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

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 12/09/2013 03:59 PM, Ian Campbell wrote:
> 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"?

Right, I will fix it.

> 
>> + * 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?

The BUILD_BUG_ON is added by patch #4.

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

Thanks.

-- 
Julien Grall

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