Re: [kvm-unit-tests RFC PATCH 3/5] run_tests.sh: Add kvmtool support

[Alexandru Elisei <alexandru.elisei@arm.com>]

Hi Drew,

On 9/8/21 4:49 PM, Andrew Jones wrote:
> On Wed, Sep 08, 2021 at 04:46:19PM +0100, Alexandru Elisei wrote:
>> Hi Drew,
>>
>> On 9/8/21 4:09 PM, Andrew Jones wrote:
>>> On Wed, Sep 08, 2021 at 03:33:19PM +0100, Alexandru Elisei wrote:
>>> ...
>>>>>> +fixup_kvmtool_opts()
>>>>>> +{
>>>>>> +    local opts=$1
>>>>>> +    local groups=$2
>>>>>> +    local gic
>>>>>> +    local gic_version
>>>>>> +
>>>>>> +    if find_word "pmu" $groups; then
>>>>>> +        opts+=" --pmu"
>>>>>> +    fi
>>>>>> +
>>>>>> +    if find_word "its" $groups; then
>>>>>> +        gic_version=3
>>>>>> +        gic="gicv3-its"
>>>>>> +    elif [[ "$opts" =~ -machine\ *gic-version=(2|3) ]]; then
>>>>>> +        gic_version="${BASH_REMATCH[1]}"
>>>>>> +        gic="gicv$gic_version"
>>>>>> +    fi
>>>>>> +
>>>>>> +    if [ -n "$gic" ]; then
>>>>>> +        opts=${opts/-machine gic-version=$gic_version/}
>>>>>> +        opts+=" --irqchip=$gic"
>>>>>> +    fi
>>>>>> +
>>>>>> +    opts=${opts/-append/--params}
>>>>>> +
>>>>>> +    echo "$opts"
>>>>>> +}
>>>>> Hmm, I don't think we want to write a QEMU parameter translator for
>>>>> all other VMMs, and all other VMM architectures, that we want to
>>>>> support. I think we should add new "extra_params" variables to the
>>>>> unittest configuration instead, e.g. "kvmtool_params", where the
>>>>> extra parameters can be listed correctly and explicitly. While at
>>>>> it, I would create an alias for "extra_params", which would be
>>>>> "qemu_params" allowing unittests that support more than one VMM
>>>>> to clearly show what's what.
>>>> I agree, this is a much better idea than a parameter translator. Using a dedicated
>>>> variable in unittests.cfg will make it easier for new tests to get support for all
>>>> VMMs (for example, writing a list of parameters in unittests.cfg should be easier
>>>> than digging through the scripts to figure exactly how and where to add a
>>>> translation for a new parameter), and it allow us to express parameters for other
>>>> VMMs which don't have a direct correspondent in qemu.
>>>>
>>>> By creating an alias, do you mean replacing extra_params with qemu_params in
>>>> arm/unittests.cfg? Or something else?
>>> Probably something like this
>>>
>>> diff --git a/scripts/common.bash b/scripts/common.bash
>>> index 7b983f7d6dd6..e5119ff216e5 100644
>>> --- a/scripts/common.bash
>>> +++ b/scripts/common.bash
>>> @@ -37,7 +37,12 @@ function for_each_unittest()
>>>                 elif [[ $line =~ ^smp\ *=\ *(.*)$ ]]; then
>>>                         smp=${BASH_REMATCH[1]}
>>>                 elif [[ $line =~ ^extra_params\ *=\ *(.*)$ ]]; then
>>> -                       opts=${BASH_REMATCH[1]}
>>> +               elif [[ $line =~ ^extra_params\ *=\ *(.*)$ ]]; then
>>> +                       qemu_opts=${BASH_REMATCH[1]}
>>> +               elif [[ $line =~ ^qemu_params\ *=\ *(.*)$ ]]; then
>>> +                       qemu_opts=${BASH_REMATCH[1]}
>>> +               elif [[ $line =~ ^kvmtool_params\ *=\ *(.*)$ ]]; then
>>> +                       kvmtool_opts=${BASH_REMATCH[1]}
>>>                 elif [[ $line =~ ^groups\ *=\ *(.*)$ ]]; then
>>>                         groups=${BASH_REMATCH[1]}
>>>                 elif [[ $line =~ ^arch\ *=\ *(.*)$ ]]; then
>>>
>>> and all other changes needed to support the s/opts/qemu_opts/ change
>>> should work. Also, an addition to the unittests.cfg documentation.
>> Got it, replace extra_opts with qemu_opts in the scripts.
>>
>> Yes, the documentation for unittests.cfg (at the top of the file) should
>> definitely be updated to document the new configuration option, kvmtool_params.
>>
>>> The above diff doesn't consider that a unittests.cfg file could have
>>> both an 'extra_params' and a 'qemu_params' field, but I'm not sure
>>> we care about that. Users should read the documentation and we
>>> should review changes to the committed unittests.cfg files to avoid
>>> that.
>> What do you feel about renaming extra_params -> qemu_params in unittests.cfg?
> Yes, that's what I would expect the patch to do.
>
>> I'm
>> thinking it would make the usage clearer, improve consistency (we would have
>> qemu_params and kvmtool_params, instead of extra_params and kvmtool_params), and
>> remove any confusions regarding when they are used (I can see someone thinking
>> that extra_params are used all the time, and are appended to kvmtool_params when
>> --target=kvmtool). On the other hand, this could be problematic for people using
>> out-of-tree scripts that parse the unittest.cfg file for whatever reason (are
>> there people that do that?).
> I'm not as worried about that as about people using out-of-tree
> unittests.cfg files that will break when the 'extra_params' field
> disappears. That's why I suggested to make 'extra_params' an alias.

I'm sorry, but I'm still having trouble parsing what alias means in this context.
Do you mean keep extra_params for current tests, encourage qemu_params for new
tests, document that they mean the same thing and going forward qemu_params should
be used?

Thanks,

Alex

>
> Thanks,
> drew
>
>> Thanks,
>>
>> Alex
>>
>>> Thanks,
>>> drew
>>>
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