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

Janosch Frank
2021-08-06T15:15:57Z

On 8/6/21 9:26 AM, David Hildenbrand 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@linux.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:

The only fix for the functions below that I would accept would be to
check for cc 2 and 3. A cc >= UVC_CC_BUSY confuses me way too much when
reading.

But honestly for those two I'd just keep the code as is. I only asked
Claudio to fix the code in the next patch and add this patch as it was
not clearly visible he was dealing with a CC.

>
>
> 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".
>