Re: [Xen-devel] [PATCH v3 02/10] xen: arm: Add zeroeth level page table macros and defines

[Tim Deegan <tim@xxxxxxx>]

At 13:15 +0100 on 08 Aug (1375967709), Ian Campbell wrote:
> Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

Acked-by: Tim Deegan <tim@xxxxxxx>

> ---
> v3: Don't ifdef rely on >>39 being invalid for 32-bit words
>     Update comment.
> ---
>  xen/include/asm-arm/page.h |   19 +++++++++++++++----
>  1 files changed, 15 insertions(+), 4 deletions(-)
> 
> diff --git a/xen/include/asm-arm/page.h b/xen/include/asm-arm/page.h
> index 41e9eff..93bb8c0 100644
> --- a/xen/include/asm-arm/page.h
> +++ b/xen/include/asm-arm/page.h
> @@ -309,9 +309,15 @@ static inline int gva_to_ipa(vaddr_t va, paddr_t *paddr)
>  
>  #endif /* __ASSEMBLY__ */
>  
> -/* These numbers add up to a 39-bit input address space.  The  ARMv7-A
> - * architecture actually specifies a 40-bit input address space for the p2m,
> - * with an 8K (1024-entry) top-level table. */
> +/*
> + * These numbers add up to a 48-bit input address space.
> + *
> + * On 32-bit the zeroeth level does not exist, therefore the total is
> + * 39-bits. The ARMv7-A architecture actually specifies a 40-bit input
> + * address space for the p2m, with an 8K (1024-entry) top-level table.
> + * However Xen only supports 16GB of RAM on 32-bit ARM systems and
> + * therefore 39-bits are sufficient.
> + */
>  
>  #define LPAE_SHIFT      9
>  #define LPAE_ENTRIES    (1u << LPAE_SHIFT)
> @@ -326,8 +332,12 @@ static inline int gva_to_ipa(vaddr_t va, paddr_t *paddr)
>  #define FIRST_SHIFT  (SECOND_SHIFT + LPAE_SHIFT)
>  #define FIRST_SIZE   (1u << FIRST_SHIFT)
>  #define FIRST_MASK   (~(FIRST_SIZE - 1))
> +#define ZEROETH_SHIFT  (FIRST_SHIFT + LPAE_SHIFT)
> +#define ZEROETH_SIZE   (1u << ZEROETH_SHIFT)
> +#define ZEROETH_MASK   (~(ZEROETH_SIZE - 1))
>  
>  /* Calculate the offsets into the pagetables for a given VA */
> +#define zeroeth_linear_offset(va) ((va) >> ZEROETH_SHIFT)
>  #define first_linear_offset(va) ((va) >> FIRST_SHIFT)
>  #define second_linear_offset(va) ((va) >> SECOND_SHIFT)
>  #define third_linear_offset(va) ((va) >> THIRD_SHIFT)
> @@ -336,8 +346,9 @@ static inline int gva_to_ipa(vaddr_t va, paddr_t *paddr)
>  #define first_table_offset(va)  TABLE_OFFSET(first_linear_offset(va))
>  #define second_table_offset(va) TABLE_OFFSET(second_linear_offset(va))
>  #define third_table_offset(va)  TABLE_OFFSET(third_linear_offset(va))
> +#define zeroeth_table_offset(va)  TABLE_OFFSET(zeroeth_linear_offset(va))
>  
> -#define clear_page(page)memset((void *)(page), 0, PAGE_SIZE)
> +#define clear_page(page) memset((void *)(page), 0, PAGE_SIZE)
>  
>  #define PAGE_ALIGN(x) (((x) + PAGE_SIZE - 1) & PAGE_MASK)
>  
> -- 
> 1.7.2.5
> 
> 
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