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

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Message-ID: <f3fc81a7-ea71-56f6-16e0-e43fc36d646e@redhat.com>
Date:   Fri, 6 Aug 2021 09:26:11 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Claudio Imbrenda <imbrenda@...ux.ibm.com>, kvm@...r.kernel.org
Cc:     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 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.

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".

-- 
Thanks,

David / dhildenb