Re: [PATCH v9] qapi: introduce 'query-kvm-cpuid' action

[Claudio Fontana]

On 6/18/21 10:40 PM, Eduardo Habkost wrote:
> On Fri, Jun 18, 2021 at 07:52:47AM +0200, Markus Armbruster wrote:
>> Eduardo Habkost <ehabkost@redhat.com> writes:
>>
>>> On Thu, Jun 17, 2021 at 05:53:11PM +0200, Claudio Fontana wrote:
>>>> On 6/17/21 5:39 PM, Valeriy Vdovin wrote:
>>>>> On Thu, Jun 17, 2021 at 04:14:17PM +0200, Markus Armbruster wrote:
>>>>>> Claudio Fontana <cfontana@suse.de> writes:
>>>>>>
>>>>>>> On 6/17/21 1:09 PM, Markus Armbruster wrote:
>>
>> [...]
>>
>>>>>>>> If it just isn't implemented for anything but KVM, then putting "kvm"
>>>>>>>> into the command name is a bad idea.  Also, the commit message should
>>>>>>>> briefly note the restriction to KVM.
>>>>>>
>>>>>> Perhaps this one is closer to reality.
>>>>>>
>>>>> I agree.
>>>>> What command name do you suggest?
>>>>
>>>> query-exposed-cpuid?
>>>
>>> Pasting the reply I sent at [1]:
>>>
>>>   I don't really mind how the command is called, but I would prefer
>>>   to add a more complex abstraction only if maintainers of other
>>>   accelerators are interested and volunteer to provide similar
>>>   functionality.  I don't want to introduce complexity for use
>>>   cases that may not even exist.
>>>
>>> I'm expecting this to be just a debugging mechanism, not a stable
>>> API to be maintained and supported for decades.  (Maybe a "x-"
>>> prefix should be added to indicate that?)
>>>
>>> [1] 
>>> 20210602204604.crsxvqixkkll4ef4@habkost.net">https://lore.kernel.org/qemu-devel/20210602204604.crsxvqixkkll4ef4@habkost.net
>>
>> x-query-x86_64-cpuid?
>>
> 
> Unless somebody wants to spend time designing a generic
> abstraction around this (and justify the extra complexity), this
> is a KVM-specific command.  Is there a reason to avoid "kvm" in
> the command name?
> 

If the point of all of this is "please get me the cpuid, as seen by the guest", 
then I fail to see how this should be kvm-only.
We can still return "not implemented" of some kind for HVF, TCG etc.

But maybe I misread the use case?

Thanks,

C