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

Paolo Bonzini
2021-12-17T14:52:38Z

On 12/17/21 14:21, Mark Rutland wrote:
> I'm not immediately sure what we*should* do here. What does x86 do for an IRQ
> taken from a guest mode? I couldn't spot any handling of that case, but I'm not
> familiar enough with the x86 exception model to know if I'm looking in the
> right place.

ARM is missing something like commit 160457140187 ("KVM: x86: Defer
vtime accounting 'til after IRQ handling", 2021-05-05).

With that change, it would be possible to move guest_exit() in the
irq-disabled region without breaking time accounting.

RISC-V has the same issue and it would be fixed in the same way, so
let's Cc Anup too.

Paolo