Re: [RFC v2 00/18] Refactor configuration of guest memory protection

[Thiago Jung Bauermann]

David Gibson <david@gibson.dropbear.id.au> writes:

> On Fri, Jun 05, 2020 at 05:01:07PM -0300, Thiago Jung Bauermann wrote:
>> 
>> Paolo Bonzini <pbonzini@redhat.com> writes:
>> 
>> > On 05/06/20 01:30, Thiago Jung Bauermann wrote:
>> >> Paolo Bonzini <pbonzini@redhat.com> writes:
>> >>> On 04/06/20 23:54, Thiago Jung Bauermann wrote:
>> >>>> QEMU could always create a PEF object, and if the command line defines
>> >>>> one, it will correspond to it. And if the command line doesn't define 
>> >>>> one,
>> >>>> then it would also work because the PEF object is already there.
>> >>>
>> >>> How would you start a non-protected VM?
>> >>> Currently it's the "-machine"
>> >>> property that decides that, and the argument requires an id
>> >>> corresponding to "-object".
>> >>
>> >> If there's only one object, there's no need to specify its id.
>> >
>> > This answers my question.  However, the property is defined for all
>> > machines (it's in the "machine" class), so if it takes the id for one
>> > machine it does so for all of them.
>> 
>> I don't understand much about QEMU internals, so perhaps it's not
>> practical to implement but from an end-user perspective I think this
>> logic can apply to all architectures (since my understanding is that all
>> of them use only one object): make the id optional. If it's not
>> specified, then there must be only one object, and the property will
>> implicitly refer to it.
>> 
>> Then, if an architecture doesn't need to specify parameters at object
>> creation time, it can be implicitly created and the user doesn't have to
>> worry about this detail.
>
> Seems overly complicated to me.  We could just have it always take an
> ID, but for platforms with no extra configuration make the
> pre-fabricated object available under a well-known name.
>
> That's essentially the same as the way you can add a device to the
> "pci.0" bus without having to instantiate and name that bus yourself.

Ok, that sounds good to me.

-- 
Thiago Jung Bauermann
IBM Linux Technology Center