On 05/03/20 16:10, David Laight wrote: >>> index = (msr - 0x200) / 2; >>> - is_mtrr_mask = msr - 0x200 - 2 * index; >>> + is_mtrr_mask = (msr - 0x200) % 2; >>> cur = &mtrr_state->var_ranges[index]; >>> >>> /* remove the entry if it's in the list. */ >>> @@ -424,7 +424,7 @@ int kvm_mtrr_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata) >>> int is_mtrr_mask; >>> >>> index = (msr - 0x200) / 2; >>> - is_mtrr_mask = msr - 0x200 - 2 * index; >>> + is_mtrr_mask = (msr - 0x200) % 2; >>> if (!is_mtrr_mask) >>> *pdata = vcpu->arch.mtrr_state.var_ranges[index].base; >>> else >>> >> If you're going to do that, might as well use ">> 1" for index instead >> of "/ 2", and "msr & 1" for is_mtrr_mask. > Provided the variables are unsigned it makes little difference > whether you use / % or >> &. > At least with / % the two values are the same. Yes, I'm old-fashioned, but also I prefer ">>" and "&" for both signed and unsigned, because if ever I need to switch from unsigned to signed I will get floor-division instead of round-to-zero division (most likely the code doesn't expect negative remainders if it was using unsigned). (That perhaps also reflects on me working a lot with Smalltalk long before switching to the kernel...). Paolo
