Re: [Qemu-devel] [PATCH uq/master 2/2] KVM: make XSAVE support more robust

[Paolo Bonzini]

Il 09/09/2013 12:41, Gleb Natapov ha scritto:
>>>> In fact, perhaps even XSTATE_SUPPORTED is not restrictive enough here,
>>>> and we should hide all features that are not visible in CPUID.  It is
>>>> okay, however, to test it in cpu_post_load.
>>>
>>> The kernel should not even return state that is not visible in CPUID.
>>
>> That's an interesting point of view that I hadn't considered.  But just
>> like you asked me why it should return state that is not visible in
>> CPUID, I'm asking you why it should not...
>>
> For number of reasons. First because since a sate is not used there is no
> point in migrating it. Second to make interface more deterministic for
> QEMU. i.e QEMU configures only features it supports and gets
> exactly same state from the kernel no matter what host cpu is and what
> kernel version is. This patch will not be needed since kernel will do
> the job.

Good reasons, thanks.  Let's do it in the kernel then and avoid this
patch altogether.

Paolo