.kernel.org, 
	kvm-riscv@...ts.infradead.org, linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	linux-kselftest@...r.kernel.org
Subject: Re: [PATCH 4/4] KVM: riscv: selftests: Allow number of interrupts to
 be configurable

On Wed, Feb 26, 2025 at 12:25:06PM -0800, Atish Patra wrote:
> It is helpful to vary the number of the LCOFI interrupts generated
> by the overflow test. Allow additional argument for overflow test
> to accommodate that. It can be easily cross-validated with
> /proc/interrupts output in the host.
> 
> Signed-off-by: Atish Patra <atishp@...osinc.com>
> ---
>  tools/testing/selftests/kvm/riscv/sbi_pmu_test.c | 36 ++++++++++++++++++++----
>  1 file changed, 30 insertions(+), 6 deletions(-)
> 
> diff --git a/tools/testing/selftests/kvm/riscv/sbi_pmu_test.c b/tools/testing/selftests/kvm/riscv/sbi_pmu_test.c
> index 533b76d0de82..7c273a1adb17 100644
> --- a/tools/testing/selftests/kvm/riscv/sbi_pmu_test.c
> +++ b/tools/testing/selftests/kvm/riscv/sbi_pmu_test.c
> @@ -39,8 +39,10 @@ static bool illegal_handler_invoked;
>  #define SBI_PMU_TEST_SNAPSHOT	BIT(2)
>  #define SBI_PMU_TEST_OVERFLOW	BIT(3)
>  
> +#define SBI_PMU_OVERFLOW_IRQNUM_DEFAULT 5
>  struct test_args {
>  	int disabled_tests;
> +	int overflow_irqnum;
>  };
>  
>  static struct test_args targs;
> @@ -478,7 +480,7 @@ static void test_pmu_events_snaphost(void)
>  
>  static void test_pmu_events_overflow(void)
>  {
> -	int num_counters = 0;
> +	int num_counters = 0, i = 0;
>  
>  	/* Verify presence of SBI PMU and minimum requrired SBI version */
>  	verify_sbi_requirement_assert();
> @@ -495,11 +497,15 @@ static void test_pmu_events_overflow(void)
>  	 * Qemu supports overflow for cycle/instruction.
>  	 * This test may fail on any platform that do not support overflow for these two events.
>  	 */
> -	test_pmu_event_overflow(SBI_PMU_HW_CPU_CYCLES);
> -	GUEST_ASSERT_EQ(vcpu_shared_irq_count, 1);
> +	for (i = 0; i < targs.overflow_irqnum; i++)
> +		test_pmu_event_overflow(SBI_PMU_HW_CPU_CYCLES);
> +	GUEST_ASSERT_EQ(vcpu_shared_irq_count, targs.overflow_irqnum);
> +
> +	vcpu_shared_irq_count = 0;
>  
> -	test_pmu_event_overflow(SBI_PMU_HW_INSTRUCTIONS);
> -	GUEST_ASSERT_EQ(vcpu_shared_irq_count, 2);
> +	for (i = 0; i < targs.overflow_irqnum; i++)
> +		test_pmu_event_overflow(SBI_PMU_HW_INSTRUCTIONS);
> +	GUEST_ASSERT_EQ(vcpu_shared_irq_count, targs.overflow_irqnum);
>  
>  	GUEST_DONE();
>  }
> @@ -621,8 +627,11 @@ static void test_vm_events_overflow(void *guest_code)
>  
>  static void test_print_help(char *name)
>  {
> -	pr_info("Usage: %s [-h] [-t <test name>]\n", name);
> +	pr_info("Usage: %s [-h] [-t <test name>] [-n <number of LCOFI interrupt for overflow test>]\n",
> +		name);
>  	pr_info("\t-t: Test to run (default all). Available tests are 'basic', 'events', 'snapshot', 'overflow'\n");
> +	pr_info("\t-n: Number of LCOFI interrupt to trigger for each event in overflow test (default: %d)\n",
> +		SBI_PMU_OVERFLOW_IRQNUM_DEFAULT);
>  	pr_info("\t-h: print this help screen\n");
>  }
>  
> @@ -631,6 +640,8 @@ static bool parse_args(int argc, char *argv[])
>  	int opt;
>  	int temp_disabled_tests = SBI_PMU_TEST_BASIC | SBI_PMU_TEST_EVENTS | SBI_PMU_TEST_SNAPSHOT |
>  				  SBI_PMU_TEST_OVERFLOW;
> +	int overflow_interrupts = -1;

Initializing to -1 made me think that '-n 0' would be valid and a way to
disable the overflow test, but...

> +
>  	while ((opt = getopt(argc, argv, "h:t:n:")) != -1) {
>  		switch (opt) {
>  		case 't':
> @@ -646,12 +657,24 @@ static bool parse_args(int argc, char *argv[])
>  				goto done;
>  			targs.disabled_tests = temp_disabled_tests;
>  			break;
> +		case 'n':
> +			overflow_interrupts = atoi_positive("Number of LCOFI", optarg);

...here we use atoi_positive() and...

> +			break;
>  		case 'h':
>  		default:
>  			goto done;
>  		}
>  	}
>  
> +	if (overflow_interrupts > 0) {

...here we only change from the default of 5 for nonzero.

Should we allow '-n 0'? Otherwise overflow_interrupts can be initialized
to zero (not that it matters).

> +		if (targs.disabled_tests & SBI_PMU_TEST_OVERFLOW) {
> +			pr_info("-n option is only available for overflow test\n");
> +			goto done;
> +		} else {
> +			targs.overflow_irqnum = overflow_interrupts;
> +		}
> +	}
> +
>  	return true;
>  done:
>  	test_print_help(argv[0]);
> @@ -661,6 +684,7 @@ static bool parse_args(int argc, char *argv[])
>  int main(int argc, char *argv[])
>  {
>  	targs.disabled_tests = 0;
> +	targs.overflow_irqnum = SBI_PMU_OVERFLOW_IRQNUM_DEFAULT;
>  
>  	if (!parse_args(argc, argv))
>  		exit(KSFT_SKIP);
> 
> -- 
> 2.43.0
>

Thanks,
drew