On 03/14/17 12:08, Kyle Huey wrote: > > That's largely what we ended up doing. See > https://lkml.org/lkml/2017/2/14/80 and the latest version of this > patch, https://lkml.org/lkml/2017/3/11/197. > Yes, as I said, my mistake. I would still like to see an early-out when none of these flags are set (I just discussed this with tglx on IRC): if (likely(!((tifp|tifn) & (_TIF_BLOCKSTEP|_TIF_NOTSC|_TIF_IO_BITMAP| _TIF_NOCPUID|_TIF_USER_RETURN_NOTIFY)))) return; The USER_RETURN_NOTIFY could really use some sanity: it is a notifier chain with a single in-kernel user, which is KVM on x86 only, but we most likely will need to propagate the flag even if it ends up getting specialized. -hpa
