On Tue, Jan 18, 2022 at 05:50:51PM +0000, Mark Rutland wrote: > On Tue, Jan 18, 2022 at 05:09:25PM +0100, Sven Schnelle wrote: > > I wonder whether the code in irqentry_enter() should call a function > > is_eqs() instead of is_idle_task(). The default implementation would > > be just a > > > > #ifndef is_eqs > > #define is_eqs is_idle_task > > #endif > > > > and if an architecture has special requirements, it could just define > > is_eqs() and do the required checks there. This way the architecture > > could define whether it's a percpu bit, a cpu flag or something else. > > I had come to almost the same approach: I've added an arch_in_rcu_eqs() > which is checked in addition to the existing is_idle_thread() check. > > In the case of checking is_idle_thread() and checking for PF_VCPU, I'm > assuming the compiler can merge the loads of current->flags, and there's > little gain by making this entirely architecture specific, but we can > always check that and/or reconsider in future. FWIW, I've pushed out my WIP to: https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/log/?h=kvm/entry-rework ... and I intend to clean that up and get it out on the list tomorrow. The new entry/exit helpers are: https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/commit/?h=kvm/entry-rework&id=df292ecabba50145849d8c8888cec9153267b31d The arch_in_rcu_eqs() bit is: https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/commit/?h=kvm/entry-rework&id=6e24c5ed7558ee7a4c95dfe62891dfdc51e6c6c4 The s390 changes are: https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/commit/?h=kvm/entry-rework&id=ca8daba1809b6e4f1be425ca93f6373a2ea0af6b I need to clean up the commit messages (including typos, TODOs, and deleting some stale gunk), and there are some comments to write, but by and large I think the structure is about right. Thanks, Mark.
