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    SubjectRe: [Xen-devel] [xen vMCE RFC V0.2] xen vMCE design
    On 07/03/12 15:26, Luck, Tony wrote:

    >> I'm not convinced of the need, and would prefer aiming at a
    >> shared implementation unless issues arise that make this
    >> impossible.
    >
    > It does sound odd. Yes, Intel and AMD have differences around CMCI ... but we are never
    > going to send a CMCI to a guest (there is no point, it can't do anything useful with the
    > information, it may do something pointlessly stupid like stop using a guest physical page).
    > The only reason I suggested making MCG_CAP pretend that CMCI was supported was a
    > small optimization ... if a Linux guest sees that CMCI is supported, it will not poll the machine
    > check banks looking for corrected errors.


    Are you talking about PV or HVM guest?

    For HVM guests yes it makes sense to disable CMCI in MCG_CAP for both
    AMD and Intel.

    PV guests never read MCE MSRs directly. They install a trap handler and
    use the hypercall to fetch the error telemetry. The xen interface is
    common to both AMD and Intel - it's basically just an array of bytes.
    The first bytes tell you how you can cast and interpret the bytes.
    That *content* is specific to AMD or Intel.

    How much logic can be shared is almost a matter of software design
    and not hardware design.

    Christoph

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