On 15/10/2018 19:16, H. Peter Anvin wrote: > On 10/7/18 6:04 PM, peng.hao2@xxxxxxxxxx wrote: > \>>>>> >>>>>> #define AVIC_LOGICAL_ID_ENTRY_GUEST_PHYSICAL_ID_MASK (0xFF) >>>>>> -#define AVIC_LOGICAL_ID_ENTRY_VALID_MASK (1 << 31) >>>>>> +#define AVIC_LOGICAL_ID_ENTRY_VALID_MASK (1UL << 31) >>>> >>>>> It is reasonable to change to unsigned, while not necessary to unsigned >>>>> long? >>>> AVIC_LOGICAL_ID_ENTRY_VALID_MASK is used in function avic_ldr_write. >>>> here I think it doesn't matter if you use unsigned or unsigned long. Do you have any suggestions? >> >>> In current case, AVIC_LOGICAL_ID_ENTRY_VALID_MASK is used to calculate >>> the value of new_entry with type of u32. So the definition here is not >>> harmful. >> >>> Also, I did a quick grep and found similar definition (1 << 31) is popular >>> in the whole kernel tree. >> >>> The reason to make this change is not that strong to me. Would you >>> minding sharing more reason behind this change? >> oh, I'm just thinking logically, not more reason. > > The right way to do this would be to use the _BITUL() (or _BITULL()) macro. Even for a value from a 32-bit register? That would be _BIT, which doesn't exist. Paolo
