Re: [RESEND][PATCH v2 5/7] xen: include xen/guest_access.h rather than asm/guest_access.h

[Julien Grall <julien@xxxxxxx>]

On 18/08/2020 09:50, Jan Beulich wrote:
> On 14.08.2020 21:07, Julien Grall wrote:
> > Hi Jan,
> >
> > On 31/07/2020 12:36, Jan Beulich wrote:
> > > On 30.07.2020 20:18, Julien Grall wrote:
> > > > From: Julien Grall <jgrall@xxxxxxxxxx>
> > > >
> > > > Only a few places are actually including asm/guest_access.h. While this
> > > > is fine today, a follow-up patch will want to move most of the helpers
> > > > from asm/guest_access.h to xen/guest_access.h.
> > > >
> > > > To prepare the move, everyone should include xen/guest_access.h rather
> > > > than asm/guest_access.h.
> > > >
> > > > Interestingly, asm-arm/guest_access.h includes xen/guest_access.h. The
> > > > inclusion is now removed as no-one but the latter should include the
> > > > former.
> > > >
> > > > Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>
> > > Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
> > >
> > > Is there any chance you could take measures to avoid new inclusions
> > > of asm/guest_access.h to appear?
> > It should be possible.
> >
> > How about this:
> >
> > diff --git a/xen/include/asm-arm/guest_access.h 
> > b/xen/include/asm-arm/guest_access.h
> > index b9a89c495527..d8dbc7c973b4 100644
> > --- a/xen/include/asm-arm/guest_access.h
> > +++ b/xen/include/asm-arm/guest_access.h
> > @@ -1,3 +1,7 @@
> > +#ifndef ALLOW_INCLUDE_ASM_GUEST_ACCESS_H
> > +#error "asm/guest_access.h should not be included directly"
> > +#endif
> > +
> >   #ifndef __ASM_ARM_GUEST_ACCESS_H__
> >   #define __ASM_ARM_GUEST_ACCESS_H__
> >
> > diff --git a/xen/include/asm-x86/guest_access.h 
> > b/xen/include/asm-x86/guest_access.h
> > index 369676f31ac3..e665ca3a27af 100644
> > --- a/xen/include/asm-x86/guest_access.h
> > +++ b/xen/include/asm-x86/guest_access.h
> > @@ -4,6 +4,10 @@
> >    * Copyright (c) 2006, K A Fraser
> >    */
> >
> > +#ifndef ALLOW_INCLUDE_ASM_GUEST_ACCESS_H
> > +#error "asm/guest_access.h should not be included directly"
> > +#endif
> > +
> >   #ifndef __ASM_X86_GUEST_ACCESS_H__
> >   #define __ASM_X86_GUEST_ACCESS_H__
> >
> > diff --git a/xen/include/xen/guest_access.h b/xen/include/xen/guest_access.h
> > index 75103d30c8be..814e31329de9 100644
> > --- a/xen/include/xen/guest_access.h
> > +++ b/xen/include/xen/guest_access.h
> > @@ -7,7 +7,9 @@
> >   #ifndef __XEN_GUEST_ACCESS_H__
> >   #define __XEN_GUEST_ACCESS_H__
> >
> > +#define ALLOW_INCLUDE_ASM_GUEST_ACCESS_H
> >   #include <asm/guest_access.h>
> > +#undef ALLOW_INCLUDE_ASM_GUEST_ACCESS_H
> >   #include <xen/types.h>
> >   #include <public/xen.h>
> One option. Personally I'd prefer to avoid introduction of yet another
> constant, by leveraging __XEN_GUEST_ACCESS_H__ instead.
I thought about it but it doesn't prevent new inclusions of 
asm/guest_access.h. For instance, the following would still compile:
#include <xen/guest_access.h>

[...]

#include <asm/guest_access.h>

If we want to completely prevent new inclusion, then we need a new 
temporary constant.
Cheers,

--
Julien Grall