Re: [Xen-devel] More questions about Xen memory layout/usage, access to guest memory

[Tamas K Lengyel <tamas.k.lengyel@xxxxxxxxx>]

> > I've found a number of files in the Xen source tree which seem to be
> > related to instruction/x86 platform emulation:
> >
> > arch/x86/x86_emulate.c
> > arch/x86/hvm/emulate.c
> > arch/x86/hvm/vmx/realmode.c
> > arch/x86/hvm/svm/emulate.c
> > arch/x86/pv/emulate.c
> > arch/x86/pv/emul-priv-op.c
> > arch/x86/x86_emulate/x86_emulate.c
> >
> > The last of these, in particular, looks especially hairy (it seems to
> > support emulation of essentially the entire x86 instruction set through
> > a quite impressive edifice of switch statements).
>
> Lovely, isn't it.  For Introspection, we need to be able to emulate an
> instruction which took a permission fault (including No Execute), was
> sent to the analysis engine, and deemed ok to continue.

That's not a requirement for introspection and I find that kind of use
of the emulation very hairy, especially for anything security related.
IMHO it's nothing more then a convenient hack.

Tamas

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