Re: [Qemu-devel] [RFC ppc-next PATCH 5/6] kvm: export result of irqchip config check

[Alexander Graf]

On 21.03.2013, at 09:45, Jan Kiszka wrote:

> On 2013-03-21 09:34, Alexander Graf wrote:
>> 
>> On 14.02.2013, at 07:32, Scott Wood wrote:
>> 
>>> This allows platform code to register in-kernel irqchips that
>>> don't use the legacy KVM_CAP_IRQCHIP/KVM_CREATE_IRQCHIP interface.
>>> 
>>> Signed-off-by: Scott Wood <address@hidden>
>>> ---
>>> include/sysemu/kvm.h |   10 ++++++++++
>>> kvm-all.c            |   11 +++++++++--
>>> 2 files changed, 19 insertions(+), 2 deletions(-)
>>> 
>>> diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
>>> index f2d97b5..b9a8701 100644
>>> --- a/include/sysemu/kvm.h
>>> +++ b/include/sysemu/kvm.h
>>> @@ -45,6 +45,7 @@ extern bool kvm_async_interrupts_allowed;
>>> extern bool kvm_irqfds_allowed;
>>> extern bool kvm_msi_via_irqfd_allowed;
>>> extern bool kvm_gsi_routing_allowed;
>>> +extern bool kvm_irqchip_wanted;
>>> 
>>> #if defined CONFIG_KVM || !defined NEED_CPU_H
>>> #define kvm_enabled()           (kvm_allowed)
>>> @@ -97,6 +98,14 @@ extern bool kvm_gsi_routing_allowed;
>>> */
>>> #define kvm_gsi_routing_enabled() (kvm_gsi_routing_allowed)
>>> 
>>> +/**
>>> + * kvm_irqchip_wanted
>>> + *
>>> + * Returns: true if the user requested that an in-kernel IRQ chip be
>>> + * used, regardless of whether support has been detected.
>>> + */
>>> +#define kvm_irqchip_wanted() (kvm_irqchip_wanted)
>>> +
>>> #else
>>> #define kvm_enabled()           (0)
>>> #define kvm_irqchip_in_kernel() (false)
>>> @@ -104,6 +113,7 @@ extern bool kvm_gsi_routing_allowed;
>>> #define kvm_irqfds_enabled() (false)
>>> #define kvm_msi_via_irqfd_enabled() (false)
>>> #define kvm_gsi_routing_allowed() (false)
>>> +#define kvm_irqchip_wanted() (false)
>>> #endif
>>> 
>>> struct kvm_run;
>>> diff --git a/kvm-all.c b/kvm-all.c
>>> index 04ec2d5..13a628d 100644
>>> --- a/kvm-all.c
>>> +++ b/kvm-all.c
>>> @@ -109,6 +109,7 @@ bool kvm_async_interrupts_allowed;
>>> bool kvm_irqfds_allowed;
>>> bool kvm_msi_via_irqfd_allowed;
>>> bool kvm_gsi_routing_allowed;
>>> +bool kvm_irqchip_wanted;
>>> 
>>> static const KVMCapabilityInfo kvm_required_capabilites[] = {
>>>    KVM_CAP_INFO(USER_MEMORY),
>>> @@ -1205,8 +1206,14 @@ static int kvm_irqchip_create(KVMState *s)
>>> 
>>>    if (QTAILQ_EMPTY(&list->head) ||
>>>        !qemu_opt_get_bool(QTAILQ_FIRST(&list->head),
>>> -                           "kernel_irqchip", true) ||
>>> -        !kvm_check_extension(s, KVM_CAP_IRQCHIP)) {
>>> +                           "kernel_irqchip", true)) {
>>> +        return 0;
>>> +    }
>>> +
>>> +    kvm_irqchip_wanted = true;
>>> +
>>> +    /* Platform code may have a different way of enabling an IRQ chip */
>>> +    if (!kvm_check_extension(s, KVM_CAP_IRQCHIP)) {
>> 
>> Does x86 have the required checks then to make sure it has the CAP?
> 
> To my understanding, x86 won't evaluate this new flag but continue to
> bail out from this service early.
> 
> However, invoking something that is called "create" to just end up with
> a set flag "wanted" and then do the creation elsewhere is not a very
> beautiful design.

Yeah. This should probably be

  kvm_irqchip_wanted(KVMState *s) {
    if (!kvm_arch_irqchip_available(s))
      return false;
    
    return qemu_opt_get_bool("kernel_irqchip", true);
  }

with kvm_arch_irqchip_available checking for KVM_CAP_IRQCHIP on x86 and the 
respective device creation capability on ppc.


Alex