Re: [PATCH kvm-unit-tests v2 5/6] s390x: smp: Create and use a non-waiting CPU restart

[Janosch Frank <frankja@linux.ibm.com>]

On 3/11/22 18:38, Eric Farman wrote:
> The kvm-unit-tests infrastructure for a CPU restart waits for the
> SIGP RESTART to complete. In order to test the restart itself,
> create a variation that does not wait, and test the state of the
> CPU directly.
> 
> While here, add some better report prefixes/messages, to clarify
> which condition is being examined (similar to test_stop_store_status()).
> 
> Signed-off-by: Eric Farman <farman@linux.ibm.com>

Reviewed-by: Janosch Frank <frankja@linux.ibm.com>

> ---
>   lib/s390x/smp.c | 24 ++++++++++++++++++++++++
>   lib/s390x/smp.h |  1 +
>   s390x/smp.c     | 21 ++++++++++++++++++---
>   3 files changed, 43 insertions(+), 3 deletions(-)
> 
> diff --git a/lib/s390x/smp.c b/lib/s390x/smp.c
> index b69c0e09..5be29d36 100644
> --- a/lib/s390x/smp.c
> +++ b/lib/s390x/smp.c
> @@ -194,6 +194,30 @@ int smp_cpu_restart(uint16_t idx)
>   	return rc;
>   }
>   
> +/*
> + * Functionally equivalent to smp_cpu_restart(), but without the
> + * elements that wait/serialize matters here in the test.
> + * Used to see if KVM itself is serialized correctly.
> + */
> +int smp_cpu_restart_nowait(uint16_t idx)
> +{
> +	check_idx(idx);
> +
> +	spin_lock(&lock);
> +
> +	/* Don't suppress a CC2 with sigp_retry() */
> +	if (sigp(cpus[idx].addr, SIGP_RESTART, 0, NULL)) {
> +		spin_unlock(&lock);
> +		return -1;
> +	}
> +
> +	cpus[idx].active = true;
> +
> +	spin_unlock(&lock);
> +
> +	return 0;
> +}
> +
>   int smp_cpu_start(uint16_t idx, struct psw psw)
>   {
>   	int rc;
> diff --git a/lib/s390x/smp.h b/lib/s390x/smp.h
> index bae03dfd..24a0e2e0 100644
> --- a/lib/s390x/smp.h
> +++ b/lib/s390x/smp.h
> @@ -42,6 +42,7 @@ uint16_t smp_cpu_addr(uint16_t idx);
>   bool smp_cpu_stopped(uint16_t idx);
>   bool smp_sense_running_status(uint16_t idx);
>   int smp_cpu_restart(uint16_t idx);
> +int smp_cpu_restart_nowait(uint16_t idx);
>   int smp_cpu_start(uint16_t idx, struct psw psw);
>   int smp_cpu_stop(uint16_t idx);
>   int smp_cpu_stop_nowait(uint16_t idx);
> diff --git a/s390x/smp.c b/s390x/smp.c
> index f70a9c54..913da155 100644
> --- a/s390x/smp.c
> +++ b/s390x/smp.c
> @@ -54,6 +54,10 @@ static void test_restart(void)
>   {
>   	struct cpu *cpu = smp_cpu_from_idx(1);
>   	struct lowcore *lc = cpu->lowcore;
> +	int rc;
> +
> +	report_prefix_push("restart");
> +	report_prefix_push("stopped");
>   
>   	lc->restart_new_psw.mask = extract_psw_mask();
>   	lc->restart_new_psw.addr = (unsigned long)test_func;
> @@ -61,17 +65,28 @@ static void test_restart(void)
>   	/* Make sure cpu is stopped */
>   	smp_cpu_stop(1);
>   	set_flag(0);
> -	smp_cpu_restart(1);
> +	rc = smp_cpu_restart_nowait(1);
> +	report(!rc, "return code");
> +	report(!smp_cpu_stopped(1), "cpu started");
>   	wait_for_flag();
> +	report_pass("test flag");
> +
> +	report_prefix_pop();
> +	report_prefix_push("running");
>   
>   	/*
>   	 * Wait until cpu 1 has set the flag because it executed the
>   	 * restart function.
>   	 */
>   	set_flag(0);
> -	smp_cpu_restart(1);
> +	rc = smp_cpu_restart_nowait(1);
> +	report(!rc, "return code");
> +	report(!smp_cpu_stopped(1), "cpu started");
>   	wait_for_flag();
> -	report_pass("restart while running");
> +	report_pass("test flag");
> +
> +	report_prefix_pop();
> +	report_prefix_pop();
>   }
>   
>   static void test_stop(void)