Re: [PATCH] xen/arm: p2m: Don't create new table when the mapping is removed

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

On 12/18/2013 07:28 PM, Stefano Stabellini wrote:
> On Wed, 18 Dec 2013, Julien Grall wrote:
>> When  Xen is removing/relinquishing mapping, it will create second/third tables
>> if they don't exist.
>>
>> Non-existent table means the address range was never mapped, so Xen can safely
>> skip them.
>>
>> Signed-off-by: Julien Grall <julien.grall@linaro.org>
>>
>> ---
>>      Release: This is an improvement for Xen 4.4. It will save time during
>>      relinquish phase and avoid dummy allocation.
>>      The downside is the patch is modifying p2m loop which is used everywhere.
>> ---
>>   xen/arch/arm/p2m.c |   22 ++++++++++++++++++++--
>>   1 file changed, 20 insertions(+), 2 deletions(-)
>>
>> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
>> index d24a6fc..9ef8819 100644
>> --- a/xen/arch/arm/p2m.c
>> +++ b/xen/arch/arm/p2m.c
>> @@ -246,10 +246,12 @@ static int create_p2m_entries(struct domain *d,
>>                     cur_first_offset = ~0,
>>                     cur_second_offset = ~0;
>>       unsigned long count = 0;
>> +    bool_t populate = (op == INSERT || op == ALLOCATE);
>
> why don't you just check for op == REMOVE?

Because you also need to check op == RELINQUISH (added by my patch 
series on foreign mapping).

-- 
Julien Grall