Excerpts from Nicholas Piggin's message of January 16, 2021 2:49 am:
> Interrupts that occur in kernel mode expect that context tracking
> is set to kernel. Enabling local irqs before context tracking
> switches from guest to host means interrupts can come in and trigger
> warnings about wrong context, and possibly worse.
I think this is not actually a fix per se with context as it is today
because the interrupt handlers will save and update the state. It only
starts throwing warnings when moving to the more precise tracking
where kernel interrupts always expect context to be in kernel mode.
The patch stands on its own just fine, but I'll reword slightly and
move it in the series to where it's needed.
Thanks,
Nick
>
> Cc: kvm-ppc@xxxxxxxxxxxxxxx
> Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx>
> ---
> arch/powerpc/kvm/book3s_hv.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
> index 6f612d240392..d348e77cee20 100644
> --- a/arch/powerpc/kvm/book3s_hv.c
> +++ b/arch/powerpc/kvm/book3s_hv.c
> @@ -3407,8 +3407,9 @@ static noinline void kvmppc_run_core(struct kvmppc_vcore *vc)
>
> kvmppc_set_host_core(pcpu);
>
> + guest_exit_irqoff();
> +
> local_irq_enable();
> - guest_exit();
>
> /* Let secondaries go back to the offline loop */
> for (i = 0; i < controlled_threads; ++i) {
> @@ -4217,8 +4218,9 @@ int kvmhv_run_single_vcpu(struct kvm_vcpu *vcpu, u64 time_limit,
>
> kvmppc_set_host_core(pcpu);
>
> + guest_exit_irqoff();
> +
> local_irq_enable();
> - guest_exit();
>
> cpumask_clear_cpu(pcpu, &kvm->arch.cpu_in_guest);
>
> --
> 2.23.0
>
>
