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Date: Mon, 13 Jan 2020 13:27:38 +0100
From: Claudio Imbrenda <imbrenda@linux.ibm.com>
Subject: Re: [kvm-unit-tests PATCH v7 3/4] s390x: lib: add SPX and STPX
 instruction wrapper
In-Reply-To: <656129b7-68f2-d3ab-7428-91999c896ca5@linux.ibm.com>
References: <20200110184050.191506-1-imbrenda@linux.ibm.com>
        <20200110184050.191506-4-imbrenda@linux.ibm.com>
        <656129b7-68f2-d3ab-7428-91999c896ca5@linux.ibm.com>
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To: Janosch Frank <frankja@linux.ibm.com>
Cc: kvm@vger.kernel.org, linux-s390@vger.kernel.org, thuth@redhat.com, david@redhat.com, borntraeger@de.ibm.com

On Mon, 13 Jan 2020 10:42:01 +0100
Janosch Frank <frankja@linux.ibm.com> wrote:

> On 1/10/20 7:40 PM, Claudio Imbrenda wrote:
> > Add a wrapper for the SET PREFIX and STORE PREFIX instructions, and
> > use it instead of using inline assembly.
> > 
> > Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> > Reviewed-by: Thomas Huth <thuth@redhat.com>  
> 
> Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
> 
> > @@ -63,14 +60,10 @@ static void test_spx(void)
> >  	 * some facility bits there ... at least some of them
> > should be
> >  	 * set in our buffer afterwards.
> >  	 */
> > -	asm volatile (
> > -		" stpx	%0\n"
> > -		" spx	%1\n"
> > -		" stfl	0\n"
> > -		" spx	%0\n"
> > -		: "+Q"(old_prefix)
> > -		: "Q"(new_prefix)
> > -		: "memory");
> > +	old_prefix = get_prefix();
> > +	set_prefix(new_prefix);
> > +	asm volatile("	stfl 0" : : : "memory");  
> 
> Couldn't we also use stfl from facility.h here?
> And do we need to add a memory clobber to it?

will do both

> > +	set_prefix(old_prefix);
> >  	report(pagebuf[GEN_LC_STFL] != 0, "stfl to new prefix");
> >  
> >  	expect_pgm_int();
> >   
> 
>