Re: [Qemu-devel] [PATCH 1/6] kvm: Decouple 'interrupt injection is async' from 'kernel irqchip'

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2012-07-25 15:24, Peter Maydell wrote:
> On x86 interrupt injection is asynchronous (and therefore
> VCPU idle management is done in the kernel) if and only
> if there is an in-kernel irqchip. On other architectures this
> isn't necessarily true (they may always do asynchronous
> injection), so define a new kvm_async_interrupt_injection()
> function instead of misusing kvm_irqchip_in_kernel().
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  cpus.c     |    3 ++-
>  kvm-all.c  |    7 ++++++-
>  kvm-stub.c |    1 +
>  kvm.h      |   11 +++++++++++
>  4 files changed, 20 insertions(+), 2 deletions(-)
> 
> diff --git a/cpus.c b/cpus.c
> index 756e624..584b298 100644
> --- a/cpus.c
> +++ b/cpus.c
> @@ -69,7 +69,8 @@ static bool cpu_thread_is_idle(CPUArchState *env)
>      if (env->stopped || !runstate_is_running()) {
>          return true;
>      }
> -    if (!env->halted || qemu_cpu_has_work(env) || kvm_irqchip_in_kernel()) {
> +    if (!env->halted || qemu_cpu_has_work(env) ||
> +        kvm_async_interrupt_injection()) {
>          return false;
>      }
>      return true;
> diff --git a/kvm-all.c b/kvm-all.c
> index 2148b20..3354c6f 100644
> --- a/kvm-all.c
> +++ b/kvm-all.c
> @@ -100,6 +100,7 @@ struct KVMState
>  
>  KVMState *kvm_state;
>  bool kvm_kernel_irqchip;
> +bool kvm_async_interrupt_injection;
>  
>  static const KVMCapabilityInfo kvm_required_capabilites[] = {
>      KVM_CAP_INFO(USER_MEMORY),
> @@ -857,7 +858,7 @@ int kvm_irqchip_set_irq(KVMState *s, int irq, int level)
>      struct kvm_irq_level event;
>      int ret;
>  
> -    assert(kvm_irqchip_in_kernel());
> +    assert(kvm_async_interrupt_injection());
>  
>      event.level = level;
>      event.irq = irq;
> @@ -1201,6 +1202,10 @@ static int kvm_irqchip_create(KVMState *s)
>          s->irqchip_inject_ioctl = KVM_IRQ_LINE_STATUS;
>      }
>      kvm_kernel_irqchip = true;
> +    /* If we have an in-kernel IRQ chip then we must have asynchronous
> +     * interrupt injection (though the reverse is not necessarily true)
> +     */
> +    kvm_async_interrupt_injection = true;
>  
>      kvm_init_irq_routing(s);
>  
> diff --git a/kvm-stub.c b/kvm-stub.c
> index d23b11c..b4023d1 100644
> --- a/kvm-stub.c
> +++ b/kvm-stub.c
> @@ -19,6 +19,7 @@
>  
>  KVMState *kvm_state;
>  bool kvm_kernel_irqchip;
> +bool kvm_async_interrupt_injection;
>  
>  int kvm_init_vcpu(CPUArchState *env)
>  {
> diff --git a/kvm.h b/kvm.h
> index 2617dd5..00abe36 100644
> --- a/kvm.h
> +++ b/kvm.h
> @@ -24,13 +24,24 @@
>  
>  extern int kvm_allowed;
>  extern bool kvm_kernel_irqchip;
> +extern bool kvm_async_interrupt_injection;
>  
>  #if defined CONFIG_KVM || !defined NEED_CPU_H
>  #define kvm_enabled()           (kvm_allowed)
>  #define kvm_irqchip_in_kernel() (kvm_kernel_irqchip)
> +/**
> + * kvm_async_interrupt_injection:
> + *
> + * Returns: true if we can inject interrupts into a KVM CPU
> + * asynchronously (ie by ioctl from any thread at any time)
> + * rather than having to do interrupt delivery synchronously
> + * (where the vcpu must be stopped at a suitable point first).
> + */
> +#define kvm_async_interrupt_injection() (kvm_async_interrupt_injection)
>  #else
>  #define kvm_enabled()           (0)
>  #define kvm_irqchip_in_kernel() (false)
> +#define kvm_async_interrupt_injection() (false)
>  #endif
>  
>  struct kvm_run;
> 

Acked-by: Jan Kiszka <jan.kiszka@siemens.com>

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