Re: [PATCH 4/8] xen/arm: Store p2m type in each page of the guest

[Julien Grall <julien.grall@linaro.org>]

On 12/05/2013 03:55 PM, Ian Campbell wrote:
> On Thu, 2013-12-05 at 15:42 +0000, Julien Grall wrote:
>> Use the field 'avail' to store the type of the page. This information will be
>> retrieved in a future patch to change the behaviour when the page is removed.
>>
>> Also introduce guest_physmap_add_entry to map and set a specific p2m type for
>> a page.
>>
>> Signed-off-by: Julien Grall <julien.grall@linaro.org>
>> ---
>>   xen/arch/arm/p2m.c        |   49 +++++++++++++++++++++++++++++++--------------
>>   xen/include/asm-arm/p2m.h |   18 +++++++++++++----
>>   2 files changed, 48 insertions(+), 19 deletions(-)
>>
>> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
>> index 8f8b47e..5449a35 100644
>> --- a/xen/arch/arm/p2m.c
>> +++ b/xen/arch/arm/p2m.c
>> @@ -124,7 +124,8 @@ int p2m_pod_decrease_reservation(struct domain *d,
>>       return -ENOSYS;
>>   }
>>
>> -static lpae_t mfn_to_p2m_entry(unsigned long mfn, unsigned int mattr)
>> +static lpae_t mfn_to_p2m_entry(unsigned long mfn, unsigned int mattr,
>> +                               p2m_type_t t)
>>   {
>>       paddr_t pa = ((paddr_t) mfn) << PAGE_SHIFT;
>>       lpae_t e = (lpae_t) {
>> @@ -132,12 +133,25 @@ static lpae_t mfn_to_p2m_entry(unsigned long mfn, unsigned int mattr)
>>           .p2m.af = 1,
>>           .p2m.sh = LPAE_SH_OUTER,
>>           .p2m.read = 1,
>> -        .p2m.write = 1,
>>           .p2m.mattr = mattr,
>>           .p2m.table = 1,
>>           .p2m.valid = 1,
>> +        .p2m.avail = t, /* Use avail to store p2m type */
>
> Can we change the name in the struct instead and have a comment "using
> avail bits for type" there instead please. We only have 5 types so could
> only steal 3 but we may as well take all 4.
>
> A BUILD_BUG_ON to check that the last p2m entry is < 2^4 would be good
> too.

I will do both modification for the next version.

-- 
Julien Grall