Re: [Xen-devel] [PATCH V9 for-4.5 4/4] xen: Handle resumed instruction based on previous mem_event reply

[Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>]

On 09/17/14 13:48, Jan Beulich wrote:
>>>> On 17.09.14 at 10:29, <rcojocaru@xxxxxxxxxxxxxxx> wrote:
>> --- a/xen/include/public/mem_event.h
>> +++ b/xen/include/public/mem_event.h
>> @@ -31,11 +31,19 @@
>>  #include "io/ring.h"
>>  
>>  /* Memory event flags */
>> -#define MEM_EVENT_FLAG_VCPU_PAUSED  (1 << 0)
>> -#define MEM_EVENT_FLAG_DROP_PAGE    (1 << 1)
>> -#define MEM_EVENT_FLAG_EVICT_FAIL   (1 << 2)
>> -#define MEM_EVENT_FLAG_FOREIGN      (1 << 3)
>> -#define MEM_EVENT_FLAG_DUMMY        (1 << 4)
>> +#define MEM_EVENT_FLAG_VCPU_PAUSED     (1 << 0)
>> +#define MEM_EVENT_FLAG_DROP_PAGE       (1 << 1)
>> +#define MEM_EVENT_FLAG_EVICT_FAIL      (1 << 2)
>> +#define MEM_EVENT_FLAG_FOREIGN         (1 << 3)
>> +#define MEM_EVENT_FLAG_DUMMY           (1 << 4)
>> +/*
>> + * Emulate the fault-causing instruction (if set in the event response 
>> flags).
>> + * This will allow the guest to continue execution without lifting the page
>> + * access restrictions.
>> + */
>> +#define MEM_EVENT_FLAG_EMULATE         (1 << 5)
>> +/* Same as MEM_EVENT_FLAG_EMULATE, but with write operations disabled. */
> 
> As we've gone through this incrementally suppressing more and more
> operations, I think you should be very explicit here and say "...
> with write operations or operations potentially having side effects
> (like memory mapped or port I/O) disabled".

Of course, thanks for the comment! Will do.


Thanks,
Razvan Cojocaru


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