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





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



 


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