Re: [Qemu-devel] [PATCH] kvm-all.c: Move init of irqchip_inject_ioctl out of kvm_irqchip_create()

[Jan Kiszka <jan.kiszka@web.de>]

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On 2012-08-06 19:05, Peter Maydell wrote:
> Move the init of the irqchip_inject_ioctl field of KVMState out of
> kvm_irqchip_create() and into kvm_init(), so that kvm_set_irq()
> can be used even when no irqchip is created (for architectures
> that support async interrupt notification even without an in
> kernel irqchip).
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
> We can't just set irqchip_inject_ioctl in target-*/kvm.c because
> the KVMState struct layout is private to kvm-all.c. Moving the
> default initialisation of this field seemed the simplest approach.
> It's safe because the use in kvm_set_irq() is guarded by a check of
> kvm_async_interrupts_enabled().
> 
> The other approach would be to have a helper function for setting
> the field, but that seems overkill when KVM_IRQ_LINE is the standard
> default value. (KVM_IRQ_LINE_STATUS seems to be undocumented,
> incidentally. I am going to assume it's another x86ism until somebody
> does document it :-))
> 
>  kvm-all.c |    3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/kvm-all.c b/kvm-all.c
> index 6def6c9..9a1f001 100644
> --- a/kvm-all.c
> +++ b/kvm-all.c
> @@ -1200,7 +1200,6 @@ static int kvm_irqchip_create(KVMState *s)
>          return ret;
>      }
>  
> -    s->irqchip_inject_ioctl = KVM_IRQ_LINE;
>      if (kvm_check_extension(s, KVM_CAP_IRQ_INJECT_STATUS)) {
>          s->irqchip_inject_ioctl = KVM_IRQ_LINE_STATUS;
>      }

Either you move both or none.

KVM_IRQ_LINE is old-style, deprecated, KVM_IRQ_LINE_STATUS (i.e
injection with feedback to allow lost-tick compensation) is the current
standard that other archs should pick up.

Jan



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