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    SubjectRe: [PATCH 1/2] VMware detection support for x86 and x86-64
    On Fri, 2008-09-26 at 06:22 -0700, wrote:
    > On Fri, 26 Sep 2008 14:47:21 +0200, Gerd Hoffmann said:
    > > Hi,
    > >
    > > > This, of course, is what CPUID is for.
    > >
    > > ... except that it doesn't always work. It requires vmx/svm, otherwise
    > > cpuid doesn't trap and thus can't be filled by the hypervisor ...
    > Which would be hardware implementers in the '80s getting wrong the first few
    > times what IBM did right the first time. Doesn't *anybody* do literature
    > searches before doing stuff anymore? ;)

    >From your description, IBM also did it wrong the first time. Having an
    instruction which operates differently when running on bare metal vs. in
    a hypervisor is never acceptible unless the instruction is trappable.

    There will always be a guest which refuses to operate propely in a
    hypervisor, either by defect or by design, so 'sensitive' instructions
    should always be trappable. Do it right and you can nest recursively ;)


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