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SubjectRe: [PATCH v2 3/3] KVM: SVM: Add irqchip_split() checks before enabling AVIC
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Radim,

On 9/14/17 08:23, Suravee Suthikulpanit wrote:
> Radim,
>
> On 9/14/17 08:20, Radim Krčmář wrote:
>>> @@ -1594,6 +1593,12 @@ static int avic_init_vcpu(struct vcpu_svm *svm)
>>> if (!avic)
>>> return 0;
>>>
>>> + if (!kvm_vcpu_apicv_active(&svm->vcpu)) {
>>> + pr_debug("%s: Disable AVIC due to non-split irqchip.\n",
>>> + __func__);
>> We need to have an extra condition just because of this print ...
>> I removed the print altogether when applying -- I thought more about
>> that and it was aimed at people who wonder why AVIC was suddenly
>> disabled and it's unlikely that they will enable a debug message without
>> already knowing the reason,
>
> Make sense. Thanks.
>
>>
>> thanks.
>>
>>> @@ -4388,7 +4393,7 @@ static void svm_set_virtual_x2apic_mode(struct kvm_vcpu
>>> *vcpu, bool set)
>>>
>>> static bool svm_get_enable_apicv(struct kvm_vcpu *vcpu)
>>> {
>> A close contender was pr_info_once() here:
>>
>> if (avic && !irqchip_split(vcpu->kvm))
>> pr_info_once(...)
>>
>
> Looks good.

Actually, thinking about it again, this would not work either since
pr_xxx_once() would only print the message once per loading of kvm_amd module.
However, we would prefer the message to be printed per VM initialization. I also
tried adding the check and print this message in the kvm_x86_ops.vm_init(), but
this also does not work since the vm_init() function is called before the
kvm_vm_ioctl_enable_cap(KVM_CAP_SPLIT_IRQCHIP).

Therefore, pr_info() might be better here, even though this would get print per
VCPU initialization. Any other suggestions?

Thanks,
Suravee

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