Re: [kvm-unit-tests PATCH v3 6/9] s390x: smp: Loop if secondary cpu returns into cpu setup again

[Cornelia Huck <cohuck@redhat.com>]

On Fri, 17 Jan 2020 05:46:37 -0500
Janosch Frank <frankja@linux.ibm.com> wrote:

> Up to now a secondary cpu could have returned from the function it was
> executing and ending up somewhere in cstart64.S. This was mostly
> circumvented by an endless loop in the function that it executed.
> 
> Let's add a loop to the end of the cpu setup, so we don't have to rely
> on added loops in the tests.
> 
> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
> ---
>  s390x/cstart64.S | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/s390x/cstart64.S b/s390x/cstart64.S
> index 9af6bb3..5fd8d2f 100644
> --- a/s390x/cstart64.S
> +++ b/s390x/cstart64.S
> @@ -162,6 +162,8 @@ smp_cpu_setup_state:
>  	/* We should only go once through cpu setup and not for every restart */
>  	stg	%r14, GEN_LC_RESTART_NEW_PSW + 8
>  	br	%r14
> +	/* If the function returns, just loop here */
> +0:	j	0

Would it make sense to e.g. load a disabled wait psw instead? Or does
that mess things up elsewhere?

>  
>  pgm_int:
>  	SAVE_REGS