diff mbox series

[05/17] xen/x86: address violations of MISRA C:2012 Directive 4.10

Message ID d67d06849732fea11391afd61ff9891ed11795e5.1719829101.git.alessandro.zucchelli@bugseng.com (mailing list archive)
State Superseded
Headers show
Series xen: address violation of MISRA C:2012 Directive 4.10 | expand

Commit Message

Alessandro Zucchelli July 1, 2024, 1:36 p.m. UTC 
From: Simone Ballarin <simone.ballarin@bugseng.com>

Add or move inclusion guards to address violations of
MISRA C:2012 Directive 4.10 ("Precautions shall be taken in order
to prevent the contents of a header file being included more than
once").

Inclusion guards must appear at the beginning of the headers
(comments are permitted anywhere).

Note that in x86_64/mmconfig.h we slightly deviate from the naming
convention in place: instead of having the inclusion guard as
X86_X86_64_MMCONFIG_H we shortened the directory prefix as X86_64 for
the sake of readability.

Mechanical change.

Signed-off-by: Simone Ballarin <simone.ballarin@bugseng.com>
Signed-off-by: Maria Celeste Cesario <maria.celeste.cesario@bugseng.com>
Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
Signed-off-by: Alessandro Zucchelli <alessandro.zucchelli@bugseng.com>

---
Changes in v4:
- modified inclusion guards and makefile.
Changes in v3:
- remove trailing underscores
- change inclusion guard name to adhere to the new standard
Changes in v2:
- remove extra blanks
- drop changes in C files

Note:
Changes in Makefile were not strictly necessary in v1 and a maintainer
asked to removing them since there was a deviation for generated headers.
Now, in v2, they are required since the deviation has been removed by
another patch of this series.
---
 xen/arch/x86/Makefile              | 9 +++++----
 xen/arch/x86/cpu/cpu.h             | 5 +++++
 xen/arch/x86/x86_64/mmconfig.h     | 5 +++++
 xen/arch/x86/x86_emulate/private.h | 5 +++++
 4 files changed, 20 insertions(+), 4 deletions(-)

Comments

Jan Beulich July 1, 2024, 2:21 p.m. UTC | #1 
On 01.07.2024 15:36, Alessandro Zucchelli wrote:
> --- a/xen/arch/x86/Makefile
> +++ b/xen/arch/x86/Makefile
> @@ -260,17 +260,18 @@ $(objtree)/arch/x86/include/asm/asm-macros.h: $(obj)/asm-macros.i $(src)/Makefil
>  	$(call filechk,asm-macros.h)
>  
>  define filechk_asm-macros.h
> +	guard=$$(echo ASM_${SRCARCH}_ASM_MACROS_H | tr a-z A-Z);  \

Nit: Hard tab slipped in.

> +    echo '#ifndef $$guard'; \
> +    echo '#define $$guard'; \
>      echo '#if 0'; \
>      echo '.if 0'; \
>      echo '#endif'; \
> -    echo '#ifndef __ASM_MACROS_H__'; \
> -    echo '#define __ASM_MACROS_H__'; \
>      echo 'asm ( ".include \"$@\"" );'; \
> -    echo '#endif /* __ASM_MACROS_H__ */'; \
>      echo '#if 0'; \
>      echo '.endif'; \
>      cat $<; \
> -    echo '#endif'
> +    echo '#endif'; \
> +    echo '#endif /* $$guard */'
>  endef
>  
>  $(obj)/efi.lds: AFLAGS-y += -DEFI
> --- a/xen/arch/x86/cpu/cpu.h
> +++ b/xen/arch/x86/cpu/cpu.h
> @@ -1,3 +1,6 @@
> +#ifndef X86_CPU_CPU_H
> +#define X86_CPU_CPU_H

This, ...

