Re: [RESEND][PATCH v2 6/7] xen/guest_access: Consolidate guest access helpers in xen/guest_access.h

[Julien Grall <julien@xxxxxxx>]

Hi Stefano,

On 30/07/2020 20:37, Stefano Stabellini wrote:
> On Thu, 30 Jul 2020, Julien Grall wrote:
> > From: Julien Grall <jgrall@xxxxxxxxxx>
> >
> > Most of the helpers to access guest memory are implemented the same way
> > on Arm and x86. The only differences are:
> >      - guest_handle_{from, to}_param(): while on x86 XEN_GUEST_HANDLE()
> It is actually just guest_handle_to_param() ?
Yes. I forgot Jan recently removed the helper in commit dd5520f9df05 
"x86: adjustments to guest handle treatment". I will update the commit 
message.
> >        and XEN_GUEST_HANDLE_PARAM() are the same, they are not on Arm. It
> >        is still fine to use the Arm implementation on x86.
> >      - __clear_guest_offset(): Interestingly the prototype does not match
> >        between the x86 and Arm. However, the Arm one is bogus. So the x86
> >        implementation can be used.
> >      - guest_handle{,_subrange}_okay(): They are validly differing
> >        because Arm is only supporting auto-translated guest and therefore
> >        handles are always valid.
> >
> > In the past, the ia64 and ppc64 port use a different model to access
> > guest parameter. They have been long gone now.
> >
> > Given Xen currently only support 2 archictures, it is too soon to have a
> > directory asm-generic as it is not possible to differentiate it with the
> > existing directory xen/. If/When there is a 3rd port, we can decide to
> > create the new directory if that new port decide to use a different way
> > to access guest parameter.
> >
> > For now, consolidate it in xen/guest_access.h.
> >
> > While it would be possible to adjust the coding style at the same, this
> > is left for a follow-up patch so 'diff' can be used to check the
> > consolidation was done correctly.
> >
> > Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>
> Looks good to me
>
> Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Thank you!

Cheers,

--
Julien Grall