Re: [PATCH v3 04/14] KVM: x86: dynamic kvm_apic_map

Wanpeng Li
2016-08-02T13:22:21Z

2016-08-02 20:22 GMT+08:00 Radim Krčmář <rkrcmar@redhat.com>:
> 2016-08-02 19:39+0800, Wanpeng Li:
>> 2016-07-13 4:09 GMT+08:00 Radim Krčmář <rkrcmar@redhat.com>:
>> [...]
>>> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
>>> @@ -152,14 +152,22 @@ static void recalculate_apic_map(struct kvm *kvm)
>>> struct kvm_apic_map *new, *old = NULL;
>>> struct kvm_vcpu *vcpu;
>>> int i;
>>> -
>>> - new = kzalloc(sizeof(struct kvm_apic_map), GFP_KERNEL);
>>> + u32 max_id = 255;
>>
>> If this should be max_id = KVM_MAX_VCPU_ID? I have a patch on hand to
>> fix it, but I didn't know whether it is your desired behavior or not.
>
> No, we could just have static array then. KVM_MAX_VCPU_ID is expected
> to be raised to INT_MAX and eventually UINT_MAX, so it would not be
> practical. The dynamic array is there to avoid wasting space in the
> common case, where VMs have only low APIC IDs.
>
> Inintial patches had 255 to minimize a chance of regressions as the
> static array was that big, but starting with max_id = 0 is our goal and
> should be ok even without other changes.

I see, thanks. :)

Regards,
Wanpeng Li