Re: [kvm-unit-tests PATCH v3 3/3] s390x/spec_ex: Add test of EXECUTE with odd target address

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

On 3/17/23 17:37, Thomas Huth wrote:
> On 17/03/2023 16.36, Claudio Imbrenda wrote:
>> On Fri, 17 Mar 2023 15:11:35 +0100
>> Thomas Huth <thuth@redhat.com> wrote:
>>
>>> On 17/03/2023 15.09, Thomas Huth wrote:
>>>> On 15/03/2023 16.54, Nina Schoetterl-Glausch wrote:
>>>>> The EXECUTE instruction executes the instruction at the given target
>>>>> address. This address must be halfword aligned, otherwise a
>>>>> specification exception occurs.
>>>>> Add a test for this.
>>>>>
>>>>> Signed-off-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
>>>>> ---
>>>>>     s390x/spec_ex.c | 25 +++++++++++++++++++++++++
>>>>>     1 file changed, 25 insertions(+)
>>>>>
>>>>> diff --git a/s390x/spec_ex.c b/s390x/spec_ex.c
>>>>> index 83b8c58e..5fa05dba 100644
>>>>> --- a/s390x/spec_ex.c
>>>>> +++ b/s390x/spec_ex.c
>>>>> @@ -177,6 +177,30 @@ static int short_psw_bit_12_is_0(void)
>>>>>         return 0;
>>>>>     }
>>>>> +static int odd_ex_target(void)
>>>>> +{
>>>>> +    uint64_t pre_target_addr;
>>>>> +    int to = 0, from = 0x0dd;
>>>>> +
>>>>> +    asm volatile ( ".pushsection .text.ex_odd\n"
>>>>> +        "    .balign    2\n"
>>>>> +        "pre_odd_ex_target:\n"
>>>>> +        "    . = . + 1\n"
>>>>> +        "    lr    %[to],%[from]\n"
>>>>> +        "    .popsection\n"
>>>>> +
>>>>> +        "    larl    %[pre_target_addr],pre_odd_ex_target\n"
>>>>> +        "    ex    0,1(%[pre_target_addr])\n"
>>>>> +        : [pre_target_addr] "=&a" (pre_target_addr),
>>>>> +          [to] "+d" (to)
>>>>> +        : [from] "d" (from)
>>>>> +    );
>>>>> +
>>>>> +    assert((pre_target_addr + 1) & 1);
>>>>> +    report(to != from, "did not perform ex with odd target");
>>>>> +    return 0;
>>>>> +}
>>>>
>>>> Can this be triggered with KVM, or is this just a test for TCG?
>>>
>>> With "triggered" I mean: Can this cause an interception in KVM?
>>
>> AFAIK no, but KVM and TCG are not the only things we might want to test.
> 
> Ok, fair, KVM unit tests are not for KVM only anymore since quite a while,
> so if this is helpful elsewhere, I'm fine with this.
> 
> Acked-by: Thomas Huth <thuth@redhat.com>

Yes, we might be due for a rename on s390x. On multiple occasions I had 
to tell people that even if the name starts with KVM we're fully capable 
of testing LPAR and zVM :-)

I also want this in for completeness, the line count is certainly of no 
concern here.