Re: [PATCH kvm-unit-tests v1 1/6] lib: s390x: smp: Retry SIGP SENSE on CC2

[Claudio Imbrenda <imbrenda@linux.ibm.com>]

On Thu,  3 Mar 2022 22:04:20 +0100
Eric Farman <farman@linux.ibm.com> wrote:

> The routine smp_cpu_stopped() issues a SIGP SENSE, and returns true
> if it received a CC1 (STATUS STORED) with the STOPPED or CHECK STOP
> bits enabled. Otherwise, it returns false.
> 
> This is misleading, because a CC2 (BUSY) merely indicates that the
> order code could not be processed, not that the CPU is operating.
> It could be operating but in the process of being stopped.
> 
> Convert the invocation of the SIGP SENSE to retry when a CC2 is
> received, so we get a more definitive answer.
> 
> Signed-off-by: Eric Farman <farman@linux.ibm.com>
> Reviewed-by: Janosch Frank <frankja@linux.ibm.com>

Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>

> ---
>  lib/s390x/smp.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/s390x/smp.c b/lib/s390x/smp.c
> index 46e1b022..368d6add 100644
> --- a/lib/s390x/smp.c
> +++ b/lib/s390x/smp.c
> @@ -78,7 +78,7 @@ bool smp_cpu_stopped(uint16_t idx)
>  {
>  	uint32_t status;
>  
> -	if (smp_sigp(idx, SIGP_SENSE, 0, &status) !=
> SIGP_CC_STATUS_STORED)
> +	if (smp_sigp_retry(idx, SIGP_SENSE, 0, &status) !=
> SIGP_CC_STATUS_STORED) return false;
>  	return !!(status &
> (SIGP_STATUS_CHECK_STOP|SIGP_STATUS_STOPPED)); }