From: Luca Miccio <lucmiccio@gmail.com>

A new allocator enforcing a cache-coloring configuration is going to be
introduced.  We thus need to distinguish the memory pages assigned to,
and managed by, such colored allocator from the ordinary buddy
allocator's ones.  Add a color flag to the page structure.

Signed-off-by: Luca Miccio <lucmiccio@gmail.com>
Signed-off-by: Marco Solieri <marco.solieri@minervasys.tech>
---
 xen/arch/arm/include/asm/mm.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/xen/arch/arm/include/asm/mm.h b/xen/arch/arm/include/asm/mm.h
index 487be7cf59..9ac1767595 100644
--- a/xen/arch/arm/include/asm/mm.h
+++ b/xen/arch/arm/include/asm/mm.h
@@ -88,6 +88,10 @@ struct page_info
          */
         u32 tlbflush_timestamp;
     };
+
+    /* Is page managed by the cache-colored allocator? */
+    bool colored;
+
     u64 pad;
 };
 
-- 
2.30.2

Hi,

On 04/03/2022 17:46, Marco Solieri wrote:
> From: Luca Miccio <lucmiccio@gmail.com>
> 
> A new allocator enforcing a cache-coloring configuration is going to be
> introduced.  We thus need to distinguish the memory pages assigned to,
> and managed by, such colored allocator from the ordinary buddy
> allocator's ones.  Add a color flag to the page structure.
> 
> Signed-off-by: Luca Miccio <lucmiccio@gmail.com>
> Signed-off-by: Marco Solieri <marco.solieri@minervasys.tech>
> ---
>   xen/arch/arm/include/asm/mm.h | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/xen/arch/arm/include/asm/mm.h b/xen/arch/arm/include/asm/mm.h
> index 487be7cf59..9ac1767595 100644
> --- a/xen/arch/arm/include/asm/mm.h
> +++ b/xen/arch/arm/include/asm/mm.h
> @@ -88,6 +88,10 @@ struct page_info
>            */
>           u32 tlbflush_timestamp;
>       };
> +
> +    /* Is page managed by the cache-colored allocator? */
> +    bool colored;

struct page_info is going to be used quite a lot. In fact, there is one 
per RAM page. So we need to avoid growing the structure.

For Arm64, there is a 4 bytes padding here. But for arm32, there are 
none. So the size will increase by another 8 bytes.

In this case, I would use a bit in count_info.

Cheers,

-- 
Julien Grall