[PATCH v5] KVM: arm/arm64: Route vtimer events to user space

[Paolo Bonzini]

On 23/09/2016 11:17, Alexander Graf wrote:
>> > 
>> > On the other hand, what happens if you run new QEMU with old userspace?
>> > With user_timer_pending you'd get an infinite stream of vmexits the
>> > first time the timer fires, wouldn't you?  Whereas if you keep it in the
>> > kernel, userspace would simply not get the interrupt (because it doesn't
>> > know about kernel_timer_pending) and think it got a spurious vmexit.
>> > The kernel's IRQ would stay masked and everything would just (not) work
>> > like before your patch?
> Yes, we'd definitely stay more compatible by tracking it only in the
> kernel. I'm not fully convinced that it's the better interface, but
> since both Christoffer and you seem to choke on that part, I'll give it
> a stab ;).

Cool!  FWIW my suggestion for kernel_timer_pending's name would be
timer_irq_level (nicely matching timer->irq.level in the kernel).

Paolo