Re: Possible nohz-full/RCU issue in arm64 KVM

Paolo Bonzini
2022-01-04T17:11:24Z

On 1/4/22 17:39, Mark Rutland wrote:
> My main issue here was just that it's really difficult to see how the
> entry/exit logic is balanced, and I reckon we can solve that by splitting
> guest_{enter,exit}_irqoff() into helper functions to handle the vtime
> accounting separately from the context tracking, so that arch code can do
> something like:
>
> guest_timing_enter_irqoff();
>
> guest_eqs_enter_irqoff();
> < actually run vCPU here >
> guest_eqs_exit_irqoff();
>
> < handle pending IRQs here >
>
> guest_timing_exit_irqoff();
>
> ... which I hope should work for RISC-V too.
>
> I've had a go, and I've pushed out a WIP to:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/log/?h=arm64/kvm/rcu

Yes, you have a point and it makes sense for x86 too. You can send me a
topic branch once you get all the acks. Thanks!

Paolo