[PATCH 3/3] KVM: arm64: Warn if accessing timer pending state outside of vcpu context

[Eric Auger]

Hi Marc,

On 6/2/22 10:30, Marc Zyngier wrote:
> A recurrent bug in the KVM/arm64 code base consists in trying to
> access the timer pending state outside of the vcpu context, which
> makes zero sense (the pending state only exists when the vcpu
> is loaded).
> 
> In order to avoid more embarassing crashes and catch the offenders
> red-handed, add a warning to kvm_arch_timer_get_input_level() and
> return the state as non-pending. This avoids taking the system down,
> and still helps tracking down silly bugs.
> 
> Signed-off-by: Marc Zyngier <maz at kernel.org>
Reviewed-by: Eric Auger <eric.auger at redhat.com>

Eric
> ---
>  arch/arm64/kvm/arch_timer.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/arch/arm64/kvm/arch_timer.c b/arch/arm64/kvm/arch_timer.c
> index 5290ca5db663..bb24a76b4224 100644
> --- a/arch/arm64/kvm/arch_timer.c
> +++ b/arch/arm64/kvm/arch_timer.c
> @@ -1230,6 +1230,9 @@ bool kvm_arch_timer_get_input_level(int vintid)
>  	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
>  	struct arch_timer_context *timer;
>  
> +	if (WARN(!vcpu, "No vcpu context!\n"))
> +		return false;
> +
>  	if (vintid == vcpu_vtimer(vcpu)->irq.irq)
>  		timer = vcpu_vtimer(vcpu);
>  	else if (vintid == vcpu_ptimer(vcpu)->irq.irq)