Gleb Natapov wrote on 2013-01-23:
> On Wed, Jan 23, 2013 at 12:45:39AM +0000, Zhang, Yang Z wrote:
>>> We are getting close so please test with userspace irq chip too.
>> Thanks for your suggestion to test with userspace irqchip. I found some
>> issues and will modify the logic: As we known, APICv deponds on TPR
>> shadow. But TPR shadow is per VM(it will
> be disabled when VM uses userspace irq chip), this means APICv also is per VM.
> But in current implementation, we use the global variable enable_apicv_reg to
> check whether APICv is used by target vcpu. This is wrong. Instead, it should to
> read VMCS to see whether the bit is set or not.
>>
> No, the apicv and TPR shadow are global for all VMs with irq chip in
> kernel and VMs without irq chip in kernel skip APIC that code entirely.
> If there is generic code that should behave differently with or without
> in-kernel irq chip make the check for the condition there.
Yes, check irqchip_in_kernel is enough. No need to check the bits in vmcs. Like this:
static int vmx_vcpu_has_apicv(struct kvm *kvm)
{
return enable_apicv_reg_vid && irqchip_in_kernel(kvm);
}
Best regards,
Yang
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