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

[Jan Beulich <jbeulich@suse.com>]

On 30.07.2020 20:18, Julien Grall wrote:
> From: Julien Grall <jgrall@amazon.com>
> 
> 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.

>     - __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@amazon.com>

Apart from the above
Acked-by: Jan Beulich <jbeulich@suse.com>

Jan