> --- a/xen/arch/x86/x86_64/mmconfig.h
> +++ b/xen/arch/x86/x86_64/mmconfig.h
> @@ -5,6 +5,9 @@
>   * Author: Allen Kay <allen.m.kay@intel.com> - adapted from linux
>   */
>  
> +#ifndef X86_64_MMCONFIG_H
> +#define X86_64_MMCONFIG_H

... this, and ...

> --- a/xen/arch/x86/x86_emulate/private.h
> +++ b/xen/arch/x86/x86_emulate/private.h
> @@ -6,6 +6,9 @@
>   * Copyright (c) 2005-2007 XenSource Inc.
>   */
>  
> +#ifndef X86_X86_EMULATE_PRIVATE_H
> +#define X86_X86_EMULATE_PRIVATE_H

... this guard can't possibly all follow the same proposed naming scheme
(wherever the final version of that is being recorded; I don't recall it
having gone in, and I didn't spot anything earlier in the series); at
least one must be wrong.

Jan
Alessandro Zucchelli July 9, 2024, 7:38 a.m. UTC | #2 
On 2024-07-01 16:21, Jan Beulich wrote:
> On 01.07.2024 15:36, Alessandro Zucchelli wrote:
>> --- a/xen/arch/x86/Makefile
>> +++ b/xen/arch/x86/Makefile
>> @@ -260,17 +260,18 @@ $(objtree)/arch/x86/include/asm/asm-macros.h: 
>> $(obj)/asm-macros.i $(src)/Makefil
>>  	$(call filechk,asm-macros.h)
>> 
>>  define filechk_asm-macros.h
>> +	guard=$$(echo ASM_${SRCARCH}_ASM_MACROS_H | tr a-z A-Z);  \
> 
> Nit: Hard tab slipped in.
> 
>> +    echo '#ifndef $$guard'; \
>> +    echo '#define $$guard'; \
>>      echo '#if 0'; \
>>      echo '.if 0'; \
>>      echo '#endif'; \
>> -    echo '#ifndef __ASM_MACROS_H__'; \
>> -    echo '#define __ASM_MACROS_H__'; \
>>      echo 'asm ( ".include \"$@\"" );'; \
>> -    echo '#endif /* __ASM_MACROS_H__ */'; \
>>      echo '#if 0'; \
>>      echo '.endif'; \
>>      cat $<; \
>> -    echo '#endif'
>> +    echo '#endif'; \
>> +    echo '#endif /* $$guard */'
>>  endef
>> 
>>  $(obj)/efi.lds: AFLAGS-y += -DEFI
>> --- a/xen/arch/x86/cpu/cpu.h
>> +++ b/xen/arch/x86/cpu/cpu.h
>> @@ -1,3 +1,6 @@
>> +#ifndef X86_CPU_CPU_H
>> +#define X86_CPU_CPU_H
> 
> This, ...
> 
>> --- a/xen/arch/x86/x86_64/mmconfig.h
>> +++ b/xen/arch/x86/x86_64/mmconfig.h
>> @@ -5,6 +5,9 @@
>>   * Author: Allen Kay <allen.m.kay@intel.com> - adapted from linux
>>   */
>> 
>> +#ifndef X86_64_MMCONFIG_H
>> +#define X86_64_MMCONFIG_H
> 
> ... this, and ...
> 
>> --- a/xen/arch/x86/x86_emulate/private.h
>> +++ b/xen/arch/x86/x86_emulate/private.h
>> @@ -6,6 +6,9 @@
>>   * Copyright (c) 2005-2007 XenSource Inc.
>>   */
>> 
>> +#ifndef X86_X86_EMULATE_PRIVATE_H
>> +#define X86_X86_EMULATE_PRIVATE_H
> 
> ... this guard can't possibly all follow the same proposed naming 
> scheme
> (wherever the final version of that is being recorded; I don't recall 
> it
> having gone in, and I didn't spot anything earlier in the series); at
> least one must be wrong.

For x86/x86_64/mmconfig.h has been made an exception as stated in the 
commit
message:
Note that in x86_64/mmconfig.h we slightly deviate from the naming
convention in place: instead of having the inclusion guard as
X86_X86_64_MMCONFIG_H we shortened the directory prefix as X86_64 for
the sake of readability.

