Re: [PATCH: kvm 3/5] Fix hotadd of CPUs for KVM.

[Zachary Amsden]

On 09/26/2009 10:52 PM, Avi Kivity wrote:
> On 09/25/2009 03:47 AM, Zachary Amsden wrote:
> > --- a/virt/kvm/kvm_main.c
> > +++ b/virt/kvm/kvm_main.c
> > @@ -1716,9 +1716,6 @@ static int kvm_cpu_hotplug(struct 
> > notifier_block *notifier, unsigned long val,
> >   {
> >       int cpu = (long)v;
> >
> > -    if (!kvm_usage_count)
> > -        return NOTIFY_OK;
> > -
>
> Why?  You'll now do hardware_enable() even if kvm is not in use.

Because otherwise you'll never allocate and hardware_enable_all will fail:

Switch to broadcast mode on CPU1
svm_hardware_enable: svm_data is NULL on 1
kvm: enabling virtualization on CPU1 failed
qemu-system-x86[8698]: segfault at 20 ip 00000000004db22f sp 
00007fff0a3b4560 error 6 in qemu-system-x86_64[400000+21f000]

Perhaps I can make this work better by putting the allocation within 
hardware_enable_all.

Zach
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