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

[Julien Grall <julien@xxxxxxx>]

Hi Jan,

On 31/07/2020 12:45, Jan Beulich wrote:
> On 30.07.2020 20:18, 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()
> >        and XEN_GUEST_HANDLE_PARAM() are the same, they are not on Arm. It
> >        is still fine to use the Arm implementation on x86.
> Is the description stale? I don't think there's any guest_handle_from_param()
> anymore.
Yes, I forgot you removed it. I will update the commit message.

> >      - __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>
> Apart from the above
> Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
Thanks!

Cheers,

--
Julien Grall