Re: [Xen-devel] [PATCH v2 03/10] xen/arm: Implement p2m_type_t as an enum

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Mon, 2013-12-09 at 03:34 +0000, Julien Grall wrote:
> Until now, Xen doesn't know the type of the page (ram, foreign page, 
> mmio,...).
> Introduce p2m_type_t with basic types:
>     - p2m_invalid: Nothing is mapped here
>     - p2m_ram_rw: Normal read/write guest RAM
>     - p2m_ram_ro: Read-only guest RAM
>     - p2m_mmio_direct: Read/write mapping of device memory
>     - p2m_map_foreign: RAM page from foreign guest
>     - p2m_grant_map_rw: Read/write grant mapping
>     - p2m_grant_map_ro: Read-only grant mapping
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
> 
> ---
>     Changes in v2:
>         - Add comment for future improvement
>         - Add p2m_max_real_type. Will be use later to check the size of
>         the enum
>         - Let the compiler choose the value for each name of the enum
>         - Add grant mapping type
> ---
>  xen/include/asm-arm/p2m.h |   21 +++++++++++++++++++--
>  1 file changed, 19 insertions(+), 2 deletions(-)
> 
> diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h
> index 0c554a5..f621d15 100644
> --- a/xen/include/asm-arm/p2m.h
> +++ b/xen/include/asm-arm/p2m.h
> @@ -20,6 +20,25 @@ struct p2m_domain {
>      uint8_t vmid;
>  };
>  
> +/* List of possible type for each page in the p2m
> + * The number of available bit per page in the p2m for this purpose  is 4 
> bits.

s/  / /.

I think you might also have meant s/p2m/pte/ or "p2m entry"?

> + * So it's possible to only have 16 fields. If we run out of value in the
> + * future, it's possible to use higher value for pseudo-type and don't store
> + * them in the p2m.
> + */
> +typedef enum {
> +    p2m_invalid = 0,    /* Nothing mapped here */
> +    p2m_ram_rw,         /* Normal read/write guest RAM */
> +    p2m_ram_ro,         /* Read-only; writes are silently dropped */
> +    p2m_mmio_direct,    /* Read/write mapping of genuine MMIO area */
> +    p2m_map_foreign,    /* Ram pages from foreign domain */
> +    p2m_grant_map_rw,   /* Read/write grant mapping */
> +    p2m_grant_map_ro,   /* Read-only grant mapping */
> +    p2m_max_real_type,  /* Types after this won't be store in the p2m */

Did you intend to add a BUILD_BUG_ON referencing this last one?

In any case:
Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

> +} p2m_type_t;
> +
> +#define p2m_is_foreign(_t)  ((_t) == p2m_map_foreign)
> +
>  /* Initialise vmid allocator */
>  void p2m_vmid_allocator_init(void);
>  
> @@ -72,7 +91,6 @@ p2m_pod_decrease_reservation(struct domain *d,
>                               unsigned int order);
>  
>  /* Look up a GFN and take a reference count on the backing page. */
> -typedef int p2m_type_t;
>  typedef unsigned int p2m_query_t;
>  #define P2M_ALLOC    (1u<<0)   /* Populate PoD and paged-out entries */
>  #define P2M_UNSHARE  (1u<<1)   /* Break CoW sharing */
> @@ -108,7 +126,6 @@ static inline int get_page_and_type(struct page_info 
> *page,
>      return rc;
>  }
>  
> -#define p2m_is_foreign(_t) (0 && (_t))
>  static inline int xenmem_rem_foreign_from_p2m(struct domain *d, 
>                                                unsigned long gpfn)
>  {



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