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

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

On Wed, 2 Jun 2021 11:47:12 +0200
David Hildenbrand <david@redhat.com> wrote:

> 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>

Reviewed-by: Claudio Imbrenda <imbrenda@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>
>