If you do not agree with this exception and you prefer to keep the 
additional
X86_ prefix let me know so as I prepare the patch series V5 I may 
reintroduce it.

Best regards,
Jan Beulich July 9, 2024, 7:45 a.m. UTC | #3 
On 09.07.2024 09:38, Alessandro Zucchelli wrote:
> On 2024-07-01 16:21, Jan Beulich wrote:
>> On 01.07.2024 15:36, Alessandro Zucchelli wrote:
>>> --- a/xen/arch/x86/Makefile
>>> +++ b/xen/arch/x86/Makefile
>>> @@ -260,17 +260,18 @@ $(objtree)/arch/x86/include/asm/asm-macros.h: 
>>> $(obj)/asm-macros.i $(src)/Makefil
>>>  	$(call filechk,asm-macros.h)
>>>
>>>  define filechk_asm-macros.h
>>> +	guard=$$(echo ASM_${SRCARCH}_ASM_MACROS_H | tr a-z A-Z);  \
>>
>> Nit: Hard tab slipped in.
>>
>>> +    echo '#ifndef $$guard'; \
>>> +    echo '#define $$guard'; \
>>>      echo '#if 0'; \
>>>      echo '.if 0'; \
>>>      echo '#endif'; \
>>> -    echo '#ifndef __ASM_MACROS_H__'; \
>>> -    echo '#define __ASM_MACROS_H__'; \
>>>      echo 'asm ( ".include \"$@\"" );'; \
>>> -    echo '#endif /* __ASM_MACROS_H__ */'; \
>>>      echo '#if 0'; \
>>>      echo '.endif'; \
>>>      cat $<; \
>>> -    echo '#endif'
>>> +    echo '#endif'; \
>>> +    echo '#endif /* $$guard */'
>>>  endef
>>>
>>>  $(obj)/efi.lds: AFLAGS-y += -DEFI
>>> --- a/xen/arch/x86/cpu/cpu.h
>>> +++ b/xen/arch/x86/cpu/cpu.h
>>> @@ -1,3 +1,6 @@
>>> +#ifndef X86_CPU_CPU_H
>>> +#define X86_CPU_CPU_H
>>
>> This, ...
>>
>>> --- a/xen/arch/x86/x86_64/mmconfig.h
>>> +++ b/xen/arch/x86/x86_64/mmconfig.h
>>> @@ -5,6 +5,9 @@
>>>   * Author: Allen Kay <allen.m.kay@intel.com> - adapted from linux
>>>   */
>>>
>>> +#ifndef X86_64_MMCONFIG_H
>>> +#define X86_64_MMCONFIG_H
>>
>> ... this, and ...
>>
>>> --- a/xen/arch/x86/x86_emulate/private.h
>>> +++ b/xen/arch/x86/x86_emulate/private.h
>>> @@ -6,6 +6,9 @@
>>>   * Copyright (c) 2005-2007 XenSource Inc.
>>>   */
>>>
>>> +#ifndef X86_X86_EMULATE_PRIVATE_H
>>> +#define X86_X86_EMULATE_PRIVATE_H
>>
>> ... this guard can't possibly all follow the same proposed naming 
>> scheme
>> (wherever the final version of that is being recorded; I don't recall 
>> it
>> having gone in, and I didn't spot anything earlier in the series); at
>> least one must be wrong.
> 
> For x86/x86_64/mmconfig.h has been made an exception as stated in the 
> commit
> message:
> Note that in x86_64/mmconfig.h we slightly deviate from the naming
> convention in place: instead of having the inclusion guard as
> X86_X86_64_MMCONFIG_H we shortened the directory prefix as X86_64 for
> the sake of readability.
> 
> If you do not agree with this exception and you prefer to keep the 
> additional
> X86_ prefix let me know so as I prepare the patch series V5 I may 
> reintroduce it.

