Re: [kvm-unit-tests PATCH v6 3/4] s390x: lib: add SPX and STPX instruction wrapper

[Thomas Huth <thuth@redhat.com>]

On 09/01/2020 17.16, Claudio Imbrenda wrote:
> Add a wrapper for the SET PREFIX and STORE PREFIX instructions, and
> use it instead of using inline assembly everywhere.
> 
> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> ---
>  lib/s390x/asm/arch_def.h | 10 ++++++++++
>  s390x/intercept.c        | 33 +++++++++++++--------------------
>  2 files changed, 23 insertions(+), 20 deletions(-)
> 
> diff --git a/lib/s390x/asm/arch_def.h b/lib/s390x/asm/arch_def.h
> index 1a5e3c6..465fe0f 100644
> --- a/lib/s390x/asm/arch_def.h
> +++ b/lib/s390x/asm/arch_def.h
> @@ -284,4 +284,14 @@ static inline int servc(uint32_t command, unsigned long sccb)
>  	return cc;
>  }
>  
> +static inline void spx(uint32_t *new_prefix)

Looking at this a second time ... why is new_prefix a pointer? A normal
value should be sufficient here, shouldn't it?

> +{
> +	asm volatile("spx %0" : : "Q" (*new_prefix) : "memory");
> +}
> +
> +static inline void stpx(uint32_t *current_prefix)
> +{
> +	asm volatile("stpx %0" : "=Q" (*current_prefix));
> +}
> +

 Thomas