linux-kernel - Re: [PATCH v3 01/14] KVM: s390: pv: add macros for UVC CC values

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Date:   Fri, 6 Aug 2021 11:34:37 +0200
From:   Claudio Imbrenda <imbrenda@...ux.ibm.com>
To:     David Hildenbrand <david@...hat.com>
Cc:     kvm@...r.kernel.org, cohuck@...hat.com, borntraeger@...ibm.com,
        frankja@...ux.ibm.com, thuth@...hat.com, pasic@...ux.ibm.com,
        linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        Ulrich.Weigand@...ibm.com
Subject: Re: [PATCH v3 01/14] KVM: s390: pv: add macros for UVC CC values

On Fri, 6 Aug 2021 09:26:11 +0200
David Hildenbrand <david@...hat.com> wrote:

> On 04.08.21 17:40, Claudio Imbrenda wrote:
> > Add macros to describe the 4 possible CC values returned by the UVC
> > instruction.
> > 
> > Signed-off-by: Claudio Imbrenda <imbrenda@...ux.ibm.com>
> > ---
> >   arch/s390/include/asm/uv.h | 5 +++++
> >   1 file changed, 5 insertions(+)
> > 
> > diff --git a/arch/s390/include/asm/uv.h b/arch/s390/include/asm/uv.h
> > index 12c5f006c136..b35add51b967 100644
> > --- a/arch/s390/include/asm/uv.h
> > +++ b/arch/s390/include/asm/uv.h
> > @@ -18,6 +18,11 @@
> >   #include <asm/page.h>
> >   #include <asm/gmap.h>
> >   
> > +#define UVC_CC_OK	0
> > +#define UVC_CC_ERROR	1
> > +#define UVC_CC_BUSY 	2
> > +#define UVC_CC_PARTIAL	3
> > +
> >   #define UVC_RC_EXECUTED		0x0001
> >   #define UVC_RC_INV_CMD		0x0002
> >   #define UVC_RC_INV_STATE	0x0003
> >   
> 
> Do we have any users we could directly fix up? AFAIKs, most users
> don't really care about the cc value, only about cc vs !cc.

maybe there will be in the future.

I wanted to split away this generic change from the patch that uses it,
to improve readability

> The only instances I was able to spot quickly:
> 
> 
> diff --git a/arch/s390/include/asm/uv.h b/arch/s390/include/asm/uv.h
> index 12c5f006c136..dd72d325f9e8 100644
> --- a/arch/s390/include/asm/uv.h
> +++ b/arch/s390/include/asm/uv.h
> @@ -233,7 +233,7 @@ static inline int uv_call(unsigned long r1,
> unsigned long r2)
> 
>          do {
>                  cc = __uv_call(r1, r2);
> -       } while (cc > 1);
> +       } while (cc >= UVC_CC_BUSY);
>          return cc;
>   }
> 
> @@ -245,7 +245,7 @@ static inline int uv_call_sched(unsigned long r1, 
> unsigned long r2)
>          do {
>                  cc = __uv_call(r1, r2);
>                  cond_resched();
> -       } while (cc > 1);
> +       } while (cc >= UVC_CC_BUSY);
>          return cc;
>   }
> 
> 
> Of course, we could replace all checks for cc vs !cc with "cc != 
> UVC_CC_OK" vs "cc == UVC_CC_OK".
>