What I have an issue with is making an exception in one place when quite
clearly would as much (or as little) benefit from one. Before there's
any further back and forth, I'd like to suggest that you wait with
adjustments here until the base scheme has really been agreed upon,
including situations where we think we'd like to make exceptions (after
all we might decide that there simply shouldn't be exceptions, and that
in order to eliminate such redundancy in guard identifiers we'd rather
like to rename some of the files).

Jan
Stefano Stabellini July 12, 2024, 10:09 p.m. UTC | #4 
On Tue, 9 Jul 2024, Jan Beulich wrote:
> On 09.07.2024 09:38, Alessandro Zucchelli wrote:
> > On 2024-07-01 16:21, Jan Beulich wrote:
> >> On 01.07.2024 15:36, Alessandro Zucchelli wrote:
> >>> --- a/xen/arch/x86/Makefile
> >>> +++ b/xen/arch/x86/Makefile
> >>> @@ -260,17 +260,18 @@ $(objtree)/arch/x86/include/asm/asm-macros.h: 
> >>> $(obj)/asm-macros.i $(src)/Makefil
> >>>  	$(call filechk,asm-macros.h)
> >>>
> >>>  define filechk_asm-macros.h
> >>> +	guard=$$(echo ASM_${SRCARCH}_ASM_MACROS_H | tr a-z A-Z);  \
> >>
> >> Nit: Hard tab slipped in.
> >>
> >>> +    echo '#ifndef $$guard'; \
> >>> +    echo '#define $$guard'; \
> >>>      echo '#if 0'; \
> >>>      echo '.if 0'; \
> >>>      echo '#endif'; \
> >>> -    echo '#ifndef __ASM_MACROS_H__'; \
> >>> -    echo '#define __ASM_MACROS_H__'; \
> >>>      echo 'asm ( ".include \"$@\"" );'; \
> >>> -    echo '#endif /* __ASM_MACROS_H__ */'; \
> >>>      echo '#if 0'; \
> >>>      echo '.endif'; \
> >>>      cat $<; \
> >>> -    echo '#endif'
> >>> +    echo '#endif'; \
> >>> +    echo '#endif /* $$guard */'
> >>>  endef
> >>>
> >>>  $(obj)/efi.lds: AFLAGS-y += -DEFI
> >>> --- a/xen/arch/x86/cpu/cpu.h
> >>> +++ b/xen/arch/x86/cpu/cpu.h
> >>> @@ -1,3 +1,6 @@
> >>> +#ifndef X86_CPU_CPU_H
> >>> +#define X86_CPU_CPU_H
> >>
> >> This, ...
> >>
> >>> --- a/xen/arch/x86/x86_64/mmconfig.h
> >>> +++ b/xen/arch/x86/x86_64/mmconfig.h
> >>> @@ -5,6 +5,9 @@
> >>>   * Author: Allen Kay <allen.m.kay@intel.com> - adapted from linux
> >>>   */
> >>>
> >>> +#ifndef X86_64_MMCONFIG_H
> >>> +#define X86_64_MMCONFIG_H
> >>
> >> ... this, and ...
> >>
> >>> --- a/xen/arch/x86/x86_emulate/private.h
> >>> +++ b/xen/arch/x86/x86_emulate/private.h
> >>> @@ -6,6 +6,9 @@
> >>>   * Copyright (c) 2005-2007 XenSource Inc.
> >>>   */
> >>>
> >>> +#ifndef X86_X86_EMULATE_PRIVATE_H
> >>> +#define X86_X86_EMULATE_PRIVATE_H
> >>
> >> ... this guard can't possibly all follow the same proposed naming 
> >> scheme
> >> (wherever the final version of that is being recorded; I don't recall 
> >> it
> >> having gone in, and I didn't spot anything earlier in the series); at
> >> least one must be wrong.
> > 
> > For x86/x86_64/mmconfig.h has been made an exception as stated in the 
> > commit
> > message:
> > Note that in x86_64/mmconfig.h we slightly deviate from the naming
> > convention in place: instead of having the inclusion guard as
> > X86_X86_64_MMCONFIG_H we shortened the directory prefix as X86_64 for
> > the sake of readability.
> > 
> > If you do not agree with this exception and you prefer to keep the 
> > additional
> > X86_ prefix let me know so as I prepare the patch series V5 I may 
> > reintroduce it.
> 
> What I have an issue with is making an exception in one place when quite
> clearly would as much (or as little) benefit from one. Before there's
> any further back and forth, I'd like to suggest that you wait with
> adjustments here until the base scheme has really been agreed upon,
> including situations where we think we'd like to make exceptions (after
> all we might decide that there simply shouldn't be exceptions, and that
> in order to eliminate such redundancy in guard identifiers we'd rather
> like to rename some of the files).

