Re: [PATCH RFC v2 3/6] KVM: introduce a wrapper function to copy dirty bitmaps to user space

Takuya Yoshikawa
2010-04-22T08:53:40Z

(2010/04/21 20:12), Avi Kivity wrote:
> On 04/20/2010 01:59 PM, Takuya Yoshikawa wrote:
>> We will replace copy_to_user() to copy_in_user() when we move
>> the dirty bitmaps to user space.
>>
>> But sadly, we have copy_in_user() only for 64 bits architectures.
>> So this function should work as a wrapper to hide ifdefs from outside.
>> Once we get copy_in_user() for 32 bits architectures, we can remove
>> this wrapper and use copy_in_user() directly.
>
> I prefer a generic copy_in_user() instead of having multiple paths in kvm.
>

I do too :).

I checked ppc64's copy_in_user().
It looks like just using __copy_tofrom_user() and it is also implemented
for ppc32, IIUC.

So yes, we may not need to implement it by ourselves!

Just ask them to make it useful for 32bit too.

And about x86_32 copy_in_user().

They are using copy_user_generic() which is implemented only for 64bit.

So I'll show them current copy_from_user() and copy_to_user() version and
see their response.

If rejected, though I hope not, please give me another option, OK?