Hi Mark, Mark Rutland <mark.rutland@xxxxxxx> writes: > On Tue, Jan 18, 2022 at 05:09:25PM +0100, Sven Schnelle wrote: >> Mark Rutland <mark.rutland@xxxxxxx> writes: >> > On Tue, Jan 18, 2022 at 01:42:26PM +0100, Christian Borntraeger wrote: >> >> Will you provide an s390 patch in your next iteration or shall we then do >> >> one as soon as there is a v2? We also need to look into vsie.c where we >> >> also call sie64a >> > >> > I'm having a go at that now; my plan is to try to have an s390 patch as >> > part of v2 in the next day or so. >> > >> > Now that I have a rough idea of how SIE and exception handling works on >> > s390, I think the structural changes to kvm-s390.c:__vcpu_run() and >> > vsie.c:do_vsie_run() are fairly simple. >> > >> > The only open bit is exactly how/where to identify when the interrupt >> > entry code needs to wake RCU. I can add a per-cpu variable or thread >> > flag to indicate that we're inside that EQS, or or I could move the irq >> > enable/disable into the sie64a asm and identify that as with the OUTSIDE >> > macro in the entry asm. >> >> 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. > Sounds good, thanks! /Sven
