Re: [GIT PULL 9/9] KVM: s390: Inject machine check into the nested guest

Christian Borntraeger
2017-06-28T19:16:08Z

On 06/28/2017 09:08 PM, David Hildenbrand wrote:
> On 28.06.2017 20:59, Christian Borntraeger wrote:
>> On 06/28/2017 08:06 PM, David Hildenbrand wrote:
>>> On 28.06.2017 19:30, Christian Borntraeger wrote:
>>>> From: QingFeng Hao <haoqf@linux.vnet.ibm.com>
>>>>
>>>> With vsie feature enabled, kvm can support nested guests (guest-3).
>>>> So inject machine check to the guest-2 if it happens when the nested
>>>> guest is running. And guest-2 will detect the machine check belongs
>>>> to guest-3 and reinject it into guest-3.
>>>> The host (guest-1) tries to inject the machine check to the picked
>>>> destination vcpu if it's a floating machine check.
>>>
>>> The subject is confusing. We don't inject anything into the nested guest
>>> here. We just catch machine checks during vsie and inject it into the
>>> ordinary kvm guest.
>>
>> Agreed, it is confusing and maybe a leftover from an early rework due to internal
>> feedback. We inject in guest-2 and rely on guest-2 to reinject to guest-3 would
>> be a better wording.
>>
>>
>>
>>
>>> Are there any SIE specific things to consider here, that may have to be
>>> translated?
>>
>> As HW exits SIE before delivering the machine check, the SIE control block
>> contains all saved guest3 registers and the host (guest1) registers contain
>> the lazy registers (as we have already restored them) just like a normal exit.
>
> As mentioned in the other mail, e.g. vector register validity should
> only be set if vector registers are enabled for the nested guest
> (execution control enabled).

Yes, but sInce we inject in the base guest (non-nested) we have to check the base guest
execution control.

>
>>>
>>>> + sie_page = container_of(scb_s, struct sie_page, sie_block);
>>>> + mcck_info = &sie_page->mcck_info;
>>>> + kvm_s390_reinject_machine_check(vcpu, mcck_info);
>>>
>>> This could be a simple
>>>
>>> kvm_s390_reinject_machine_check(vcpu, &vsie_page->mcck_info);
>>>
>>> no?
>>
>> Yes that would be simpler, I guess. Looks like is just a "do it like the low
>> level handler". The code in nmi.c has to go back from the sie control block into
>> SIE page.
>>
>> Do you want a respin of this patch?
>
> You can also send a fixup if you don't have to respin.
>
>