Re: [kvm-unit-tests PATCH v3 7/8] s390x: Add diag318 intercept test

[Janosch Frank <frankja@linux.ibm.com>]

On 12/17/20 3:31 PM, Janosch Frank wrote:
> On 12/17/20 11:34 AM, Thomas Huth wrote:
>> On 17/12/2020 10.59, Christian Borntraeger wrote:
>>>
>>>
>>> On 17.12.20 10:53, Thomas Huth wrote:
>>>> On 11/12/2020 11.00, Janosch Frank wrote:
>>>>> Not much to test except for the privilege and specification
>>>>> exceptions.
>>>>>
>>>>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>>>>> Reviewed-by: Thomas Huth <thuth@redhat.com>
>>>>> ---
>>>>>  lib/s390x/sclp.c  |  2 ++
>>>>>  lib/s390x/sclp.h  |  6 +++++-
>>>>>  s390x/intercept.c | 19 +++++++++++++++++++
>>>>>  3 files changed, 26 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/lib/s390x/sclp.c b/lib/s390x/sclp.c
>>>>> index cf6ea7c..0001993 100644
>>>>> --- a/lib/s390x/sclp.c
>>>>> +++ b/lib/s390x/sclp.c
>>>>> @@ -138,6 +138,8 @@ void sclp_facilities_setup(void)
>>>>>  
>>>>>  	assert(read_info);
>>>>>  
>>>>> +	sclp_facilities.has_diag318 = read_info->byte_134_diag318;
>>>>> +
>>>>>  	cpu = (void *)read_info + read_info->offset_cpu;
>>>>>  	for (i = 0; i < read_info->entries_cpu; i++, cpu++) {
>>>>>  		if (cpu->address == cpu0_addr) {
>>>>> diff --git a/lib/s390x/sclp.h b/lib/s390x/sclp.h
>>>>> index 6c86037..58f8e54 100644
>>>>> --- a/lib/s390x/sclp.h
>>>>> +++ b/lib/s390x/sclp.h
>>>>> @@ -105,7 +105,8 @@ extern struct sclp_facilities sclp_facilities;
>>>>>  
>>>>>  struct sclp_facilities {
>>>>>  	uint64_t has_sief2 : 1;
>>>>> -	uint64_t : 63;
>>>>> +	uint64_t has_diag318 : 1;
>>>>> +	uint64_t : 62;
>>>>>  };
>>>>>  
>>>>>  typedef struct ReadInfo {
>>>>> @@ -130,6 +131,9 @@ typedef struct ReadInfo {
>>>>>      uint16_t highest_cpu;
>>>>>      uint8_t  _reserved5[124 - 122];     /* 122-123 */
>>>>>      uint32_t hmfai;
>>>>> +    uint8_t reserved7[134 - 128];
>>>>> +    uint8_t byte_134_diag318 : 1;
>>>>> +    uint8_t : 7;
>>>>>      struct CPUEntry entries[0];
>>>>
>>>> ... the entries[] array can be moved around here without any further ado?
>>>> Looks confusing to me. Should there be a CPUEntry array here at all, or only
>>>> in ReadCpuInfo?
>>>
>>> there is offset_cpu for the cpu entries at the beginning of the structure.
>>
>> Ah, thanks, right, this was used earlier in the patch series, now I
>> remember. But I think the "struct CPUEntry entries[0]" here is rather
>> confusing, since there is no guarantee that the entries are really at this
>> location ... I think this line should rather be replaced by a comment saying
>> that offset_cpu should be used instead.
> 
> Sure, as long as it's clear that there's something at the end, I'm fine
> with it.

I would add that to the "fix style issues" patch or into an own patch.
Any preferences?

-       struct CPUEntry entries[0];
+       /*
+        * The cpu entries follow, they start at the offset specified
+        * in offset_cpu.
+        */




> 
>>
>>  Thomas
>>
>