Re: [XTF PATCH 00/16] Add test cases for nested vmxon

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 16/12/16 13:43, Haozhong Zhang wrote:
> This patch series starts to add a test selection "test-hvm64-vvmx" for
> nested VMX. This first series focuses mostly on nested vmxon.
>
> * Patch 01 - 03 test the basic environment (cpuid and MSR).
>
> * Patch 04 - 05 add functions to execute VMX instructions and to
>   collect and handle errors.
>
> * Patch 06 - 16 construct a bunch of test cases for nested vmxon per
>   its pseudo code in section "VMXON - Enter VMX Operation" of Intel
>   SDM Vol 3.
>

Thankyou for this series.  I have reviewed it now, and have no major
problems.  It is in quite good shape, other than the licensing concerns
with patch 4.

One limitation (because I haven't gotten around to implementing it yet)
is that once a test is accepted, it can't be logically extended, because
it isn't bisection-safe as far as OSSTest is concerned.

I will prioritise my work to introduce the test-revision plan, which
will allow the OSSTest bisector to work properly in the case that new
functionality in a test causes a previously-passing scenario to now fail.

Is this a complete set of vmxon scenarios, or are you working on more? 
Some which come to mind are:

* a register operand (to check that Xen decodes properly and rejects the
instruction)
* duplicate vmxon in root operation

Another area I had on my nested-virt plan was to allow rather finer
grain configuration of the vmx options, but that depends on the start of
the MSR levelling work, which is still blocked behind getting enough
time to finish the CPUID levelling plans.

In particular, I eventually want an ability for fine-grained toolstack
settings of the available VMX configuration (these being a subset of the
MSRs in the system), (all subject to auditing by Xen to keep it within
hardware and supported bounds), at which point it would be plausible to
spin up a VM, asking for VMX_BASIC_32BIT_ADDRESSES, and checking that
suitable limits were observed/enforced inside the VM.

Now, the above is part of some larger issues I need to fix for
XenServer, and I am not suggesting or hinting for you to do any of the
work  (This is a multi-year plan on my behalf).  However, I hope it
helps to see where I am trying to get to in the long term.

~Andrew

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