On 08/27/2013 06:54 PM, Alexander Graf wrote: > > On 27.08.2013, at 09:41, Alexey Kardashevskiy wrote: > >> On 08/27/2013 05:02 PM, Paolo Bonzini wrote: >>> Il 27/08/2013 08:37, Alexey Kardashevskiy ha scritto: >>>>>> So this is here to make sure we don't accidentally get out of halted >>>>>> state by an interrupt on that vcpu. Could you please somehow make that >>>>>> part obvious? Either by adding a comment or by only explicitly masking >>>>>> DEC and EE and a comment :). >>>>>> >>>>>>> + cs->exit_request = 1; >>>>>> >>>>>> This should probably be qemu_cpu_kick_self(). >>>>> >>>>> Uh, no, I don't think so. This is there purely to make sure we exit >>>>> the inner loop, and actually test cpu_can_run() which will test >>>>> halted. AFAICT qemu_cpu_kick_self() won't do anything similar. >>>> >>>> rtas_stop_self() eventually returns to kvm_cpu_exec() which calls >>>> qemu_cpu_kick_self() and resets cs->exit_request before return so I do not >>>> really see the difference in behaviour. And actually both ways CPU stops in >>>> exactly the same way. What do I miss? >>> >>> What about TCG? >> >> Oh. Right. TCG :( >> >> qemu_cpu_kick_self() crashes the guest and cs->exit_request works fine. >> >> Why? Both should work? What is the expected behavior here? Thanks. > > Hrm. To me exit_request always was an internal piece of state that the inner > loop uses to find out whether to exit, but not something we should randomly > set from a device (and hypercalls / rtas calls are very similar to devices). > So I would like to not have any code in hw/ that modifies it. > > However, we need the functionality of breaking out of the main loop, I agree.
> Maybe what you are really looking for is > cpu_interrupt(CPU_INTERRUPT_HALT). That sets halted = 1 and exits the > main loop, because it's an interrupt. cpu_interrupt(CPU_INTERRUPT_HALT) works fine for TCG but does not for KVM (the rtas call returns to the guest and it reports BUG). -- Alexey
