Re: [Qemu-devel] [PATCH 14/22] exec: only check relevant bitmaps for cleanliness

[Paolo Bonzini]

On 27/03/2015 07:10, Fam Zheng wrote:
>>  static inline bool cpu_physical_memory_range_includes_clean(ram_addr_t 
>> start,
>> -                                                            ram_addr_t 
>> length)
>> +                                                            ram_addr_t 
>> length,
>> +                                                            uint8_t mask)
>>  {
>> -    bool vga = cpu_physical_memory_get_clean(start, length, 
>> DIRTY_MEMORY_VGA);
>> -    bool code = cpu_physical_memory_get_clean(start, length, 
>> DIRTY_MEMORY_CODE);
>> -    bool migration =
>> -        cpu_physical_memory_get_clean(start, length, 
>> DIRTY_MEMORY_MIGRATION);
>> -    return vga || code || migration;
>> +    bool clean = false;
>> +    if (mask & (1 << DIRTY_MEMORY_VGA)) {
>> +        clean = cpu_physical_memory_get_clean(start, length, 
>> DIRTY_MEMORY_VGA);
>> +    }
>> +    if (!clean && (mask & (1 << DIRTY_MEMORY_CODE))) {
>> +        clean = cpu_physical_memory_get_clean(start, length, 
>> DIRTY_MEMORY_CODE);
>> +    }
>> +    if (!clean && (mask & (1 << DIRTY_MEMORY_MIGRATION))) {
>> +        clean = cpu_physical_memory_get_clean(start, length, 
>> DIRTY_MEMORY_MIGRATION);
>> +    }
>> +    return clean;
>>  }
> 
> Out of curiosity, is it valid that a mask bit is cleared but the corresponding
> dirty bit is set?

Yes, for example if migration is cancelled you'll have some bits set in
the DIRTY_MEMORY_MIGRATION bitmap, but DIRTY_MEMORY_MIGRATION itself
will not be enabled.

Paolo

>>  
>>  static inline void cpu_physical_memory_set_dirty_flag(ram_addr_t addr,
>> -- 
>> 2.3.3
>>
>>
>>