Re: [PATCH 7/9] arm/mpu: Introduce MPU memory mapping flags

[Ayan Kumar Halder <ayankuma@xxxxxxx>]

Hi Luca,

On 28/02/2025 16:18, Luca Fancellu wrote:
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>
> 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
> + * [7]   Region Present
> + */
> +#define _PAGE_AI_BIT            0
> +#define _PAGE_XN_BIT            3
> +#define _PAGE_AP_BIT            5
> +#define _PAGE_PRESENT_BIT       7
> +#define _PAGE_AI                (7U << _PAGE_AI_BIT)
> +#define _PAGE_XN                (2U << _PAGE_XN_BIT)
> +#define _PAGE_RO                (2U << _PAGE_AP_BIT)
> +#define _PAGE_PRESENT           (1U << _PAGE_PRESENT_BIT)
> +#define PAGE_AI_MASK(x)         (((x) >> _PAGE_AI_BIT) & 0x7U)
> +#define PAGE_XN_MASK(x)         (((x) >> _PAGE_XN_BIT) & 0x3U)
> +#define PAGE_AP_MASK(x)         (((x) >> _PAGE_AP_BIT) & 0x3U)
> +#define PAGE_RO_MASK(x)         (((x) >> _PAGE_AP_BIT) & 0x2U)
Can you point out to the references (in some Arm doc or somewhere) from 
where you have picked these values ?
Also, AFAICS you are not using these macros in your current patch serie. 
So can you send this patch later (along with another patch showing the 
usage).
- Ayan

> +
> +#endif /* CONFIG_MMU */
> +
>   /*
>    * _PAGE_DEVICE and _PAGE_NORMAL are convenience defines. They are not
>    * meant to be used outside of this header.
> --
> 2.34.1