Re: [PATCH v3 5/7] arm/mpu: Introduce MPU memory mapping flags

[Julien Grall <julien@xxxxxxx>]

Hi Luca,

On 11/04/2025 23:56, Luca Fancellu wrote:
> Introduce the MPU memory mapping flags in asm/page.h.
>
> Signed-off-by: Luca Fancellu <luca.fancellu@xxxxxxx>
> ---
>   xen/arch/arm/include/asm/page.h | 25 +++++++++++++++++++++++++
>   1 file changed, 25 insertions(+)
>
> diff --git a/xen/arch/arm/include/asm/page.h b/xen/arch/arm/include/asm/page.h
> index 69f817d1e68a..22f7d2c6cb30 100644
> --- a/xen/arch/arm/include/asm/page.h
> +++ b/xen/arch/arm/include/asm/page.h
> @@ -62,6 +62,7 @@
>   
>   #define MAIRVAL (MAIR1VAL << 32 | MAIR0VAL)
>   
> +#ifdef CONFIG_MMU
>   /*
>    * Layout of the flags used for updating the hypervisor page tables
>    *
> @@ -90,6 +91,30 @@
>   #define _PAGE_CONTIG_BIT    8
>   #define _PAGE_CONTIG        (1U << _PAGE_CONTIG_BIT)
>   
> +#else /* !CONFIG_MMU */
> +
> +/*
> + * Layout of the flags used for updating MPU memory region attributes
> + * [0:2] Memory attribute Index
> + * [3:4] Execute Never
> + * [5:6] Access Permission
I am rather confused why we are splitting Execute Never from the Access 
Permission. I guess you tried to match the HW, but it also means we need 
to duplicate a lot of define between the MMU and MPU code.
Instead, I would rather try to re-use the existing ones and ignore the 
ones we don't need (e.g. BLOCK_BIT and CONTIG).
Cheers,

--
Julien Grall