Re: [kvm-unit-tests PATCH] s390x: sie: Only overwrite r3 if it isn't needed anymore

[David Hildenbrand <david@redhat.com>]

On 02.06.21 11:43, Janosch Frank wrote:
> The lmg overwrites r3 which we later use to reference the fprs and fpc.
> Let's do the lmg at the end where overwriting is fine.
> 
> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
> ---
> 
> Finding this took me longer than I'd like to admit. :)
> 
> ---
>   s390x/cpu.S | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/s390x/cpu.S b/s390x/cpu.S
> index e2ad56c8..82b5e25d 100644
> --- a/s390x/cpu.S
> +++ b/s390x/cpu.S
> @@ -81,11 +81,11 @@ sie64a:
>   	stg	%r3,__SF_SIE_SAVEAREA(%r15)	# save guest register save area
>   
>   	# Load guest's gprs, fprs and fpc
> -	lmg	%r0,%r13,SIE_SAVEAREA_GUEST_GRS(%r3)
>   	.irp i, 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
>   	ld	\i, \i * 8 + SIE_SAVEAREA_GUEST_FPRS(%r3)
>   	.endr
>   	lfpc	SIE_SAVEAREA_GUEST_FPC(%r3)
> +	lmg	%r0,%r13,SIE_SAVEAREA_GUEST_GRS(%r3)
>   
>   	# Move scb ptr into r14 for the sie instruction
>   	lg	%r14,__SF_SIE_CONTROL(%r15)
> 

Oh, that's nasty

Reviewed-by: David Hildenbrand <david@redhat.com>

-- 
Thanks,

David / dhildenb