On 07/12/11 18:24, Alexander Graf wrote:
> 
> On 07.12.2011, at 08:19, Matt Evans <[email protected]> wrote:
> 
>> On 07/12/11 17:34, Sasha Levin wrote:
>>> On Wed, 2011-12-07 at 17:17 +1100, Matt Evans wrote:
>>>> On 06/12/11 19:20, Sasha Levin wrote:
>>>>> Why is it getting moved out of generic code?
>>>>>
>>>>> This is used to determine the maximum amount of vcpus supported by the
>>>>> host for a single guest, and as far as I know KVM_CAP_NR_VCPUS and
>>>>> KVM_CAP_MAX_VCPUS are not arch specific.
>>>>
>>>> I checked api.txt and you're right, it isn't arch-specific.  I assumed it 
>>>> was,
>>>> because PPC KVM doesn't support it ;-) I've dropped this patch and in its 
>>>> place
>>>> implemented the api.txt suggestion of "if KVM_CAP_NR_VCPUS fails, use 4" 
>>>> instead
>>>> of die(); you'll see that when I repost.
>>>>
>>>> This will have the effect of PPC being limited to 4 CPUs until the kernel
>>>> supports that CAP.  (I'll see about this part too.)
>>>
>>> I went to look at which limitation PPC places on amount of vcpus in
>>> guest, and saw this in kvmppc_core_vcpu_create() in the book3s code:
>>>
>>>    vcpu = kvmppc_core_vcpu_create(kvm, id);
>>>    vcpu->arch.wqp = &vcpu->wq;
>>>    if (!IS_ERR(vcpu))
>>>        kvmppc_create_vcpu_debugfs(vcpu, id);
>>>
>>> This is wrong, right? The VCPU is dereferenced before actually checking
>>> that it's not an error.
>>
>> Yeah, that's b0rk.  Alex, a patch below. :)
> 
> Thanks :). Will apply asap but don't have a real keyboard today :).

Ha!  Voice control on your phone, what could go wrong?

> I suppose this is stable material?

Good idea, (and if we're formal,
Signed-off-by: Matt Evans <[email protected]>
).  I suppose no one's seen a vcpu fail to be created, yet.


Thanks,

Matt
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