Re: [PATCH 6/6] s390: scrub registers on kernel entry and KVM exit

QingFeng Hao
2018-01-19T08:27:08Z

在 2018/1/19 15:57, Christian Borntraeger 写道:
>
> On 01/19/2018 07:29 AM, QingFeng Hao wrote:
>>
>> 在 2018/1/17 17:48, Martin Schwidefsky 写道:
>>> Clear all user space registers on entry to the kernel and all KVM guest
>>> registers on KVM guest exit if the register does not contain either a
>>> parameter or a result value.
>> I am not sure if I understand this but it will be safer?
> It ist similar to commit 0cb5b30698fd ("kvm: vmx: Scrub hardware GPRs at VM-exit").
> The idea is to minimize potential payload channels.
Got it! thanks for your explanation!
>
>> And can we abstract the operations to be a macro like CLEAR_REG_7?
> No, please.
> xgr %r7,%r7
> is absolutely clear what it does, a MACRO often is not.
nod, this makes sense!

--
Regards
QingFeng Hao