I don't think it is a good idea to introduce a naming scheme and
immediately add exceptions. I would stick to the naming scheme even if
it doesn't always lead to the best possible name. Also these are header
guards, they are not critical variables for which clarity and shortness
are paramount.

The naming scheme was written in the 0 email and copy/pasted here for
convenience:

- private headers -> <dir>_<filename>_H
- asm-generic headers -> ASM_GENERIC_<filename>_H
- arch/<architecture>/include/asm/<subdir>/<filename>.h -> ASM_<architecture>_<subdir>_<filename>_H
- include/generated/<subdir>/<filename>.h-> GENERATED_<subdir>_<filename>_H
- arch/<architecture>/include/generated/asm/<filename>.h-> <arch>_GENERATED_ASM_<name>_H

So in this patch I would sticked to the naming scheme and used:

X86_CPU_CPU_H
X86_X86_64_MMCONFIG_H
X86_X86_EMULATE_PRIVATE_H
Jan Beulich July 15, 2024, 7:27 a.m. UTC | #5 
On 13.07.2024 00:09, Stefano Stabellini wrote:
> On Tue, 9 Jul 2024, Jan Beulich wrote:
>> On 09.07.2024 09:38, Alessandro Zucchelli wrote:
>>> On 2024-07-01 16:21, Jan Beulich wrote:
>>>> On 01.07.2024 15:36, Alessandro Zucchelli wrote:
>>>>> --- a/xen/arch/x86/Makefile
>>>>> +++ b/xen/arch/x86/Makefile
>>>>> @@ -260,17 +260,18 @@ $(objtree)/arch/x86/include/asm/asm-macros.h: 
>>>>> $(obj)/asm-macros.i $(src)/Makefil
>>>>>  	$(call filechk,asm-macros.h)
>>>>>
>>>>>  define filechk_asm-macros.h
>>>>> +	guard=$$(echo ASM_${SRCARCH}_ASM_MACROS_H | tr a-z A-Z);  \
>>>>
>>>> Nit: Hard tab slipped in.
>>>>
>>>>> +    echo '#ifndef $$guard'; \
>>>>> +    echo '#define $$guard'; \
>>>>>      echo '#if 0'; \
>>>>>      echo '.if 0'; \
>>>>>      echo '#endif'; \
>>>>> -    echo '#ifndef __ASM_MACROS_H__'; \
>>>>> -    echo '#define __ASM_MACROS_H__'; \
>>>>>      echo 'asm ( ".include \"$@\"" );'; \
>>>>> -    echo '#endif /* __ASM_MACROS_H__ */'; \
>>>>>      echo '#if 0'; \
>>>>>      echo '.endif'; \
>>>>>      cat $<; \
>>>>> -    echo '#endif'
>>>>> +    echo '#endif'; \
>>>>> +    echo '#endif /* $$guard */'
>>>>>  endef
>>>>>
>>>>>  $(obj)/efi.lds: AFLAGS-y += -DEFI
>>>>> --- a/xen/arch/x86/cpu/cpu.h
>>>>> +++ b/xen/arch/x86/cpu/cpu.h
>>>>> @@ -1,3 +1,6 @@
>>>>> +#ifndef X86_CPU_CPU_H
>>>>> +#define X86_CPU_CPU_H
>>>>
>>>> This, ...
>>>>
>>>>> --- a/xen/arch/x86/x86_64/mmconfig.h
>>>>> +++ b/xen/arch/x86/x86_64/mmconfig.h
>>>>> @@ -5,6 +5,9 @@
>>>>>   * Author: Allen Kay <allen.m.kay@intel.com> - adapted from linux
>>>>>   */
>>>>>
>>>>> +#ifndef X86_64_MMCONFIG_H
>>>>> +#define X86_64_MMCONFIG_H
>>>>
>>>> ... this, and ...
>>>>
>>>>> --- a/xen/arch/x86/x86_emulate/private.h
>>>>> +++ b/xen/arch/x86/x86_emulate/private.h
>>>>> @@ -6,6 +6,9 @@
>>>>>   * Copyright (c) 2005-2007 XenSource Inc.
