Re: [Xen-devel] [DO NOT APPLY PATCH XTF 0/2] UMIP test case

[Yu Zhang <yu.c.zhang@xxxxxxxxxxxxxxx>]

Wah. Thank you,  Andrew & Wei. :-)

On 3/2/2017 5:05 PM, Andrew Cooper wrote:
> On 02/03/2017 08:42, Wei Liu wrote:
> > I wrote this long time ago before UMIP was merged.
> >
> > Yu, since you asked, I might as well post it for your reference on how to
> > do it with XTF.
> >
> > This series is not yet tested in any way.
> Unfortunately, you execute all of the sensitive instructions in kernel
> mode, where they wouldn't fault even with UMIP active.
>
> For full testing of a feature like this, the test should include a check
> that the ability to modify CR4.UMIP depends strictly on the visibility
> of the feature, that uses in the kernel still continue to work, even
> when active, and that behaviour returns back to normal after the feature
> has been deactivated.
So, before cr4 is written, a cpuid is needed first in the test code, right?

But besides the emulation of cpuid and cr4, my understanding is that 
hypervisor need to inject a GP fault if an instruction causes a VM exit, 
right? This should be different than the normal GP fault inside a VM, 
and how do we test this code path?
Our QA and I may need to have a study of the XTF, and may probably seek 
for your help in the future. :-)
Anyway, thanks a lot!

Yu

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