Re: [XEN PATCH v2] arm/mem_access: add conditional build of mem_access.c

[Julien Grall <julien@xxxxxxx>]

Hi,

On 09/05/2024 11:39, Alessandro Zucchelli wrote:
> In order to comply to MISRA C:2012 Rule 8.4 for ARM asm/mem_access.h in
> the case where MEM_ACCESS=n stubs are needed to allow the conditional
> compilation of the users of this header.
I think you need to update the commit message given ...

> Signed-off-by: Alessandro Zucchelli <alessandro.zucchelli@xxxxxxxxxxx>
> ---
> Changes from v1:
> Reverted preprocessor conditional changes to xen/mem_access.h;
> added conditional build for xen/mem_access.c;
> provided stubs for asm/mem_access.h functions.
> ---
>   xen/arch/arm/Makefile                 | 2 +-
>   xen/arch/arm/include/asm/mem_access.h | 9 +++++++++
>   2 files changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/xen/arch/arm/Makefile b/xen/arch/arm/Makefile
> index 7b1350e2ef..45dc29ea53 100644
> --- a/xen/arch/arm/Makefile
> +++ b/xen/arch/arm/Makefile
> @@ -37,7 +37,7 @@ obj-$(CONFIG_IOREQ_SERVER) += ioreq.o
>   obj-y += irq.o
>   obj-y += kernel.init.o
>   obj-$(CONFIG_LIVEPATCH) += livepatch.o
> -obj-y += mem_access.o
> +obj-$(CONFIG_MEM_ACCESS) += mem_access.o
... this not only adding stub.

>   obj-y += mm.o
>   obj-y += monitor.o
>   obj-y += p2m.o
> diff --git a/xen/arch/arm/include/asm/mem_access.h 
> b/xen/arch/arm/include/asm/mem_access.h
> index 35ed0ad154..2f73172e39 100644
> --- a/xen/arch/arm/include/asm/mem_access.h
> +++ b/xen/arch/arm/include/asm/mem_access.h
> @@ -17,6 +17,7 @@
>   #ifndef _ASM_ARM_MEM_ACCESS_H
>   #define _ASM_ARM_MEM_ACCESS_H
>   
> +#include <xen/types.h>
Can you explain why this is needed?

Style: Newline here please.

>   static inline
>   bool p2m_mem_access_emulate_check(struct vcpu *v,
>                                     const struct vm_event_st *rsp)
> @@ -35,12 +36,20 @@ static inline bool p2m_mem_access_sanity_check(struct 
> domain *d)
>    * Send mem event based on the access. Boolean return value indicates if trap
>    * needs to be injected into guest.
>    */
> +#ifdef CONFIG_MEM_ACCESS
>   bool p2m_mem_access_check(paddr_t gpa, vaddr_t gla, const struct npfec npfec);
>   
>   struct page_info*
>   p2m_mem_access_check_and_get_page(vaddr_t gva, unsigned long flag,
>                                     const struct vcpu *v);
> +#else
>   
> +static inline bool p2m_mem_access_check(paddr_t gpa, vaddr_t gla, const struct npfec npfec) {return false;}
Coding style: The line is well over the 80 characters limit. Also we 
don't tend to provide the implementation of the stub in the single line 
if it is more than {}. So "{return false;}" should look like:
{
   return false;
}

> +
> +static inline struct page_info*
> +p2m_mem_access_check_and_get_page(vaddr_t gva, unsigned long flag,
> +                                  const struct vcpu *v) {return NULL;}
Ditto.

> +#endif /*CONFIG_MEM_ACCESS*/
>   #endif /* _ASM_ARM_MEM_ACCESS_H */
>   
>   /*
Cheers,

--
Julien Grall