Re: [Xen-devel] [for-4.7] x86/emulate: synchronize LOCKed instruction emulation

[Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>]

On 04/14/2016 06:31 PM, Jan Beulich wrote:
>>>> Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx> 04/14/16 10:50 AM >>>
>> On 04/14/2016 07:35 AM, Jan Beulich wrote:
>>>> --- a/xen/arch/x86/hvm/emulate.c
>>>>> +++ b/xen/arch/x86/hvm/emulate.c
>>>>> @@ -25,6 +25,8 @@
>>>  >#include <asm/hvm/svm/svm.h>
>>>  >#include <asm/vm_event.h>
>>>  >
>>>>> +DEFINE_PERCPU_RWLOCK_GLOBAL(emulate_locked_rwlock);
>>> You should try hard to make this static.
>>
>> On second though, this would make the code somewhat more convoluted, as
>> the functions in emulate.c need to access this variable, and so does the
>> code in domain.c that initializes the lock when the domain is created.
>>
>> What I've done is similar to what I found in the current source code with:
>>
>> arch/x86/mm/p2m.c:DEFINE_PERCPU_RWLOCK_GLOBAL(p2m_percpu_rwlock);
>> common/grant_table.c:DEFINE_PERCPU_RWLOCK_GLOBAL(grant_rwlock);
> 
> Well, that's why I said "you should try hard" instead of "you have to".
> 
>> But I could add a function to emulate.h, for example:
>>
>> void init_emulate_smp_lock();
> 
> Exactly (just that this is perhaps again the wrong header, considering you
> also need this for PV emulation).

I understand, I'll look for a more suitable place for the function
declarations and definitions then (unless a specific place is requested).


Thanks,
Razvan

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