Re: [Xen-devel] [PATCH v7 02/15] argo: introduce the argo_op hypercall boilerplate

[Julien Grall <julien.grall@xxxxxxx>]

Hi Stefano,

On 2/6/19 7:35 PM, Stefano Stabellini wrote:
> On Wed, 6 Feb 2019, Julien Grall wrote:
> > However, I think we should add some sanity check in arch_set_info_guest for
> > our peace of mind. For guest entry/exit, rather than zero the upper 32-bits I
> > would also add sanity check in enter_hypervisor_head and leave_hypervisor_tail
> > but only in debug build. Any opinions?
> Definitely we should have sanity checks.
I will add this one and ...

> > In the official public headers, I can't find anything telling you the size of
> > each arguments and the number of arguments. Instead you have to look at Xen
> > code to know the exact number of arguments and the size. Did I miss anything?
> No, it is like you wrote. I think I should have pushed the discussion
> further and added more information to the Xen public headers back in
> those days.
... and this one in my list of things to improve.

> > > In conclusion, if you and other maintainers prefer unsigned long I'll
> > > drop my reservation.
> > The summary of my e-mail is:
> >      - we need to add sanity check (or zero) upper-bits for 32-bit guest
> >      - unsigned long should be fine for 64-bit only features
> I take that you mean that unsigned long should be fine, and would also
> allow us to introduce 64-bit only features in the future, right? 
that's correct.

You are
> *not* saying that unsigned long should only be used with 64-bit
> guests/hypervisor?
unsigned long == uint32_t on 32-bit. So it would be silly of me to 
suggest that :).
> >      - we need to document the behavior of each hypercall and provide
> > guidelines for new one.
> >
> > None of this is specific to Argo and I would be happy to defer this as a
> > follow-up series.
> Assuming my understanding is right, I agree with you.
You understood right.

Cheers,

--
Julien Grall

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