Re: Possible nohz-full/RCU issue in arm64 KVM
From: Paolo Bonzini
Date: Fri Dec 17 2021 - 09:51:23 EST
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