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Re: [Xen-devel] [PATCH 07/14] Nested Virtualization: trap

On Thursday 19 August 2010 16:30:56 Tim Deegan wrote:
> At 14:53 +0100 on 19 Aug (1282229594), Dong, Eddie wrote:
> > I see the real
> > code start from "exitcode = nestedhvm_exception2exitcode(trapnr);"
> > (half of this function code is just for wrapper check.). The real work
> > is ~20LOC. However we added at least 2 new wrapper APIs:
> > nestedhvm_exception2exitcode & nestedhvm_exception2exitcode.
> That's one. :)  And it wouldn't be needed if the call to arch-specific
> code to cause a vmexit and the test for interception took trapnr
> directly (which they probably could).
> If the new namespace of vmexit codes goes away entirely, that's fine by
> me, btw.

Using namespace is the C-way to "define" a class and prevents
namespace pollution for other things in the future.

> Maybe the generic code can pass exit codes as opaque numbers, 
> with a few flags to steer it?  Christoph, what do you think?  You'll
> have the best idea of how useful the new namespace is.

Look at the nh_structdata patch, you find a nh_forcevmexit structure
within nestedhvm. It contains the generic exit code and additional
information for the conversion and the vmexit injection code in exitinfo1
and exitinfo2. The meanings of exitinfo1 and exitinfo2 are directly related
to the generic exitcode in use and are described in the nh_core patch
in the C comments within the enum nestedhvm_intercepts.


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