>>>>>   */
>>>>>
>>>>> +#ifndef X86_X86_EMULATE_PRIVATE_H
>>>>> +#define X86_X86_EMULATE_PRIVATE_H
>>>>
>>>> ... this guard can't possibly all follow the same proposed naming 
>>>> scheme
>>>> (wherever the final version of that is being recorded; I don't recall 
>>>> it
>>>> having gone in, and I didn't spot anything earlier in the series); at
>>>> least one must be wrong.
>>>
>>> For x86/x86_64/mmconfig.h has been made an exception as stated in the 
>>> commit
>>> message:
>>> Note that in x86_64/mmconfig.h we slightly deviate from the naming
>>> convention in place: instead of having the inclusion guard as
>>> X86_X86_64_MMCONFIG_H we shortened the directory prefix as X86_64 for
>>> the sake of readability.
>>>
>>> If you do not agree with this exception and you prefer to keep the 
>>> additional
>>> X86_ prefix let me know so as I prepare the patch series V5 I may 
>>> reintroduce it.
>>
>> What I have an issue with is making an exception in one place when quite
>> clearly would as much (or as little) benefit from one. Before there's
>> any further back and forth, I'd like to suggest that you wait with
>> adjustments here until the base scheme has really been agreed upon,
>> including situations where we think we'd like to make exceptions (after
>> all we might decide that there simply shouldn't be exceptions, and that
>> in order to eliminate such redundancy in guard identifiers we'd rather
>> like to rename some of the files).
> 
> I don't think it is a good idea to introduce a naming scheme and
> immediately add exceptions. I would stick to the naming scheme even if
> it doesn't always lead to the best possible name. Also these are header
> guards, they are not critical variables for which clarity and shortness
> are paramount.
> 
> The naming scheme was written in the 0 email and copy/pasted here for
> convenience:
> 
> - private headers -> <dir>_<filename>_H
> - asm-generic headers -> ASM_GENERIC_<filename>_H
> - arch/<architecture>/include/asm/<subdir>/<filename>.h -> ASM_<architecture>_<subdir>_<filename>_H
> - include/generated/<subdir>/<filename>.h-> GENERATED_<subdir>_<filename>_H
> - arch/<architecture>/include/generated/asm/<filename>.h-> <arch>_GENERATED_ASM_<name>_H
> 
> So in this patch I would sticked to the naming scheme and used:
> 
> X86_CPU_CPU_H
> X86_X86_64_MMCONFIG_H
> X86_X86_EMULATE_PRIVATE_H

Uniformly sticking to the scheme is definitely an option. Provided we're
happy with excessively long identifiers (think of, sooner or later, there
going to be style violations wrt line length) and ones having overly
redundant name components. Yet as said elsewhere, first and foremost I
think we need a scheme where collisions cannot occur.

Jan
diff mbox series

Patch

diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
index d902fb7acc..06d1bab43c 100644
--- a/xen/arch/x86/Makefile
+++ b/xen/arch/x86/Makefile
@@ -260,17 +260,18 @@  $(objtree)/arch/x86/include/asm/asm-macros.h: $(obj)/asm-macros.i $(src)/Makefil
 	$(call filechk,asm-macros.h)
 
 define filechk_asm-macros.h
+	guard=$$(echo ASM_${SRCARCH}_ASM_MACROS_H | tr a-z A-Z);  \
+    echo '#ifndef $$guard'; \
+    echo '#define $$guard'; \
     echo '#if 0'; \
     echo '.if 0'; \
     echo '#endif'; \
-    echo '#ifndef __ASM_MACROS_H__'; \
-    echo '#define __ASM_MACROS_H__'; \
     echo 'asm ( ".include \"$@\"" );'; \
-    echo '#endif /* __ASM_MACROS_H__ */'; \
     echo '#if 0'; \
     echo '.endif'; \
     cat $<; \
-    echo '#endif'
+    echo '#endif'; \
+    echo '#endif /* $$guard */'
 endef
 
 $(obj)/efi.lds: AFLAGS-y += -DEFI
diff --git a/xen/arch/x86/cpu/cpu.h b/xen/arch/x86/cpu/cpu.h
index 8be65e975a..ee1c176ca4 100644
--- a/xen/arch/x86/cpu/cpu.h
+++ b/xen/arch/x86/cpu/cpu.h
@@ -1,3 +1,6 @@ 
+#ifndef X86_CPU_CPU_H
+#define X86_CPU_CPU_H
+
 /* attempt to consolidate cpu attributes */
 struct cpu_dev {
 	void		(*c_early_init)(struct cpuinfo_x86 *c);
@@ -26,3 +29,5 @@  void amd_init_spectral_chicken(void);
 void detect_zen2_null_seg_behaviour(void);
 
 void intel_unlock_cpuid_leaves(struct cpuinfo_x86 *c);
+
+#endif /* X86_CPU_CPU_H */
diff --git a/xen/arch/x86/x86_64/mmconfig.h b/xen/arch/x86/x86_64/mmconfig.h
index 3da4b21e9b..722bf67975 100644
--- a/xen/arch/x86/x86_64/mmconfig.h
+++ b/xen/arch/x86/x86_64/mmconfig.h
@@ -5,6 +5,9 @@ 
  * Author: Allen Kay <allen.m.kay@intel.com> - adapted from linux
  */
 
+#ifndef X86_64_MMCONFIG_H
+#define X86_64_MMCONFIG_H
+
 #define PCI_DEVICE_ID_INTEL_E7520_MCH    0x3590
 #define PCI_DEVICE_ID_INTEL_82945G_HB    0x2770
 
@@ -72,3 +75,5 @@  int pci_mmcfg_reserved(uint64_t address, unsigned int segment,
 int pci_mmcfg_arch_init(void);
 int pci_mmcfg_arch_enable(unsigned int idx);
 void pci_mmcfg_arch_disable(unsigned int idx);
+
+#endif /* X86_64_MMCONFIG_H */
diff --git a/xen/arch/x86/x86_emulate/private.h b/xen/arch/x86/x86_emulate/private.h
index 0fa26ba00a..8429b30b5e 100644
--- a/xen/arch/x86/x86_emulate/private.h
+++ b/xen/arch/x86/x86_emulate/private.h
@@ -6,6 +6,9 @@ 
  * Copyright (c) 2005-2007 XenSource Inc.
  */
 
+#ifndef X86_X86_EMULATE_PRIVATE_H
+#define X86_X86_EMULATE_PRIVATE_H
+
 #ifdef __XEN__
 
 # include <xen/bug.h>
@@ -836,3 +839,5 @@  static inline int read_ulong(enum x86_segment seg,
     *val = 0;
     return ops->read(seg, offset, val, bytes, ctxt);
 }
+
+#endif /* X86_X86_EMULATE_PRIVATE_H */